The Mechanisms Of Seed Germination And Stomatal Movement Regulated By Sinapate Ester Biosynthesisin Arabidopsisthaliana

Sinapic acid and its derivatives are important intermediate products of phenylpropanoid metabolic pathway.They widely involved in the physiological activities of the different stages,such as seed germination,plant growth.Sinapic acid esters including sinapoylglucose,sinapine,sinapoylmalate,were accumulated in Arabidopsis and other cruciferae plants,their content regulatedby plant life cycle.Studies have reported that sinapine is important for seed germination.Sinapine,however,how to regulate seed germination,and wherether sinapine regulates seed germination is related to the inhibition of ABA is unclear.The seeds of WT pretreated with 0.5 mM sinapic acid was used in this experiment and tatistics the germination of seed.The results showed that low concentration of sinapic acid can promote the seed germination and partly rescue the ABA-induced seeds dormance.We speculate that this regulation has a connection with ABA in the germination process.We used high performance liquid mass spectrometry?LC-MS?to detect the content of endogenous ABA and ABA-GE?abscisic acid glucose ester,ABA-GE?in seeds pretreated with sinapic acid.The results showed that sinapic acid can promote the transformation of ABA to ABA-GE.That was to mean,sinapic acid reduced the ABA content and increased the content of ABA-GE.Using Real time PCR to research expression quantity of ABA glycosylation genes,such as UGT71C5,UGT71B6,UGT71B7,UGT71B8.The results showed that sinapic acid can induce the expression of these genes,and the expression of UGT71B7 increased about three times.Then,UGT84A2 was used to glycosylate reaction in vitro and analysed the expression of ABA glycosylation gene.These results suggest that sinapic acid metabolism may be affected the expression of ABA glycosylation genes,and break the balance of the ABA homeostasis,and regulate the germination of seeds,then regulate the germination process of seeds.This study provides a new model that sinapic acid affect the ABA homeostasis in the process of germination.Sinapic acidester metabolic pathways not only play a role in seed germination stage,but also in growth and development stage.Ultraviolet?UV?is damage for most plants,they use a variety of ways to avoid this kind of damage.The accumulated of 2-O-sinapoyl-L-malate in leaves can protect plants defence UV stress,and at the same time,stomatal closure.However,the role of sinapic acid in the process of plant response to UV-B is unclear.To explore the mechanism of sinapic acid in the process of plant response to UV-B.We used sinapic acid ester synthesis mutants sng1-1,sng2-2 and brt1-1 were exposed to 0.5 Wm^-2 UV-B for 4 h in this experiment.The results showed that sinapic acid affects the accumulation of malateand H₂O₂ in UV-B-induced stomatal closure process.We speculated that the possible mechanism is:sinapic acid affects the accumulation of malate and reactive oxygen species,then influence the stomatal movement.