Key message Genetic diversity of Monoon tirunelveliense is reported here from India to facilitate its conservation and to take up such studies for conserving threatened plants from different parts of the world.
Abstract
As endemic and threatened species are susceptible to loss of genetic variation due to stochastic factors, investigation was carried out to assess genetic diversity of Monoon tirunelveliense (Annonaceae), which is a steno endemic and a critically endangered species from the Kalakkad-Mundanthurai Tiger Reserve in India, using inter-simple sequence repeats (ISSRs). Thirty-five samples collected from seven populations were screened by 34 primers, wherein 11 primers produced 65 clear and reproducible bands that included 43.08 % of polymorphic bands (PPB), at the rate of 1–6 bands population −1 and 5.90 bands primer −1 . Nei’s genetic diversity ( H ) was 0.1428, on an average. Analysis of Shannon information index ( I ) showed 0.2120, on an average, and total genetic diversity ( H T ) was moderate with 0.2651 and genetic diversity within populations ( H S ) was a low of 0.1428. Proportion of total diversity among populations ( G ST ) was 0.4613. Gene flow among populations ( Nm ) was 0.5839 individuals generation −1 indicating a low migration rate among populations. Mantel test showed no significant correlation among genetic differentiation and geographical distance ( r = 0.489, p = 0.007). Phylogenetic relationship among Monoon species using rbcL and matK gene sequences derived by combined Bayesian analysis is given. Besides conserving all the existing populations, matured fruits should be collected and sown in debris-free soil to increase the percentage of seed germination as seeds are highly vulnerable to the attack of termites and microbial decay. Seeds from genetic diversity-rich Populations 2 and 3 are recommended for propagation to increase the extent and occurrence of the species.