Overexpression of the peanut CLAVATA1-like leucine-rich repeat receptor-like kinase AhRLK1， confers increased resistance to bacterial wilt in tobacco.

Bacterial wilt caused by Ralstoniasolanacearum is a devastating disease affecting hundreds of plant species， yet the host factors remain poorly characterized. The leucine-rich repeat receptor-like kinase AhRLK1， characterized as CLAVATA1， was found to be up-regulated in peanut upon inoculation with R. solanacearum. The AhRLK1 protein was localized in the plasma membrane and cell wall. The qPCR results showed AhRLK1 was induced in susceptible variety but little changed in resistant cultivar after inoculated with R. solanacearum. Hormones like salicylic acid， abscisic acid， methyl jasmonate and ethephon， induced AhRLK1 expression. In contrast， AhRLK1 expression was down-regulated under cold and drought treatments. Transient overexpression of AhRLK1 led to a hypersensitive response (HR) in Nicotianabenthamiana. Furthermore， AhRLK1 overexpression in tobacco significantly increased the resistance to R. solanacearum. Besides， the transcripts of most representative defense responsive genes in HR and hormones signal pathways were significantly increased in the transgenic lines. EDS1 and PAD4 in the R gene signaling pathway were also up-regulated， but NDR1 downregulated. Accordingly， the AhRLK1 may increases the defense response to R. solanacearum via HR and hormone defense signaling， in particular through the EDS1 pathway of R gene signaling. These results provide new understanding of CLAVATA1 function and will contribute to genetic enhancement of peanut.