Transcription factor WRKY22 regulates canker susceptibility in sweet orange (Citrus sinensis Osbeck) by enhancing cell enlargement and CsLOB1 expression  

作　　者：Qin Long Meixia Du Junhong Long Yu Xie Jingyun Zhang Lanzhen Xu Yongrui He Qiang Li Shanchun Chen Xiuping Zou 

机构地区：[1]Citrus Research Institute,Southwest University/Chinese Academy of Agricultural Sciences,Chongqing,People’s Republic of China

出　　处：《Horticulture Research》2021年第1期508-522,共15页园艺研究（英文）

基　　金：the National Key Research and Development Program of China(2018YFD1000300,to S.C.);the National Natural Sciences Foundation of China(31972393,to X.Z.);the Natural Science Foundation Project of Chongqing City(cstc2019jcyj-bshX0024 to Q.L.);the Fundamental Research Funds for the Central Universities(XDJK2019C027,to Q.L.);the Earmarked Fund for China Agriculture Research System(CARS-26,to S.C.).

摘　　要：Pathological hypertrophy(cell enlargement)plays an important role in the development of citrus canker,but its regulators are largely unknown.Although WRKY22 is known to be involved in pathogen-triggered immunity and positively regulates resistance to bacterial pathogens in Arabidopsis,rice and pepper,the CRISPR/Cas9-mediated partial knockout of CsWRKY22 improves resistance to Xanthomonas citri subsp.citri(Xcc)in Wanjincheng orange(Citrus sinensis Osbeck).Here,we demonstrate that CsWRKY22 is a nucleus-localized transcriptional activator.CsWRKY22-overexpressing plants exhibited dwarf phenotypes that had wrinkled and thickened leaves and were more sensitive to Xcc,whereas CsWRKY22-silenced plants showed no visible phenotype changes and were more resistant to Xcc.Microscopic observations revealed that the overexpression of CsWRKY22 increased cell size in the spongy mesophyll.Transcriptome analysis showed that cell growth-related pathways,such as the auxin and brassinosteroid hormonal signaling and cell wall organization and biogenesis pathways,were significantly upregulated upon CsWRKY22 overexpression.Interestingly,CsWRKY22 activated the expression of CsLOB1,which is a key gene regulating susceptibility to citrus canker.We further confirmed that CsWRKY22 bound directly to the W-boxes just upstream of the transcription start site of CsLOB1 in vivo and in vitro.We conclude that CsWRKY22 enhances susceptibility to citrus canker by promoting host hypertrophy and CsLOB1 expression.Thus,our study provides new insights into the mechanism regulating pathological hypertrophy and the function of WRKY22 in citrus.

关 键 词：CITRUS CANKER CITRUS 

分 类 号：S666.4[农业科学—果树学]