INFLUENCE OF SALT AND DROUGHT STRESSES ON ANTIOXIDANT AND LIPID SYSTEMS DURING SEED-TO- SEEDLING TRANSITION IN SAFFLOWER
Functional transition, hydrogen peroxide, ascorbate peroxidase, catalase isocitrate lyase, malate synthase.
During the post-germinative development, drought and toxic salts concentrations can affect physiological and metabolic processes of cotyledonary tissues, such as growth, enzyme activity and mobilization of lipid reserves, besides the generation of a cellular redox imbalance. However, studies generally report metabolic changes throughout the development under stresses applied only at the time of sowing. Therefore, this study aimed to evaluate the phenological and physiological changes caused by drought and salt stresses applied at the same time during sowing or during the seed-to-seedling establishment. In addition, this study characterizes the activity of APX, CAT and SOD enzymes and APX, CAT, ICL and MLS mRNA expression of safflower seedlings subjected to stress only during the seed-to-seedling transition. We found that NaCl and PEG decreased the germination rate, root length, germination speed index, cotyledons water content and humidity. However, in both treatments was observed lower levels of lipid peroxidation, SOD and CAT activity and CAT expression. The activity and expression of APX remained high during treatments, as well as MLS expression. From this, we conclude that NaCl and PEG treatments affected the phenological and biochemical aspects evaluated during seed-to-seedling transition and that APX system and H2O2 content may be linked to the maintenance of photosynthetic establishment.