Myco-fabricated nano-selenium mediated aggregation of phytophtora infestans zoospores: the future of crop protection Shreya M Joshi1 and Sudisha Jogaiah1*, 1 Laboratory of Plant Healthcare and Diagnostics, PG Department of Biotechnology and Microbiology, *Corresponding Author: Sudisha Jogaiah (Email: jsudish@kud.ac.in) Karnatak University, Dharwad – 580 003 Karnataka India Abstract: Nanoscience and nanotechnology have been proved to possess enormous potential to contend present-day global challenges like environmental security and sustainability, food production, food safety, food security and threats of climate change. Myconanotechnology is an emerging branch of nanotechnology that has the potential to meet the essential needs of disease control and management. These myco-nanostructures hold the promise of controlled release of agrochemicals and site targeted delivery of various macromolecules for improved plant disease resistance, efficient nutrient utilization and improved plant defence in an eco-friendly way. The present study aimed to synthesise, charcterise and study the in vitro activity of selenium nanoparticles (nSe) derived from previously identified rhizospheric fungi Trichoderma atroviride1. From this study it was observed that the size of the nanoparticles ranged from 93.2nm to 98.5nm and the the crystalline nature of the nano-selenium was confirmed by Powder-X Ray Diffraction studies (P-XRD). The myco-fabricated nano-selenium was found to possess a unique ability of aggregating the zoospores of Phytophthora infestans, the incitant of late blight of tomato, owing to the opposite electrostatic forces on the spores and the nanoparticles. Thus, it can be hypothesized that the nSe prove as novel nano-fungicides that aid in the disease protection by limiting the spread of disease causing structures.
Methodology
T. atroviride grown in PDB for seven days
AGGREGATION OF SPORES BY nSe a b
CHARACTERISATION STUDIES UV-Vis spectroscopy
FT-IR
presence of several important functional groups like –OH, -NH, -CH and – C=O corresponding to their characteristic peaks, thus depicting the involvement of functional groups in reducing Se+4 to elemental Se
Peak at 259nm indicating the formation of nSe after 24h of incubation
Vacuum filtration to separate culture filtrate (CF) from fungal mass
c
Myco-fabrication of nano-selenium (nSe)2
d
SEM
(100mL CF + 25mL 25mM sodium selenite )
Characterisation: UV-Vis, FT-IR and SEM
In vitro aggregation of P. infestans zoospores
Images representing the aggregation of zoospores of P. infestans on treatment with 200ppm of nSe (a) & (c) represent spores without nSe treatment under light micrscopy and AFM; (b) & (d) represent aggregated spores treated with 100ppm nSe treatment under light micrscopy and AFM
nSE
40mV
Visualisation by light microscopy and atomic force micrscopy (AFM)
Negative charged
Aggregation of spores by nSe
P. infestans zoospores
Inhibition of spread of spores; control of late blight
References: 1. Jogaiah, S., Mostafa, A., Tran, L.S.P., & Ito, S-I. (2013). Characterization of rhizosphere fungi that mediate resistance in tomato against bacterial wilt disease. J. of Experimental Botany, 64, 3829-3842. 2. Nandini, B., Hariprasad, P., Prakash, H. S., Shetty, H. S., & Geetha, N. (2017). Trichogenic-selenium nanoparticles enhance disease suppressive ability of Trichoderma against downy mildew disease caused by Sclerospora graminicola in pearl millet. Scientific reports, 7(1), 2612.