荷花腐败病病原菌的形态学与多基因分子系统学鉴定

Identification of pathogen causing rhizome rot of lotus(Nelumbo nucifera) based on morphology and multi-gene sequence analysis

荷花(Nelumbo nucifera)是我国十大名花中唯一的水生花卉,在珠三角等湿地广泛栽培。近年来,荷花栽培集中区,大范围发生腐败病,影响了正常的生产与旅游观光产业,为了有效控制病害发生蔓延,生产上急需明确荷花腐败病的病原。本研究通过病原菌致病力测定、形态比较、分子特异检测,以及基于翻译延伸因子(TEF-1α)、rDNA基因内间隔区(IGS)、线粒体小亚基(mtSSU)等基因片段的系统发育分析,对采自广东、广西、江西、福建、湖南、湖北等地的荷花腐败病病原菌进行鉴定及系统发育研究,结果如下:(1)形态学与分子鉴定均表明荷花腐败病菌为Fusarium commune,该菌为尖孢镰孢菌(F.oxysporum)的近缘种,首次在荷花上报道。(2)F.commune与尖孢镰孢菌(F.oxysporum)在形态上非常相似,F.commune能产生长度大于25μm的细长形单瓶梗及偶尔产生复瓶梗的形态特征,区别于F.oxysporum。MtSSU、EF-1及IGS等基因位点可用于F.commune和F.oxysporum这两个种的明确区分。(3)我国不同地区的荷花腐败病菌存在一定的遗传分化,荷花腐败病菌与分离自我国的荸荠枯萎病菌(Fusarium commune)为同一个种。

Lotus（Nelumbo nucifera） was the unique aquatic one ranked in the top ten famous flowers and plants in China,and was cultivated extensively in the pearl river delta wetlands. In recent years,rhizome rot of lotus took place in large area,affecting the production and tourism industry of lotus. In order to effectively control this disease,it is necessary to clarify its causal agent. In this study,the pathogen causing rhizome rot of lotus was identified through pathogenicity tests,morphological studies,specific PCR diagnosis,and phylogenetic analysis based on combined sequences of translation elongation factor 1-α（EF-1α）,the mitochondrial small subunit（mtSSU） ribosomal DNA,and the nuclear ribosomal intergenic spacer region（IGS）. The results showthat：（i） both the morphological and molecular identification confirmed that the pathogen was Fusarium commune,which is a sister taxon of F. oxysporum and was firstly reported on lotus.（ii） F. commune was highly similar to F. oxysporum on morphology,whereas production of longer monophialides（〉25 μm） and polyphialides by F. commune can distinguish it from F. oxysporum. Moreover,DNA sequences of the mt SSU、EF-1α and IGS regions were also useful to distinguish F. commune from F. oxysporum.（iii） Genetic differentiation existed among the pathogens of lotus rot from different areas,and the pathogens of both lotus rhizome rot and Chinese water chestnut（Eleocharis dulcis） wilt belong to the same species.