一株地黄根腐病致病菌的鉴定及生物学特性研究

Identification and biological characterization of a fungal strain causing root rot of Rehmannia glutinosa

根腐病作为地黄连作障碍中一种较为严重的土传病害,严重影响地黄药材的品质与产量。该研究对采自河南温县地黄种植间隔根际土壤进行致病真菌的分离、致病性测定、形态学特征及分子生物学特性鉴定确定地黄根腐病主要致病菌,并对致病菌进行生物学特性研究。结合RPB2与EF1-α基因序列比对及系统发育分析,将其鉴定为镰状镰刀菌Fusarium falciforme,该菌侵染地黄引起根腐病害尚未见报道,是一株的新型致病菌。生物学特性结果表明,该菌株最适培养条件:马铃薯葡萄糖琼脂(PDA)培养基、28℃、全光照。该菌株对pH不敏感;以蔗糖、麦芽糖和葡萄糖为碳源时生长较快,以硝酸钠、硝酸钾、硫酸铵、硝酸铵、尿素为氮源时,菌丝生长速率均有所下降,但在菌丝浓密程度上均大于察氏阴性对照组。其中,以硝酸钠为氮源菌丝生长最快。菌丝和孢子的致死温度分别为69、61℃。对该病菌的分离鉴定及生物学特性研究,为地黄根腐病害有效防控提供了重要依据。

Root rot is a serious soil-borne disease in the field of Rehmannia glutinosa with continuous cropping obstacle,which se-riously affects the quality and yield of Rehmanniae Radix.In this study,a fungal strain causing root rot of R.glutinosa was isolated from the rhizosphere soil of R.glutinosa planted in Wenxian county,Henan province and identified based on the morphological characteristics and molecular evidence.The pathogenicity and biological characteristics of the isolate were studied.The sequence alignments of RPB2 and EF1-αgenes and the phylogenetic analysis identified the isolate as Fusarium falciforme.This pathogen has not been reported to cause root rot in R.glutinosa,being a new pathogen.The optimal culture conditions of the strain were PDA medium,28℃,full light.The strain was not sensitive to pH.The strain experienced rapid mycelial growth with sucrose,maltose,and glucose as the carbon sources.Although the mycelial growth of the strain slowed down when sodium nitrate,potassium nitrate,ammonium sulfate,ammonium nitrate,and urea were used as nitrogen sources,the mycelial density was greater than that of the Czapek negative control group.The mycelial growth was the fastest when sodium nitrate was used as the nitrogen source.The lethal temperatures for mycelia and spores of the strain were 69,61℃,respectively.The findings provide a basis for the prevention and control of root rot in R.glutinosa.