野大豆内生假单胞菌YDX26的鉴定及促生抗逆特性

Identification of endophytic Pseudomonas sp. YDX26 in Glycine soja and its growth-promoting and stress-resistant characteristics

摘要:

[背景] 野大豆具有栽培大豆所不具有的一些优良特性，这与其特有内生菌有关，已成为当下研究热点。[目的] 对野大豆内生细菌进行分离鉴定，并从中筛选出具有促生和抗逆潜能菌株。[方法] 以组织分离法和涂布划线法进行细菌分离培养；根据形态特征、生理生化特性及基于16S rRNA基因序列系统发育分析对菌株进行菌种鉴定；通过选择性培养基或比色法等对菌株进行促生特性分析，采用水培试验分析菌株对水稻幼苗生长的影响；利用盐胁迫及聚乙二醇（Polyethylene Glycol，PEG）-6000模拟干旱胁迫探究菌株抗逆性。[结果] 分离得到一株编号为YDX26的细菌，基于菌株形态、理化特性和16S rRNA基因序列系统发育分析，将菌株YDX26初步鉴定为假单胞菌（Pseudomona s sp.）。该菌株溶磷量为46.12 mg/L，吲哚-3-乙酸（Indole-3-Acetic Acid，IAA）活性为19.97 μg/mL， 1-氨基环丙烷-1-羧酸（1-Amino-Cyclopropane-1-Carboxylic Acid，ACC）脱氨酶活性为3.95μmol/（mg·h）。菌株YDX26对水稻幼苗株高、根长、地上部干重与地下部干重均有明显促进作用，分别提高了17.34%、12.19%、5.32%和10.70%。相较于对照菌株DX22，在盐胁迫和干旱胁迫下，菌株YDX26表现出较好的耐盐和抗旱能力。[结论] 野大豆内生细菌菌株YDX26具有较好的促生、耐盐和抗旱能力，可以作为农业生产上新的菌种资源。

Abstract:

[Background] Glycine soja has some excellent characteristics over the cultivated soybean, which is related to its unique endophytic bacteria and has become a research hotspot. [Objective] The endophytic bacteria of G. soja were isolated and identified. The strains with growth-promoting activity and stress-resistant potential were screened out. [Methods] The endophytic bacteria were isolated by tissue culture and streaking method. The strains were identified based on morphological, physiological, and biochemical characteristics and the 16S rRNA gene sequence-based phylogenetic analysis. The growth-promoting characteristics of the strains were analyzed by selective media or colorimetric method. Hydroponic experiment was carried out to analyze the effect of strain on the growth of rice seedlings. Salt stress and PEG-6000 simulated drought stress were used to explore the stress resistance of the strain. [Results] A strain YDX26 was isolated. According to the morphological, physiological and biochemical characteristics, and the results of phylogenetic analysis based on 16S rRNA gene sequence, the strain YDX26 was primarily identified as Pseudomonas sp. This strain had the phosphorus solubilization of 46.12 mg/L, the IAA activity of 19.97 μg/mL, and the ACC deaminase activity of 3.95 μmol/(mg·h). Moreover, it significantly increased the height, root length, aboveground dry weight, and underground dry weight of rice seedlings by 17.34%, 12.19%, 5.32%, and 10.70%, respectively. Compared with the control strain DX22, strain YDX26 showed improved salt and drought tolerance. [Conclusion] The endophytic bacterial strain YDX26 has better growth-promoting ability and salt and drought tolerance, and thus can be used as a new strain resource for agricultural production.