Preferential occurrence of diazotrophic endophytes, Azoarcus spp., in wild rice species and land races of Oryza sativa in comparison with modern races
Preferential occurrence of diazotrophic endophytes, Azoarcus spp., in wild rice species and land races of Oryza sativa in comparison with modern races
复制标题
DOI：
10.1046/j.1462-2920.2000.00078.x
复制
发表时间：
2000-04-01
影响因子：
5.1
通讯作者：
Reinhold-Hurek, B
中科院分区：
文献类型：
--
作者：
Engelhard, M;Hurek, T;Reinhold-Hurek, B
几种固氮菌属物种。作为内生菌存在于先锋植物卡拉草中。本研究的目的是筛选亚洲野生稻和栽培稻品种与这些内生菌的自然关联。通过16S rDNA序列分析鉴定了表面灭菌根中可培养固氮菌的种群，并通过基因组指纹鉴定了固氮菌属的物种。A.在淹水的水稻样品中，固氮菌D组的检出率较高：75%的野生稻，80%的野生稻、80%现代栽培品种中有33%来自尼泊尔和意大利。水稻内生固氮菌的多样性随水稻基因型的不同而不同，野生稻中固氮菌的多样性显著低于现代栽培稻。在Oryza officinalis（来自尼泊尔）和O，minuta（来自菲律宾）中，Azoarcus sp，group D是根系中优势的固氮内生菌。与此相反，它们的数量显着低于现代品种的O。而其他固氮生物，如固氮菌属，克雷伯氏菌属，少动鞘氨醇单胞菌、伯克霍尔德氏菌和茎瘤固氮根瘤菌数量增加。在O，sativa，固氮生物多样性也同样高，但是，Azoarcus sp，被发现在高的表观数量。在一种非培养的方法中，也观察到了类似的群体差异，比较了野生稻（O。officinalis）和现代O.在根相关固氮酶（nifH）基因片段克隆文库中，野生稻的固氮多样性较低。nifH基因的新谱系被检测到，例如，在anf（铁）固氮酶中的一个深分支簇。我们的研究表明，Azoarcus spp的自然寄主范围扩展到水稻，野生稻和老品种比现代栽培品种更受欢迎。
Several diazotrophic species of Azoarcus spp. occur as endophytes in the pioneer plant Kallar grass. The purpose of this study was to screen Asian wild rice and cultivated Oryza sativa varieties for natural association with these endophytes. Populations of culturable diazotrophs in surface-sterilized roots were characterized by 16S rDNA sequence analysis, and Azoarcus species were identified by genomic fingerprints. A. indigens and Azoarcus sp. group C were detected only rarely, whereas Azoarcus sp. group D occurred frequently in samples of flooded plants: in 75% of wild rice, 80% of land races of O. sativa from Nepal and 33% of modern cultivars from Nepal and Italy. The putatively endophytic populations of diazotrophs differed with the rice genotype, The diversity of cultured diazotrophs was significantly lower in wild rice species than in modern cultivars. In Oryza officinalis (from Nepal) and O, minuta (from the Philippines), Azoarcus sp, group D were the predominant diazotrophic putative endophytes in roots. In contrast, their number was significantly lower in modern cultivars of O. sativa, whereas numbers and diversity of other diazotrophs, such as Azospirillum spp., Klebsiella sp., Sphingomonas paucimobilis, Burkholderia sp. and Azorhizobium caulinodans were increased. In land races of O, sativa, the diazotrophic diversity was equally high; however, Azoarcus sp, was found in high apparent numbers. Similar differences in populations were also observed in a culture-independent approach comparing a wild rice (O. officinalis) and a modern-type O. sativa plant: in clone libraries of root-associated nitrogenase (nifH) gene fragments, the diazotrophic diversity was lower in the wild rice species. New lineages of nifH genes were detected, e,g, one deeply branching cluster within the anf (iron) nitrogenases, Our studies demonstrate that the natural host range of Azoarcus spp, extends to rice, wild rice species and old varieties being preferred over modern cultivars.