产吲哚乙酸耐盐促生菌的筛选及其对盐胁迫下油莎豆幼苗的促生作用

Screening and effect evaluation of IAA-producing salt-tolerant bacterial strains promoting the growth of Cyperus esculentus seedlings under salt stress

摘要:

【背景】 油莎豆具有抗逆性强、适应性广、耐瘠薄等特性，是一种集粮、油、牧、饲、药、绿化观赏于一体的高产经济作物，适宜在新疆维吾尔自治区土壤盐碱化的后备耕地进行种植。【目的】 从新疆维吾尔自治区盐碱沙土中筛选高产吲哚乙酸(indole-3-acetic acid, IAA)的耐盐促生菌，提高油莎豆中高盐胁迫下的耐受性，进而为新疆维吾尔自治区盐碱沙土改良提供菌种资源。【方法】 采用传统定向筛选培养基培养、摇瓶培养和16S rRNA基因鉴定的方法，从新疆维吾尔自治区盐碱沙土筛选产IAA耐盐促生菌并测定其促生特性，通过油莎豆种子萌发和盆栽幼苗试验进一步验证产IAA耐盐促生菌的促生效果。【结果】 从新疆维吾尔自治区盐碱沙土中分离出4株(Y8, Y35, Y46, Y4-20)高产IAA菌株，分别为鲁戈斯芽孢杆菌(Bacillus rugosus)、阿氏芽孢杆菌(Bacillus aryabhattai)、耐盐芽孢杆菌(Bacillus halotolerans)和南极碱盐单胞菌(Halomonas alkaliantarctica)。4株菌均具有耐盐、固氮和解无机磷能力，菌株Y35、Y46、Y4-20还具有解钾能力。油莎豆种子萌发和盆栽幼苗试验结果表明，4株产IAA耐盐促生菌在盐胁迫下均能促进油莎豆种子萌发和幼苗生长，其中菌株Y8对种子萌发和幼苗生长效果尤为突出。【结论】 新疆维吾尔自治区盐碱沙土中存在高产IAA的耐盐促生菌，可提高油莎豆在中高盐胁迫下的耐受性，本研究可为新疆维吾尔自治区盐碱沙土改良提供微生物肥料菌种资源。

Abstract:

[Background] Cyperus esculentus, a high-yield cash crop with remarkable stress and barren soil tolerance and broad adaptability, serves multiple purposes including grain production, oil extraction, forage production, medicinal applications, and ecological landscaping. Its cultivation holds significant potential for rehabilitating saline-alkali abandoned farmlands in Xinjiang. [Objective] To isolate salt-tolerant plant growth-promoting rhizobacteria (PGPR) with high indole-3-acetic acid (indole-3-acetic acid, IAA) production from the saline-alkali sandy soils in Xinjiang to enhance C. esculentus tolerance to moderate-to-high salt stress, thereby providing microbial resources for soil amelioration. [Methods] Bacteria were screened via selective culture, shake-flask fermentation, and 16S rRNA gene sequencing. The plant growth-promoting effects of these bacteria were determined. The plant growth-promoting effects of these bacteria were then examined through seed germination and pot experiments with C. esculentus under salt stress. [Results] Four IAA-producing strains were isolated as Y8, Y35, Y46, and Y4-20, which were identified as Bacillus rugosus, Bacillus aryabhattai, Bacillus halotolerans, and Halomonas alkaliantarctica, respectively. All the four strains demonstrated salt tolerance, nitrogen fixation, and inorganic phosphate solubilization. Furthermore, Y35, Y46, and Y4-20 exhibited potassium-solubilizing ability. The results from both seed germination and pot experiments demonstrated that all the four IAA-producing salt-tolerant PGPR strains significantly promoted the seed germination and seedling growth of C. esculentus under salt stress. Notably, strain Y8 exhibited particularly outstanding promotion effects. [Conclusion] The saline-alkali soils in Xinjiang harbor salt-tolerant PGPR with high IAA production, which can significantly enhance the salt tolerance of C. esculentus under moderate-to-high salt stress. This study provides valuable microbial resources for developing bio-fertilizers to ameliorate saline-alkali soils in Xinjiang.