烟草根际可培养微生物多样性及防病促生菌的筛选

The culturable microbial diversity in tobacco rhizosphere and their plant growth-promoting and biocontrol properties

摘要:

[背景] 根际微生物在植物根部生态系统中扮演着重要角色，影响着植物的营养吸收和健康生长。[目的] 了解常年不发病烟田烤烟品种K326根际可培养微生物的多样性，筛选具有防病促生功能的菌株，为烟草病害绿色防控提供资源。[方法] 采用传统培养方法对烟草根际土壤中的细菌和真菌进行分离鉴定，评价菌株的促生特性及病原菌拮抗能力，并进一步验证典型菌株对盆栽烟苗的促生效果。[结果] 共获得261株微生物菌株，包括160株细菌和101株真菌。经分子鉴定，细菌中以变形菌门（Proteobacteria）和厚壁菌门（Firmicutes）为主要类群；真菌中以子囊菌门（Ascomycota）和毛霉菌门（Mucoromycota）为主要类群。在属水平上，细菌以假单胞菌属（Pseudomonas）和芽孢杆菌属（Bacillus）为主，真菌以曲霉属（Aspergillus）和青霉属（Penicillium）为主。从不同种水平上进一步选择44株细菌为代表菌株，发现它们均具有不同程度的吲哚-3-乙酸（Indole-3-Acetic Acid，IAA）产生能力，9株能够溶解有机磷，16株能够溶解无机磷，13株产生铁载体，14株产生生1-氨基环丙烷-1-羧酸（1-Aminocyclopropane-1-Carboxylate，ACC）脱氨酶。从160株细菌中筛选得到抑制青枯病菌和黑胫病菌的菌株数目分别为25、26株。经盆栽试验发现韩国假单胞菌（P. koreensis） HCH2-3、浅黄绿假单胞菌（P. lurida） FGD5-2和贝莱斯芽孢杆菌（B. velezensis） EM-1对烟苗呈现不同程度的促生作用，其中3株菌联合施加对烟苗的促生效果最明显。[结论] 烟草根际存在着丰富多样的具有防病促生潜力的微生物，并且合成菌群或功能互补的菌株联合施用是未来微生物菌剂研发的重要方向。

Abstract:

[Background] Studies have shown that rhizosphere microorganisms play an important role in the root ecosystem, influencing the nutrient absorption and health of plant. [Objective] To understand the culturable microbial diversity in the rhizosphere of flue-cured tobacco variety K326 growing in four tobacco fields, which does not occur disease for many years, and to screen strains with the biocontrol and plant-growth promoting function for tobacco diseases control. [Methods] Traditional culture-dependent methods were used to isolate and identify bacteria and fungi in tobacco rhizosphere soil. The plant growth-promoting characteristics and pathogen antagonism of the strains were evaluated, and the growth-promoting effects of typical strains were further verified on tobacco seedlings. [Results] In this study, 261 isolates were obtained, including 160 bacterial strains and 101 fungal strains. Bacterial phyla of Proteobacteria and Firmicutes and fungal phyla of Ascomycota and Mucoromycota are the main groups. At the genus level, Pseudomonas and Bacillus were the most abundant genera in bacteria, and Aspergillus and Penicillium dominated in fungi. Next, 44 bacterial strains were selected from different species as representatives. We found that they all have IAA production ability, 9 strains can dissolve organic phosphorus, 16 strains can dissolve inorganic phosphorus, 13 strains produce siderophores, and 14 strains produce ACC deaminase. 25 and 26 strains that inhibiting the pathogens of bacterial wilt and black shank diseases were obtained from 160 bacterial strains, respectively. The pot experiment found that P. koreensis HCH2-3, P. lurida FGD5-2 and B. velezensis EM-1 can promote growth of tobacco seedlings, and consortium of these three strains has the most obvious growth-promoting effect. [Conclusion] There are numerous microorganisms with the potential to control disease and promote plant growth in the tobacco rhizosphere. Application of synthetic bacteria or functional complementary strains is an important direction for the development of microbial agents in the future.