The Role Of PIFs In Blue Light Regulating Arabidopsis Endogenous H₂S Signal

Light is one of the necessary environmental factors for plant growth,and blue light as a component of the natural light spectrum regulating physiological processes such as plant hypocotyl growth,shade response and flowering.Arabidopsis CRY1 and CRY2 had been shown to be the major blue light receptors that mediate blue light regulating signal transduction processes in plant growth and development.Studies have shown that the red light/far-red light receptor phytochrome PHY interactors PIFs are also involved in blue light receptor-mediated signal transduction.The gas signaling molecule H₂S is involved in various physiological processes including plant growth and development and stress stress response.In the preliminary laboratory stage,arabidopsis blue light receptor mutants cry1and cry2 were used as experimental materials to demonstrate that blue light activated endogenous H₂S signaling in arabidopsis by regulating LCD phosphorylation and LCD gene expression.This project used the arabidopsis phytochrome interactors PIF1,PIF4,and the endogenous H₂S production enzyme LCD or DES1 genes mutants as experimental materials to investigate whether PIFs participate in blue light in regulating endogenous H₂S signaling in arabidopsis.The main research results are shown as follows:1.The H₂S content of Col was significantly increased between 5-10 min of blue light treatment and decreased to the dark level after 15 min in arabidopsis hypocotyl.The H₂S content in pif1 and OE-PIF1 did not change significantly with in 15 min of blue light irradiation,while increased in pif4 after 15 min irradiation significantly.Its content increased significantly after 10-15 min in OE-PIF4,and a 5 min lag in pif Q（At PIF1,3,4,5four gene deletion mutations）.2.The H₂S production rate of Col and pif1 increased significantly from 5 min,and quickly returned to dark levels after continued light illumination;while the H₂S production rate of OE-PIF1 and OE-PIF4 increased significantly with in 10 min of blue light irradiation,the H₂S production rate of pif4 did not change with in 15 min of blue light treatment,while decreased in pif Q after 10 min irradiation significantly.3.No phosphorylation modification of the His-DES1 protein was detected in the in vitro experimental system.4.Blue light treatment resulted in reduced LCD and DES1 gene expression in Col and pif1,after 5 min of blue light treatment,LCD and DES1 gene expression levels were significantly increased in pif4,OE-PIF4,and pif Q,and LCD and DES1 expression of OE-PIF1 were significantly increased after 15 min of blue light treatment.5.The His-PIF1 recombinant protein was purified from from E.coli BL21,and displayed the binding activity to the LCD and DES1 gene promoters.Using the PIFs over-expression mutants of OE-PIF1-GFP,OE-PIF3-GFP,OE-PIF4-GFP or OE-PIF5-GFP as materials,the in vivo Ch IP experiments demonstrated that both PIF1 and PIF4 can bind to the LCD gene promoter in the dark,while a decreased binding activity between PIF4 to the LCD gene promoter after 10 min of blue light irradiation.The binding activity of PIF1 or PIF4 to the LCD gene promoter was not detected after 20 min of blue light irradiation.The results show that the PIF1 and PIF4 can bind to the LCD gene promoter to regulate the LCD gene expression and participate in the activation of endogenous H₂S signaling in arabidopsis caused by blue light.The regulation of endogenous H₂S signaling in arabidopsis includes gene expression of LCD and DES1,and the PIF1 plays a major activation role.