Differentially Expressed Long-Term Salinity Responsive Sequences in Halophyte Suaeda maritima (L.) Dumort

Salinity is a major abiotic stress that affects plant growth and productivity. To cope with salt stress, plants express large number of salt responsive genes and proteins that are involved in a wide range of cellular functions. In the present study, halophytic plant Suaeda maritima (L.) Dumort. were hydroponically exposed to NaCl for understanding the molecular mechanisms behind salinity tolerance using PCR-based Suppressive Subtractive Hybridization (SSH). Two cDNA subtraction libraries were constructed between Suaeda maritima X Sesuvium portulacastrum and Suaeda maritima X Salicornia brachiata to identify differentially expressed genes from leaves exposed to 200mM NaCl treatment for 14 days. A total of 224 clones from both libraries were assembled into 109 unique-ESTs grouped into different functional categories. Based on GO functional annotation, the expressed sequences like Oxygen-evolving enhancer protein1, AARF domain-containing kinase protein, V-type proton ATPase subunitd2, RMD5 homologA, and ABC transporter G35 that are involved in photosynthesis, cellular transport, cell rescue and defense, polyubiquitination and secondary metabolism played a significant role implying a complex response to salt in S. maritima. This is the first report that SSH could facilitate screening across species and family specific identification of salt responsive genes provides insight into biological mechanisms underlying salinity response.