oa Molecular and cellular responses of date palm roots to salinity stress

The ability of date palm (Phoenix dactylifers L.) to grow in hot and dry regions of the world makes it an important subsistence crop in most arid areas. Nevertheless, salinity and drought are the main abiotic stresses causing loss of date palm yield. Here we employed the next generation sequencing technology for high-throughput sequencing of date palm transcripts in response to salinity. cDNA libraries, from roots treated with 100 mM Sodium Chloride and mock treated roots, were sequenced via Illumina HiSeq2000 system. Data analysis identified 1940 genes that are differentially expressed between treated and mock treated roots. MYB transcription factors, protein kinase, E3 ubiquitin ligase, calmodulin, polyamine oxidase and acetyltransferase transcripts are regulated in response to salinity stress suggesting potential roles of these genes in tolerance to salinity stress. Additionally, we examined the cellular responses of date palm tissue to salinity stress using transmission electron microscopy (TEM). Results from TEM show that stressed roots exhibited plasmolysis in cortical cells while epidermal cells did not appear to plasmolyze. Columnar cells in the distal root region might form a barrier to salt intrusion, which would make the older regions of the root less susceptible to salt plasmolysis. Output from this project will help in enhancing our understanding of date palm signaling mechanisms and developing new strategies to control salinity stress.