Deciphering the Molecular Mechanism of Salinity Tolerance in Halophytes Using Transcriptome Analysis

Salinity stress is a major threat to agricultural crops and productivity. The majority of crop plants are susceptible to salinity stress, and rapidly expanding salinity stress in cultivable areas is a serious issue for crop yield. In contrast to crop plants, halophytes grow on highly saline soil, and understanding the molecular basis of the salinity tolerance of halophytes could give valuable clues to improve crop plants using genetic engineering techniques. Genes responsible for ion transport, detoxification of reactive oxygen species (ROS), stomatal regulation and hormonal signalling are considered to achieve salinity tolerance. Transcriptome sequencing is a useful technique to reveal a snapshot of the whole transcript expressed under salinity stress. The technique is rapid, cost-effective and robust to estimate genes involved in specific pathways along with their expression. Several transcriptome studies have been carried out in halophytes in different stages and tissues under salinity stress. In the present chapter, we emphasize the molecular mechanism of salinity tolerance of halophytes using transcriptome sequencing. We also aim to discuss the role of the ion transporter in maintaining the Na+/K+ ratio in root and shoot, transcription factors and their regulation, and the role of hormonal signalling and its crosstalk during salinity. Genes highly expressed in different species of halophytes and their interaction during salinity are also discussed.