南美蟛蜞菊霜霉病病原鉴定及系统发育分析  

Pathogen identification of downy mildrew on Sphagneticola trilobata and its phylogenetic analysis

作　　者：李华洪 何成成 习平根[1] 姜子德[1] 李敏慧[1] LI Huahong;HE Chengcheng;XI Pinggen;JIANG Zide;LI Minhui(College of Plant Protection/Guangdong Province Key Laboratory of Microbial Signals and Disease Control,South China Agricultural University,Guangzhou,Guangdong 510642,China)

机构地区：[1]华南农业大学植物保护学院/广东省微生物信号与作物病害防控重点实验室,广东广州510642

出　　处：《生物安全学报》2022年第2期156-162,共7页Journal of biosafety

基　　金：广东省重点领域研发计划项目(2018B020205003)。

摘　　要：【目的】为从天敌病原生物方面探索外来入侵植物南美蟛蜞菊的生物防治,对新发现的南美蟛蜞菊霜霉病进行病原鉴定和系统发育分析。【方法】在广东省广州市对南美蟛蜞菊霜霉病的发生及危害情况进行调查,并通过病害症状识别、病原显微形态记录与比较、病原菌及其近似种ITS序列结构比较、LSU序列和ITS序列系统发育分析,对南美蟛蜞菊霜霉病病原进行鉴定和系统发育分析。【结果】南美蟛蜞菊霜霉病在广州零星发生,但该病害在华南农业大学校园内发生较严重,发病率达50%~70%,病情指数为30~35。经鉴定,其病原菌为南美蟛蜞菊单轴霉,是国内一新记录种。基于病原菌LSU序列和ITS序列的系统发育分析显示,侵染菊科植物的单轴霉属菌种聚在一个分枝,亲缘关系密切,与侵染其他不同科寄主植物的单轴霉亲缘关系较远。ITS序列结构比较显示,寄生于菊科向日葵族植物的单轴霉属菌种的ITS2区包含多个重复序列,不同菌种间的ITS2区重复序列相似度不同,说明侵染菊科向日葵簇植物的单轴霉属菌物可细分成多个种,而不是只有向日葵单轴霉。【结论】广州发生的南美蟛蜞菊霜霉病是该寄主上首次正式报道的病害,鉴定的病原菌也是国内一新记录种;寄生在菊科植物上的单轴霉属种类不尽相同,但亲缘关系紧密。【Aim】To explore a biological control method for the invasive plant Sphagneticola trilobata,we identified a new downy mildew-causing pathogen on S.trilobata.We also performed phylogenetic analysis of the pathogen.【Method】The occurrence of downy mildew on S.trilobata and its damage were investigated in Guangzhou,Guangdong.Based on the host and symptoms of the disease,as well as the comparison of morphological characteristics,the pathogen was identified.Phylogenetic trees were constructed,and the structure of the ITS sequence was analyzed through cloning and sequencing of the LSU and ITS regions of the pathogen.【Result】Downy mildew of S.trilobata occurred sporadically in Guangzhou.The disease on the campus of South China Agricultural University was serious,and the incidence rate of the disease was 50%-70%,while the disease index was 30-35.The pathogen was identified as a newly recorded species,Plasmopara sphagneticolae McTaggart&R.G.Shivas in China.Based on the LSU and ITS sequences,phylogenetic analysis indicated that the isolates of Plasmopara spp.that were parasitic on the plants of Asteraceae were closely clustered in one group suggesting these isolates with close phylogenetic relationship.The ITS sequence structure analysis showed that the ITS2 region of Plasmopara spp.that were parasitic of Asteraceae species contained multiple repetitive units,and this sequence was different among the different species.And the results indicate the Plasmopara parasitized on the different Asteraceae plants could be divided into several distinct species rather than a restricted species of P.halstedii.【Conclusion】This is the first report of downy mildew on S.trilobata in China,and the identified pathogen is a newly recorded species in China.The results of the phylogenetic analysis showed that the parasitic species of Plasmopara on Asteraceae species are different,but their phylogenetic relationships are remarkably close.

关 键 词：南美蟛蜞菊 霜霉病 LSU序列 ITS序列 蟛蜞菊单轴霉 向日葵单轴霉 

分 类 号：S436.8[农业科学—农业昆虫与害虫防治]