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【目的】大豆是我国重要的农作物,利用大豆-根瘤菌共生体系能有效减少化学氮肥的用量。将初筛的大豆根瘤菌SCAUs8在四川两个重要的大豆种植生态区进行田间接种验证试验,同时对该菌株进行分类地位研究。【方法】在四川丘陵区和攀西地区,采用大田试验调查接种大豆根瘤菌SCAUs8对大豆的增产效果。采用点接种法研究SCAUs8的抗逆性,用Salkowski比色法检测供试菌分泌吲哚乙酸(IAA)的能力。用多位点基因(16S r RNA,atp D,rec A,glnⅡ,nod C,nif H)序列分析对供试菌株SCAUs8进行分类地位的确定。【结果】大田试验表明,接种大豆根瘤菌SCAUs8后,大豆植株的产量、鲜重、干重等指标明显高于不接种对照(CK)处理,其中大豆植株产量比不接种CK增产21.4%-29.7%,其差异达显著水平。对供试菌株SCAUs8进行的耐酸碱性、耐盐性、生长温度范围以及分泌IAA能力测定的结果表明,供试菌株SCAUs8能在p H5.0-10.0正常生长,可耐受Na Cl浓度为0.5%,生长温度范围是10-40°C,能分泌IAA。综合16S r RNA、atp D、rec A、glnⅡ、nod C、nif H基因的序列分析,发现供试菌株SCAUs8与Bradyrhizobium diazoefficiens USDA110T相似性高达100%。【结论】供试菌株SCAUs8是与四川主栽大豆品种共生匹配性较好的广谱菌株。该菌株耐盐性较差,但具有较强的耐酸碱性、较宽的生长温度范围及分泌IAA的能力。系统发育研究将供试菌株SCAUs8确定为B.diazoeffciens。
【Objective】 Soybean is an important crop in China. Using soybean-Rhizobium symbiosis system can effectively reduce the amount of chemical nitrogen fertilizer. The preliminary screening of soybean rhizobia SCAUs8 in two important soybean planting ecotope in Sichuan field inoculation test, at the same time, the taxonomic status of the strain. 【Method】 Field experiments were conducted to investigate the effects of inoculation with soybean rhizobia SCAUs8 on soybean yield in Sichuan hilly area and Panxi area. The inoculation method was used to study the resistance of SCAUs8, and Salkowski’s colorimetric assay was used to test the ability of the tested bacteria to secrete indole acetic acid (IAA). The identification of the taxonomic status of the tested strain SCAUs8 was carried out by using the multi-site gene (16S rRNA, atpD, rec A, glnII, nod C, nif H) sequence analysis. 【Result】 The results of field experiments showed that after inoculated with soybean rhizobia SCAUs8, the yield, fresh weight and dry weight of soybean plants were significantly higher than those of non-inoculated control (CK). The yield of soybean plants increased 21.4% -29.7 %, The difference reached significant level. The results of acid-base resistance, salt tolerance, growth temperature range and IAA secretion assay of the tested strains SCAUs8 showed that the tested strains SCAUs8 can grow normally at p H 5.0-10.0, the tolerable Na Cl concentration is 0.5%, growth temperature range is 10-40 ° C, can secrete IAA. The sequence analysis of 16S rRNA, atp D, rec A, glnⅡ, nod C and nif H gene revealed that the tested strains SCAUs8 and Bradyrhizobium diazoefficiens USDA110T had high similarity of 100%. 【Conclusion】 The tested strain SCAUs8 is a broad-spectrum strain that has good symbiosis with Sichuan main soybean varieties. The salt-tolerant strains of the poor, but with strong acid and alkali resistance, a wide range of growth temperature and the ability to secrete IAA. Phylogenetic study identified the tested strain SCAUs8 as B. diazoeffciens.