Transcriptome Analysis and RNA Interference Reveal Regulating Cotton Resistance to Verticillium Wilt by JA and SA Signaling Pathways.

Verticillium wilt, caused by , is one of the most damaging and widespread soil-borne cotton diseases. The molecular mechanisms underlying the cotton defense against remain largely elusive. Here, we compared the transcriptional differences between Upland cotton cultivars: one highly resistant (HR; Shidalukang 1) and one highly susceptible (HS; Junmian 1). This was done at multiple time points after inoculation, which identified 2010 and 1275 differentially expressed genes (DEGs) in HR and HS, respectively. Plant hormone signal transduction-related genes were enriched in HR, whereas genes related to lignin biosynthesis were enriched in both HR and HS. Weighted gene co-expression network analysis (WGCNA) using the 2868 non-redundant genes differentially expressed between the infected and uninfected samples in HR or HS identified 10 different gene network modules and 22 hub genes with a potential role in regulating cotton defense against infection. , encoding glutamate dehydrogenase (GDH), was selected for functional characterization. Suppressing the expression level of by virus-induced gene silencing (VIGS) in HS led to inhibition of the salicylic acid (SA) biosynthesis/signaling pathways and activation of the jasmonic acid (JA) biosynthesis/signaling pathways, which resulted in an increase of 42.1% JA content and a reduction of 78.9% SA content in cotton roots, and consequently enhanced resistance. Our finding provides new insights on the molecular mechanisms of cotton resistance to infection and candidate genes for breeding resistance cotton cultivars by genetic modification.