多功能根际生防促生放线菌的分离鉴定及其对辣椒的益生效果

Screening,identification,and characterizations of antagonistic actinomycetes strains with plant growthpromoting properties and beneficial effects on pepper

从健康辣椒根际土壤筛选具防病促生功能的菌种并应用于生物障碍土壤,可为辣椒提质增产和根腐病的防治提供优质的菌剂资源。本研究以辣椒根腐病的病原菌——腐皮镰孢菌(Fusarium solani)为靶标菌,采用平板对峙法筛选优良生防菌株,对其固氮、溶磷、解钾、分泌3-吲哚乙酸(3-indole acetic acid,IAA)、产铁载体、产纤维素酶和蛋白酶、利用酚酸类连作障碍物质等能力进行定性和定量测定。采用形态学、生理生化及16S rRNA基因序列对分离菌株进行鉴定,并采用田间原位栽培试验检测其生防和促生效果。结果表明,从设施连作抗病辣椒根际土中获得6株具有抑菌作用的放线菌,通过定性、定量测试发现菌株G-1拮抗效果最强,其对设施蔬菜5种常见病原菌均具有较好的抑制效果,抗菌谱广,且具有分泌IAA、产铁载体、产纤维素酶和蛋白酶、溶解有机磷、利用酚酸类化感物质等特性。结合形态学、生理生化及16S rRNA进化树分析结果,将其鉴定为弗氏链霉菌(Streptomyces fradiae)。田间原位栽培试验显示,G-1菌剂对辣椒根腐病具有较好的防病作用,可显著降低根腐病的病情指数,促进辣椒根系生长,且可使辣椒增产31.04%。研究表明,弗氏链霉菌G-1具有优良的防病促生功能,其固体菌剂的田间应用对辣椒根腐病具有较好的防治效果,且对辣椒具有明显的促生增产作用,可作为辣椒益生菌剂的候选菌株资源。

The objective was to screen strains with excellent disease-controlling and plant growth-promoting properties from healthy pepper rhizosphere and apply them to bio-barrier soil,so as to provide probiotic resources for biocontrol of pepper root rot.The plate confrontation method was used to screen biocontrol strains to Fusarium solani,the causal agent of pepper root rot.The nitrogen fixation,phosphate solution,potassium solution,3-indole acetic acid(IAA),siderophore,cellulase,and protease producing capacity and degradation of phenolic acids of the strains were measured.The actinomycetes were identified by morphological,physiological,biochemical,and 16S rRNA gene sequence analysis.In field experiments,plant growth-promoting effects were analyzed by measuring pepper yield and disease index of root rot.A total of six strains of biocontrol actinomycetes showed an antagonistic effect on F.solani.Strain G-1 was explored for the strongest inhibition rates to the five pathogens of the vegetable in greenhouse,and the superior charactersof IAA,siderophore,cellulase,protease producing,organic-phosphorus dissociation and degradation of phenolic acids.Combined withcolony morphological,physiological,biochemical,and 16S rRNA phylogenetic tree analysis,strain G-1 was identified as Streptomycesfradiae.In-situ field experiment showed that the strain G-1 had obvious disease prevention effect on pepper Fusarium root rot(P<0.05).Ithad certain growth-promoting effect on pepper plants,and G-1 increased the yield of pepper by 31.04%.S.fradiae(G-1)is considered aprobiotic resource for pepper green agriculture,and we provide superior microbial inoculants that cater to the yield of pepper and thebiocontrol of Fusarium root rot.