Salt-responsive differential gene expression analysis by RNA sequencing in the roots of a mangrove Avicennia officinalis

The roots of halophytes such as mangroves provide the first line of defense against the constant salt stress they experience. Such adaptation should include major reprogramming of the gene expression profiles. Using RNA-sequencing approach we identified 101,446 ‘all-unigenes’ from the seedling roots of the mangrove tree Avicennia officinalis. From the data 6618 genes were identified to be differentially regulated by salt when two-month-old greenhouse-grown seedlings without prior exposure to sea water were subjected to 24 h of 500 mM NaCl treatment. About 1,404 genes were significantly up-regulated, while 5214 genes were down-regulated. Based on Gene Ontology analysis, they could be classified under various categories, including metabolic processes, stress and defense response, signal transduction, transcription-related and transporters. Our analysis provides the baseline information towards understanding salt balance in mangroves and hence mechanism of salt tolerance in plants. Overall design: Differential gene expression was studied upon salt treatment using two controls and two salt treated (24h with 500 mM NaCl) samples.