Physiological and gene expression analysis of extreme chickpea (Cicer arietinum L.) genotypes in response to salinity stress

Salinity is a major abiotic stress, which reduces productivity of a broad range of crops, especially legumes. This study provides a comparative overview of physiological responses and expression patterns of critical genes in chickpea genotypes during five time courses of NaCl treatment. Considering lipid peroxidation (MDA), electrolyte leakage, proline content and relative water content which are considered to be direct indicators of salinity tolerance, the Flip 97-43c (T1) and Flip 97-196c (S2) genotypes displayed, respectively, maximum and minimum maintenance of cell membrane integrity, osmolyte accumulation and water retention capacity during salinity stress. Relative gene expression analysis of extreme genotypes was carried out using semi-quantitative RT-PCR and the up- and down regulation of the genes was confirmed by real-time qPCR for nine putative salinity responsive genes. However, up-regulation of salinity responsive genes and sequences including late embryogenesis abundant (CapLEA-1), H1 and 219 cDNA sequences, Nonspecific LTP precursor (LTP), Cu/Zn superoxide dismutase (Cu/Zn SOD) and protein kinase (PK) in tolerant genotype was significantly more than control (no-salinity seedlings) and S2 genotype (p ≤ 0.05). Transcript accumulation of trehalose 6 phosphate synthase (T6PS) and NADPH: isoflavone oxide reductase (IFR) genes in T1 did not record significant differences with the control or S2 genotype. These results suggested that, faster activation of studied genes in T1 genotype and higher accumulation of transcripts, especially LEA and H1, could be possible reasons for its higher tolerance under salinity stress.