柑橘SAR及其信号转导基因CsSABP2在黄龙病菌侵染中的响应特征  

Response Characteristics of Plant SAR and Its Signaling Gene CsSABP2 to Huanglongbing Infection in Citrus

作　　者：赵珂 郑林 杜美霞 龙俊宏 何永睿[1] 陈善春[1] 邹修平[1] ZHAO Ke;ZHENG Lin;DU MeiXia;LONG JunHong;HE YongRui;CHEN ShanChun;ZOU XiuPing(Citrus Research Institute,Southwest University/Chinese Academy of Agricultural Sciences/National Citrus Engineering Research Center/National Center for Citrus Varieties Improvement,Chongqing 400712)

机构地区：[1]西南大学/中国农业科学院柑桔研究所/国家柑桔工程技术研究中心/国家柑桔品种改良中心,重庆400712

出　　处：《中国农业科学》2021年第8期1638-1652,共15页Scientia Agricultura Sinica

基　　金：国家自然科学基金(31972393);国家重点研发计划(2018YFD0201500);国家现代农业产业技术体系建设专项(CARS-26);广西创新驱动发展专项(桂科AA18118046-6)。

摘　　要：【背景】柑橘系统获得性抗性(systemic acquired resistance,SAR)在柑橘抗黄龙病(Huanglongbing,HLB)过程中起着重要作用。水杨酸(SA)和水杨酸甲酯(MeSA)信号互换是激活植物SAR的关键信号转导途径,但其在抗HLB危害中的作用依然不清楚。【目的】以柑橘HLB不同耐病品种为材料,研究柑橘SAR及其信号转导的关键酶基因CsSABP2(salicylic acid binding protein 2)在HLB病原菌‘Candidatus Liberibacter asiaticus’(CLas)侵染中的响应特征,了解柑橘SAR及CsSABP2响应CLas侵染的作用。【方法】从SAR Marker基因CsPR1、CsPR2、CsPR5表达、活性氧H_(2)O_(2)水平和淀粉含量变化等方面分析CLas侵染、外施SA和MeSA调控柑橘SAR的特征。进一步,基于易感HLB锦橙(Citrus sinensis)和耐HLB酸柚(C.grandis)感染CLas转录组测序比较分析,筛选和克隆响应CLas侵染的CsSABP2差异表达基因;生物信息学分析预测差异基因的生物学功能;qRT-PCR分析差异表达基因在锦橙、酸柚和耐HLB马蜂柑(C.hystrix)中响应CLas感染的表达变化;以锦橙叶片为试材分析差异表达基因响应外源SA和MeSA诱导的表达特征。【结果】SAR Marker基因响应CLas表达分析表明,CsPR1、CsPR2和CsPR5均正向响应CLas侵染上调表达,CsPR2和CsPR5在酸柚和马蜂柑中表达水平高于锦橙,特别是叶肉中两个基因的表达水平均显著高于锦橙;相反,CsPR1在叶脉中上调表达水平明显高于叶肉,且在锦橙叶脉中表达水平显著高于酸柚和马蜂柑叶脉中。离体模拟SA和MeSA调控柑橘SAR反应显示,与SA处理相比,MeSA处理明显诱导CsPR1、CsPR2和CsPR5上调表达,同时非处理部位基因(特别是CsPR5)表达水平也明显上调。H_(2)O_(2)检测结果表明,外源MeSA诱导非处理部位H_(2)O_(2)积累显著强于SA。同时,通过对外施MeSA、SA的感病叶片进行连续5周的淀粉含量检测,发现MeSA能明显减少感病叶片中淀粉的积累。进一步转录组数据和生物信息学分析表�【Background】Plant systemic acquired resistance(SAR)plays an important role in citrus against Huanglongbing(HLB).The signal exchange between salicylic acid(SA)and methyl salicylate(MeSA)is a key signaling for activating SAR,but its roles in HLB is still unclear.【Objective】In order to understand regulation mechanisms of citrus SAR in HLB,response characteristics of SAR and its key enzyme gene CsSABP2(salicylic acid binding protein 2)in‘Candidatus Liberibacter asiaticus’(CLas)infection were compared among citrus varieties with different HLB disease-tolerance.【Method】The response characteristics of citrus SAR in CLas,SA,and MeSA inoculation were determined based on the expression of SAR Marker gene CsPR1,CsPR2,CsPR5,levels of reactive oxygen species(H_(2)O_(2))and starch.Furthermore,according to comparative transcriptome data between HLB-susceptible variety Jincheng orange(JC,Citrus sinensis)and HLB-tolerant variety Sour pomelo(SP,C.grandis),the differentially expressed genes of CsSABP2s were screened and cloned.The biological function of selected genes was predicted by bioinformatics analysis.qRT-PCR was further used to analyze expression profiles of CsSABP2s induced by Clas infection in JC,SP and other HLB-tolerant variety Kaffir lime(KL,C.hystrix)and induced by exogenous SA and MeSA in JC variety.【Result】qRT-PCR analysis showed that CsPR1,CsPR2 and CsPR5 were up-regulated in response to CLas infection,and the expression level of CsPR2 and CsPR5 in SP and KL,especially in mesophyll,was significantly higher than that in JC.On the contrast,the expression level of CsPR1 in vein was significantly higher than that in mesophyll,and its expression level in JC vein was significantly higher than that in SP and KL vein.Hormone treatment showed that MeSA treatment obviously induced up-regulated expressions of CsPR1,CsPR2 and CsPR5 in treated and non-treated sites compared to SA treatment.Exogenous MeSA induced H_(2)O_(2) accumulation in non-treated sites,which was stronger than that of SA treatment.MeSA si

关 键 词：柑橘黄龙病 韧皮部杆菌亚洲种 系统获得性抗性 水杨酸 水杨酸甲酯 SABP2 基因表达 

分 类 号：S436.66[农业科学—农业昆虫与害虫防治]