Genetic diversity and population structure analysis of the endangered endemic and economically important plant, Red Sanders, distributed in the Eastern Ghats. India

Pterocarpus santalinus , or Red Sanders, is an Indian native tree species that is under threat of decline in natural populations due to illicit felling in Eastern Ghats. In the present study, we assessed the genetic variation and population structure across 22 natural populations 16 highly polymorphic SSR markers in 361 individuals. The average number of alleles (Na) was 7.79, with an expected heterozygosity (He) of 0.65, which is lower than that of other woody plants. Interestingly, the Tirupati base-Sadashiva Kona population presented the greatest genetic diversity (He = 0.87), whereas the Chitaleti Pati base Camp population presented the least genetic diversity (He = 0.44). The analysis revealed that extensive genetic variation among populations (72%) contrasted with that within populations (28%). The Tirupati circle (He = 0.93) and Chittor divisions (He = 0.91) presented high genetic diversity. The FST values revealed considerable genetic differentiation among the populations, with a value of 0.31 and poor gene flow (Nm = 0.82). Cluster analysis of 361 samples from 22 populations revealed three main genetic groups. Populations located at lower latitudes presented greater genetic diversity than those located at higher latitudes did, and geographical and genetic distances were positively correlated. The population as a whole presented moderate level of genetic diversity, with clear variation between the populations at lower and higher latitudes and positive geographical and genetic correlations. These results indicate the importance of conserving P. santalinus .