Wheat Gene Expression Differences Induced By Six Puccinia triticina Races

Puccinia triticina, the casual agent of wheat leaf rust, is a devastating disease that can cause up to 40% yield loss. During fungal infection the host plant recognizes proteins, secreted effectors, and other molecules, which trigger a host defense response. Changes in the pathogen effectors and strong varietal selection pressure are responsible for the rapid development of new rust races. The objectives of this study are to identify and characterize wheat genes that are utilized by races differently throughout infection. Six races of leaf rust were evaluated on a single susceptible variety of wheat in a time course study to determine if different rust races utilize different infection pathways in wheat. RNA was sequenced and 63 wheat genes were identified that showed varying expression in response to six different leaf rust races. Of the 63 genes, 54 wheat genes have been characterized for timing of expression during leaf rust infection. Race specific expression was found in two wheat genes that are affected by race shifts on Lr2A, Lr2C, and Lr17A. RNAi was used to silence nine wheat genes to further understand their role in leaf rust infection. Transgenic plants were inoculated and observed for changes in susceptibility. Gene expression data is being obtained to show gene knock down in the transgenic plants.