The gene fimbriata interacts non-cell autonomously with floral regulatory genes.
In Antirrhinum majus, one proposed role of the gene fimbriata (fim) is as a mediator between the floral meristem identify gene floricaula (flo) and floral organ identity genes such as deficiens (def) and plena (ple). The mechanism of fim activity is probably unique as, while the other genes in the hierarchy are thought to be transcription factors, fim is thought to target proteins to a ubiquitin-mediated destruction pathway. Both flo and def have been shown to act non-cell autonomously. We tested the hypotheses that (i) fim acts in a non-cell autonomous manner; and (ii) non-cell autonomy of flo might be through activation and subsequent non-cell autonomous activity of fim. Plants bearing an unstable fim allele were monitored for revertant shoots. Analysis of fim RNA expression in plants derived from revertant shoots, and segregation of revertant phenotype in progeny from revertant plants, indicated that all were periclinal chimeras with wild-type fim expression only in subepidermal layers. Despite the absence of fim in the epidermal layer, expression of downstream genes was normal, suggesting non-cell autonomous activity of fim. Subsequently, we tested the hypothesis that fim is the mediator of flo non-cell autonomy by examining fim expression in flo periclinal chimeras. In these chimeras, fim is activated in cells where flo is not expressed, indicating that fim cannot be the sole mediator of flo non-cell autonomy.
Schultz
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Department of Genetics, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK. schultz@uleth.ca
Carpenter
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R
Doyle
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S
Coen
E
E
D002678:Chimera; D026281:DEFICIENS Protein; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D017403:In Situ Hybridization; D026161:MADS Domain Proteins; D019684:Magnoliopsida / Q000235:genetics* / Q000378:metabolism; D018519:Meristem / Q000235:genetics* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018749:RNA, Plant / Q000032:analysis; D014452:Ubiquitins / Q000378:metabolism
D026281:DEFICIENS Protein; C088434:FIM protein, Antirrhinum majus; C083654:FLO protein, Antirrhinum majus; D018398:Homeodomain Proteins; D026161:MADS Domain Proteins; C079380:PLE protein, Antirrhinum majus; D010940:Plant Proteins; D018749:RNA, Plant; D014452:Ubiquitins