Peanut(Arachis hypogea L)bacterial wilt(BW)is a devastating disease caused by Ralstonia solanacearum that results in severe yield and quality losses.Plant defensins are short cysteine-rich peptides with antimicrobial activity.The role of defensin genes(AhDef)in peanut is unclear.A genome-wide investiga-tion of AhDef genes was undertaken,and 12 identified AhDef genes were classified into two groups con-taining the gamma-thionin domain formed by four disulfide pairs:Cys1-Cys8,Cys2-Cys5,Cys3-Cys6,and Cys4-Cys7.In silico analysis revealed that AhDef genes showed highly conserved architectural features and contained cis-elements associated with phytohormone signaling and defense responses.A highly resistant cultivar,H108(R)and a susceptible accession,H107(S)were tested by R.solanacearum inocu-lation.H1 08(R)showed fewer symptoms than H1 07(S)owing to inhibition of bacterial reproduction and spread in the vascular bundles of roots and stems.In a transcriptomic expression profile,AhDef genes,particularly AhDefl.6 and AhDef2.2,were up-regulated in H108(R)compared with H1 07(S)under R.sola-nacearum infection and phytohormone treatment.Subcellular localization showed that the AhDef1.6 and AhDef2.2 proteins were both expressed specifically on the plasma membrane.Overexpression of protein fusion AhDef2.2-YFP in Nicotiana benthamiana and peanut leaves increased resistance to R.solanacearum,suggesting its role in response to BW infection.AhDef2.2 may be valuable for peanut resistance breeding.

College of Agronomy&Center for Crop Genome Engineering,Henan Agricultural University,Zhengzhou 450046,Henan,China

[1]Kai Zhao;Rui Ren;Xingli Ma;Kunkun Zhao;Chengxin Qu;Di Cao;Qian Ma;Yingying Ma;Fangping Gong;Zhongfeng Li;Xingguo Zhang;Dongmei Yin-.Genome-wide investigation of defensin genes in peanut(Arachis hypogaea L.)reveals AhDef2.2 conferring resistance to bacterial wilt)[J].作物学报（英文版）,2022(03):809-819

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