辣椒根际细菌的分离筛选及回接辣椒促生效果

Isolation and Screening of Bacteria from Pepper Rhizosphere and their Growth-Promoting Effects on Pepper

为验证在种苗基质培养中添加作物自身根际细菌的促生效应,本研究以辣椒为研究对象,利用16S rDNA高通量测序分析其根际细菌的组成特征,通过平板培养分离纯化辣椒特征细菌群落;对分离的根际细菌采用对峙试验分析其对9种辣椒病原菌的抑制作用,采用平板筛选的方法分析其解磷、铁载体和IAA活性;利用基质盆栽试验将筛选的活性菌株单独或混合接种同品种辣椒,测定其鲜重、根长和叶面积,验证菌株促生效果。结果表明,在辣椒3个生长期(幼苗期、初花期、结果期)相对丰度均在前30的细菌属有14个,通过平板分离鉴定得到其中7个属的82株细菌。通过抑菌试验及对促生指标的检测,筛选出15株同时具有抑菌及促生活性的细菌进行基质盆栽试验,结果表明,多粘类芽孢杆菌(Paenibacillus polymyxa)W33等9株菌显著提高根鲜重,解淀粉芽孢杆菌(Bacillus amyloliquefaciens)W3-F9等13株菌显著提高根长,多粘类芽孢杆菌W33显著提高地上部鲜重,根瘤菌(Rhizobium sp.)W38-2等4株菌显著提高根冠比,其中多粘类芽孢杆菌W33对辣椒的促生作用最显著,混合菌接种的促生效果整体优于单菌接种。

In order to verify the growth-promotion effect of adding crop’s own rhizospheric bacteria into seedling culture substrates,pepper was used as research object to analyze the composition characteristics of bacteria in its rhizosphere using 16 S rDNA high-throughput sequencing,and then the characteristic bacterial communities were isolated and purified by plate culture.The isolated rhizospheric bacteria were analyzed on antibacterial effect against 9 pepper pathogens using confrontation test and the phosphate solubilization,siderophore and IAA activities using plate screening.The selected active strains were individually or mixed used to treat the same variety of pepper through a substrate pot experiment,and the fresh weight,root length and leaf area were measured to verify their growth promotion effect.The results showed that there were 14 bacterial genera with relative abundances at Top30 in the three growth phases of pepper(seedling,flowering and fruiting stages),and 82 strains from 7 genera of them were identified by plate isolation.After plate tests of antibacterial and growth promotion indicators,15 bacteria strains with both antibacterial and growth promotion properties were screened for substrate pot test.The results showed that nine strains e.g.Paenibacillus polymyxa W33 significantly increased root fresh weight;13 strains e.g.Bacillus amyloliquefaciens W3-F9 significantly increased root length;P.polymyxa W33 significantly increased the fresh weight of aboveground part;4 strians e.g.Rhizobium sp.W38-1 significantly increased the root-shoot ratio.Of all the strains,P.polymyxa W33 had the most significant growth-promotion effect on pepper,and that of mixed bacteria inoculation was better than that of single bacteria inoculation.