Cloning and expression analysis of 14 lipid transfer protein genes from Tamarix hispida responding to different abiotic stresses

Plant lipid transfer proteins (LTPs) are ubiquitous lipid-binding proteins that are involved in various stress responses. In this study, we cloned 14 unique LTP genes (ThLTP 1-14) from Tamarix hispida Willd. (Tamaricaceae) to investigate their roles under various abiotic stress conditions. The expression profiles of the 14 ThLTPs in response to NaCl, polyethylene glycol (PEG), NaHCO(3), CdCl(2) and abscisic acid (ABA) exposure in root, stem and leaf tissues were investigated using real-time RT-PCR. The results showed that all 14 ThLTPs were expressed in root, stem and leaf tissues under normal growth conditions. However, under normal growth conditions, ThLTP abundance varied in each organ, with expression differences of 9000-fold in leaves, 540-fold in stems and 3700-fold in roots. These results indicated that activity and/or physiological importance of these ThLTPs are quite different. Differential expression of the 14 ThLTPs was observed (> 2-fold) for NaCl, PEG, NaHCO(3) and CdCl(2) in at least one tissue indicating that they were all involved in abiotic stress responses. All ThLTP genes were highly induced (> 2-fold) under ABA treatment in roots, stems and/or leaves, and particularly in roots, suggesting that ABA-dependent signaling pathways regulated ThLTPs. We hypothesize that ThLTP expression constitutes an adaptive response to abiotic stresses in T. hispida and plays an important role in abiotic stress tolerance.