Rhizobial diversity from stem and root nodules of Discolobium and Aeschynomene

Among the genera that exhibit stem nodulation, Aeschynomene and Discolobium are found in the Pantanal Mato-grossense (wetlands in the state of Mato Grosso, Brazil). Isolates obtained from the stem and root nodules of D. pulchellum, D. psoraleaefolium, D. leptophyllum and A. fluminensis were collected from various locations in the Pantanal de Poconé sub-region and phenotypically characterized and genotyped by restriction analysis of the 16S rDNA gene. Of the 282 isolates obtained from the stem and root nodules, 84.3% alkalized YMA media and 74.1% showed slow growth. No differences in either the phenotype or the genotype among the rhizobial populations isolated from the root or stem nodules of the species Discolobium and A. fluminensis were observed. Among the isolates obtained from D. pulchellum, there was a group that was not similar to any of the reference strains used, and most of the isolates analyzed by PCR-RFLP were similar to the genus Bradyrhizobium.在具备茎结瘤（stem nodulation）特性的菌属中，田菁属（Aeschynomene）与碟形豆属（Discolobium）分布于巴西马托格罗索州境内的马托格罗索潘塔纳尔湿地（Pantanal Mato-grossense）。研究人员从潘塔纳尔波科内亚区（Pantanal de Poconé sub-region）的多个采样点，采集了分离自D. pulchellum、D. psoraleaefolium、D. leptophyllum及A. fluminensis的茎部与根部根瘤的菌株，并对其开展了表型表征与16S核糖体DNA（16S rDNA）基因限制性酶切分析的基因分型鉴定。在总计282株从茎部与根部根瘤分离得到的菌株中，84.3%的菌株可使酵母甘露醇琼脂（YMA）培养基发生碱化反应，74.1%的菌株表现出缓慢生长特性。未观察到分离自碟形豆属与A. fluminensis的根部根瘤、茎部根瘤的根瘤菌种群在表型或基因型层面存在差异。在分离自D. pulchellum的菌株中，存在一类与本次研究所用全部参考菌株均不具有相似性的类群；而经聚合酶链式反应-限制性片段长度多态性（PCR-RFLP）分析的绝大多数菌株，均与布拉迪根瘤菌属（Bradyrhizobium）具有较高相似性。