Division of Crop Sciences, Central Research Institute for Dryland Agriculture, Hyderabad, India.
FEMS Microbiol Lett. 2012 Nov;336(2):148-58. doi: 10.1111/1574-6968.12001. Epub 2012 Oct 18.
Millettia pinnata (Synonym Pongamia pinnata) is a viable source of oil for the mushrooming biofuel industry, source for agroforestry, urban landscaping, and the bio-amelioration of degraded lands. It also helps in maintaining soil fertility through symbiotic nitrogen fixation. However, not much work is reported on classification and characterization of the rhizobia associated with this plant. In the present study, an attempt was made to isolate rhizobial strains nodulating Millettia from soils collected from southern regions of India. The isolates were characterized using numerical taxonomy, 16S rRNA gene sequencing, and cross nodulation ability. The results showed high phenotypic and genetic diversity among the rhizobia symbiotic with Millattia pinnata. The isolates formed five clusters at similarity level of 0.82 based on the results of numerical taxonomy. Results on 16S rRNA gene sequence analysis revealed that most microsymbionts of M. pinnata belonged to Rhizobium and Bradyrhizobium, which are closely related to Rhizobium sp., B. elkanii and B. yuanmingense. Among these isolates, some isolates could grow in a pH range of 4.0-10.0, some could tolerate a high salt concentration (3% NaCl) and could grow at a maximum temperature between 35 and 45 °C. M. pinnata formed nodules with diverse rhizobia in Indian soils. These results offered the first systematic information about the microsymbionts of M. pinnata grown in the soils from southern part of India.
重瓣紫荆（别名麻疯树）是生物燃料产业蓬勃发展的一种可行的油源，也是农林业、城市景观美化和退化土地生物改良的来源。它还通过共生固氮帮助维持土壤肥力。然而，关于与这种植物相关的根瘤菌的分类和特性研究报告并不多。在本研究中，尝试从印度南部地区采集的土壤中分离出能与重瓣紫荆共生的根瘤菌菌株。通过数值分类学、16S rRNA 基因测序和交叉结瘤能力对分离株进行了表征。结果表明，与重瓣紫荆共生的根瘤菌具有很高的表型和遗传多样性。根据数值分类学的结果，这些分离株在相似性水平为 0.82 时形成了五个聚类。16S rRNA 基因序列分析结果表明，重瓣紫荆的大多数微共生体属于根瘤菌属和慢生根瘤菌属，与根瘤菌属、B. elkanii 和 B. yuanmingense 密切相关。在这些分离株中，一些分离株可以在 pH 值为 4.0-10.0 的范围内生长，一些可以耐受高盐浓度（3%NaCl），并可以在 35 到 45°C 的最高温度下生长。重瓣紫荆在印度土壤中与不同的根瘤菌形成根瘤。这些结果提供了关于在印度南部土壤中生长的重瓣紫荆微共生体的第一个系统信息。
