Effects of water stress on leaf antioxidant enzymes activities and protein contents in five Prunus rootstocks

In this study, the effects of water stress on the ascorbate peroxidase (APX), peroxidase (POD), catalase (CAT) and superoxide dismutase (SOD) antioxidant enzyme activities and total soluble protein contents in the leaves of five Prunus rootstocks (Arda, GF 677, Garnem, Rootpac-20 and Nemaguard) were investigated. One-year-old plants were grown in 18-L containers and treated with two levels of deficit irrigation regimes for water stress: 50% field capacity (FC) and 25% FC. Control plants were irrigated at field capacity (100% FC). Leaf samples were taken on day 24 after starting the treatments. Antioxidant enzyme activities and protein contents of leaves showed variations with both rootstocks and levels of irrigation. Stressed plants exposed to 25% FC showed the tendency to have higher APX activity than control plants, and the contrary for those exposed to 50% FC, although differences among rootstocks and treatments were not significant in most cases. POD and SOD activities (0.63 A460 min^‑1 mg^‑1 protein and 9.56 U mg^‑1 protein, respectively) were higher in the leaves of Garnem rootstock exposed to 50% FC, although it did not differ significantly from Arda 25%FC. Total protein (6.26 mg mL^‑1) was higher in the control plants of Rootpac-20 and Arda rootstock. In general, water stress reduced leaves protein content. In addition, the Garnem rootstock seemed to induce a higher enzymatic response based on POD and SOD activities under severe water stress conditions compared to the other rootstocks.