Rhizobia Indigenous to the Okavango Region in Sub-Saharan Africa: Diversity, Adaptations, and Host Specificity
Rhizobia Indigenous to the Okavango Region in Sub-Saharan Africa: Diversity, Adaptations, and Host Specificity
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DOI：
10.1128/aem.02417-14
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发表时间：
2014-12-01
影响因子：
4.4
通讯作者：
Reinhold-Hurek, Barbara
中科院分区：
文献类型：
--
作者：
Groenemeyer, Jann L.;Kulkarni, Ajinkya;Reinhold-Hurek, Barbara
奥卡万戈地区本土的根瘤菌群落尚未被描述。本地根瘤菌的分离可以为根瘤菌接种剂的配制提供依据。此外，它们的鉴定和特征有助于对物种分布和生态学的总体认识。从当地豆类品种豇豆、班巴拉花生、花生、风信子豆和普通豆的根瘤中分离得到分离株。采用BOX重复元件PCR （BOX-PCR）和16S-23S rRNA内转录间隔段（ITS）、recA、glnII、rpoB、nih基因序列分析鉴定其中91株。观察到惊人的地理分布。安哥拉取样点以酸性土壤和半湿润气候为特征，以厚根瘤菌生长缓慢为主。从纳米比亚半干旱取样点分离的菌株种类更为多样，多数与元明慢生根瘤菌和大清慢生根瘤菌有亲缘关系。寄主植物特异性仅观察到风信子豆，这是根瘤菌可能代表尚未描述的物种结瘤。此外，该菌株还具有对高温、干旱和当地寄主植物的适应性。适应性实验表明，纳米比亚分离株具有特别的高温耐受性，但没有一个分离株对干旱表现出相当大的适应性。此外，菌株在不同寄主上的表现也不尽相同，大多数纳米比亚菌株对花生和扁豆的结瘤效果优于安哥拉菌株。不同基因型的本地优势意味着本地菌株可能在接种配方中表现出更好的性能。
The rhizobial community indigenous to the Okavango region has not yet been characterized. The isolation of indigenous rhizobia can provide a basis for the formulation of a rhizobial inoculant. Moreover, their identification and characterization contribute to the general understanding of species distribution and ecology. Isolates were obtained from nodules of local varieties of the pulses cowpea, Bambara groundnut, peanut, hyacinth bean, and common bean. Ninety-one of them were identified by BOX repetitive element PCR (BOX-PCR) and sequence analyses of the 16S-23S rRNA internally transcribed spacer (ITS) and the recA, glnII, rpoB, and nifH genes. A striking geographical distribution was observed. Bradyrhizobium pachyrhizi dominated at sampling sites in Angola which were characterized by acid soils and a semihumid climate. Isolates from the semiarid sampling sites in Namibia were more diverse, with most of them being related to Bradyrhizobium yuanmingense and Bradyrhizobium daqingense. Host plant specificity was observed only for hyacinth bean, which was nodulated by rhizobia presumably representing yet-undescribed species. Furthermore, the isolates were characterized with respect to their adaptation to high temperatures, drought, and local host plants. The adaptation experiments revealed that the Namibian isolates shared an exceptionally high temperature tolerance, but none of the isolates showed considerable adaptation to drought. Moreover, the isolates' performance on different local hosts showed variable results, with most Namibian isolates inducing better nodulation on peanut and hyacinth bean than the Angolan strains. The local predominance of distinct genotypes implies that indigenous strains may exhibit a better performance in inoculant formulations.