cDNA-AFLP Analysis of Plant Defense Genes Expressed in Wheat (cv. Chamran) Infected with Mycosphaerella graminicola

Differential induction of genes in wheat (cv. Chamran) in response to Mycosphaerella graminicola was studied using cDNA-AFLP analysis. The three weeks old wheat seedlings were inoculated by the fungal pathogen, then the samples were collected at six time points (0, 12, 24, 48, 72, 96 hours) after inoculation with pathogen. By comparing the expression patterns of induced (infected) with non-induced (uninfected) plants, 276 differentially expressed fragments were identified and sequenced. Blast search of wheat genes assigned these sequences to different functional categories including defense, metabolism, energy, transcription, transport, signal transduction, stress response, secondary metabolism, and unknown sequences. Eight defense-related genes including lipoxygenase, peroxidase (PR 9), chitinase (PR 2, 4, 8) , PR-1, thaumatin-like protein (PR5), Phenylalanine Ammonia Lyase (PAL), β-1-3 glucanase (PR3), disulfide isomerase, and methionine sulfoxide reductase were induced 12 to 24 hours after inoculation in this cultivar of wheat. Induction of glucosyltransferase, Catalase, and putative xylanase inhibitor genes were observed around 48 h after inoculation with pathogen. Expression patterns of the other three genes, i.e., chalcone synthase, EXECUTER 1 protein, and nonspecific lipid transfer protein showed that these genes were induced later after inoculation (72-96 hours). Our data showed that expression of the PR- proteins were enhanced 24 h after inoculation, suggesting that they may play a role in the defense against M. graminicola. Expression of lipoxygenase, glycosyltransferase, thaumatin like protein, putative xylanase inhibitor, EXECUTER 1 protein and Nonspecific lipid transfer protein are reported for the first time in this interaction.