The role of wheat jasmonic acid and ethylene pathways in response to Fusarium graminearum infection

Abstract

To study the roles of jasmonic acid (JA) and ethylene (ET) pathways in mediating defense against wheat Fusarium head blight (FHB), the expression patterns of genes in the Fusarium graminearum-challenged spikes between Wangshuibai and its susceptible mutant NAUH117 at the Fhb1 locus were compared using wheat microarray. The results showed that most of JA-associated genes were induced in Wangshuibai while only a few were induced in NAUH117, and most ET-associated genes were up-regulated in both genotypes. ELISA assay showed that in the F. graminearum-challenged spikes, endogenous JA content was increased in Wangshuibai while not in NAUH117. Pre-treatment with exogenous methyl JA could decrease the wheat disease severity. However, pretreatment by exogenous ethephon had no such effect. A lipid transfer protein gene, which is a representative gene for JA pathway, was selected for function analysis in Arabidopsis system using a T-DNA insertion mutant line for LTP gene. It was found that the mutant showed compromised FHB resistance compared with its wildtype, proving the possible role of LTP in FHB resistance of Arabidopsis. These results demonstrated that JA pathway should play a critical role in FHB resistance.