Development and validation of EST-SSR markers in Gymnema sylvestre R.Br.
Known for its anti-diabetic properties, the Gymnema sylvestre belonging to the family Asclepiadaceae is native to South-Indian forests. It is also found in tropical Africa and in Australia. All arial parts of this plant contain alkaloids, flavones and saponins, but the leaves are mainly used for its medicinal properties. The diversity based on morphological, anatomical and chemo-profiles, and Randomly Amplified Polymorphic DNA (RAPD) and Inter Simple Sequence Repeats (ISSR) markers is reported however, the genetic diversity at molecular level through the most efficient, the expressed sequence tags-SSR (EST-SSR) markers is lacking in this plant. A huge transcriptome data was generated and 5276 SSRs loci were identified in this study. The frequency of SSRs in Gymnema sylvestre was 1/12.16 kB. The AAG/CTT repeats were nearly ten times higher than the CCG/CGG repeats. Total 40 pairs of primers were synthesized, and 27 primers gave polymorphic amplification in 25 genotypes of G. sylvestre collected from different parts of India. Genotypes DGS 16 and DGS 34 were the most dissimilar genotypes. This was the first study revealing genetic diversity and high polymorphisms in G. sylvestre with the help of EST-SSR markers having a higher transfer rate of 67.5%. The disorderly distribution of genotypes of same state in different clusters was reported which may be because that the G. sylvestre is an important medicinal plant people are using from ancient time and it is presumed that it would have been migrated to different places.