Development and Characterization of Est Based Ssr Markers in Madagascar Periwinkle (catharanthus Roseus) and Their Transferability in Other Medicinal Plants

Simple sequence repeat (SSR) markers derived from expressed sequence tags (ESTs) are important resources for gene discovery and mapping. The objectives of the work presented here are to develop EST based SSR markers, their polymorphism in Catharanthus roseus and to study Cross-species transferability in other medicinal plants. C. roseus is a plant of great medicinal value and contains more than 130 alkaloids namely vincristine, vinblastine, ajamalcine, serpentine, etc. In this study, we analyzed 19899 ESTs and identified 2034 SSRs from 1763 SSR-containing unique ESTs. Of the 2034 EST-SSRs, 42.8% were dinucleotide repeats, 41.9% tri, 6.8% tetra, 4.7% penta and 3.6% were hexanucleotide repeats. From these SSR-containing ESTs, a total of 170 primer pairs were designed among them 20 were selected randomly for the validation of amplification and polymorphism in C. roseus. Out of these 20 primer pairs, 16 (80%) primer pairs could amplify and among them 11 (55%) exhibited polymorphic profiles in C. roseus genotypes. Furthermore, transferable analysis of these primer pairs revealed high Cross-species transferability (31-57%) in three medicinally important plants Croton macrostachyus, Salvia schimperi and Ageratum conizoides. The high reproducibility, scorable bands per marker (3.2), transferability and polymorphism demonstrate the potential utility of these EST-SSR markers in molecular mapping, quantitative trait loci (QTL) analysis and comparative mapping in C. roseus and other medicinal plants.