Ashwani K. Rai and Teruhiro Takabe (eds), Abiotic Stress Tolerance in Plants. ' 2005 Springer The netherlands. 16. GENETIC DIVERSITY OF SALINE COASTAL

Abstract. Traditional rice landraces from coastal Bangladesh are adapted not only to soil salinity but also to excess magnesium, calcium and sulphate as well as zinc deficiency. They can also tolerate water inundation to a certain extent, because they may be subjected to tidal saline intrusion as well as water stagnation during the monsoon season. These landraces are diverse with respect to their morphology, saline stress response as well as yield components. Characterization of these landraces can suggest how they survive in adverse soils and indicate suitable target genes for transfer to modern rice varieties. Genetic variation of 31 landraces (LRs) collected from the saline coastal belt of Bangladesh, salt tolerant Pokkali, Nona Bokra and sensitive IR29 and BRRIdhan 29 were analyzed with 60 evenly distributed rice microsatellite DNA markers. A total of 196 reproducible polymorphic alleles were identified from the band loci. Computation of genetic similarity with this data, using Jaccard’s coefficient followed by UPGMA clustering, divided the landraces into 6 distinct groups. Three groups were composed of LRs only from the highly saline southwest. Two groups consisted of LRs from the mild to moderately saline mid-east and northeast coasts. The sixth group was heterogeneous, with LRs from the northeast, LRs from the southwest and Nona Bokra. Pokkali and Gunshi, a LR of the southwest, branched out individually