Azevedo A L S, Costa P P, Machado M A, de Paula C M P, Sobrinho F S
Embrapa Gado de Leite, Juiz de Fora, MG, Brasil.
Genet Mol Res. 2011 Nov 17;10(4):3530-8. doi: 10.4238/2011.November.17.5.
The grasses of the genus Brachiaria account for 80% of the cultivated pastures in Brazil. Despite its importance for livestock production, little information is available for breeding purposes. Embrapa has a population of B. ruziziensis from different regions of Brazil, representing most of existing variability. This population was used to initiate an improvement program based on recurrent selection. In order to assist the genetic improvement program, we estimated the molecular variability among 93 genotypes of Embrapa's collection using ISSR (inter-simple sequence repeat) markers. DNA was extracted from the leaves. Twelve ISSR primers generated 89 polymorphic bands in the 93 genotypes. The number of bands identified by each primer ranged from two to 13, with a mean of 7.41. Cluster analysis revealed a clearly distinct group, containing most of the B. ruziziensis genotypes apart from the outgroup genotypes. Genetic similarity coefficients ranged from 0.0 to 0.95, with a mean of 0.50 and analysis of molecular variance indicated higher variation within (73.43%) than among species (26.57%). We conclude that there is a high genetic diversity among these B. ruziziensis genotypes, which could be explored by breeding programs.
臂形草属的牧草占巴西人工牧场的80%。尽管其对畜牧生产很重要，但用于育种目的的信息却很少。巴西农牧业研究公司（Embrapa）拥有来自巴西不同地区的鲁齐兹臂形草种群，代表了现有的大部分变异性。该种群被用于启动基于轮回选择的改良计划。为了协助遗传改良计划，我们使用简单序列重复区间（ISSR）标记估计了巴西农牧业研究公司收集的93个基因型之间的分子变异性。从叶片中提取DNA。12个ISSR引物在93个基因型中产生了89条多态性条带。每个引物鉴定出的条带数量从2条到13条不等，平均为7.41条。聚类分析揭示了一个明显不同的组，除了外类群基因型外，包含了大多数鲁齐兹臂形草基因型。遗传相似系数范围为0.0至0.95，平均为0.50，分子方差分析表明组内变异（73.43%）高于种间变异（26.57%）。我们得出结论，这些鲁齐兹臂形草基因型之间存在高度的遗传多样性，育种计划可以对其加以利用。
