Isolation and Characterization of Salt-Induced Genes from Rhizophora apiculata Blume, a True Mangrove by Suppression Subtractive Hybridization

Mangroves are plants that can tolerate salinity equiva-lent to that present in seawater. In the present study, we have attempted to isolate the genes upregulated at the early stage of salt stress response in Rhizophora apiculata Blume, a true mangrove, through suppression subtractive hybridization technique. Several genes were isolated, which were then classified to nine func-tional categories, viz. metabolism, protein degradation and folding, secondary metabolism, cell rescue and defence, transport facilitation, signal transduction, transcription and translation, photosynthesis and un-classified genes of unknown function. The expression patterns of 12 of the genes thus obtained were studied at 6, 12 and 24 h time points of salinity stress using real-time PCR. Most genes were found to be upregu-lated under salt stress and showed maximum upregu-lation at the 6 h time point. Two of the genes studied were downregulated after 6 h, implying that the pat-tern of gene expression varies with time of application of stress. The genes thus isolated may be used to con-fer the trait of salt tolerance to non-tolerant geno-types, which can ultimately prove beneficial for crop improvement programmes.