Regulation Of Seed Germination By Glutathione S-Transferase U7(AtGSTU7) In Arabidopsis Thaliana

Glutathione S-transferases(GSTs)play an important role in the metabolism and detoxification of plant cells,but their functions during development are little known.The Arabidopsis genome contains 48 GST genes,28 of which belong to the Tau class of genes(GSTU),which are divided into several different clades.The largest GSTU gene cluster is located on chromosome 2,and it includes 7 members GSTU1-GSTU7.This gene cluster has not been studied in detail before.AtGSTU7 expression is induced by SA but was independent of NONEXPRESSOR OF PATHOGENESIS-RELATED GENES 1(NPR1),a co-activator of pathogenesis-related gene expression.Arabidopsis AtGSTU7(AT2G29420)encodes Tau-like GST.The full-length mRNA of AtGSTU7 is 887 bp,including one intron and two exons.According to PLACE data prediction,it is found that the 1000 bp sequence upstream of AtGSTU7 transcription start site contains 4 ABA-responsive ABRE elements and 5 W-box(TGAC)nucleotide sequences.It indicates that the expression of AtGSTU7 may respond to ABA and environmental stress.Investigate the expression characteristics of GSTU7 during the development of Arabidopsis,determine its detailed expression location,and its expression characteristics under various stress conditions,order deletion mutants,and use germination rate statistical experiments for related functional analysis.The mechanism of AtGSTU7 regulating seed germination under the conditions of GSH and hydrogen peroxide was explored,and the relationship between the nine important genes of the ABA signaling pathway and AtGSTU7 was investigated by qRT-PCR method.Through analysis,we draw the following 6 conclusions:1.AtGSTU7 expression responds to ABA and drought stress,and is mainly expressed in large quantities during uptake 24-48 h,and accumulates in the roots of germinated seeds.Under ABA stress,deletion of AtGSTU7 gene inhibited seed germination.Under Mannitol stress,the deletion of AtGSTU7 gene promoted seed germination.2.Under stress and non-stress conditions,the loss of AtGSTU7 function leads to an increase in GSH content and a decrease in H2O2 content in germinated seeds;GSH participates in the germination of Wt and atgstu7 seeds under ABA and drought stress.With the addition of exogenous H2O2,the seed germination rate of atgstu7 was inhibited,indicating that ROS is involved in seed germination,and ROS-mediated seed germination is regulated by AtGSTU7 activity.3.Under normal culture,ABA and mannitol treatment conditions,the expression of ABI3 mRNA in atgstu7 mutants was greatly reduced,and ABI3 was mainly expressed in a large amount in dry seeds.Phenotypic analysis showed that the abi3 seeds were fuller,and the width and length of 20 seeds had no significant difference compared with Wt,the volume of abi3 seeds under the same quality is slightly higher than that of Wt.4.The absence of ABI3 reduces the sensitivity of seeds to ABA.5.Deletion of ABI3 gene increases AtGSTU7 expression.6.The participation of AtGSTU7 in seed germination is mediated by GSH-ROS homeostasis and ABA signaling.