Regulation Of Siliques Morphology By AtOFP16,a Member Of The Class ? OVATE Family Proteins In Arabidopsis

OVAYE FAMILY PROTEINS are new type of transcription factors that regulate many aspects of plant growth and development.Based on different phenotypes in overexpression plants,the family is classified into three subfamilies and the first subfamily has been studied a lot.In this paper,we mainly focus on the characterization of a member of the third subfamily AtOFP16.Firstly,we confirmed that AtOFP16 functions as transcriptional repressor.In order to verify whether it is an active suppressor or a passive suppressor,we fused AtOFP16 with VP,a strong activator,and examined its transcriptional activities in a protoplast transient expression system.The experiment results showed that the transcriptional activity is not changed,which means AtOFP16 is an active suppressor.Further,we built the overexpression plants of AtOFP16-VP and found that its phenotype is different from the plants of AtOFP16 overexpression.It implies that the strong activator,VP affect the function of AtOFP16 in plant probably.We built the plants AtOFP16-GR over expression and we found there is no evident difference for phenotype between the plant with DEX spraying and without DEX spraying.It suggests that GR fusion has the similar effect on AtOFP16 with VP in plant.We found that blunt-end siliques phenotypes observed in transgenic overexpres-sing class III OFPs genes was similar to that in the erecta(er)mutants.In order to dissect the relationship between them,we generated the ERECTA(ER)overexpression plants on the AtOFP16 overexpression background,we found the blunt-end siliques phenotype in the AtOFP16 overexpression plants was recovered.It indicates that At OFP16 may functions the same singal pathways of ER to control the siliques phenotype.To further dissect the relationship between AtOFP16 and ER,we made the double mutant and found the double mutant phenocopied the erecta mutant.We infer it is caused by the redundant function among OFPs probably,AtOFP16 gene knockout but there are other genes that function,so still er mutant phenotype.ER signal functions through regulating the stability of the downstream transcription factors which is controlled by the phosphorylation through MPK3 and MPK6,hence regulating the downstream genes.We verified that there is interaction between AtOFP16 and MPK3 through yeast two hybrid experiment and bimolecular fluorescence complementation.Based on the above AtOFP16 is probably located in the downstream of ER signal pathway for regulating blunt-end siliques phenotype.