title: Hypomorphic alleles reveal FCA-independent roles for FY in the regulation of FLOWERING LOCUS C.
abstract: The autonomous floral promotion pathway plays a key role in the regulation of flowering in rapid-cycling Arabidopsis (Arabidopsis thaliana) by providing constitutive repression of the floral inhibitor FLOWERING LOCUS C (FLC). As a result, autonomous pathway mutants contain elevated levels of FLC and are late flowering. Winter annual Arabidopsis, in contrast, contain functional alleles of FRIGIDA (FRI), which acts epistatically to the autonomous pathway to up-regulate FLC and delay flowering. To further explore the relationship between FRI and the autonomous pathway, we placed autonomous pathway mutants in a FRI-containing background. Unexpectedly, we found that a hypomorphic allele of the autonomous pathway gene fy (fy null alleles are embryo lethal) displayed background-specific effects on FLC expression and flowering time; in a rapid-cycling background fy mutants contained elevated levels of FLC and were late flowering, whereas in a winter annual background fy decreased FLC levels and partially suppressed the late-flowering phenotype conferred by FRI. Because FY has been shown to have homology to polyadenylation factors, we examined polyadenylation site selection in FLC transcripts. In wild type, two polyadenylation sites were detected and used at similar levels. In fy mutant backgrounds, however, the ratio of products was shifted to favor the distally polyadenylated form. FY has previously been shown to physically interact with another member of the autonomous pathway, FCA. Interestingly, we found that fy can partially suppress FLC expression in an fca null background and promote proximal polyadenylation site selection usage in the absence of FCA. Taken together, these results indicate novel and FCA-independent roles for FY in the regulation of FLC.
authors.affiliation: Department of Biology, Indiana University, Bloomington, Indiana 47405, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Feng
authors.forename: Yannick
authors.initials: Y
authors.lastname: Jacob
authors.forename: Kira M
authors.initials: KM
authors.lastname: Veley
authors.forename: Lei
authors.initials: L
authors.lastname: Ding
authors.forename: Xuhong
authors.initials: X
authors.lastname: Yu
authors.forename: Goh
authors.initials: G
authors.lastname: Choe
authors.forename: Scott D
authors.initials: SD
authors.lastname: Michaels
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000235:genetics* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D035264:Flowers / Q000235:genetics / Q000648:ultrastructure; D018506:Gene Expression Regulation, Plant; D007178:Inbreeding; D026161:MADS Domain Proteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D026723:Polyadenylation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D013997:Time Factors; D039221:mRNA Cleavage and Polyadenylation Factors / Q000235:genetics* / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C418902:At5g10140 protein, Arabidopsis; C518020:FY protein, Arabidopsis; C106535:Flowering time control protein FCA, Arabidopsis; D026161:MADS Domain Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; D039221:mRNA Cleavage and Polyadenylation Factors