Références sur les Plantes

DOI: 10.1094/PDIS-11-09-0742 Label: ViRe Bioengineering Abstract: Production of oriental melon (Cucumis melo var. makuwa) in Asia is often limited by two potyviruses, the watermelon infecting type of Papaya ringspot virus (PRSV W) and Zucchini yellow mosaic virus (ZYMV). In order to engineer transgenic resistance to these two viruses, an untranslatable chimeric DNA comprising partial coat protein (CP) sequences of ZYMV and PRSV W was constructed and used to transform the elite cultivar of oriental melon, Silver Light, by Agrobacterium. Greenhouse evaluation by mechanical challenges with ZYMV and PRSV W, alone or together, identified transgenic lines exhibiting different levels of resistance or complete immunity to ZYMV and PRSV W. Molecular analyses of transgenic lines revealed random insertion of transgene into the host genome, with insert numbers differing among transformants. There was no correlation between transgene insert numbers and the degree of resistance expressed by transgenic lines.

The levels of accumulation of transgene transcript varied among transgenic lines. However, an inverse correlation was observed between the level of accumulation of transgene transcripts and the degree of virus resistance. Moreover, small interfering (si)RNA was readily detected from the immune and highly resistant lines, but not from the weakly resistant and susceptible lines. Altogether, our results indicated that RNAmediated post-transcriptional gene silencing (PTGS) was the underlying mechanism of double-virus resistance of the transgenic melon lines. The segregation analysis of the R1 progeny of the immune line ZW-1 indicated that the single inserted transgene is associated with the resistance phenotype and is inherited as a dominant trait.

These transgenic melon lines with high degrees of resistance to ZYMV and PRSV W have great potential for the control of ZYMV and PRSV W in C. melo in Asia and elsewhere.

Author Address: Department of Plant Pathology, National Chung Hsing University, Taichung, Taiwan; Department of Molecular Biotechnology, Da-Yeh University, Changhua, Taiwan; Department of Plant Pathology, National Chung Hsing University, Taichung, Taiwan.

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX Author: Xie Z, Li D, Wang L, Sack FD, Grotewold E, Year: 2010 Title: * Role of the Stomatal Development Regulators FLP/MYB88 in Abiotic Stress Responses.

Journal: The Plant Journal Received - Date: 22-Jul-2010 - Revised Date : 30-Aug-2010 - Accepted Date: 08Sep-2010 Pages: no Label: ReEn Physiol Keywords: FLP/MYB88 MYB salt stress abscisic acid Arabidopsis stomata Abstract: Stomata are vital for plant adaptation to abiotic stress, and in turn stomatal density is modulated by environmental factors. Less clear, however, is whether regulators of stomatal development themselves participate in the sensing or response of stomata to abiotic stress. FOUR LIPS (FLP) and its paralog MYB88 encode MYB proteins that establish stomatal patterning by permitting only a single symmetric division before stomata differentiate. Hence, flp-1 myb88 double mutants have an excess of stomata, which are often misplaced in direct contact. Here, we investigated the consequences of loss of FLP/MYB88 function on the ability of Arabidopsis plants to respond to abiotic stress. While flp-1 myb88 double mutants are viable and display no obvious aerial phenotypes under normal greenhouse growth conditions, we show that flp-1 myb88 plants are significantly more susceptible to drought and high salt, and have increased rates of water loss. To determine whether flp-1 myb88 plants are already challenged under normal growth conditions, we compared genomewide transcript levels between flp-1 myb88 and wild type green tissues. Unexpectedly, uninduced flp-1 myb88 plants showed a reduced accumulation of many typical abiotic stress gene transcripts. Moreover, the induction of many of these stress genes under high salt conditions was significantly lower in flp-1 myb88 plants. Our results provide evidence for a new function of FLP/MYB88 in sensing and/or transducing abiotic stress, which is severely compromised in flp-1 myb88 mutants.

URL: http://dx.doi.org/10.1111/j.1365-313X.2010.04364.x Author Address: 1Department of Plant Cellular and Molecular Biology, Ohio State University, Columbus, Ohio,43210 USA 2Department of Public Health Sciences, University of Hawaii at Manoa, Honolulu, 96822 Hawaii USA 3Plant Biotechnology Center, Ohio State University, Columbus, Ohio, 43210 USA 4Department of Botany, University of British Columbia, Vancouver, Canada.

5Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.