Hunan Agricultural Biotechnology Research Institute, Hunan Academy of Agricultural Sciences, Changsha, 410125, Hunan, China.
Hunan Institute of Plant Protection, Hunan Academy of Agricultural Sciences, Changsha 410125, Hunan, China.
Environ Sci Pollut Res Int. 2022 Jul;29(32):49136-49146. doi: 10.1007/s11356-022-19335-3. Epub 2022 Feb 25.
Kudzu (Pueraria lobata) is an important medicinal plant, which can associate with rhizobia for nitrogen fixation. The mutualistic symbiosis between rhizobium and kudzu is not well understood, but it is necessary to fully utilize kudzu. Nodules and rhizosphere soils collected from 16 sampling sites were characterized based on phylogenetic analyses of the rpoB gene; 16S rRNA gene; the housekeeping genes SMc00019, truA, and thrA; and the symbiotic genes nodA and nifH. The relationships between biogeographic pattern, nitrogenase activity, and environmental factors were studied. Results indicated that a clear biogeographic pattern of rhizobial communities in the kudzu rhizosphere existed in southern China; latitude and soil pH were found to be the most important factors affecting the biogeographic pattern. Bradyrhizobium diazoefficiens and Bradyrhizobium erythrophlei were the dominant species in kudzu rhizosphere. The symbiotic rhizobia in kudzu nodules mainly belonged to B. lablabi, B. elkanii, B. pachyrhizi, and B. japonicum. Nitrogenase activities in the nodules of kudzu in the Jiangxi sampling region were significantly higher than those in the Guangxi and Hunan sampling regions, and they were significantly negatively correlated to pH and exchangeable Ca. These results constitute the first report of the existence of symbiotic genes in kudzu bradyrhizobia, which are similar to those in B. elkanii and B. pachyrhizi. Our findings could improve the understanding of kudzu-rhizobium symbiosis and could advance the application of rhizobial inoculation in medicinal legumes in terms of increasing the content of active ingredients.
葛根（Pueraria lobata）是一种重要的药用植物，它可以与根瘤菌共生固氮。根瘤菌与葛根的共生关系尚不清楚，但充分利用葛根是必要的。本研究基于 rpoB 基因、16S rRNA 基因、看家基因 SMc00019、truA 和 thrA 以及共生基因 nodA 和 nifH 的系统发育分析，对来自 16 个采样点的根瘤和根际土壤进行了表征；研究了生物地理格局、固氮酶活性与环境因子之间的关系。结果表明，在中国南方，葛根根际土壤中根瘤菌群落存在明显的生物地理格局；纬度和土壤 pH 是影响生物地理格局的最重要因素。B. diazoefficiens 和 B. erythrophlei 是葛根根际的优势种。葛根根瘤中的共生根瘤菌主要属于 B. lablabi、B. elkanii、B. pachyrhizi 和 B. japonicum。江西采样区葛根根瘤的固氮酶活性显著高于广西和湖南采样区，与 pH 和可交换钙呈显著负相关。这些结果首次报道了葛根慢生根瘤菌中存在共生基因，与 B. elkanii 和 B. pachyrhizi 中的共生基因相似。我们的研究结果可以提高对葛根-根瘤菌共生关系的认识，并可以推进根瘤菌接种在药用豆科植物中的应用，以提高有效成分的含量。
