江苏省水稻恶苗病菌种群鉴定及抗药性检测

Population identification and resistance detection of the pathogen causing rice bakanae disease in Jiangsu province

由藤仓赤霉复合种Gibberella fujikuroi species complex引起的恶苗病(rice bakanae disease)是严重危害水稻的种传病害。为探明江苏省水稻恶苗病菌的种群结构及对多菌灵、咪鲜胺和氰烯菌酯的抗药性现状,分别对2019年江苏省13个县(市)和2020年18个县(市)采集的恶苗病植株样本的123株和182株单孢菌株进行了形态学初步鉴定,并基于翻译延伸因子1-α(translation elongation factor 1-α,TEF1-α)序列对其进行了分子鉴定和系统发育分析;采用区分剂量法分别检测了菌株对多菌灵、咪鲜胺和氰烯菌酯的抗药性。结果表明,2019年和2020年收集的菌株均被鉴定为藤仓镰孢Fusarium fujikuroi、拟轮枝镰孢F.verticillioides、层出镰孢F.proliferatum和新知镰孢F.andiyazi,分别占比为87.80%、4.07%、5.69%、2.44%和90.11%、1.65%、2.75%、5.49%;基于TEF1-α序列的系统发育分析,镰孢菌可清晰分为4个不同种群,菌株间具遗传多样性。2019年和2020年菌株对多菌灵、咪鲜胺和氰烯菌酯的总抗性频率分别为67.48%、23.58%、9.76%和41.21%、43.96%、29.12%。依据菌株对3种杀菌剂的抗药性表现,可分为7种表现型,其中2019年和2020年对多菌灵、咪鲜胺和氰烯菌酯有抗性的菌株分别占4.07%和1.65%;对多菌灵、咪鲜胺和氰烯菌酯敏感的菌株分别占28.46%和17.58%。江苏省恶苗病菌优势种为藤仓镰孢,病菌对多菌灵和咪鲜胺抗性频率较高,对氰烯菌酯抗性已逐渐扩展。研究结果可为镰孢菌分类鉴定及水稻恶苗病综合防治提供理论依据。

Rice bakanae disease(RBD)caused by Gibberella fujikuroi species complex(GFSC)is a serious seed-borne disease of rice(Oryza sativa L.).In order to investigate the population structure and the resistance of the pathogen of RBD to carbendazim,prochloraz and phenamacril in Jiangsu province,123 and 182 single-spore strains collected from RBD-infected rice plants in 13 and 18 counties(cities)in Jiangsu province in 2019 and 2020 were preliminarily identified by morphology,respectively,and then molecular identification and phylogenetic analysis based on translation elongation factor 1-α(TEF1-α)sequences were conducted,and their resistance to carbendazim,prochloraz and phenamacril was detected by using a distinguishing dosage method.The results showed that the strains collected in 2019 and 2020 were identified as Fusarium fujikuroi,F.verticillioides,F.proliferatum and F.andiyazi,accounting for 87.80%,4.07%,5.69%,2.44%and 90.11%,1.65%,2.75%,5.49%,respectively.Phylogenetic analysis based on TEF1-αsequences showed abundant inter-and intra-specific genetic variations among the strains,which were clearly grouped into four different populations.The total resistance frequency of different strains to carbendazim,prochloraz and phenamacril were 67.48%,23.58%,9.76%and 41.21%,43.96%,29.12%in 2019 and 2020,respectively.According to the resistance phenotypes of all strains to three fungicides,seven resistance types were identified.In 2019 and 2020,the strains resistant to carbendazim,prochloraz and phenamacril accounted for 4.07%and 1.65%,respectively,and the strains sensitive to carbendazim,prochloraz and phenamacril accounted for 28.46%and 17.58%,respectively.The dominant population of the pathogens of RBD in Jiangsu province was F.fujikuroi.The pathogens of RBD in Jiangsu province had relatively high resistance frequencies to carbendazim and prochloraz,and their resistance to phenamacril was gradually expanding.These results provided a theoretic and scientific basis for Fusarium taxonomy and integrated control of RBD.