摘要
The chloroplast is a critical battleground in the arms race between plants and pathogens.Among microbe-secreted mycotoxins,tenuazonic acid(TeA),produced by the genus Alternaria and other phytopathogenic fungi,inhibits photosynthesis,leading to a burst of photosynthetic singlet oxygen(1O2)that is implicated in damage and chloroplast-to-nucleus retrograde signaling.Despite the signicant crop damage caused by Alternaria pathogens,our understanding of the molecular mechanism by which TeA promotes pathoge-nicity and cognate plant defense responses remains fragmentary.We now reveal that A.alternata induces necrotrophic foliar lesions by harnessing EXECUTER1(EX1)/EX2-mediated chloroplast-to-nucleus retro-grade signaling activated by TeA toxin–derived photosynthetic 1O2 in Arabidopsis thaliana.Mutation of the 1O2-sensitive EX1-W643 residue or complete deletion of the EX1 singlet oxygen sensor domain compro-mises expression of 1O2-responsive nuclear genes and foliar lesions.We also found that TeA toxin rapidly induces nuclear genes implicated in jasmonic acid(JA)synthesis and signaling,and EX1-mediated retro-grade signaling appears to be critical for establishing a signaling cascade from 1O2 to JA.The present study sheds new light on the foliar pathogenicity of A.alternata,during which EX1-dependent 1O2 signaling in-duces JA-dependent foliar cell death.
基金
funded by the National Key R&D Program (2021YFD1700100,2017YFD0201304)
the Jiangsu Agricultural Science and Technology Innovation Fund (CX (21)3093)to S.C.
the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB27040102)
the National Natural Science Foundation of China (NSFC) (31871397)to C.K.
