关键词:  

Abstract: Phenylalanin ammonia-lyase (PAL) plays a pivotal role in the production of phenolic compounds, which are responsible for the success of the defense strategies in harsh environments in response to different stimuli. Measurements of the PAL activity, total phenolics, total flavonoids and anthocyanin contents were performed in flowers, leaves and fruits of three pistachio cultivars “Ahmadaghaii”, “Ohadi” and “Kallehghuchi”. The results showed that PAL activity was different in cultivars and in plant organs of pistachio trees (flowers, leaves and fruits). The highest activity rate of their compounds was observed in Ahmadaghaii cultivar. A positive correlation was observed between PAL activity, total phenolics and total flavonoids in leaves, and a negative correlation between PAL activity and anthocyanin contents in leaves and flowers of Ahmadaghaii cultivar. PAL activity and total phenolics in fruits of pistachio suffered a decrease when the maturation processes began. It is suggested that the hulls of the pistachio fruits, containing high level of phenolic compounds (especially in Ahmadaghaii cultivar), may function as a protective layer of defense chemicals against ultraviolet radiation and pathogens. The final concentration of phenolic compounds, flavonoids and antocyanins in the kernel depend on PAL activity in the kernel’s cultivar. The results led to the conclusion that increase in PAL activity, phenolic compounds and flavonoids in Ahmadaghaii can help the plant to cope with the stresses better than the other cultivars. Since phenolic compounds are antioxidant and scavenge free oxygen, it is postulated that Ahmadaghaii is the most resistant cultivar to the environmental stresses.

Key words: PAL activity, Phenolic compound, Pistachio, Cultivar, Environmental stress