Estimation of genetic diversity and population genetic structure in Gymnema sylvestre (Retz.) R. Br. ex Schult. populations using DAMD and ISSR markers
Background
Gymnema sylvestre(Retz.) R. Br. ex Schult. is a well-knownmedicinal plantagainst diabetes in India. There is as such no organized cultivation in India, and the plant is still being collected from the wild for theirtherapeutic uses. It is, therefore, important to estimate thegeneticdiversity andpopulation geneticstructure ofG. sylvestreto ascertain the genetically diversegermplasm. The present study, therefore, was undertaken to analyze the genetic variability in 118 accessions belonging to 11 wild populations ofG. sylvestreusing directed amplification of minisatellite-region DNA (DAMD) andinter simple sequence repeats(ISSR).
Results
The present genetic analyses of 11 populations with 25 markers (8 DAMD and 17 ISSR) revealed significantgenetic diversity(H= 0.26,I= 0.40,PPL= 80.89%) at a species level, while the averagegenetic diversityat the population level was low. Among the 11 populations studied, PCH and UTK populations showed maximum genetic diversity, followed by KNR and AMB, while TEL population revealed the lowest genetic diversity. AMOVA andGstvalues (0.18) revealed that most of the genetic variations are found within populations and very less among populations, and higher gene flow (Nm= 2.29) was found to be responsible for the genetic homogenization of the populations. The clustering pattern resulting from the UPGMAdendrogramwas in congruence with STRUCTURE and PCoA, segregating all the 11 populations into two main genetic clusters: cluster I (populations of North and Central India) and cluster II (populations of South India). The clustering patterns obtained from all three statistical methods indicate that the genetic structure inG. sylvestrepopulations corresponds to the geographical diversity of the populations and represents a strong genetic structure.
Conclusion
The genetically diverse populations identified during the present study could be a potential genetic resource for further prospecting and conserving this important plant resource.