吉林省玉米穗腐病致病镰孢菌的鉴定与部分菌株对杀菌剂的敏感性

Identification of Pathogenic Fusarium spp. Causing Maize Ear Rot and Susceptibility of Some Strains to Fungicides in Jilin Province

【目的】明确吉林省玉米穗腐病主要致病镰孢种群分布及杀菌剂对镰孢菌菌丝生长的抑制效果,为针对性地开展玉米镰孢穗腐病的防治提供依据。【方法】通过组织分离法和分子生物学方法对2020年采自吉林省36个市(县)的149份玉米穗腐病样品进行病原菌分离鉴定,利用禾谷镰孢复合种(Fusarium graminearum species complex,FGSC)毒素合成相关基因特异性引物检测其产生毒素的化学型,对部分禾谷镰孢复合种进行致病力测定;采用菌丝生长速率法测定7种杀菌剂对禾谷镰孢复合种的抑制效果。【结果】分离获得233株镰孢菌,隶属4个镰孢复合种,含9种镰孢菌,包括拟轮枝镰孢(F.verticillioides)、布氏镰孢(F.boothii)、禾谷镰孢(F.graminearum)、层出镰孢(F.proliferatum)、亚洲镰孢(F.asiaticum)、厚垣镰孢(F.chlamydosporum)、藤仓镰孢(F.fujikuroi)、木贼镰孢(F.equiseti)和亚黏团镰孢(F.subglutinans),分离频率依次为33.05%、26.18%、25.32%、12.45%、0.86%、0.86%、0.43%、0.43%和0.43%,其中禾谷镰孢复合种分离频率最高,为52.36%,是吉林省玉米穗腐病的优势致病镰孢菌。布氏镰孢、禾谷镰孢和亚洲镰孢在禾谷镰孢复合种中的占比分别为50.00%、48.36%和1.46%。系统发育树结果表明禾谷镰孢复合种种间、种内遗传多样性均较为丰富。致病力测定结果表明52.73%的禾谷镰孢复合种为中致病型菌株,东部玉米主产区分离的禾谷镰孢致病力最强。毒素化学型检测表明,亚洲镰孢为雪腐镰刀烯醇(NIV)化学型,禾谷镰孢与布氏镰孢为15-乙酰基-脱氧雪腐镰刀烯醇(15-AcDON)化学型。7种杀菌剂抑制禾谷镰孢复合种菌丝生长的EC50介于0.02-19.45μg·mL^(-1),其中咯菌腈(FS)、抑霉唑(FS)、氟硅唑(EC)、戊唑醇(TC)和腈菌唑(EW)对禾谷镰孢复合种抑制效果较好且差异不大,EC50小于1.20μg·mL^(-1),EC90小于100μg·mL^(-1);30%吡唑醚菌酯抑制禾谷镰孢和布氏镰孢生长的EC50差异明显,抑制禾谷镰孢的EC50是布氏镰孢的10.24倍。【结论】吉林省不同玉米产区的玉米穗腐病的优势致病镰孢不同,东部和西部为禾谷镰孢和布氏镰孢,中部为拟轮枝镰孢。禾谷镰孢复合种种间、种内遗传多样性均较丰富。咯菌腈、抑霉唑、氟硅唑、戊唑醇和腈菌唑对禾谷镰孢复合种的抑菌效果较好且在禾谷镰孢复合种间的药剂敏感性差别不明显。

【Objective】The objective of this study is to clarify the population distribution of Fusarium spp.of maize ear rot in Jilin Province and the inhibitory effect of fungicides on the growth of Fusarium mycelium,and to provide a basis for the targeted control of maize ear rot.【Method】149 samples of maize ear rot collected from 36 cities and counties in Jilin Province in 2020 were isolated and identified by tissue isolation and molecular biology methods.The specific toxin synthesis primers of related genes were synthesized using Fusarium graminearum species complex (FGSC) toxin.The toxigenic chemotypes were detected,and the pathogenicity of some FGSC was determined.The inhibitory effect of 7 fungicides on FGSC was determined by the mycelial growth rate method.【Result】A total of 233 Fusarium strains were isolated,belonging to 4 Fusarium complex species,including 9 Fusarium species,which were F.verticillioides,F.boothii,F.graminearum,F.proliferatum,F.asiaticum,F.chlamydosporum,F.fujikuroi,F.equiseti and F.subglutinans.The isolation frequencies were 33.05%,26.18%,25.32%,12.45%,0.86%,0.86%,0.43%,0.43%and0.43%,respectively.The isolate frequency of FGSC was the highest,which was 52.36%,and it was the dominant pathogen of maize ear rot in Jilin Province.The proportions of F.boothii,F.graminearum and F.asiaticum in FGSC were 50.00%,48.36% and 1.46%,respectively.The phylogenetic tree showed that the interspecific and intraspecific genetic diversity of FGSC was rich.The results of pathogenicity assay showed that 52.73% of FGSC were medium pathogenic strains.F.graminearum isolated from the main maize producing areas in the east had the strongest pathogenicity.Toxigenic chemotype detection showed that F.asiaticum produced nivalenol (NIV) chemotype,F.graminearum and F.boothii produced 15-acetyl-deoxynivalenol (15-AcDON) chemotype.The EC50of the 7 fungicides for inhibiting the growth of FGSC ranged from 0.02 to 19.45μg·mL^(-1).Fludioxonil (FS),imazalil (FS),flusilazole(EC),tebuconazole (TC) and myclobutanil (EW) had good inhibitory effects on FGSC and the difference was not significant.The EC50of FGSC was less than 1.20μg·mL^(-1)and EC90was less than 100μg·mL^(-1).The difference of EC50between F.graminearum and F.boothii was significant under 30% pyraclostrobin treatment.The EC50of F.graminearum was 10.24 times higher than that of F.boothii.【Conclusion】The dominant pathogenic Fusarium of maize ear rot in different maize producing areas of Jilin Province is different.F.graminearum and F.boothii are dominant species in the east and west,and F.verticillioides is dominant species in the middle.The interspecific and intraspecific genetic diversity of FGSC is rich.Fludioxonil,imazalil,flusilazole,tebuconazole and myclobutanil have better antifungal effect on FGSC.There is no significant difference in the fungicides susceptibility among FGSC.