Function And Molecular Mechanism Of Pseudo-response Regulator GmPRR7a In Soybean Photoperiod Regulating Flowering Time

Flowering,one of the most important agronomic traits of the crop,affects crop yield,plant morphology and ecological adaptability directly.The photoperiodic sensitivity of soybean severely limits its ecological adaptability.Although 16 soybean flowering and maturation genes have been cloned,the mechanism of photoperiodic regulation of flowering in soybean is still unclear.Based on fine mapping,clock gene GmPRR7 a was cloned.In this study,the function complementation experiment,transcriptional expression,yeast hybridization and bimolecular fluorescence complementation techniques were used to disclose the delayed flowering of this gene.The regulatory relationship with known soybean photoperiod genes was revealed.Three proteins interacting with GmPRR7 a were identified.The study of GmPRR7 a is of advantage to understand the photoperiodic sensitivity of soybean and provide new targets and molecular components for soybean molecular design and breeding.The main findings are as follows:(1)Functional test of GmPRR7 a.The mutant and overexpression materials were cultured under long daylight conditions,and flowering was significantly earlier in the mutant,while late in overexpression materials compared with the wild type under long daylight conditions.The result showed that the GmPRR7 a delay flowering in soybean.(2)The relationship between GmPRR7 a and E1-E4 genes.The materials of E1,e1,E2,e2,E3,e3,E4 and e4 near gene lines were cultured under long daylight conditions,and the expression of GmPRR7 a gene was analyzed.The expression of GmPRR7 a gene in e1 and e2 materials was found to be significantly lower than that of in E1 and E2 materials,and it was inferred that GmPRR7 a gene was regulated by E1 and E2.(3)The relationship between GmPRR7 a and other known flowering genes.The expression of other known flowering genes was analyzed using the GmPRR7 a mutant material(prr)and its wild-type material(williams 82).It was found that the expression of GmPRR7 b,GmPRR7 c and GmPRR7 d in the mutant material was significantly higher than that in the control group,indicating that the homologous genes of GmPRR7 a could compensate expression for the absence of GmPRR7 a.COL2b,LCLs were significantly more expressed in the mutant prr than in the wild-type,inferring that COL2 b and LCLs genes are regulated by GmPRR7 a and repressed by this gene under normal conditions.The expression of COP1 a and COP1 b in the wild-type is significantly higher than that in the prr,inferring that GmPRR7 a could be the upstream gene that promotes the expression of COP1 a and COP1 b.Under normal conditions,GmPRR7 a promotes the expression of COPs and suppresses the expression of downstream florigenic factors.(4)GmPRR7 a interacting proteins.By yeast two-hybrid screening,we obtained that the proteins encoded by GmPRR5/9a and GmPRR5/9b interact with the proteins encoded by GmPRR7 a,and then we verified the interaction between GmPRR5/9a,GmPRR5/9b,GmPRR5/9d and GmPRR7 a proteins by bimolecular fluorescence complementation technique,and the interaction occurred at the cell membrane.