UJ Botany Postgrad Symposium 2022 Abstracts Booklet

Department of Botany and Plant Biotechnology University of Johannesburg Postgraduate Symposium

BSc HONOURS PROGRAMME

DAY 1 21 NOVEMBER 2022

09:00 – 10:00 REGISTRATION

10:00 – 10:10 OPENING Prof Eduard Venter

10:10 – 10:50 GUEST SPEAKER Prof Olaniyi Amos Fawole

CHAIRPERSON Ms Tsietso Khajoane

TIME NAME & SURNAME LEVEL INSTITUTION TITLE OF PRESENTATION

10:50 – 11:05 Ambesa Mantewu Hons UJ

11:05 – 11:20 Bongiwe Mbombo Hons UJ

Authentication of selected herbal medicines containing Agathosma spp. using DNA barcoding and chemical profiling

The effect of selected extracts obtained from indigenous plants on the seed germination of Pisum sativum L., Strychnos spinosa Lam, Vigna unguiculata L. and Zea mays L.

11:20 – 11:35 Charl Cillé Hons UFS Evaluation of Hemerocallis accessions towards breeding for pollinators 11:35 – 11:55 COFFEE BREAK

CHAIRPERSON Ms Priscilla Mukwevho

11:55 – 12:10 Walter von Brandis Hons UJ

12:10 – 12:25 Dumisile Dube Hons UJ

12:25 – 12:40 Jessica Howard Hons UJ

12:40 – 12:55 Kabelo Mapheto Hons UJ

12:55 – 13:55 LUNCH

CHAIRPERSON Ms Zobabalo Mina

13:55 – 14:10 Kamogelo Langa Hons UJ

14:10 – 14:25 Nosipho Mbonambi Hons UJ

14:25 – 14:40 Tshamisane Mkhari Hons UJ

14:40 – 14:55 Tumo Makhetha Hons UFS

Wood anatomy of some eastern African species of Protea (Proteaceae)

Preparation and application of prickly cactus mucilage edible coating for the preservation of fresh-cut butternut (Cucurbita mochata)

Some trends in wood diversity within the African Proteaceae: Effects of climate and fire survival strategies

Expression analysis of putative aphid effectors from the Russian wheat aphid

Demonstrating the potential of iNaturalist as a tool for scientific curation to maintain the value of herbarium collections

Regeneration capacity of potatoes treated with SmartBlock: A new sprout suppressant

Encapsulation and characterization of betalain rich extract from beetroot waste for potential food applications

The phenotypic and genotypic validation of leaf rust resistance in wheat varieties 15:00 REMARKS OF THE DAY

SPEAKER

Prof Olaniyi A. Fawole (PhD Agric)

Professor of Postharvest and Agroprocessing Research Postharvest and Agroprocessing Research Laboratory (PARL)

D2 Lab 240, Department of Botany and Plant Biotechnology, University of Johannesburg, South Africa +27 11 559 7237 olaniyif@uj.ac.za https://www.linkedin.com/in/fawole https://twitter.com/fawwyb Scopus Author ID: 25723180300 https://orcid.org/0000-0001-5591-4633 https://www.researchgate.net/profile/Olaniyi-Fawole https://scholar.google.co.za/citations?user=pPtv5wIAAAAJ&hl=en

Prof. Olaniyi Fawole initially wanted to be a medical doctor, and his dream has always been to support wellness and well-being. Having obtained a BSc in Botany, it turns out Prof Fawole’s academic career has not strayed away from this idea, as it is strongly focused on how the preservation of nutritious food can ultimately improve health outcomes. Reducing food loss and waste in food crops is important because it contributes to increased food availability and nutrition to the most vulnerable and economic growth, reduced greenhouse gas emissions, and reduced pressure on land and water resources.

Prof Fawole prepares his undergraduate and postgraduate students to be career- and society-ready and promotes career and growth opportunities in the horticultural and food industries. His research program provides a high-level vehicle to ensure the permeation of research excellence into teaching with a clear link to undergraduate and postgraduate training.

Prof Fawole has mentored and graduated 36 postgraduate students, including 10 doctoral, 9 master’s, and 18 honours, with 24 postgraduate students currently under his supervision. He is an affiliate member of reputable international organisations, including the World Academy of Sciences (Italy), the African Academy of Sciences (Kenya), the African Science Leadership Program (South Africa) and Science and Technology in Society (Japan).

Prof Fawole holds the title of Full Professor (Extraordinary) at Stellenbosch University and the Tshwane University of Technology in South Africa. He also holds a Visiting Full Professor position at Precious Cornerstone University (Nigeria) and is a Senior Research Fellow at the UNESCO International Centre for Biotechnology, Nigeria.

According to Scopus, Prof Fawole has authored over 145 scientific papers, with an H-index of 30. He cochaired the 3rd All Africa Postharvest Congress and Exhibition hosted by the African Union Commission in 2021. He convened the Vth International Symposium on Pomegranate and Minor Mediterranean Fruits under the aegis of the International Society for Horticultural Science (ISHS) in Feb 2022. Prof Fawole was elected the Chair of the ISHS working group on Pomegranate and Minor Mediterranean Fruits and was awarded the ISHS medal for his meritorious service to society in May 2022. In his spare time, Prof Fawole engages in Social Media Scholarship, creating awareness about food loss and waste on LinkedIn, with a following exceeding 27,000. You can listen to his professorial inaugural lecture on YouTube https://www.youtube.com/watch?v=U6SEMvsJ2po&t=1765s

DISCLAIMER This events may be photographed and video recorded for marketing, social media and media purposes. By attending this event, you grant the University of Johannesburg permission to use and publish any recorded material.

SYNOPSYS

Saving the harvest, one crop at a time: a decade of research on pomegranate fruit

While world hunger, unemployment and economic crisis continue to be an issue globally, especially since the covid era, one-third of all the food produced goes to waste (FAO, 2011). This amounts to about 1.3 billion tons of food that either never leave the farm, get lost or spoiled during distribution, or are discarded at the consumer level, with an estimated $750 million worth of food – fruit and vegetables accounting for over 45% (FAO, 2011). But food loss and waste is not just a humanitarian concern; it also contributes to greenhouse gas emission from the energy used during production, distribution, and storage. Also, it produces methane, which traps heat 21 times more than carbon dioxide (Adhikari et al., 2006). This makes food loss and waste a serious economic, social, environmental, and ethical problem that does not spare any nation or continent. As the world’s population continues to grow and is projected to reach 9 billion people by 2050, our challenge should not be how to grow more food but how to feed more people sustainably and efficiently, with a significant reduction in food loss and waste. The reduction of food loss and waste directly affects the Sustainable Development Goal (SDG)12, most specifically SDG 12.3, which seeks to halve global food waste at retail and consumer levels and reduce food loss during production and supply by 2030. With food waste being a large contributor to the global drain of resources, hunger and climate crisis, reducing food waste will help meet various Sustainable Development Goals, including SDGs 1, 2, 9, 10, 11, 12, 13, 14 and 15.

Prof Fawole’s lecture entitled “saving the harvest, one crop at a time: a decade of research on pomegranate fruit” will introduce you to pomegranate fruit, the industry, a few impact studies on postharvest preservation, agroprocessing and valorisation of pomegranate fruit.

Ambesa Mantewu, Michelle van der Bank and Estherna Pretorius

Email: ambesamantewu@gmail.com

Department of Botany and Plant Biotechnology University of Johannesburg PO Box 524, Auckland Park 2006, South Africa

Agathosma species are extensively utilized herbal products, as these herbs contain many health benefits. Broad research on the phytochemical makeup of the Agathosma has been conducted over the years, while their DNA barcoding analysis has not been explored. The identification of medicinal organic material procedures can be accelerated by using molecular methods like DNA barcoding, which in combination with phytochemical analysis, will provide the data required to guarantee the highest level of efficacy of commercially accessible herbal medicines. Sixteen, A. betulina and ten, A. crenulata authentic reference materials were acquired and used to construct the Standard Reference Barcode Library. The search terms “Agathosma” or “Buchu” were used to buy thirteen commercial items from various health stores in Johannesburg, South Africa. The Buchu products were barcoded using the plastid regions matK and ycf1, and BRONX analysis verified the samples’ taxonomic identity. Additionally, UPLC-MS analyses were completed for the authentication of the herbal products. Only sixty percent of the traded samples tested, from thirteen suppliers, contained A. betulina in their herbal products. Similar outcomes for the UPLC-MS analysis were also attained. As a result, the work demonstrates how DNA barcoding and chemical profiling may be utilized to ensure the quality control/ assurance of medical herbal products.

Authentication of selected herbal medicines containing Agathosma spp. using DNA barcoding and chemical profiling

The effect of selected extracts obtained from indigenous plants on the seed germination of Pisum sativum L., Strychnos spinosa Lam, Vigna unguiculata L. and Zea mays L.

Bongiwe Mbombo1, NZ Ngobese and B-E van Wyk1

Email: bongiwe.mbombo98@gmail.com

1 Department of Botany and Plant Biotechnology University of Johannesburg, Gauteng, South Africa

2 School of Geo and Spatial Sciences Faculty of Natural and Agricultural Sciences, North-West University Private Bag X6001, Potchefstroom, South Africa

Indigenous species are mostly known for their medicinal use and food security. However, their extracts can be used to improve seed germination and remove unwanted vegetation by acting as herbicides. A number of these plants have a history of traditional use. For example, Vhavenda villages the Limpopo province use Anthocleista grandiflora leaves to cover maize and millet grains during malting to stimulate germination, but few studies have tested their efficacy or even formulated extracts out of them. Therefore, Aloe ferox, Aloe marlothii and Anthocleista grandiflora leaves as well as Pollichia campestris shoots were used to obtain extracts that were applied at a 100% or 50% concentration on Pisum sativum, Strychnos spinosa, Vigna unguiculata and Zea mays seeds. The results showed that the extracts had a significant effect (P<0.001) on the germination of all species but suppressed germination instead of enhancing it. The highest inhibition was observed in the crude extract of Anthocleista grandiflora (100%), it inhibited Pisum sativum germination with a percentage inhibition of 76%.  All extracts inhibited the seed germination of Zea mays with the highest germination of 52% was achieved (compared to 87% germination in the control [no extracts applied]. None of the different extract concentrations (100% or 50%) or application (irrigation and soaking) methods improved the seed germination of all species. These results suggest the tested extracts could be useful as herbicides (especially Anthocleista grandiflora) but more research is required.

Evaluation of Hemerocallis accessions towards breeding for pollinators

Charl D Cillié, Lize Joubert and Rouxléne van der Merwe

Email: 2017258530@ufs4life.co.za

Department of Plant Sciences

University of the Free State, Bloemfontein, South Africa PO Box 339, Bloemfontein 9300, South Africa

Insects provide an important ecosystem service as pollinators of many wild plants and crops. Pollinators are threatened by urbanization, but urban gardens may mitigate the negative effects of urbanization through providing pollinators with a continuous food supply. Hemerocallis is a popular and widely cultivated ornamental plant and could be a good option to breed for support of pollinators in urban landscapes. This study aims to assess Hemerocallis accessions with respect to their pollinator rewards and floral accessibility for pollinators as well as their suitability for a breeding program. Several morphological features as well as breeding aspects were investigated to determine the best preforming accessions which can be used as possible parents in a breeding program to improve Hemerocallis as a food plant for urban pollinators. Sugar concentration of nectar and pollen viability have been found as the most important morphological features in a breeding program for pollinators.

Sellassie Dumisile Dube and Olaniyi Amos Fawole

Email: Doubledee.dd32@gmail.com

Postharvest Research Laboratory Department of Botany and Plant Biotechnology University of Johannesburg PO Box 524, Auckland Park 2006, South Africa Butternut squash (Cucurbita mochata) is a non-climacteric commodity belonging to the Cucurbitaceae family. It is a high-yielding vegetable cultivated in many varieties. Due to its sheer size and weight, harvesting, handling, packaging, transportation, storage, and marketing of butternut squash is challenging. As a result, minimal processing of butternut squash has been adopted to provide convenience at retail stores. However,  reduced shelf life due to spoilage is prevalent in freshcut butternut squash. Sustainable postharvest technology, such as edible coating technology, has shown to be a viable option to increase the shelf-life of perishable crops. In this study, mucilage from prickly cactus (Opuntia ficus-indica) was extracted and co-formulated at 0.5% with cellulose nanofibers (CNF) at different concentrations (0, 0.03, 0.06 and 0.09%) for shelf life extension of fresh-cut butternut squash. The edible coating formulations were applied by dipping for 3 min on the fresh-cut butternut and stored for 20 days at 4°C at 90% relative humidity. An array of quality attributes were investigated at 4 day intervals. The efficacy of the formulated coatings varied significantly. For instance, weight loss, vitamin C content and total soluble solids were significantly (p > 0.05%) reduced with 0.5% mucilage + 0% CNF, firmness was maintained with 0.5% mucilage + 0.09% CNF, whereas 0.5% mucilage + 0.06% CNF reduced loss of total phenolic content.

Preparation and application of prickly cactus mucilage edible coating for the preservation of fresh-cut butternut (Cucurbita mochata)

Some trends in wood diversity within

survival strategies

Jessica Howard and Aleksei Oskolskii

Email: jessielynnhoward2001@gmail.com

Plant Biotechnology

Department of Botany and Plant Biotechnology, University of Johannesburg PO Box 524, Auckland Park 2006, South Africa

The subfamily Proteoideae (Proteaceae) is richly represented in the Cape Floristic Region (CFR), but the genera Protea and Faurea are also widely distributed up to tropical Africa. The recent wood anatomical study of this group (Stepanova et al., 2021) shown that the increases in size of fibres and diameter of fibre wall pits in this group is associated with a shift from a winter-dry climate to a climate with winter rainfall. Also, the seeders showed a higher vessel frequency and narrower rays than sprouters. These trends have been revealed, however, mostly for the Proteoideae from CFR, whereas the non-Cape species were underrepresented. Our study aims to test these trends on broader sampling including the nonCape Proteoideae. We examined the wood structure in four non-Cape species of Protea and two Faurea species. Their quantitative anatomical traits were analyzed together with the published data for the Cape species. We found that the increases in length and diameter of fibres are associated with plant height rather than with climate. We confirmed the association between the increase in diameter of fibre wall pits and the shift from winter-dry to winter rainfall climate suggesting the transition from nonconducting imperforate tracheary elements to conducting elements in Mediterranean-type climatic regions. We also found that seeders have wider rays than sprouters supposedly serving as the sites of epicormic buds that provide for resprouting after fire. Seeders also have greater vessel frequency and grouping than spouters, but we cannot explain this trend yet.

the African Proteaceae: effects of climate and fire

Expression analysis of putative aphid effectors from the

Russian wheat aphid

Kabelo Mapheto and Eduard Venter

Email: kaybeemapheto33@gmail.com

Plant Biotechnology, Department of Botany and Plant Biotechnology, University of Johannesburg PO Box 524, Auckland Park 2006, South Africa

The Aphididae family is a large diverse family of phloem feeders with a large global distribution, predominantly being a major pest on the Poaceae. The pests make use of effector proteins to overcome resistance utilized by plants upon infestation. Several studies have characterised the putative effectors expressed by different Aphididae species in suppressing and inhibiting plant response to infestation. The current project concentrates on the expression of putative effector proteins from the Russian wheat aphid, Diuraphis noxia (Kurdjumov), feeding on susceptible and resistant wheat plants. The aim of the project was tracking the expression of three effector genes over 96 hours post-infestation (h.p.i.) to investigate the expression of aphid effectors on Gamtoos carrying resistance gene Dn7. Three biotypes RWA-SA1, RWA-SA2 and RWA-SA5 were raised on PAN3434 to infest wheat plants in a greenhouse environment. The data will provide information on the varying effector utilisation upon infestation on wheat plants.

Kamogelo Langa and Ashton K Welcome

Email: mariakamogelo5@gmail.com

Department of Botany and Plant Biotechnology University of Johannesburg PO Box 524, Auckland Park 2006, South Africa

Herbarium specimens are an invaluable resource for conservation and monitoring biodiversity, only if they are correctly identified and georeferenced. Most specimens can be accurately georeferenced due to the availability of geographic information systems, freely available shapefiles and plugins. However, with the worldwide decline of taxonomic expertise, it is more difficult to ensure that specimens are accurately identified and that identifications are kept up to date. The aim of this study was to determine if iNaturalist, a citizen scientist observation and identification platform, can be used as a tool for scientific curation. The Hermannia genus was selected as a case study for this project. As part of the digitization process, the collection label data of the JRAU Hermannia specimens were captured in an Excel spreadsheet along with unique barcodes for each specimen. The specimens were georeferenced using the QGIS (Quantum GIS) software. Each specimen was scanned and individual images of important plant parts were uploaded as backdated observations on the iNaturalist platform. This allowed scientists and the public to assist with confirming, correcting and updating identifications. The iNaturalist tool has been found to be a reliable solution to the taxonomic impediment and will ensure that the value of herbarium collections as biodiversity monitoring resources is maintained over time.

Demonstrating the potential of iNaturalist as a tool for scientific curation to maintain the value of herbarium collections

Regeneration capacity of potatoes treated with SmartBlock: a new sprout suppressant

Nosipho P Mbonambi1 and Nomali Z. Ngobese2

Email: nosiphombonambi77@gmail.com

1 Department of Botany and Plant Biotechnology University of Johannesburg, Gauteng, South Africa

2 School of Geo and Spatial Sciences Faculty of Natural and Agricultural Sciences, North-West University Private Bag X6001, Potchefstroom, South Africa

The potato is one of the most important crop plants in the world (Solanum tuberosum L.).Due to their large yield, potatoes are a crucial crop for cereal production and food security. All year long, there is a rising need for potatoes. Throughout the whole supply chain and in the post-harvest storage of potato tubers, sprouting is one of the most significant issues. Chlorpropham chemical which has been used as a sprout suppressant for more than 50 years has been banned due to toxicity to humans and environmental impact concerns. Chlorpropham being banned has led researchers to do more research on the alternatives sprout suppressants. The sprout suppressant that has shown to be very effective is SmartBlock, it has been tested on several potato species and under a variety of storage settings. The aim of this study is to evaluate the regeneration capacity of potatoes treated with SmartBlock. A 0,1 ml/kg and 0,3 ml/ kg dosage of SmartBlock were used. Potatoes were treated with 0,1 ml/ kg and 0,3 ml/kg of SmartBlock. After 4 days of treatment they were planted in the greenhouse to check regeneration capacity and the effect of different dosages. The results have shown that there is no significant difference between the means of the used different dosages and control. In conclusion, the regeneration capacity of potatoes was not affected by the Smartblock chemical.

Encapsulation

Tshamisane Mkhari and Olaniyi Amos Fawole

Email: tshamisanem@gmail.com Postharvest Research Laboratory Department of Botany and Plant Biotechnology Faculty of Science, University of Johannesburg PO Box 524, Auckland Park 2006, South Africa Beetroot is one of the most potent vegetables well known for its antioxidant and other bioactive compound. It is rich in betalains and its bioactive compound has great potential for food applications. Betalains are nitrogen-containing water-soluble colorants with increasing interest in use in the food industry. The effect of carriers on encapsulating betalain extract to create a rich stable powder was researched. The beetroot extract was prepared using 50% ethanol and 0.5% acetic acid, and the extracts was encapsulated using different blends of Gum Arabic (GA) and Maltodextrin (MLT) (GA: MLT at 1:1, 1:2. 2:1, 1:0 and 0:1) and freeze dried to obtain beetroot powders. The powders were characterized based on their antioxidant activity and rheological, phytochemical and physiochemical properties. The individual carriers (GA or MLT) produced powders with better colour and exhibited higher betalain content and radical scavenging activity compared to the blends. However, the GA: MLT blends; 1:2 and 2:1, exhibited high levels of solubility, oil holding capacity and bulk density, which are desirable in food applications. Overall, the results showed great potential of encapsulated beetroot powder as a natural additive and preservatives in the food industry.

and characterization of betalain rich extract from beetroot waste for potential food applications

The phenotypic and genotypic validation of leaf rust resistance in wheat varieties

Tumo Makhetha, WHP Boshoff and A Maré

Email: 2017272184@ufs4life.ac.za

Department of Plant Sciences, University of the Free State, PO Box 339, Bloemfontein 9301, South Africa

Wheat (Triticum aestivum L.) is an important crop in South Africa and its production is threatened by the common occurrence of leaf rust, caused by Puccinia triticina (Pt). In this study, two commercial wheat cultivars from Sensako (SST) and three Lr9 differential varieties were evaluated. Phenotypic evaluations were done in seedling- and adult plant stages with isolates of Pt races CFPS+Lr20 and CPPS. Molecular markers linked to the all-stage resistance (ASR) gene Lr9 and to adult plant resistance genes (APR) were applied. The results confirmed the avirulence of Pt race CFPS+Lr20 to Lr9 with fleck seedling infection types (ITs) and race CPPS as virulent. The genotypic evaluation confirmed that the SST cultivars possess the Lr9 gene and suggested the presence of the APR gene(s) Lr34 in one and Lr68 in both. This study is the first report of the presence of the Lr9 gene in local wheat and confirmed the vulnerability of ASR sources of resistance to this evolving pathogen.

Keywords: Puccinia triticina, leaf rust, molecular markers

Wood anatomy of some eastern African species of Protea (Proteaceae)

Walter von Brandis and Aleksei Oskolskii

Email: waltervbrandis@gmail.com

Department of Botany and Plant Biotechnology Faculty of Science, University of Johannesburg PO Box 524, Auckland Park 2006, South Africa

The genus Protea (Proteaceae) shows the greatest diversity and endemism (69 of 112 species) in the Cape Floristic Region, it also extends through tropical Africa north to Eritrea and west toAngola. While a recent wood anatomical study of South African Proteoideae (Stepanova et al., 2021) has been focused mostly on the Cape species of Protea, the wood structure of the non-Cape members of this genus remains underexplored. We examined the wood structure of four Protea species (P. caffra, P. gaguedi, P. roupelliae and P. welwitschii) collected in KwaZulu-Natal, Limpopo and Gauteng. These species are similar to twelve Cape endemics in their overall wood anatomy, but they are distinctive from the latter ones in having a higher percentage of solitary vessels with 68.65% of vessel elements being solitary compared to 42.53% from the Cape species. The vertical length of rays for Protea species endemic to the Cape was longer than those in other regions, with the average height being 1145.3 µm compared to 778.7 µm in species found in non-Cape regions. Fiber pits on Protea species found KwaZulu-Natal, Limpopo, and Gauteng was found to be larger at 3.96 µm compared to 3.43 µm of Cape species. When looking at fire survival strategies the resprouting Protea species had wider vessel elements of average 55.98 µm, 80.98% of which being solitary, compared to 43.33 µm for seeding species with 63.81% being solitary for seeding species, the resprouting species also have wider rays on average with 180.6 µm compared to 107 µm for seeding species, the wider rays could provide a larger surface for shoot formation. The wider solitary vessels in resprouting species could disperse water conductance over the plant body in case a part of the stem is damaged.

PROGRAMME

DAY 2 23 NOVEMBER 2022

08:00 – 09:00 REGISTRATION

09:00 – 09:10 OPENING Prof Eduard Venter

09:10 – 09:50 GUEST SPEAKER Dr Nicholas Sadgrove

CHAIRPERSON Mr Charl Cillé

TIME NAME & SURNAME LEVEL INSTITUTION TITLE OF PRESENTATION

09:50 – 10:05 Confidence Nthimole MSc UJ

Optimization and microencapsulation of raspberry juice powder using blends of Gum Arabic and maltodextrin for potential applications in the food industry

10:05 – 10:20 Kutloano Mangope MSc UJ Encapsulation and characterization of pomegranate seed oil for potential use in the food industry

10:20 – 10:35 Lebohang Selepe MSc UJ

10:35 – 10:55 COFFEE BREAK

CHAIRPERSON Ms Kamogelo Langa

10:55 – 11:10 Marvin Khoza MSc UJ

Repurposing rooibos waste through encapsulation for potential food and postharvest applications

Phylogenetic diversity and pathogenicity within Fusarium sambucinum species complex

11:10 – 11:25 Nomcebo Mngomezulu MSc UFS Salt marsh habitat loss due to erosion at the Berg River Estuary

11:25 – 11:40 Priscilla Mukwevho MSc UJ

11:40 – 11: 55 Tshiamo Leta MSc UJ

11:55 – 12:55 LUNCH

CHAIRPERSON Mr Tumo Makhetha

12:55 – 13:10 Tsietso Khajoane MSc UFS

13:10 – 13:25 Zobabalo Mina MSc UJ

13:25 – 13:40 Alec Edwards PhD UFS

Optimisation of microwave roasting of pecan nuts for improved quality and storage life using response surface methodology

Green synthesis of zinc oxide nanoparticles from pomegranate (Punica granatum L.) fruit peel and seed waste: characterization and potential for postharvest applications.

Genotype and environmental effects on maize grain yield, nutritional value and milling quality

Quality, sustainability and cost implication of combined drying methods for carrot slices

Characterising plant growth promoting microorganisms (PGPM’s) and potential biological control agents (BCA’s) from the soybean microbiome

13:40 – 13:55 Funmilade Akinlabi PhD UJ Trends of wood Anatomical Diversity within Fynbos Biome

13:55 – 14:10 Mawande Shinga PhD UJ

14:10 – 14:30 COFFEE BREAK

CHAIRPERSON Ms Nosipho Mbonambi

14:30 – 14:55 Ross Stewrart PhD UJ

14:55 – 15:10 Ryan Rattray PhD UJ

15:10 – 15:35 Sbulelo Mwelase PhD UJ

15:35 – 15:50 Wilku Meyer PhD UFS

15:50 REMARKS OF THE DAY

Opuntia ficus-indica mucilage edible coating regulates cell wall softening enzyme activities in bananas at retail conditions

Investigating the relationships between plants and arthropods across South African biomes

The Lamiaceae of southern Africa: An overview of an ethnobotanically important family and insights into several medicinal species

Chitosan-24-Epibrassinolide Composite Coating Alleviated Chilling Injury and Maintained Quality of Cold-Stored Pomegranate Fruit (cv. Wonderful) by Enhancing Antioxidant System Capacity

Puccinia helianthi race variants and sunflower hybrids responses

Where taxonomy hits a fork in the road: Chemophenetics and how we should think of plants?

Classical taxonomy classified plants according to finite details that can be observed, either with the naked eye or with a lens. Taxonomy has progressed to molecular phylogenies that tease apart genera and families according to perceived ancestral lineages, sometimes making morphology secondary to taxonomic placement. While DNA and morphological characters are meaningful in contemporary botany, these characters were not so useful to the traditional people who valued plants for their utility, classifying them according to their properties, rather than by their perception of an evolutionary pathway that determined the relatedness between species. Modern taxonomy has gained much and lost much, as traditional people may have recognized several different entities within a single species, and conversely, recognised several different species as a single taxon. To recover this lost knowledge, a new branch of botany has emerged under the term ‘chemophenetics’. This enables us to recognise differences within single taxa as reflective of pharmacological properties that might vary between specimens. Conversely, chemophenetics might also group taxa according to those same properties.

Dr Nicholas John Sadgrove is an Australian natural product chemist and pharmacologist who graduated with his PhD in 2014. Dr Sadgrove has worked in several different countries on natural product projects, such as England, India, and previously South Africa. He is also co-founder of a UK based company called Systems Dermatology, which markets a nutraceutical that he developed over a period of three years. He is an advisory board member of WETHRIVV, an American company that markets a topical product for healthy hair, and consults for another American company called ‘Perfect Hair Health.’ Dr Sadgrove has returned to South Africa out of a love of the flora and the people, taking up a position at the University of Johannesburg as a research fellow where he worked previously, during the years of 2016 - 2018.

DISCLAIMER This events may be photographed and video recorded for marketing, social media and media purposes. By attending this event, you grant the University of Johannesburg permission to use and publish any recorded material.

Confidence T Nthimole, Tafadzwa Kaseke and Olaniyi A Fawole

Email: confidence.nthimole@gmail.com Postharvest Research Laboratory Department of Botany and Plant Biotechnology Faculty of Science, University of Johannesburg PO Box 524, Auckland Park 2006, South Africa

Raspberry fruits Rubus idaeus species were juiced and encapsulated separately with Gum Arabic (GA) and maltodextrin (MT) (1:10, w/v) carrier agents. Functional properties of the carrier agents were optimized by integrating blends of the carrier agents at ratios GA: MT (1:1), (2:1) and (3:1). The raspberry juice powder was formed by implementing the freezedrying process. The encapsulated powders were characterized according to their physical, technofunctional properties, phytochemical composition and antioxidative properties. Blends of the carrier agents significantly affected the functional properties of the powders. The physical attributes of the powders; redness (a*) and total colour difference (TCD), showed a significant difference (P > 0.05) among the carrier agents encapsulated separately (GA=53.6 and MT=56.7) and the blends (1:1)=49.68, (2:1)=47.19 and (3:1)=47.35. Furthermore,  powders produced with blends of GA and MT exhibited a significant increase in solubility, ranging from 98.20 to 98.37%, compared to the individual carrier agents (60.25-60,75%). However, the total anthocyanin content of the GA:MT blends significantly decreased but did not affect the radical scavenging activity. The energy dispersive X-ray analysis (EDX) detected Na element for the ratio 3:1 GA:MT at a peak between 0.00k-0.20k, while no major elements were detected in the other powder blends. In conclusion, the optimization approach by blending GA and MT significantly improved the functional properties of the raspberry juice powder.

Optimization and microencapsulation of raspberry juice powder using blends of Gum Arabic and maltodextrin for potential applications in the food industry

Encapsulation

Kutloano Mangope, Tafadzwa Kaseke and Olaniyi A. Fawole

Email: kutloanomangope@gmail.com

Postharvest Research Laboratory Department of Botany and Plant Biotechnology Faculty of Science, University of Johannesburg PO Box 524, Auckland Park 2006, South Africa

Processing of pomegranate (Punica granatum L.) juice generates substantial amounts of by-products such as seeds, which are regarded as waste. Despite being underutilized, the seed is a source of oil, which contains punicic acid, an important bioactive conjugated fatty acid with various health properties. Given that pomegranate seed oil (PSO) is highly unsaturated it is susceptible to oxidation when exposed to oxygen, light, high temperature, and moisture. Therefore, protection of PSO from these adverse conditions is important. The present study investigated the potential of encapsulating and freeze-drying PSO (15%, w/w) using different blending ratios of gum Arabic (GA) and maltodextrin (MD) (1:0, 3:1, 1:1, 1:3 and 0:1, respectively). The developed powders were evaluated for physicochemical, rheological, phytochemical, and antioxidant properties. Blending GA and MD produced powders with significantly (p<0.05) different quality attributes. Powder produced by blending GA and MD at a ratio of 1:1 exhibited better hygroscopicity (lower), colour, total phenolic content, ferric reducing antioxidant powder, and DPPH radical scavenging activity when compared with the rest of the powders. Meanwhile, solubility and encapsulation efficiency were not significantly (p>0.05) affected by varying the GA and MD blending ratios. These results suggest that blending GA and MD at a ratio of 1:1 could give better protection of the PSO phenolic compounds, and antioxidant activity, and produce powder with qualities desired by the food industry.

and characterization of pomegranate seed oil for potential use in the food industry

Lebohang B Selepe, Tafadzwa Kaseke and Olaniyi A Fawole

Email: lesedi976@gmail.com

Postharvest Research Laboratory Department of Botany and Plant Biotechnology Faculty of Science, University of Johannesburg PO Box 524, Auckland Park 2006, South Africa Rooibos (Aspalathus linearis) is an indigenous South African species cultivated to produce rooibos tea from its fermented leaves. In addition, rooibos leaves are also extracted for food applications. However, rooibos leaves processing generates a significant amount of waste which ends up in landfills. Rooibos is rich in polyphenols which are implicated in antioxidative, antimicrobial and chemotherapeutic properties. The main goal of this study was to repurpose the waste generated during processing of rooibos products through encapsulation technology to develop a polyphenolic rich powder. Rooibos waste was procured and extracted using 50% ethanol (1:10 w/v) and encapsulated using GA:MT at ratios 1:1; 1:2 and 2:1, and non-encapsulated powder was used as control. The mixture was homogenized and frozen at -80°C before freeze-drying at -50°C for 48h. The powders developed were characterized based on physical, chemical, antioxidant, morphological and accelerated degradation test. The encapsulation process yielded 1.38-10.02% powders, with the lowest obtained from non-encapsulated powder. GA:MT (2:1) improved the colour lightness and solubility of the powder. Moisture content was <10% in all the powders, suggesting microbial stability. However, the control was more hygroscopic, suggesting instability over time. Encapsulated powders had uniform and small particle sizes while the control had larger sizes and irregular shapes. The highest polyphenols were recovered from the control sample while encapsulated powders of GA:MT at 1:1 had the highest polyphenol recovery . Radical scavenging capacity was exhibited in the order of control > GA: MT (1:2) > GA: MT (1:1) > GA:MT (2:1). The highest degradation rate was observed for control samples while GA:MT powders had the slower quality degradation. Overall, encapsulation of rooibos waste extract could resort in utilization for potential food and postharvest applications.

Repurposing rooibos waste through encapsulation for potential food and postharvest applications

Phylogenetic diversity and pathogenicity within Fusarium sambucinum species complex

NK Marvin Khoza1 , Brett A Summerell1,3, Rian Pierneef4, Adriaana Jacobs1,2 and Eduard Venter1

Email: Khozamarvin1@gmail.com

1 Department of Botany and Plant Biotechnology University of Johannesburg, Auckland Park, 2006, South Africa

2 National Collection of Fungi, Plant Health and Protection Agricultural Research Council, Pretoria, 0001, South Africa

3 Australian Institute of Botanical Science Royal Botanic Garden and Domain Trust, Sydney, Australia

4 Biotechnology Platform, Agricultural Research Council Pretoria 0001, South Africa

The genus Fusarium harbours some of the most economically restrictive phytopathogens. These phytopathogenic species are divided into species complexes based on symptoms they induce. Fusarium brachygibbosum is a developing phytopathogen with increasing reports of infections from fruits and vegetables. It was recently demarcated as the F. brachygibbosum clade rather than a single species within the F. sambucinum species complex (FSamSC). Isolates that are closely related to F. brachygibbosum were some of the dominant species isolated from the South African grassland soil biome from recent studies conducted from our research group. The main objective was to conduct pathogenicity trials of the F. brachygibbosum. isolates on cucumber plants. The preliminary trials displayed the Fusarium isolates having various effects on the cucumber plants. The plants showed inhibited germination of seeds, reduced, and promoted growth.

at the Berg River Estuary

Nomcebo T Mngomezulu1 , Dimitri A Veldkornet1, Anusha Rajkaran2 and Nasreen Peer3

Email: 2021557364@ufs4life.ac.za

1 Department of Plant Sciences, University of the Free State PO Box 339, Bloemfontein 9300, South Africa

2 Department of Biodiversity and Conservation Biology University of the Western Cape Robert Sobukwe Way, Bellville 7535, South Africa

3 Department of Botany and Zoology, Stellenbosch University PO Box 241, Cape Town 8000, South Africa.

The Berg River Estuary is the second largest estuary in South Africa with the greatest intertidal habitat and macrophyte species richness. Habitat destruction and erosion resulted in the loss of intertidal habitat, threatening the biodiversity and ecosystem services of the Estuary. Salt marsh creeks are known to be good nursery grounds but their influence on species distribution has not been investigated. The aim of this study was to investigate the influence of creek dynamics and physiochemical variables on the diversity and distribution of estuarine macrophytes at the Berg River Estuary. Three sites, prone to erosion in the lower reaches of the estuary, were chosen to assess the vegetation in creeks and noncreeks. Changes in species composition and abundance were analysed by replicate quadrats along six transects across creeks. Sediment and groundwater characteristics were measured at the edge of creeks and in intertidal and supratidal habitats. Non-creek sites were dominated by Salicornia pillansii which had the lowest species richness (five). Sites with creeks had the highest species richness (15). Macrophytes that were found only associated with creeks are Ulva intestinalis, Ecklonia maxima, Cotula coronopifolia, Spartina maritima and Salicornia natalensis. Species richness significantly increased with decreases in creek depth (r = -0.419; p < 0.005). The most important physiochemical variables that influences community composition were groundwater pH (DCA1 = 0.83583, DCA2 = 0.54899, r = 0.2079, p = 0.001), depth to groundwater (DCA1 = 0.60878, DCA2 = -0.79334, r = 0.0726, p = 0.029), Temperature (DCA1 = 0.96573, DCA2 = 0.25955, r = 0.0628, p = 0.050) and percentage sand (DCA1 = -0.72502, DCA2 = 0.68872, r = 0.0329, p = 0.212). The results from this study indicates that creeks are important in maintaining intertidal macrophytes species richness, where creeks act as refugia. The ongoing erosion at the Berg River Estuary needs to be reduced in order to preserve the intertidal habitat and the ecosystem services it provides.

The influence of creek dynamics and physiochemical variables on the diversity and distribution of estuarine macrophytes

Priscilla L Mukwevho, Tafadzwa Kaseke and Olaniyi A Fawole

Email: priscillamukwevho@gmail.com Postharvest Research Laboratory Department of Botany and Plant Biotechnology Faculty of Science, University of Johannesburg PO Box 524, Auckland Park 2006, South Africa Pecan (Carya illinoinensis) nuts are a treasure of functional compounds (unsaturated fatty acids, phytosterols, polyphenols and tocopherols) associated with various health benefits. Commercially pecan nuts are roasted to enhance their physical, chemical, and sensory properties. Depending on the roasting conditions, roasted pecan nuts may be prone to oxidation and rancidity during processing and storage as they are highly unsaturated. Optimising the pecan nut roasting conditions is thus vital. In the present study, response surface methodology was used to optimize the microwave roasting process over a range of microwave power (100–800 W) and roasting time (1–6 min). The microwave roasted pecan nuts were analysed for hardness, total colour difference (TCD), total phenolic content (TPC) and 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging activity and modelled using the central composite design. The results showed that microwave power and roasting time significantly (p < 0.05) influenced the quality attributes of the pecan nut. The quadratic model adequately described the changes in TCD, and hardness, respectively, whilst the linear and 2FI model adequately described the changes in TPC and DPPH radical scavenging activity, respectively (R2 >0.6; lack of fit>0.05). To obtain the desired pecan nut quality attributes (TCD =1835.496; hardness = 27.283 N; TPC =1.374 mg GAE/100 g and DPPH radical scavenging activity = 34.859 mmol Trolox/g) the optimum microwave roasting condition was determined as 700 W for 2.27 min, with desirability of 0.585. The findings of this study can be used to develop an optimum microwave roasting protocol for improved pecan nut quality.

Optimisation of microwave roasting of pecan nuts for improved quality and storage life using response surface methodology

Green synthesis of zinc oxide nanoparticles from pomegranate (Punica granatum L.) fruit peel and seed waste: characterization and potential for postharvest applications.

Tshiamo B Leta and Olaniyi A Fawole Email: letatshiamo@gmail.com

Postharvest Research Laboratory Department of Botany and Plant Biotechnology Faculty of Science, University of Johannesburg PO Box 524, Auckland Park 2006, South Africa

Green synthesis of zinc oxide nanoparticles from fruit waste has become an emerging field in nanotechnology, and its application for postharvest preservation has been on the rise. In this study, zinc oxide nanoparticles (ZnONPs) were synthesized using pomegranate peels and seeds waste as reducing agents of zinc nitrate hexahydrate. The synthesized nanoparticles were characterized by Ultraviolet-visible spectroscopy (UV–Vis), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning Electron microscopy (SEM), and Energy Dispersive X-Ray Analysis (EDX). Furthermore, total phenolic content (TPC) using Folin C assay and antioxidant capacity was assessed using 2,2-diphenyl2-picryl-hydrazyl (DPPH) and 2,2’ -azino-bis (3-ethylbenzothiazoline-6sulphonic acid) (ABTS) assays. According to the results, zinc oxide from pomegranate peel waste (ZnO-PPW) and zinc oxide from pomegranate seed waste (ZnO-PSW) displayed the typical UV–vis absorption peaks at around 369 and 372 nm, respectively. FT-IR showed the absorption peak of Zn–O bonding between 400 and 600 cm-1 for both synthesized ZnONPs. XRD confirmed the presence of a hexagonal ZnO (wurtzite) structure, and SEM analysis indicated that the nanoparticles were spherical with some agglomeration. EDX provided the elemental details of zinc and oxygen in the nanoparticles. TPC for ZnO-PPW and ZnO-PSW were 5.4 mg GAE/ml DM and 5.3 mg GAE/ml DM, respectively. The minimum inhibitory concentration at 50% (IC50) of ZnO-PPW and ZnO-PSW was 2.97 (mg/ml) and 3.43 (mg/ml) for DPPH and 2.57 (mg/ml) and 3.33 (mg/ml) for ABTS, respectively. Overall, the study shows the promise of synthesizing green zinc oxide nanomaterials from pomegranate fruit wastes and presents the potential use of nanomaterials as antioxidants in food preservation.

Tsietso J Khajoane 1, Maryke Labuschagne 1, Sanesh Ramburan 2 and Ntombokulunga W Mbuma1

Email: tjkhajoane@gmail.com

1 Department of Plant Sciences, University of the Free State PO Box 339, Bloemfontein 9300, South Africa

2 Bayer Pharmaceutical Company, 27 Wrench Rd, Isando Johannesburg 1600, South Africa

In hybrid maize breeding, genotype by environment interaction (GEI) influences the performance of hybrids and their adaptability when breeding populations are evaluated in diverse agroecological areas. Knowledge of genetic diversity and GEI increases the breeding and selection efficiency, and the adaptability and stability of populations. The study objectives were to determine the phenotypic variation on maize grain yield, nutritional quality traits, and milling quality, to determine the interrelationship between the measured traits, and to evaluate GEI for grain yield and stability of the genotypes. Eighteen maize genotypes were planted in a randomised complete block design with six replications in seven environments. Genotype and GEI effects were highly significant (P≤0.001) for all traits, indicating large variability in the maize breeding populations. Broad-sense heritability was high (30.86 to 82.50%) for all traits and low for grain yield (17.63%). Superior genotypes, G15-Ex (grain yield, fat, moisture and milling quality), G16-Ex (protein), G11-Ex (starch) and G14-Ex (fibre) were identified. Genotypes G2-C and G4-Ex had low mean values for defective grain. Milling quality was positively correlated with almost all traits measured. Starch was negatively associated with protein and grain yield. High yielding and most stable experimental genotypes (G4-Ex, G15-Ex and G17-Ex) were identified. Genotypes with specific (G2-C, G7-C, G8-C, G16-Ex and G17-Ex) and broad (G1-C, G4-Ex, G13-Ex and G15-Ex) adaptation in test environments were identified. Two mega environments were also identified. Superior maize hybrids with high grain yield, good nutritional quality, and good adaptability and stability can be released and recommended for commercial production.

Genotype and environmental effects on maize hybrids for grain yield, nutritional value and milling quality in South Africa

Quality, sustainability and cost implication of combined drying methods for carrot slices

Zobabalo P Mina, Tafadzwa Kaseke, Tobi Fadiji and Olaniyi A Fawole

Email: Zobabalop@gmail.com

Postharvest Research Laboratory Department of Botany and Plant Biotechnology Faculty of Science, University of Johannesburg PO Box 524, Auckland Park 2006, South Africa

Drying is one of the common methods of maintaining the quality and extending the shelf-life of horticultural produce; however, it is one of the most energy-consuming processes in food production. Current challenges include reducing drying costs through proper energy management. The present study investigated the effect of combining oven drying (OD) with freeze-drying (FD) on the drying behaviour, colour, phytochemicals content, antioxidant activity of the dried carrots, energy requirements and cost implications of the drying processes. The drying conditions were 36h FD, 1h OD+ 21h FD, 2h OD+ 18h FD, 3h OD+ 15h FD and 9h OD. The results showed that the total drying time was the shortest (9h) when using OD and the longest when using FD (36h, 4x OD). However, combined drying in all cases significantly shortened the drying time of FD by 39% for 1h OD+ 21h FD, 44% for 2h OD+ 18h FD and 50% for 3h OD+ 15h FD. Freeze dried samples had significantly (p ≤ 0.05) higher contents of β-carotene (0.30 – 0.72 mg /g DM), lycopene (0.36 – 0.87 mg /g DM), total phenolic content (7.12 – 10.36 mg GAE/100g DM) and antioxidant capacity (6.54 – 9.88 mM AAE/100 g DM) compared to OD and OD-FD. OD-FD provided significant advantages in decreasing the drying time, the total colour difference (8.05 – 20.76), energy requirements and costs by 40 – 56% compared to FD. Drying conditions of 2h OD+ 18h FD were the most effective in terms of the overall product quality compared with FD, OD and the OD-FD combinations. Therefore, the 2h OD + 18FD combination could be an energy-efficient and time-saving method for drying carrots with good product quality and nutrient retention.

A Edwards, LA Rothmann and WJ Swart Email: ae.alecedwards@gmail.com Department of Plant Sciences University of the Free State, PO Box 339, Bloemfontein 9300, South Africa Modern agriculture is moving away from conventional agro-chemicals and embracing new biological products to promote plant health and control highly aggressive plant pathogens. In this study, the soybean microbiome was investigated to elucidate whether it can be a source of plant growth promoting microorganisms (PGPM’s) and biological control agents (BCA’s) for controlling Sclerotinia stem rot caused by Sclerotinia sclerotiorum.  In 2021, phyllosphere, rhizosphere and endosphere samples of soybean plants from a field site in Delmas, Mpumalanga were collected. A total of 112 morphologically distinct microorganisms were isolated. The study yielded bacteria and yeast that have plant growth promoting properties including, phosphate solubilisation, IAA production and nitrogen fixation.  More than 20 isolates were shown to significantly (P<0.05) increase shoot and root length of seedlings. Furthermore, in vitro trials conducted revealed that 30 of the 112 isolates showed varying degrees of growth inhibition of S. sclerotiorum mycelium, with three isolates showing great potential. Selected isolates showing potential to be utilised as PGPM’s or BCA’s are currently being studied in glasshouse and field trials. These results provide evidence for the use of indigenous microorganisms associated with crops to be developed into commercial biological products, fostering a change in conventional agricultural practices, to promote plant health, manage crop diseases and offer sustainable production strategies.

Characterising plant health promoting microorganisms (PGPM’s) and potential biological control agents (BCA’s) from the soybean microbiome

Trends of wood anatomical diversity within fynbos biome

Funmilade Akinlabi and Aleksei Oskolskii

Email: funmilad@gmail.com

Plant Biotechnology

Department of Botany and Plant Biotechnology Faculty of Science, University of Johannesburg PO Box 524, Auckland Park 2006, South Africa

The fynbos community is in the belt of eastern and western Cape of South Africa.  It is richly endowed with wide variety of diverse flora. This study examined the wood traits diversity of fynbos based on compilation of previous studies by different authors who reported on the wood anatomical structure on fynbos coupled with our ongoing project work. The anatomical data for 133 species representing the families Araliaceae, Bruniaceae, Ericaceae Fabaceae (tribes Podalyrieae and Crotalarieae), Geissolomataceae, Geraniaceae, Grubbiaceae, Penaeaceae, Proteaceae, Retziaceae, Rosaceae, Rutaceae, Stilbaceae, and Thymelaeaceae have been analyzed. We found that the fynbos biome is characterized by high incidence of the species with short vessel elements (57%), short imperforate tracheary elements (85%) and small (< 50 µm in average diameter) vessel lumina, which are likely related to their predominantly shrubby habit. Relatively high incidences of dendritic, tangential or radial vessel arrangement (32%), the presence of helical thickenings (14%) and vestured intervessel pits (34%) are probably associated with hydraulic adaptations to the water stress during the dry seasons. High incidence of fibre tracheids (45%), as well as the common occurrence of scalariform perforation plates (21%) and of vascular tracheids (17%) can be adaptations to the water conductance during cold season with higher risk of frost (that was more significant during the Pleistocene glaciations than now). Finally, high incidence of broad (> 4-seriate) rays (53%) is thought to be adaptation to resprouting in the course of post-fire regeneration.

Mawande H Shinga and Olaniyi A Fawole

Email: 222243408@uj.ac.za

Postharvest Research Laboratory Department of Botany and Plant Biotechnology Faculty of Science, University of Johannesburg PO Box 524, Auckland Park 2006, South Africa

Banana is one of the most popular and important commercial fruits among horticultural crops in the world. Banana ripening is accompanied by softening and cell wall degradation during postharvest storage. Banana ripening is accompanied by rapid softening and cell wall degradation at the retail point, resulting in high postharvest losses if not consumed. Mucilage from Opuntia ficus-indica was extracted and used as a sustainable raw material at 1, 2 and 3 % concentrations in formulating edible coatings to suppress softening and degradation of banana cell wall subjected retail conditions (23 ± 2 ℃ and 85 ± 2 %). Physicochemical quality attributes, including pulp firmness, total soluble solids (TSS) and titratable acidity (TA) in pulp, peel colour, fruit weight loss, physiological responses (ethylene production, respiration rate, ion leakage), peel pigments (total carotenoids and chlorophyll) and cell wall degrading enzymes (cellulase, pectin methyl esterase (PME) and polygalacturonase (PG)) and chlorophyll degrading enzyme activities (chlorophyllase and chlorophyll degrading POD activities) in peel were measured. The results indicated that mucilage treatments effectively suppressed the chlorophyll and cell wall degrading enzymes, ultimately delaying peel colour changes and carotenoid accumulation and inhibiting ripening-associated processes compared to control fruit (uncoated). Fruit treated with 2% mucilage showed higher firmness, chlorophyll content and TA. In addition, 2% mucilage delayed the accumulation of TSS and reduced ethylene production, respiration rate, and ion leakage compared to other treatments, including the control (uncoated). The treatment also regulated the investigated cell wall softening enzyme activities. These findings could provide a practical approach to reducing postharvest losses of bananas at retail markets. However, further research is still required to verify this in a semi-commercial setup.

Opuntia ficus-indica mucilage edible coating regulates cell wall softening enzyme activities in bananas at retail conditions

African biomes.

RD Stewart, J van Rooyen, RD Rattray, K Perez, P Herbert, MT Sethusa, TJ Davies and M van der Bank

Email: rosss@uj.ac.za

Department of Botany and Plant Biotechnology Faculty of Science, University of Johannesburg PO Box 524, Auckland Park 2006, South Africa South Africa is recognised as being one of the most biological diverse countries in the world, with an estimated ca. 24,000 flowering plants and ca. 44,000 insect species. This biodiversity may be explained by the countries various climates, geography and geology, which have resulted in high levels of endemism. Insect species are intrinsically linked to their surrounding communities and a loss of insect biodiversity could have a cascading impact on ecosystems. Here we aim to assess weather the compositional turnover in arthropods can be predicted by the turnover in plant composition among South African biomes (Grassland, Savanna, Fynbos, and Albany ticket). Two Malaise traps were set up at all 11 National Botanical Gardens (NBG) covering four of the nine major South African biomes. Samples were collected every week and sent to the Centre for Biodiversity Genomics (CBG) for processing and sequencing. Species distribution maps (SDM) were used to generate a list of plant species that overlap in each of the NBGs. The compositional turnover of plants and insects across various gradients was then evaluated. A multivariable analysis of the preliminary data revealed that there is a signal between insect communities and plants within the gardens. A better understanding of what drives insect diversity within an environment would help determine the best methods for conserving biodiversity and the ecosystems services they provide.

Investigating the relationships between plants and arthropods across South

The Lamiaceae of southern Africa: An overview of an ethnobotanically important family and insights into several medicinal species

Ryan D.Rattray and Ben-Erik van Wyk

Email: ryanr@uj.ac.za

Department of Botany and Plant Biotechnology Faculty of Science, University of Johannesburg PO Box 524, Auckland Park 2006, South Africa

The Lamiaceae is a plant family of global importance encompassing ca. 7,800 species in 250 genera. Many notable genera include Lavandula L., Mentha L., Ocimum L., Salvia L., and Thymus L., with numerous species playing important roles in the cosmetic, culinary, nutraceutical and pharmaceutical industries. Members of this family have been used as traditional and folk medicines across the globe, largely due to their biologically active aromatic and secondary compounds. The southern African Lamiaceae comprise 297 species (in 42 genera), 94 of which have documented medicinal uses within the region. In this paper presentation, a birds-eye view of the family will be presented and insights into several medicinal genera will be discussed in detail (namely Salvia, Stachys and Pseudodictamnus), as new findings regarding their chemistry and biological activity have been reported for the first time.

Chitosan-24-Epibrassinolide Composite Coating Alleviated Chilling Injury and Maintained Quality of Cold-Stored Pomegranate Fruit (cv. Wonderful) by Enhancing Antioxidant System Capacity

Sbulelo Mwelase1, Umezuruike Linus Opara2,3 and Olaniyi Amos Fawole1

Email: sbulelomwelase@gmail.com

1 Postharvest Research Laboratory Department of Botany and Plant Biotechnology University of Johannesburg PO Box 524, Auckland Park 2006, South Africa

2 SARChI Postharvest Technology Research Laboratory Africa Institute for Postharvest Technology, Faculty of AgriSciences Stellenbosch University, Stellenbosch 7602, South Africa

3 UNESCO International Centre for Biotechnology Nsukka 410001, Enugu State, Nigeria

Low-temperature storage is highly accepted to maintain quality and prolong storage life of fresh produce; however, pomegranate fruits are prone to chilling injury during cold storage, which greatly affects quality and results in food losses. This study evaluated the efficacy of chitosan24-epibrassinolide (CH-EBR) composite coating in alleviating chilling injury (CI) and maintaining the quality of cold-stored pomegranate fruit (cv. Wonderful). Further, this study investigated the mechanism involved in chilling injury alleviation by CH-EBR. Following our previous study, the pomegranate fruit were treated with CH + 10 µM EBR and distilled water was used as a control treatment. The fruit were then subjected to long storage for 4 months at 4.5 ± 1 °C; 85 ± 5 RH and quality was evaluated at 4-week intervals. The results showed that the CH + 10 µM EBR coating significantly reduced fruit weight loss, decay, and susceptibility to CI. This was highly correlated with lower electrolyte leakage (EL). Moreover, the treated pomegranate fruit had higher antioxidant capacity (DPPH, FRAP and ABTS+) and lower hydrogen peroxide (H2O2) accumulation, which is attributed to the higher antioxidant enzymes activity, CAT and POD. Also, the higher PAL/ PPO enzyme activity ratio in treated fruit resulted in enhanced total flavonoid accumulation, contributing to the higher antioxidant capacity. The treated pomegranate fruit also showed higher titratable acidity (TA), with slight differences observed in total soluble solids (TSS). These results suggest that chitosan-24-epibrassinolide (CH-EBR) composite coating is a promising technology for maintaining quality and alleviating the chilling injury of pomegranate fruit.

Wilku B Meyer, Willem HP Boshoff and Botma Visser

Email: 2012077505@ufs4life.ac.za

Department of Plant Sciences, University of the Free State PO Box 339, Bloemfontein 9300, South Africa

Sunflower rust, caused by Puccinia helianthi Schw. (Phe), is a major disease of sunflower (Helianthus annuus L.) and, when left uncontrolled, can result in significant yield losses. In this study, ninety South African Phe isolates, representing eight of the nine to date described Phe races, were used to screen 12 additional sunflower differentials. Four differentials produced low infection types to all Phe isolates. The remaining eight differentials had several unique resistant/susceptible patterns varying from all low to all high. A total of sixteen unique avirulence/virulence patterns were observed among the 90 Phe race isolates. Thus, isolates available from the eight originally described Phe races could be grouped into 23 unique sub-races when combining the results from the previous study with the current data set. No changes were observed for isolates from races Phe3621 and Phe7331, while Phe3320 was sub-divided into two sub-races, Phe3000 and Phe3001 into three sub-races, Phe3401 into four, and Phe7221 and Phe7320 into five sub-races, respectively. Variation in virulence among Phe isolates of races Phe3001 and Phe7721 on the extended differentials correlated with their responses on 30 Agricultural Research Council national sunflower trial hybrids. Four of the sunflower hybrids were resistant to all the Phe isolates. This study presents the most comprehensive report on Phe race analysis and sunflower hybrid response in South Africa, and both breeders and producers will benefit from this.

Puccinia helianthi race variants and sunflower hybrid responses