GSE174508
Transcriptome and oxylipin profiling joint analysis reveals the opposite roles of 9-oxylipins and jasmonic acid in maize resistance to Gibberella stalk rot
Gibberella stalk rot (GSR) caused by Fusarium graminearum is one of the devastating diseases causing significant losses to maize production worldwide. Although plant oxylipins have been widely reported as potent signals to activate diverse biotic stress responses, the roles of distinct oxylipin pathway branches initiated by either 9- or 13-lipoxygenases (LOXs) in defense against GSR remain unexplored. In this study, the functional analysis showed that disruption of ZmLOX5, a maize 9-LOX gene, resulted in increased susceptibility to GSR. To identify the key genes and metabolites associated with GSR resistance, we profiled transcriptome and oxylipins in the lox5 mutant and near-isogenic wild type. The results showed that JA biosynthetic pathway genes are highly up-regulated, whereas multiple 9-LOX pathway genes down-regulated in lox5-3 mutant in response to F. graminearum infection. Furthermore, oxylipin profiling of the mutant and corresponding wild type, B73, as well as a more resistant line, W438, uncovered significantly higher contents of JA-isoleucine (JA-Ile) and other jasmonates but relatively lower levels of 9-oxylipins in lox5-3 upon infection. By contrast, resistant line W438 and B73 displayed relatively lower levels of JAs, yet considerable increase of 9-oxylipins. Taken together, these results clearly indicated that the signaling pathways of 9-oxylipins and JAs antagonize each other, and that while ZmLOX5-produced 9-oxylipins contribute to resistance, JAs are likely to function as negative regulator in maize defense against GSR. Overall design: the RNA-seq analysis using B73 and mutant lox5-3 at different time points (0h,12h and 24h) after infection with F. graminearum.