Analysis of differential transcriptional profiling in wheat infected by Blumeria graminis f. sp. tritici using GeneChip.

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a devastating disease of wheat. The use of wheat cultivars resistant to powdery mildew provides an effective, economical, and environmentally friendly method to control the disease. Previously, we identified a dominant resistance gene, temporarily named Pmhym, from the wheat cultivar Hongyoumai. In order to screen differential transcripts related to Pmhym-mediated resistance, four F3 homozygous resistant and four susceptible progenies derived from the Hongyoumai/Yumai13 cross were selected to construct two different pools, respectively, representing an incompatible and compatible interaction with Bgt. Pre-inoculated control and the pathogen-inoculated treatments at 24 h post inoculation (hpi) were used. Three groups of differential genes were categorized from three comparisons as pre- and post-induced, respectively, in two interactions, and post-induced between incompatible and compatible interaction. It was found that salicylic acid (SA), jasmonate (JA), and ethylene (ET) signaling-related genes were differentially expressed, thus suggesting that they are involved in the defensive response against Bgt infection. In compatible interactions, the genes involved in the abscisic acid (ABA) signaling pathway might be inhibitory to the above-mentioned three pathways, resulting in a susceptible reaction. Genes involved in disease/defense, signal transduction, and reactive oxygen species (ROS) metabolism were up-regulated in incompatible interactions, implying a role in resistant response. The results of qRT-PCR analysis on several candidate genes were consistent in their expression patterns as revealed by microarray analysis. The differential expression analyses in the present study are good candidates for further elucidation of wheat defensive response to powdery mildew.