Investigation of the effects of salt stress on morphological, physiological, biochemical, antioxidant characteristics, and gene expression responses in pistachio(Pistacia vera L.)

Salt stress is a major limiting factor for agricultural productivity, particularly in arid and semi-arid regions. It adversely impacts plant growth and physiological functions. Understanding the morphological, biochemical, and molecular responses of pistachio to salinity is crucial for developing salt tolerant cultivars. In this study, UCB-1 pistachio seedlings (Pistacia vera L.) were subjected to 0, 100, and 200 mM NaCl for 7 and 21 days to investigate their morphological, physiological, biochemical, and molecular responses to salt stress. Salinity significantly reduced fresh and dry weights of roots and stems, as well as chlorophyll and carotenoid contents. In contrast, proline, soluble carbohydrates, and phenolic compounds increased, indicating adaptive metabolic responses. Salt stress also enhanced the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), reflecting oxidative stress. Enzymatic activities of SOD, CAT, APX, and GPX were significantly upregulated under salt stress. Gene expression analysis revealed a marked induction of NHX1, Dehydrin, CAT, and DREB2 genes, particularly at 200 mM NaCl after 21 days, indicating their pivotal roles in ion homeostasis, osmoprotection, and antioxidant defense. These findings highlight the complex physiological and molecular mechanisms involved in salt tolerance of pistachio. The activation of antioxidant systems and stress responsive genes contributes to mitigating oxidative damage and maintaining cellular homeostasis. These results provide insights into the adaptive responses of pistachio to salinity and may contribute to breeding efforts aimed at developing salt tolerant cultivars suitable for saline environments.