Salt Stress Tolerance of Pyrus spp. and Cydonia oblonga Genotypes Assessed by Morphological, Biochemical and Dehydrin Gene Expression Analysis

Salt stress influences the physiological, biochemical, and molecular processes in plants affecting growth and development. This research aims to determine the salt stress tolerance of wild pear genotypes AH-1, AH-2, AH-3 (Pyrus elaeagrifolia Pall.), Ankara Pear clone 19 (AN-19) (P. communis L.) and clonal pear rootstocks OHxF 333 (P. communis L.) and quince (QA) (Cydonia oblonga Mill.) under in vitro conditions. Microshoots of each genotype were cultured in MS medium and subjected to NaCl combined with CaCl2 at four different concentrations for 4 weeks. The survival percentage of the OHxF 333, AN-19, QA, and AH-3 microshoots was found to be high (77.66-97.16%) at high salt concentrations. Number of shoots was significantly lower (1.0-2.52/explant) in salt treatments. While shoot length was generally similar to the control, shoot thickness, callus diameter, and fresh weight decreased with increasing salt concentration. Dehydrin gene (MdDHN) expression analysis revealed that QA, AH-3, OHxF 333, AH-2, and AN-19 genotypes responded to salinity stress earlier than others. The genotypes AH-3, OHxF 333, QA, and AN-19 exhibiting high survival percentage and earlier MdDHN expression were further evaluated for antioxidant activity (SOD, CAT, APX), total chlorophyll and proline contents and mineral elements that are involved in salt stress response of plants. Proline, H2O2 content and SOD activity were highest in AH-3, APX, and CAT activity were highest in QA at high salt concentration. Our findings revealed the salt stress response of Pyrus spp. and Cydonia oblonga genotypes used as rootstocks for pears.