水稻白叶枯病菌的一个非典型趋化受体基因与游动性和早期侵染相关  

An atypical chemotactic receptor gene of Xanthomonas oryzae pv.oryzae is associated with bacterial swimming and early infection

作　　者：雷诗敏 欧阳燕菲 吴侨智 许力丹 曾晨 伍慧红 谢云巧 何勇强[1,2] LEI Shimin;OUYANG Yanfei;WU Qiaozhi;XU Lidan;ZENG Chen;WU Huihong;XIE Yunqiao;HE Yongqiang(Guangxi Key Laboratory for Agro-Environment and Agro-Product Safety,College of Agriculture,Guangxi University,Nanning 530004,China;State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources,College of Life Science and Technology,Guangxi University,Nanning 530004,China)

机构地区：[1]广西大学农学院,广西农业环境与农产品安全重点实验室,南宁530004 [2]广西大学生命科学与技术学院,亚热带农业生物资源保护与利用国家重点实验室,南宁530004

出　　处：《植物病理学报》2024年第3期522-534,共13页Acta Phytopathologica Sinica

基　　金：国家自然科学基金(32060600)。

摘　　要：在对水稻白叶枯病菌(Xanthomonas oryzae pv.oryzae,Xoo)PXO99A-GX菌株的基因组注释过程中发现了一个非典型趋化受体基因PXO_01024,预测其产物具有2个跨膜结构域(TMD)和1个甲基接收结构域(MA),但缺少配体结合结构域(LBD)。为明确该基因的生物学功能,本研究通过同源双交换的方法构建了PXO_01024的缺失突变体DM01024。该基因缺失导致细菌的游动性几乎丧失,生物被膜减少,而互补菌株CDM01024的这些性状又恢复至野生型水平;在有伤接种条件下,DM01024的毒力与野生型相比并无明显变化,但是在喷雾接种(无伤)条件下,DM01024的病情指数相比野生型显著降低,而CDM01024的毒力又恢复至野生型水平,说明PXO_01024在侵染早期发挥作用;利用毛细管法对野生型及突变体DM01024进行趋化性检测,发现DM01024对甲硫氨酸、丙氨酸、亮氨酸、甘氨酸、天冬酰胺、苯丙氨酸、异亮氨酸、葡萄糖、麦芽糖、木糖、果糖、琥珀酸和酒石酸的趋向性相比野生型显著下降。本研究表明,非典型趋化受体基因PXO_01024与Xoo的趋化性、游动性和早期侵染相关。After annotating the genome of Xanthomonas oryzae pv.oryzae strain PXO99A-GX,we found an atypical chemoreceptor gene PXO_01024,which encodes a protein with two transmembrane domains(TMD)and a methyl-accepting domain(MA)but without the ligand-binding domain(LBD).To understand the biological function of PXO_01024,we constructed the PXO_01024 deletion mutant DM01024 and its complemented strain CDM01024 by homologous double exchange method.Deletion of PXO_01024 resulted in the reduced formation of biofilm and almost loss of bacterial swimming,while in CDM01024 the swimming motility and biofilm formation ability were restored to wild-type levels.The virulence of DM01024 was not significantly different from that of the wild-type strain when inoculation of wounded host plants was performed.However,when unwounded plants were inoculated with the spraying inoculation method,the disease index caused by DM01024 was significantly reduced compared with that caused by the wild-type strain and complemented strain CDM01024,indicating that PXO_01024 played a role in early infection of Xoo.The chemotaxis of these strains was subsequently detected by capillary method,and the results showed that DM01024 showed significantly reduced chemotaxis to methionine,alanine,leucine,glycine,asparagine,phenylalanine,isoleucine,glucose,maltose,xylose,fructose,succinic acid,and tartaric acid compared with the wild-type strain.This study demonstrated that the atypical chemotactic receptor gene PXO_01024 is associated with chemotaxis,swimming motility,and early infection of Xoo.

关 键 词：水稻白叶枯病菌 趋化性 趋化受体 游动性 早期侵染 

分 类 号：S432.42[农业科学—植物病理学]