Genetic diversity of Trifolium polymorphum Poir. (Fabaceae) in natural populations of Rio Grande do Sul, Brazil

The genus Trifolium (Fabaceae) is composed of herbaceous plants of forage interest that contribute to the maintenance of the productive capacity of soils, enabling the fixation of atmospheric nitrogen. Genetic diversity is an important factor for the response of populations to environmental changes. The present work aimed at analyzing the genetic diversity and population structure of Trifolium polymorphum Poir., a native species of the Pampa biome, using ISSR (Inter Simple Sequence Repeat) molecular markers. Leaves and stolons from five populations were collected in São Borja, São Gabriel, Tupanciretã, Eldorado do Sul, and São Pedro do Sul and stored in silica gel until DNA extraction. The DNA was extracted and quantified in 1% agarose gel. Regions were amplified via ISSR-PCR with four primers: (GA)8 YC, (AG)8 T, (GACAC)3, and (AG)8 TA. The data were analyzed using statistical software GenAlEx 6.5, Structure, and Structure Harvester. The results showed greater genetic variation within populations (56%) than between populations (44%). Cluster analysis and the scatter plot from the main coordinate analysis separated the accessions according to geographical origin. However, the mean genetic diversity (H=0.113) for all primers was low when compared to other studies with the same genus and marker. This diversity information can be used to adopt measures that favor the best forms of conservation and management for the sustainable use of the biodiversity of native species.