Diversidade genética e estrutura populacional de Trifolium polymorphum Poir. e Trifolium riograndense Burkart

Abstract

The genus Trifolium belongs to Fabaceae, and popularly includes herbaceous and forage plants, popularly known as clovers. They contribute to the maintenance of the soil's productive capacity, enabling the fixation of atmospheric nitrogen. The present work aims to analyze the genetic diversity and population structure of Trifolium polymorphum Poir. and Trifolium riograndense Burkart, species native to the southern grasslands. To access the diversity, molecular markers ISSR (Inter Simple Sequence Repeat) were used, which are dominant markers. Five natural populations were sampled from the respective cities of the state of Rio Grande do Sul for T. polymorphum: São Borja, São Gabriel, Tupanciretã, Eldorado do Sul and São Pedro do Sul. And two natural populations for the species T. riograndense: Agudo and Cambará do Sul. The samples were conditioned in silica gel until the moment of DNA extraction. One specimen of each plant collected was registered as a voucher in the SMDB herbarium. DNA was extracted by the technique of Doyle and Doyle (1987), and quantified in a 1% agarose gel. Regions were amplified via ISSR-PCR using four primers: (GA)8YC, (AG)8T, (GACAC)3 and (AG)8TA. From the analysis of the gels, they were photodocumented and a binary matrix was created considering the presence (1) and absence (0) of the amplified fragments. Data were analyzed using statistical software (GenAlEx 6.5; Structure and Structure Harvester; Principal Coordinate Analysis (PCoA). Based on the results, the genetic variation for the patterns of all primers is higher within populations with 56% for T. polymorphum and 71% for T. riograndense Cluster analysis and principal coordinate analysis (PCoA) scatter plot showed that ISSR primers were able to clearly separate the accessions of the species according to origin (municipality). The selected ISSR markers were efficient to reveal and quantify genetic diversity in T. polymorphum, however, the average genetic diversity (h=0.113) for all primers was low when compared to other studies with the same genus and marker. , for all primers in T. riograndense, the average when compared was higher (h= 0.225).With this information it is possible to adopt measures that favor the best forms of conservation and management for the sustainable use of the biodiversity of native species.