Genetic Diversity in Diploid Cultivars of Rhodesgrass Determined on the Basis of Amplified Fragment Length Polymorphism Markers
2003
Ubi, Benjamin Ewa | Kölliker, Roland | Fujimori, Masahiro | Komatsu, Toshinori
Rhodesgrass (Chloris gayana Kunth) is a highly variable, perennial forage grass widely cultivated in all tropical and subtropical regions of the world. Despite its economic importance, there is a lack of information on the genetic diversity within and among rhodesgrass cultivars, which are all based on genetic resources initially introduced from East and South Africa. The objective of this study was to assess genetic diversity within and among 13 cultivars of diploid rhodesgrass and to determine whether recent breeding efforts have resulted in cultivars distinct from the African source populations. For each cultivar, 15 individuals were examined for 237 amplified fragment length polymorphism (AFLP) markers generated from three EcoRI/MseI primer pairs. Partition of the variation revealed that the major proportion of the total genetic variation occurred within cultivars and with only 12 to 13% attributed to geographical origin or breeding history. Cluster analysis revealed three distinct groups among the cultivars investigated. Group one consisted mainly of recent Japanese cultivars and their African source population, group two contained mostly African cultivars, and group three contained one African cultivar. However, the genetic diversity within recent Japanese cultivars was comparable to the diversity within old African cultivars and there was no evidence of a reduced genetic base because of breeding efforts.
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