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 [log 2 (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.