Genetic Diversity and Population Structure of Swamp Forest Eleiodoxa conferta (Griff.) Burr. Based on Simple Sequence Repeats (SSRs)

Eleiodoxa conferta (Griff.) Burr. (family Arecaceae) is widely distributed in peat swamp forests throughout the tropical zone in Thailand. In this study, genetic diversity within and among 4 natural populations of E. conferta (Griff.) Burr. sampled from three provinces in southern peninsular Thailand was determined using SSR analysis. Our results show a low level of genetic diversity (A(r) 1.743, H-e 0.423, and N-e 1.793). Most of the locus populations were in Hardy-Weinberg equilibrium (HWE) but the 14-locus population of E. conferta had departures from HWE; however, the inbreeding coefficient (F-is) indicated no inbreeding in this population. The genetic differentiation between groups was strong (mean F-st 0.171) so each group significantly differed from the others, except for Salacca and Calamus. Moreover, a high genetic identity of E. conferta subgroups Kan-Thu-Le (KL), Chaiburee (CB), Songkhla (SK), and Narathiwat (NW) was observed (F-st 0.0386-0.1239), indicating similar genetic backgrounds. The genetic differentiation agreed with the genetic distance, which showed that the E. conferta populations are closely related and clearly differ from Salacca and Calamus populations. Neighbor-joining cluster analysis divided the population into three 3 groups; group I (KL and CB) and group II (SK and NW) belong to E. conferta based on their geographical origin at the upper and the lower southern peninsular Thailand, respectively, and group III consisted of Salacca and Calamus. Furthermore, a phylogenetic tree confirmed the close genetic relationship of E. conferta and Salacca. The less informative marker system used in this study indicated a low level of genetic diversity in E. conferta, but the population structure analysis tended to group them by geographic origin. Our findings contribute to the protection of plant germplasm of E. conferta for future conservation.