Differential Expression of Salt Responsive Genes in Saltbush

Saltbush (Atriplex halimus L.) is a halophyte wild plant distributed in Arabian deserts and salt marshes. This study was carried out to investigate salt responsive genes in saltbush shoots and roots. Two months old in vitro plantlets of A. halimus line AhPTC01-01 were utilized. The roots were exposed either to 0 or 250 mM NaCl for 18 h, indicating control and stress treatment, respectively. Total RNA was isolated using RNeasy Midi kit (Qiagen) from shoots and roots. The cDNA was amplified using SMARTer cDNA Synthesis kit (Clontech). Four cDNA libraries (control root, control shoot, stress root, stress shoot) were prepared and run for single reads of 101-cycle in one sequencing lane in the GAIIx (Illumina). A self assembled and annotated A. halimus transcriptome containing 48000 ESTs was used as reference sequence. The reads were mapped to the reference using CLC Genomics Workbench 5. Specific group of stress responsive genes were identified upon salt treatment both in shoots and roots, which contains both known and novel stress responsive genes. The expression of identified candidate genes needs further investigation under different salt levels and exposure times.