ERF056 And ERF060 Modulate ABA And Salt Stress Responses In Arabidopsis Thaliana

Abscisic Acid(ABA)is one of the plant hormones that can regulate the growth and development of plants.It is also the key plant hormone that can regulate various stress responses in plants,especially abiotic stress responses.ABA regulates plant growth and development,as well as plant responses to abiotic stresses via regulating the expression of downstream response genes through signal transduction.ERF(Ethylene Response Factor)transcription factor family belongs to the AP2(APETALA2)/ERF transcription factor superfamily and is one of the largest transcription factor families in plants.Currently,several members of the ERF family have been found to play important roles in regulating plant growth and development,plant responses to stresses,and ABA signaling.However,the roles of ERF056 and ERF060 in ABA signaling remain unknown.By using transcriptome data to search ABA responsive genes with unknown functions,our lab found that ERF056,a member of the ERF transcription factor family,was induced by ABA,and the ERF060 shared high amino acid sequence identity with ERF056.By using RT-PCR,we confirmed that the expression of ERF056 was induced by ABA,while the expression level of ERF060 remained largely unchanged in response to ABA treatment.By constructing p UC19-GFP-ERF056 and p UC19-GFP-ERF060 and using transient protoplast transfection assays,we found that both ERF056 and ERF060 were mainly localized in the nucleus.By constructing p UC19-GD-ERF056 and p UC19-GD-ERF060 and using transient protoplast transfection assays,we found that both ERF056 and ERF060 had a transcriptional inhibitory activity,indicating that they are transcription repressors.To study the role of ERF056 and ERF060 in Arabidopsis(Arabidopsis thaliana),we generated two gene edited mutant lines of ERF056,i.e.,erf056-c1 and erf056-c2,two gene edited mutant lines of ERF060,i.e.,erf060-c1 and erf060-c2,and one line of gene edited double mutant of ERF056 and ERF060,i.e.,erf056 erf060-c1 by using CRISPR/Cas9 gene editing technique.We also generated a homozygous overexpression line of ERF056,i.e.,35S:ERF056 #11 by using plant transformation.We examined ABA responses of the erf056-c1,erf056-c2,erf060-c1 and erf060-c2 mutants,and 35S:ERF056 #11 overexpression plants,we found that the cotyledon greening rate of the mutant seedlings of the ERF056 and ERF060 genes were lower than Col-0 after ABA treatment,and the cotyledon greening rate of the ERF056 overexpression seedlings were higher than Col-0.Therefore,ERF056 and ERF060 may have redundant functions in ABA response in Arabidopsis.We also examined salt responses of the erf056-c1,erf056-c2,erf060-c1 and erf060-c2 mutants,and the 35S:ERF056 #11 overexpression plants,we observed that the cotyledon greening rate of the over-expressing ERF056 were slightly lower than Col-0,while that in the mutants of ERF060 seedlings were higher than the contrast group.Therefore,ERF056 and ERF060 may have redundant functions in salt response in Arabidopsis.In summary,our results show that ERF056 and ERF060 are transcription repressors that may have redundant functions in ABA and salt stress responses in Arabidopsis.