Sequencing the Transcriptome of Prosopis chilensis Shoots and Roots in Response to Seawater Saline Concentration

Salinity has been identified as one of the most significant osmotic stress affecting plants in arid and semi-arid environments. Nitrogen-fixing Prosopis chilensis trees possess great plasticity and extraordinary capacity in dealing with environmental variations of abiotic stress such as salinity. Although the physiological mechanism underlying saline adaptation has been largely studied in this tree, molecular mechanisms are still unexplored. In the present study, we conducted a mRNA-Seq assay by the Illumina platform to identify saline stress induced genes in P. chilensis at the whole transcriptome level. Total RNA from shoots and roots of trees treated with and without 450 mM NaCl (sea water concentration) were used to prepare four cDNA libraries. We obtained more than 50 million of paired end reads per each cDNA library that was assembled into 134,200 contigs varying from 201 bp to 15,8 kbp. Semi qRT-PCR validation suggested a high reliability of the RNA-Seq results. Gene ontology analyses were conducted to gain insight into gene pathways and we identified several genes involved in metallochaperone and electron carrier activities, protein folding and degradation, and metabolic processing in response to saline stress. This is the first RNA-Seq-based expression study in P. chilensis in response to saline stress.