叶绿体基因序列数据表明被子植物中共生固氮倾向有单一的起源。
Chloroplast gene sequence data suggest a single origin of the predisposition for symbiotic nitrogen fixation in angiosperms.
作者信息
Soltis D E, Soltis P S, Morgan D R, Swensen S M, Mullin B C, Dowd J M, Martin P G
机构信息
Department of Botany, Washington State University, Pullman 99164-4238, USA.
出版信息
Proc Natl Acad Sci U S A. 1995 Mar 28;92(7):2647-51. doi: 10.1073/pnas.92.7.2647.
Of the approximately 380 families of angiosperms, representatives of only 10 are known to form symbiotic associations with nitrogen-fixing bacteria in root nodules. The morphologically based classification schemes proposed by taxonomists suggest that many of these 10 families of plants are only distantly related, engendering the hypothesis that the capacity to fix nitrogen evolved independently several, if not many, times. This has in turn influenced attitudes toward the likelihood of transferring genes responsible for symbiotic nitrogen fixation to crop species lacking this ability. Phylogenetic analysis of DNA sequences for the chloroplast gene rbcL indicates, however, that representatives of all 10 families with nitrogen-fixing symbioses occur together, with several families lacking this association, in a single clade. This study therefore indicates that only one lineage of closely related taxa achieved the underlying genetic architecture necessary for symbiotic nitrogen fixation in root nodules.
在大约380个被子植物科中，已知只有10个科的代表植物能与根瘤中的固氮细菌形成共生关系。分类学家提出的基于形态学的分类方案表明，这10个植物科中的许多科之间亲缘关系甚远，由此产生了一种假说，即固氮能力即使不是多次，也是独立进化了好几次。这反过来又影响了人们对于将负责共生固氮的基因转移到缺乏这种能力的作物物种的可能性的态度。然而，对叶绿体基因rbcL的DNA序列进行的系统发育分析表明，所有10个具有固氮共生关系的科的代表植物，与几个没有这种共生关系的科一起，都出现在一个单一的进化枝中。因此，这项研究表明，只有一个亲缘关系密切的分类群谱系获得了根瘤中共生固氮所需的潜在遗传结构。
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