滨海盐渍土野大豆根瘤菌分离筛选及其在大豆中的应用

【目的】了解盐渍土野大豆根瘤菌的多样性，筛选具有耐盐促生作用的菌株，为栽培大豆耐盐菌剂的开发提供菌种资源。【方法】采用传统培养方法从滨海盐渍土野大豆中分离根瘤菌，评价菌株的促生特性，并验证其对野大豆和栽培大豆的促生效果。【结果】从野大豆根和根瘤样品中分离出87株根瘤菌，主要为中华根瘤菌属(Sinorhizobium)、根瘤菌属(Rhizobium)和慢生根瘤菌属(Bradyrhizobium)。测定了24株代表性菌株的促生特性，发现有16株根瘤菌具有产吲哚-3-乙酸(indole-3-acetic acid, IAA)能力，6株能够产生1-氨基环丙烷-1-羧酸(1-amino-cyclopropane-1- carboxylic, ACC)脱氨酶，16株具有溶磷活性，6株能够产生铁载体。根据以上促生特性，选择了11株优良根瘤菌进行野大豆促生和结瘤能力评价，发现美洲中华根瘤菌(Sinorhizobium americanus) DL3的性能优于其他菌株。最后，通过盆栽试验检测了菌株DL3对野大豆和栽培大豆耐盐能力的影响，发现菌株DL3在盐胁迫下能促进野大豆和大豆的生长，同时，降低了叶片脯氨酸水平，缓解了植物的盐胁迫程度。【结论】菌株DL3在提高植物耐盐性方面具有一定的作用，对实现大豆的盐碱地种植具有重要的理论意义和实践价值。

Glycine soja-associated rhizobia: isolation from coastal saline soil and application in soybean

Objective] To investigate the rhizobial diversity of wild soybean (Glycine soja) in saline soil and screen out the salt-tolerant and plant growth-promoting strains for the cultivation of soybean. Methods] We used the culture-dependent method to isolate rhizobia from wild soybean growing in coastal saline soil and then evaluated their growth-promoting characteristics and effects on wild soybean and cultivated soybean. Results] A total of 87 rhizobial strains were isolated from the root and nodule samples of wild soybean, belonging to Sinorhizobium, Rhizobium, and Bradyrhizobium. Next, 24 strains of different species or from different samples were selected as representatives. Among the 24 strains, 16, 6, 16, and 6 strains had the abilities of producing indole-3-acetic acid (IAA), producing 1-amino-cyclopropane-1-carboxylic (ACC) deaminase, dissolving phosphorus, and producing siderophores, respectively. According to the above growth-promoting characteristics, we evaluated the growth-promoting and nodulation effects of 11 strains on wild soybean. The performance of Sinorhizobium americanus DL3 was superior to that of other strains. Finally, pot experiments were carried out to examine the effects of strain DL3 on the salt tolerance of wild soybean and cultivated soybean. Strain DL3 promoted the growth and lowered the level of proline in leaves, thus alleviating the salt stress of wild soybean and cultivated soybean. Conclusion] Strain DL3 improves the salt tolerance of plants, which has important theoretical and practical significance for soybean cultivation in saline soil.