Diversidade genética estimada por meio de marcadores microssatélites em populações de Lolium multiflorum

Abstract

The genetic diversity estimation is important to characterize plant populations including forage species. The increase of productivity is a constant objective in forage breeding programs and is directly dependent of the genetic diversity. The ryegrass (Lolium multiflorum Lam.) is a winter grass, widely used for cattle due to its high palatability, digestibility and resistance to trampling. The species was introduced from Europe and is widely used in southern Brazil. As part of The Embrapa Dairy Cattle Ryegrass Breeding Program, the present work aimed to estimate the genetic diversity among 32 ryegrass populations. The DNA of 628 individuals was extracted and microsatellite markers obtained by cross amplification were used. A dendrogram was generated by UPGMA algorithm, using NTSYS software and Dice’s similarity coefficient. Among the thirty-five pairs of tested primers, twenty five (71.5%) showed cross amplification in L. multiflorum, demonstrating the efficiency of using cross amplification of microsatellite markers from related species. Fifteen markers were chosen based on the cross amplification success and the level of polymorphism. The values of similarity coefficient matrix varied from 0.43 to 0.93. Genetic divergence among the populations was observed, indicating that the populations possess a wide genetic base. This result corroborates the wide geographical distribution and the allogamous reproduction system previously reported for the species.