Poor Competitiveness of Bradyrhizobium in Pigeon Pea Root Colonization in Indian Soils.
Poor Competitiveness of Bradyrhizobium in Pigeon Pea Root Colonization in Indian Soils.
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DOI：
10.1128/mbio.00423-21
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发表时间：
2021-08-31
期刊：
影响因子：
6.4
通讯作者：
Tkacz A
中科院分区：
文献类型：
--
作者：
Chalasani D;Basu A;Pullabhotla SVSRN;Jorrin B;Neal AL;Poole PS;Podile AR;Tkacz A
木豆是一种原产于印度的豆类作物，是发展中国家10亿多人的主要蛋白质来源。该植物可以与固氮细菌形成共生;然而，农业土壤中作物生长不良的报道比比皆是。我们在这里报告的细菌群落与木豆的研究，特别关注的共生种群在不同的土壤和营养和非营养植物生长。相对于植物根系的位置被确定为控制细菌群落的主要因素，其次是发育阶段和土壤类型。植物基因型只起次要作用。与周围土壤相比，木豆根的微生物多样性降低，并选择变形菌，特别是根瘤菌，在营养生长期间。虽然慢生根瘤菌是木豆的原生共生体，但它的存在取决于植物品种和土壤条件。结合16 S rRNA基因扩增调查，菌株分离，并与结瘤形成慢生根瘤菌的共同接种。和非固氮根瘤菌属（Rhizobium spp.）证明后者是一个更成功的殖民者的木豆根。在印度土壤中木豆的接种能力差可能是由于慢生根瘤菌对非接种根定殖菌（如根瘤菌）的竞争力差所致。因此，木豆共生菌接种菌株的选择不仅应基于其固氮潜力，但更重要的是，在农业土壤中的竞争力。
Pigeon pea, a legume crop native to India, is the primary source of protein for more than a billion people in developing countries. The plant can form symbioses with N2-fixing bacteria; however, reports of poor crop nodulation in agricultural soils abound. We report here a study of the bacterial community associated with pigeon pea, with a special focus on the symbiont population in different soils and vegetative and non-vegetative plant growth. Location with respect to the plant roots was determined to be the main factor controlling the bacterial community, followed by developmental stage and soil type. Plant genotype plays only a minor role. Pigeon pea roots have a reduced microbial diversity compared to the surrounding soil and select for Proteobacteria, especially for Rhizobium spp., during vegetative growth. While Bradyrhizobium, a native symbiont of pigeon pea, can be found associating with roots, its presence is dependent on plant variety and soil conditions. A combination of 16S rRNA gene amplicon survey, strain isolation, and co-inoculation with nodule-forming Bradyrhizobium spp. and non-N2-fixing Rhizobium spp. demonstrated that the latter is a much more successful colonizer of pigeon pea roots. Poor nodulation of pigeon pea in Indian soils may be caused by a poor Bradyrhizobium competitiveness against non-nodulating root colonizers such as Rhizobium. Hence, inoculant strain selection of symbionts for pigeon pea should be based not only on their nitrogen fixation potential but, more importantly, on their competitiveness in agricultural soils.