CBC Members Receive a New Award from USDA-NSF Joint Program

Crop Bioengineering Consortium member Bing Yang (Associate Professor of Genetics, Development & Cell Biology) has received an award from the USDA-NSF joint program: Plant Biotic Interactions for his proposal entitled “iTALES: Investigating the role of interfering TAL effectors in virulence”. This 3-year grant intends to investigate how rice pathogen Xanthomonas oryzae co-evolve mechanisms to interfere plant resistance to the bacteria. Rice, a staple food crop, is a premier model species for understanding host/microbe interactions that involve co-evolution of new virulence strategies in pathogens and counteracting resistance mechanism in hosts. The Yang lab recently made a surprising discovery in their studies of the biology of bacterial TALEs (transcription activator-like effectors). TALE pseudogenes of two pathovars of Xanthomonas oryzae function as bacterial virulence determinants by interfering with resistance in rice that is mediated by a subfamily of resistance (R) genes in response to all tested TALEs. Their preliminary results demonstrate that the previously annotated TALE “pseudogenes” are not pseudogenes; instead they are expressed as TALE variants to interfere with the plant resistance triggered by the pathogen’s progenitor TALEs. These variants are now named as iTALEs (interfering TALEs). The Yang group also found that the rice Xa1, Xa2 and Xa14 genes form a new subfamily of NBS-LRR R genes whose broad spectrum of TALE-triggered resistance can be effectively limited by iTALEs prevalent in the majority of pathogen isolates. They hypothesize that rice has evolved a group of R genes to counteract TALEs, while pathogens have coevolved virulence strategies by mutating the elicitor TALE genes to evade the R gene recognition/resistance in host and, thereby, suppress resistance triggered by the progenitor TALEs.