Molecular Assessment of Variation in Stylosanthes fruticosa Accessions Employing STS and RAPD Markers

Abstract

Genetic variations in two accessions of S. fruticosa (41117 and 41117A) was carried out employing random amplified polymorphic DNA (RAPD) and sequence-tagged-sites (STS) markers to establish the accession closely resembles to the mapping population developed using one of these as a anthracnose susceptible parent along with S. scabra cv Seca as resistant source. Sixty-four RAPD and 15 STS primers generated 469 and 59 fragments respectively. Of these, 90 (19.2%) RAPD and 6 (10.2%) STS fragments showed polymorphism between two accessions of S. fruticosa. When same primers sets were used with F₂ progeny, the segregated RAPD fragments showed patterns belonging to S. scabra cv Seca×S. fruticosa 41117A rather S. scabra cv Seca×S. fruticosa 41117 cross. Of 15 STS primers pairs, SHPALF2/R2, SHST2F3/T2R16 and SHST1F3/T1R3 clearly demonstrated that 41117A line was closer to population as SHPALF2/R2 showed absence of a 480-bp fragment in S. fruticosa 41117 and present in other two parents i.e., S. scabra cv Seca and S. fruticosa 41117A and 78 F₂ plants tested whereas rest two primer pairs amplified a fragment of smaller size in 41117 only. Though most of the STS primer sequences used were derived from S. scabra cv Fitzroy and S. hamata cv Verano, the level of reaction in S. fruticosa accessions indicated low genome specificity of STS primers and hence low level of genetic divergence in different species of Stylosanthes. Results also provided the list of potential STS and RAPD primers could be used in studying the genetic relationships among S. fruticosa accessions, which is the only species of the genus Stylosanthes native and endemic to the southern peninsular regions of India, for plant conservation and breeding programs.