Comparative Adaptation Responses of Melon (Cucumis melo L.) Genotypes to Salinity Stress

The objective of this work was to understand the mechanisms of physiological, biochemical, and molecular responses to salinity stress of three Turkish melon genotypes (YYU 1, YYU 4 and CU 196) and cv. Ananas. The study used Randomized Complete Block Design (RCBD) and pots were irrigated with Hoagland nutrient solution after two-leaf stage until harvesting by 50 and 75 mM NaCl concentrations. For evaluation of responses, chlorophyll and carotenoid content, total phenolic and flavonoid amount, proline variations, and nutrient elements were determined. Moreover, qRT-PCR analyses were performed to identify the expression level of six TF (Transcription Factors) genes (WRKY24, TCP15, CmHD-Zip, mTERF2, Dof3 and CmADH2). Increase in salt application led to increase in chlorophyll content in the melon genotypes, but decrease (about 55%) in cv. Ananas. Phenolic, flavonoid, and proline contents varied based on the melon genotypes, but generally increased in Ananas. Expression levels of TCP15 and WRKY24 showed more fold change at 75 mM NaCl treatment. On the other hand, the expression of CmADH2 and Dof3 showed more fold change at 50 mM NaCl treatment. Finally, according to adaptation mechanisms of melon genotypes, the study might help in selection and detection of the salt tolerant ones.