新疆鼠尾草内生细菌多样性及功能菌株筛选

Diversity and functional strain screening of endophytic bacteria isolated from the medicinal plant Salvia deserta Schangin

摘要:

【背景】植物内生细菌与宿主植物长期共同进化的过程中，能够与宿主植物形成互利共生的关系。植物生长环境的改变会影响植物内生细菌的种类、数量及分布，而内生细菌具有增强植物抗病性、促进植物生长等作用。新疆鼠尾草(Salvia deserta Schangin)是一种具有多种药理活性的植物，而有关新疆鼠尾草的内生细菌研究较少，具有潜在的研究价值。【目的】探究新疆鼠尾草内生细菌的多样性并挖掘药用植物内生细菌资源。【方法】通过纯培养分离方法对3个地区药用植物新疆鼠尾草组织进行内生细菌的分离纯化，基于16S rRNA基因序列分析探究3个地区新疆鼠尾草内生细菌的多样性；对分离获得的部分菌株进行产酶、促生属性和拮抗能力的筛选。【结果】从新疆3个地区新疆鼠尾草中共分离获得386株内生细菌，经鉴定隶属于3个门4个纲6个目14个科23个属70个种，主要优势属为短小杆菌属(Curtobacterium)、假单胞菌属(Pseudomonas)、芽孢杆菌属(Bacillus)和肠杆菌属(Enterobacter)；相对低海拔低降水量的新源地区新疆鼠尾草内生细菌物种多样性较昭苏和霍城地区更高；新疆鼠尾草经80 ℃、1 h处理后分离得到的放线菌门(Actinomycetota)高于常温处理，并且属水平上的多样性有所提高；共鉴定出68株菌具有溶磷能力，80株菌具有固氮能力，35株菌具有产铁载体能力，47株菌可以产生蛋白酶，57株菌可以产生纤维素酶；拮抗试验表明有48株菌对苹果树腐烂病病原菌黑腐皮壳菌(Valsa mali)有抑制效果，有37株菌对番茄枯萎病病原菌尖孢镰刀菌(Fusarium oxysporum)有抑制效果，有20株菌对哈密瓜根腐病病原菌少根根霉(Rhizopus arrhizus)有抑制效果。【结论】新疆鼠尾草内生细菌具有丰富的物种多样性，不同生境的新疆鼠尾草内生细菌丰度存在差异。部分新疆鼠尾草内生细菌在促生及抗真菌活性方面具有一定潜力。

Abstract:

[Background] Endophytic bacteria form a mutually beneficial symbiotic relationship with the host plant in the process of long-term co-evolution. The growth environment of plants will affect the species, number, and distribution of endophytic bacteria. Endophytic bacteria have the effects of enhancing plant resistance to diseases and promoting plant growth. Salvia deserta Schangin is a plant with a variety of pharmacological activities. However, there are few studies on the endophytic bacteria of S. deserta Schangin, which have a potential research value. [Objective] To explore the diversity of endophytic bacteria in S. deserta Schangin and explore the endophytic bacterial resources of medicinal plants. [Methods] The culture-dependent method was used to isolate endophytic bacteria of S. deserta Schangin growing in three regions. The diversity of endophytic bacteria was explored by 16S rRNA gene sequence analysis. Some of the isolated strains were characterized in terms of enzyme production, growth-promoting properties, and antifungal effect. [Results] A collection of 386 strains of endophytic bacteria were isolated from S. deserta Schangin, and they were identified as 70 species belonging to 23 genera, 14 families, 6 orders, 4 classes of 3 phyla. The dominant genera were Curtobacterium, Pseudomonas, Bacillus, and Enterobacter. The diversity of endophytic bacteria of S. deserta Schangin in Xinyuan with lower altitude and precipitation was higher than that in Zhaosu and Huocheng. The Actinomycetota strains isolated from S. deserta Schangin samples treated at 80 ℃ for 1 h were more than those from the samples treated at room temperature, and the diversity of S. deserta Schangin at the genus level was significantly improved after the high temperature treatment of the plant samples. A total of 68, 80, 35, 47, and 57 strains were able to solubilize potassium, fix nitrogen, produce siderophores, produce protease, and produce cellulase, respectively. In addition, 48, 20, and 37 strains showed inhibitory effects on Valsa mali, Rhizopus arrhizus, and Fusarium oxysporum, respectively. [Conclusion] S. deserta Schangin harbors rich endophytic bacteria. The abundance of endophytic bacteria is different among hosts in different habitats. Some endophytic bacteria have the potential of promoting plant growth and antifungal effect.