青稞根腐病生防放线菌的筛选及防效研究

Screening and Effect of Biocontrol Actinomycetes against Noked Barley Root Rot

为获得防治青稞根腐病的生防放线菌,从大田采集健康青稞植株及其根际土壤,利用选择性培养基对青稞根表及根际土壤进行放线菌分离筛选;以青稞根腐病原菌木贼镰孢为靶标,利用平板对峙法进行初筛,选取平均抑菌圈大于20 mm的放线菌,用发酵液法进行复筛并计算其生长抑制率;采用盆栽法测定生长抑制率较高菌株的防效及致病性,并通过分子鉴定确定其分类地位。结果表明,从初筛得到16株抑菌圈大于20 mm的放线菌中,复筛得到2株对青稞根腐病生长抑制率大于70%的菌株,分别为H35-1和AP11;测定其对青稞根腐病的防效发现,H35-1的防效为30.74,AP11的防效为48.31。对防效较好菌株AP11的16S rDNA序列进行测定并构建系统发育树发现,其与酸疮癖链霉菌(Streptomyces acidisabies)的遗传距离为零,1000次重复自展支持值为100,鉴定其为酸疮痂链霉菌。致病性分析发现,该酸疮痂链霉菌不具有致病性。本研究为青稞根腐病生防菌剂的研制提供了菌种资源,为青稞根腐病生物防治提供参考。

In order to obtain biocontrol actinomycetes strains against naked barley root rot,samples of healthy naked barley plants and their rhizosphere soil were collected from field,and actinomycetes of naked barley root surface and rhizosphere soil were isolated and screened by selective medium.With Fusarium equisetias the target,a highly pathogenic pathogen of naked barley root rot,primary screening was conducted by dual culture method.Actinomycetes with an average inhibition zone larger than 20 mm were selected and screened again by fermentation broth method to calculate the growth inhibition rate,and the biocontrol effect and pathogenicity of strains with a high growth inhibition rate were measured by pot culture.Finally,the taxonomic status was determined by molecular identification.The results showed that 16 actinomycetes with an inhibition zone larger than 20 mm were obtained through primary screening,of which two strains with a growth inhibition rate above 70%(H35-1 and AP11)were obtained through secondary training.After measuring their biocontrol effect,the control effect of H35-1 was 30.74%,and that of AP11 was 48.31%.After determining the 16S rDNA sequence of AP11 with better biocontrol effect and constructing the phylogenetic tree,the genetic distance between AP11 and Streptomyces acidiscabies was 0 and the bootstrap value of 1000 repetitions was 100,indicating AP11 was identified as a Streptomyces acidiscabies.Pathogenicity analysis found that this Streptomyces acidiscabies had no pathogenicity.This study not only provides effective strain resources for the development of naked barley biocontrol agents,but also lays a solid foundation for the biocontrol of naked barley root rot.