Genetic diversity and population structure of the Brachiaria brizantha germplasm.
Genetic diversity and population structure of the Brachiaria brizantha germplasm.
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DOI：
10.1007/s12042-011-9078-1
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发表时间：
2011-01-01
影响因子：
2
通讯作者：
de Souza, A. P.
中科院分区：
文献类型：
--
作者：
Vigna, B. B. Z.;Jungmann, L.;de Souza, A. P.
Brachiaria brizantha (Hochst. ex A. Rich.) Stapf. （同义词：Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster）是热带美洲和东南亚主要用作饲料的物种。自 20 世纪 80 年代以来，巴西农业研究公司 (Empresa Brasileira de Pesquisa Agropecuaria; EMBRAPA) 启动了热带牧草育种计划，对 B. brizantha 进行了广泛的研究，该公司拥有世界上最大的种质资源库之一。这项工作为该物种鉴定了 15 个新的微卫星标记，除了之前报道的 5 个标记外，还使用这些标记来估计该物种 172 个种质和 6 个品种之间的遗传相似性。相似性指数值范围为 0.40 至 1.00。在种质中发现了两个重复。使用 STRUCTURE 2.3.3 程序进行的贝叶斯分析揭示了具有不同等位基因池的三个簇的存在。该分析对于探索杂种优势的杂交表现很有价值；然而，为了有效探索，必须观察种质的繁殖方式和倍性障碍。使用邻接方法的分组分析与结构分析一致，并且组合方法表明，尽管存在三个不同的等位基因库，但该种质集合并未表现出相当大的遗传变异性。还讨论了遗传距离和地理距离之间缺乏相关性。
Brachiaria brizantha (Hochst. ex A. Rich.) Stapf. (syn. Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster) is a species used primarily as forage in tropical America and Southeast Asia. B. brizantha has been extensively researched since the 1980s with the initiation of the Tropical Forages Breeding Program conducted by the Brazilian Agricultural Research Corporation (Empresa Brasileira de Pesquisa Agropecuaria; EMBRAPA), holding one of the largest germplasm collections in the world. This work has identified 15 new microsatellite markers for this species, which have been used in addition to five previously reported markers, to estimate the genetic similarities among 172 accessions and six cultivars of this species. Similarity index values ranged from 0.40 to 1.00. Two duplications were found in the germplasm. A Bayesian analysis performed using the STRUCTURE 2.3.3 program revealed the presence of three clusters with different allelic pools. This analysis is valuable for the performance of crosses to explore heterosis; however, the mode of reproduction of the accessions and ploidy barriers must be observed for effective exploration. A grouping analysis using the neighbor-joining method was consistent with the STRUCTURE analysis, and a combination approach suggested that this germplasm collection does not exhibit considerable genetic variability despite the presence of three distinct allelic pools. The lack of correlation between the genetic and geographic distances is also discussed.