Genetic variation between ecotypic populations of Chloris roxburghiana grass detected through RAPD analysis

Chloris roxburghiana is an important rangeland grass in Kenya. In some areas it has disappeared due to land degradation resulting from overgrazing and drought. Efforts to re-introduce the grass through re-seeding using seeds from research stations have had little success. One possible reason for low establishment is attributed to transplanting spatially separated populations that may represent genetically distinct ecotypes. To test this hypothesis, germplasm diversity within and among four populations of C. roxburghiana from four ecologically distinct sites was analysed using random amplified polymorphic DNA (RAPD) markers. A total of 131 polymorphic markers were identified using nine RAPD primers. There was significant variation among populations, with genetic diversity (H) ranging from 0.134 to 0.206. Analysis of molecular variance (AMOVA) revealed most variance within populations (76%). However, the variation among populations was also significant (24%). The UPGMA of the population frequency indicated that the four populations of C. roxburghiana were genetically distinct, probably as a result of variation in soil fertility, geographical isolation and socio-ecological history of the study sites. Although there are differences for neutral genetic markers between the populations, it is difficult to relate this directly to ecotype since correlation does not imply causality. The implication for optimising future seed collection is discussed and potential areas for further studies identified.