Light Regulation of Arabidopsis PIRIN1 Indicates Functions in Environmentally-induced Stress Physiology of the Seedling

Plants develop various ways to accommodate a continuously changing environment. In response to light and hormones, a cupin superfamily member Pirin1 (PRN1), acts as a transcriptional activator, as well as an enzyme that can cleave the UV-induced and UV-screening compound quercetin (flavonoid). Our lab recently published findings which indicate that Pirin1 (PRN1) in Arabidopsis thaliana is critical for seedlings to orient and respond to light in the seed-to-seedling transition. The pool of flavonoids in the seedling is regulated by PRN1 activity, and PRN1 is expressed in a tissue specific manner depending on developmental state. Based on genetic studies of mutant and transgenic (complementation and overexpressors) seedlings, PRN1 directs organ and overall hypocotyl growth of the young seedling. Human pirin (hPir) was transformed into prn1 Arabidopsis mutants. We evaluated plant-specific and non-plant specific responses/ activities for ability of hPir to rescue defects of prn1 under a number of abiotic signals that in excess can be stressors. We report that PRN1 is critical for proper response to abiotic signals in general and plays a role in the leaves and root in how the seedling is able to respond to the environment. In addition, light plays a major role in permitting PRN1 to play a role in responding to the abiotic signals in the environment. PIRINs hence, may be excellent targets for improving responses to stress in plants of economic importance.