Melia dubia Cav. (Family Meliaceae) is a highly valued multipurpose tree species commonly known as Malabar Neem or Dreak. The tree is native to India and widely distributed in Khasi Hills, upper Assam, Sikkim Himalayas, North Bengal, Deccan, and Western Ghats (altitude 1,500–1,800 m). It is common in the moist deciduous forests of Kerala [1]. At the end of 20 years, the Melia tree can attain a height of 6–30 m, clear bole up to 8 m and a girth at a breast height of 1.5 m [2]. This tree is usually leafless from December to March and new leaves appear from February to March. It has exceptional wood properties for pulp, paper, plywood and timber industries. As reported, in the world, this is one of the fastest-growing moneymaking tree species under a short rotation agroforestry system [3]. The wood of the species has been reported to be moderately hard, light in weight, easy to saw and durable [4]. Due to the increase in populations of M. dubia in the Indian sub-continent, the genetic diversity of the species has increased. However, very less data is available on intra-specific variation in Melia under the Indian subcontinent [5]. As suggested by evolutionary evidence, high levels of genetic diversity are depicted by the species with diverse ecotypes and broad distribution [6]. This necessitated the initiation of a tree improvement program for identifying superior and diverse genotypes for developing breeding strategies. One of the most vital steps is the assessment of genetic diversity, which can be achieved quickly and efficiently using molecular markers. Estimation of genetic diversity can be done with the help of DNA-based molecular. Mostly in molecular studies, RAPDs (randomly amplifies polymorphic DNAs) have been used in genetic analysis, but due to their limitation of reproducibility, SSR markers are preferred more for their formativeness and efficiency in the study of genetic diversity.
Despite the importance of the species and its commercial potential, there is a lack of information on the extent of genetic diversity and knowledge about its genetic improvement is scanty. There is a fragmentation of habitats for various species in the natural forests of tropical and subtropical regions due to anthropogenic activities [7]. Habitat fragmentation is one of the major challenges for biological diversity conservation [8]. Genetic diversity in natural populations occurs due to the interaction of drift, migration and selection which is required for population adaptation, persistence and evolution [9]. The greater the diversity, the greater the adaptability; a species’ adaptability to a wide range of climatic conditions is dependent on genetic diversity [10]. Despite the positive outlook on M. dubia’s marketable improvement, knowledge about the species' genetic diversity is lacking and widespread misuse of this species leads to further genetic resource depletion. As a result, there is an immediate need to instigate breeding programs for this species to make improved planting stock commercially viable. Recently, 10 populations of Melia dubia trees from 8 districts of Karnataka were assessed using SSR markers [11]. Similarly, ISSR markers were used to assess the genetic variability of 232 trees from 7 plantations (147 trees) and 11 natural populations (85 trees) was assessed [12]. There is a lack of information on the genetic diversity of this species through co-dominant markers for the region of Arunachal Pradesh. In light of the foregoing, the current study was undertaken to determine the genetic diversity and differentiation of this species, which could aid in the identification of genetic resources to assist in improvement activities and conservation strategies.