Isolation and characterization of microsatellite markers from guineagrass (Panicum maximum) for genetic diversity estimate and cross-species amplification

Guineagrass (Panicum maximum Jacq.) is one of the major forage grasses in tropical and semitropical regions, largely apomictic and predominantly exist as tetraploid. Non-availability of polymorphic molecular markers has been a major limitation in its characterization and improvement. We report isolation and characterization of microsatellites in P. maximum and cross-species results with other five Panicum species. Based on microsatellite-motifs, 15 functional and polymorphic simple sequence repeat (SSR) primer-pairs were designed, validated and employed in estimating genetic relationship among 34 guineagrass accessions. Thirteen primer-pairs amplified single locus and remaining two generated more than two loci with an average of 3.57 bands per locus amounts to 63 bands with 34 guineagrass accessions. Average expected heterozygosity (H(E)) of 0.35 (maximum 0.97) and observed heterozygosity (H(O)) of 0.37 (maximum 0.91) established the efficiency of developed markers for discriminating guineagrass accessions. Dice's similarity coefficients-based unweighted pair group with arithmetic average method-clustering supported with high bootstrap values (>= 40) indicated its significance and distinguished all accessions except IG97-93 and IG97-6. Utility of these new SSR loci in genetic diversity study of P. maximum and other cross-amplified species is discussed.