Preliminary Study On The Functional Mechanism Of Decapping Enzyme DCP2 In Ethylene Signaling Pathway In Arabidopsis

Ethylene is an essential phytohormone,which plays an important role in a series of physiological processes of plants,and ethylene signaling has comprehensive and complicated cross-talk with other endogenous development signals(e.g.other hormone signals)and exogenous environmental stimuli.Identification of novel ethylene regulatory factors is of great significance for the intensive analysis of ethylene signaling pathway and ethylene integrated regulatory networks.Here,we generated a pool of EMS mutagenized ctr1-1 mutant,which has constitutive ethylene response,and obtained two mutants ctr1-1 EMS55 and ctr1-1EMS64 that can suppress the developmental defect and ACC response of ctr1-1.Further whole-genome sequencing revealed an identical mutation occurring at G795(mutated to A)of the DECAPPING 2(DCP2)gene,resulting in Arg138 mutation of DCP2 to His.By transformation of wild-type DCP2 into ctr1-1 EMS64 mutant,we found that the developmental phenotype as well as ACC response of the mutant was restored to the level of ctr1-1,indicating that DCP2 is the target gene.We then generated the EMS64 mutant in the absence of ctr1-1 genetic background,and confirmed the ACC response of DCP2.Furthermore,we performed transcriptome analysis of seedlings under both light and dark conditions,and demonstrated that DCP2 is involved in ethylene signaling pathway.We also showed that the short-term ACC-induced ERF1 expression,which is an important downstream gene of ethylene signaling,was reduced in plants lacking DCP2,indicating that DCP2 presumably regulates early ethylene signaling.In addition,we found that DCP2 could physically interact with the C-terminus of EIN2(EIN2-C),and that such interaction was specifically localized in the P-body,implying that DCP2 may function in translational repression of EBF1/2 mRNAs.We further showed that while DCP2 R138 mutation did not affect the interaction between DCP2 and EIN2-C,the mutation obviously compromised the interaction between DCP2 and DCP1,an another essential component in the P-body.In summary,our preliminary data demonstrate that the decapping enzyme DCP2 is likely involved in the EIN2-dependent ethylene signaling pathway.