番茄根内促生放线菌的分离鉴定及其促生效果

【背景】植物体内普遍存在一定数量的内生放线菌,对植物的生长发育具有促生作用。【目的】从番茄根内分离、筛选并鉴定出能够有效促进植物生长发育的内生放线菌,为生物菌肥的开发奠定基础。【方法】采用组织研磨培养法和放线菌分离培养基对番茄根内放线菌进行分离,利用Salkowski比色法、钼锑抗比色法和CAS平板检测法进一步筛选出具有较强促生特性的菌株,通过番茄和黄瓜苗期盆栽试验验证其促生效果。结合形态、生理生化以及16S r RNA基因序列相似性和系统发育分析,对菌株进行鉴定。【结果】分离筛选出一株吲哚乙酸(Indole-3-acetic acid,IAA)产量达25.56 mg/L的内生放线菌NEAU-D1,能够产生铁载体并且对多种难溶性磷酸盐具有良好溶解效果,通过16S r RNA基因序列分析,该菌株属链霉菌属。番茄和黄瓜苗期盆栽试验结果表明,接种该菌株的番茄幼苗其根长、株高、植株鲜重和干重较对照分别显著增加了9%、23%、47%和92%,而接种该菌株的黄瓜幼苗根长、株高、植株鲜重和干重较对照分别显著增加了43%、47%、134%和58%。【结论】链霉菌NEAU-D1可以作为潜在的促生菌资源用于设施蔬菜多功能生物菌肥的研发。

Isolation and identification of tomato-associated endophytic actinomyces and their potential for plant growth promotion

Background] Endophytic actinomycetes are ubiquitous in all the plant species. The use of plant growth-promoting endophytes has become of great interest as a way to enhance plant growth. Objective] Endophytic actinomyces that could effectively promote the growth of plant were isolated, screened and identified from the tomato root, laying a foundation for the development of biological fertilizer. Methods] Endophytic actinomyces in the tomato root were isolated with tissue sand culture method and actinomyces isolation medium; bacterial strains with strong growth promotion characteristic were screened through Salkowski colorimetric method, Mo-Sb colorimetric method and CAS plate detection method, and their growth promotion effect was verified through the pot experiment of tomato and cucumber seedling. Bacterial strains were identified through analyses of morphology, physiological biochemistry, 16S rRNA gene sequence similarity and phylogeny. Results] Endophytic actinomyces NEAU-D1 with an Indole-3-acetic acid (IAA) yield of 25.56 mg/L was isolated and screened, which could produce siderophore and had good dissolving effect on various insoluble phosphate. 16S rRNA gene sequence analysis showed that the bacterial strains were Streptomyces. Pot experiment of tomato and cucumber seedling showed that, compared with the control group, the root length, plant height, fresh weight and dry weight of the tomato seedling were significantly increased by 9%, 23%, 47% and 92% respectively, while those of the cucumber seedling were significantly increased by 43%, 47%, 134% and 58% respectively. Conclusion] Streptomyces NEAU-D1 can be used as a potential growth promoting endophytic actinomyces for the research and development of multifunctional biological fertilizer for facility vegetables.