Jasmonate and ethylene signaling pathway may mediate Fusarium head blight resistance in wheat

Fusarium head blight (FHB), caused by Fusarium graminearum Schw. [teleomorph: Gibberella zeae (Schw.) Petch], can be a devastating disease in small grains production. Understanding its molecular pathogenesis will help identifying key steps in disease development and developing a strategy for efficiently preventing FHB epidemics. As the first step toward our goal, gene expression in the FHB-resistant wheat (Triticum aestivum L.) cultivar Sumai 3 and the FHB-susceptible wheat landrace Y1193-6 was profiled with Affymetrix Wheat Genome GeneChip in 24 h after inoculation by F graminearum isolate Fg4 and compared. Twofold change 11092(Signal ratio) = 1] in expression was set as the threshold for data selection. Comparing the FHB-inoculated and the mock-inoculated wheat spikelets in both Sumai 3 and Y1193-6 revealed a total of 677 possible FHB-responsive genes. Further analysis and comparison revealed that, among these FHB-responsive genes, 69 were F. graminearum genes. Of the 608 wheat genes, 243 showed similar expression in both Sumai 3 and Y1193-6; 281 and 79 significantly changed expression pattern only in Sumai 3 or Y1193-6, respectively; and five had opposite expression pattern between the two wheat genotypes. Functional genomics and physiological analyses both suggested that FHB resistance in Sumai 3 involves defense pathways regulated by jasmonic acid and ethylene signaling, while salicylic acid-regulated systematic acquired resistance is insignificant in this process.