RAPD AND SSR ANALYSIS OF AFFORESTED SONNERATIA APETALA BUCH.-HAM. POPULATION FROM THE COASTAL AREAS OF BANGLADESH

Random amplification of polymorphic DNA (RAPD) and simple sequence repeats (SSR) primers were used to estimate and compare the genetic diversity within and among populations of Sonneratia apetala Buch. -Ham. from the mangrove forests in the coastal islands of Bangladesh. A total of 15 individuals were studied which produced a total of 32 bands from 05 random RAPD primers and 11 allele fragments from 05 SSR primers. At the species level, SSR primers detected relatively less polymorphic loci (40%) than RAPD primers (56.25%). Both primers revealed a moderate level of genetic diversity (average I = 0.310 for RAPD and average Ho = 0.239 for SSR). At the population level, Nijhum Dwip population contained a low level of genetic diversity compared to the other populations that might be due to selfing within population. Therefore, seed collection from Nijhum Dwip for further afforestation should be avoided. Introduction Bangladesh has 436570 hectares of mangrove forest representing about 3.2% of global mangroves (Giri et al. 2011). Sonneratia apetala Buch. -Ham. is the most abundant mangrove species with high adaptability and seed production in the natural mangrove forest in Bangladesh (Iftekher and Saenger 2008). It is a pioneer, true woody, and crypto-viviparous mangrove species (Tomlinson 1986). This species has been widely planted and the most successful in the mangrove afforestation program in the coastal regions and offshore islands, including Chittagong, Noakhali, Bhola, Barisal and Patuakhali in Bangladesh since 1966 (Saenger and Siddiqi 1993). The core objectives of the mangrove afforestation program involve to the protection of the residents of shoreline and their property against natural disasters. Monospecific stands of S. apetala dominated about 80% areas of the early plantations due to high survival and growth rate (Saenger and Siddiqi 1993). Seedlings grown in the nursery bed from the collected seeds are planted from July to August (Saenger and Siddiqi 1993). Afforestation strategies, including suitable plantation sites, the quality of planting materials (i.e., seeds and seedlings), post-establishment are not carefully maintained yet (Rahman et al. 2010). The baseline information on the status of planting materials is required to improve the understanding of mangrove species conservation (Rao and Hodgkin 2001). Genetic diversity is a crucial component for the long-term survival, adaptation, and evolution of species (Maguire et al. 2002). Various evolutionary forces such as mutation, natural selection, genetic drift, and gene flow affect the genetic diversity of the population, thereby enhancing or reducing the adaptive ability of populations to an environment (Ratnam et al. 2014). Besides, demographic factors, including the quantity of pollen, female flower, flowering synchronicity and geographical distributions along with demographic processes such as mating systems, bottlenecks and long distance dispersal contribute to shaping the genetic diversity and structure of a forest population (Vekemans and Hardy 2004). Development of PCR-based DNA marker methods ∗Author for correspondence: <aashfaque67@yahoo.com>. Department of Botany, Jagannath University, Dhaka-1100, Bangladesh.