Lipoxygenase Activity and Key Photosynthesis Parameters in Wheat Triticum aestivum L. under Different Water Supply Conditions

Lipoxygenase (LOX) and products of LOX pathway are known to influence photosynthesis and adaptation to adverse factors, including drought. We have studied the effect of LOX activity on gas exchange and chlorophyll fluorescence under water deficiency in three unrelated cultivars of wheat Triticum aestivum L. Plants were grown under controlled conditions in a growth chamber with an optimal water regime and under simulated soil drought. The cv. Saratovskaya 29 (S29), known for its high drought resistance, was characterized by stability of LOX activity, gas exchange and chlorophyll fluorescence parameters under water deficiency. Unlike S29, wheat cultivars, Yanetzkis Probat and Rodina, demonstrated a classic adaptive strategy—an increase in water use efficiency by reducing transpiration and stomatal conduction. The decrease in the level of gas exchange parameters was inversely proportional to the increase in the level of LOX activity. This fact may indicate the involvement of LOX in the regulation of gas exchange during the adaptation of these wheat cultivars to drought. Adaptive changes contributed to maintaining photosynthesis efficiency in conditions of water deficiency. Based on the results obtained and publications by other researchers, we associate the adaptive increase in LOX activity with the regulation of redox homeostasis to ensure a growth-defense trade-off in wheat.