Inter-Simple Sequence Repeat Markers Reveal Genetic Relatedness Between Natural Aquilaria Populations in Peninsular Malaysia

Abstract

Aquilaria is a major agarwood-producing genus from the Indomalesian region. The high demand for natural agarwood resources in the market is increasing, directly threatening the survival of the trees in the wild. In order to develop proper conservation strategies for these species, information on their genetic variation is needed. The current levels of genetic variation found in Aquilaria populations in Peninsular Malaysia, as well as their genetic relationships, were evaluated using inter-simple sequence repeat (ISSR) markers. A total of 42 individuals, from 21 populations of three different Aquilaria species were collected and genotyped using 25 ISSR primers. Twenty four primers amplified bands in all three species, and showed 95%, 82.6%, and 63% polymorphic bands in A. malaccensis, A. hirta, and A. rostrata, respectively. Clustering analyses through the construction of a UPGMA dendrogram and a principal component analysis (PCA) plot revealed three major clusters, grouping samples of each species into their respective clusters. The A. malaccensis populations seemed to also be divided into two sub-clades, most probably as a result of isolation by mountain ranges as physical barriers to gene flow between the populations. Findings in this study provide valuable information for the planning of more effective management and conservation of existing Aquilaria populations in Peninsular Malaysia.