SSR-based genetic analysis depicted high gene diversity with subtle population genetic structure in Myrica esculenta, a high-valued edible fruit tree of the Western Himalayas

Abstract

Key message

SSR-based characterization revealed a high genetic diversity, negligible genetic differentiation, insignificant inbreeding, and subtle genetic structure in Myrica esculenta populations of Western Himalayas, indicating a high adaptive and evolutionary potential.

Myrica esculenta is a high-valued wild edible fruit-bearing tree of sub-Himalayan region experiencing noticeable deterioration in its stand structure. This study aimed to unveil the gene diversity and spatial genetic structure of M. esculenta populations in the Western Himalayas under the state of Uttarakhand (India) using nuclear simple sequence repeat (SSR) markers. By investigating 23 populations at 8 SSR loci, high genetic diversity (expected heterozygosity, He = 0.90; allelic richness, Ar = 13.65) was recorded with little genetic differentiation (fixation index, F_ST = 0. 025). Bayesian analysis revealed a weak genetic structure with no discrete genetic lineages from which ancestry can be inferred. Furthermore, genetic clustering among populations was conspicuous but not in accordance with their spatial distribution. Geographically separated populations are genetically well connected due to long-distance gene flow via pollen as well as seed. Hence, the meta-population in the Western Himalayas demonstrated a subtle spatial genetic structure with negligible genetic divergence, where genetic admixing is not modulated by geographical constraints. Viewing the substantial anthropogenic pressure over wild populations, conservation strategies must be adopted synergistically based on scientific knowledge. As center of diversity is centered toward the Kumaon region capturing higher allelic richness, we recommend the populations of this region to be prioritized for in situ conservation. Further, it will be important to harvest seeds from genetically diverse populations for raising plantations or ex situ field gene banks. As its fruits are mostly harvested from wild, local communities need to be sensitized and encouraged to establish private plantations or orchards.