Growth responses and aquaporin expression in grape genotypes under salinity

The effects of salinity on growth, leaf area and water relations of two grape genotypes (Gharashani and Shirazi) were studied under 2-week salinity (25, 50 and 100 mM NaCl). Growth and fresh weights of all plant parts were significantly (p < 0.05) decreased by increasing salinity in both genotypes. Shirazi showed a higher decrease in shoot and root lengths and fresh weights than Gharashani. It also had a higher decrease in water potential and relative water content and a lower increase in leaf area as compared with Gharashani. There was a significant positive correlation (p < 0.05) between water potential and leaf area in two genotypes. Under salinity stress the expression of aquaporin PIP2.2 decreased significantly (p < 0.05) in roots and leaves of Gharashani, but it was higher in roots than in leaves. In roots and leaves of Shirazi the expression of this gene was partly increased. Considering growth factors and water relations, it seems that Shirazi is a sensitive genotype, but Gharashani can partly tolerate salinity.