Sugar beet contains a large CONSTANS-LIKE gene family including a CO homologue that is independent of the early-bolting (B) gene locus

• Published in: Journal of experimental botany 2008-07, Vol.59 (10), p.2735-2748
• Main Authors: Chia, T.Y.P, Müller, A, Jung, C, Mutasa-Göttgens, E.S
• Format: Article
• Language: English
• Subjects: Amino Acid Motifs; Amino Acid Sequence; Arabidopsis; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis - physiology; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; B gene; Beets; Beta vulgaris; Beta vulgaris - chemistry; Beta vulgaris - classification; Beta vulgaris - genetics; Beta vulgaris - metabolism; Biological and medical sciences; Caryophyllids; Chromosomes, Plant - genetics; CONSTANS-LIKE gene; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Flowering; flowering time; Flowers - chemistry; Flowers - genetics; Flowers - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Genes; Genes. Genome; Genetic loci; Light; MADS Domain Proteins - genetics; MADS Domain Proteins - metabolism; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Multigene Family; Phenotype; Photoperiod; Phylogeny; Plant physiology; Plant Proteins - chemistry; Plant Proteins - genetics; Plant Proteins - metabolism; Plants; Promoter Regions, Genetic; Research Papers; Rice; Sequence Alignment; Sugar beets; Transcription Factors - genetics; Transcription Factors - metabolism; Transcription, Genetic; Transgenic plants
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/ern129

Floral transition in the obligate long-day (LD) plant sugar beet (Beta vulgaris ssp. vulgaris) is tightly linked to the B gene, a dominant early-bolting quantitative trait locus, the expression of which is positively regulated by LD photoperiod. Thus, photoperiod regulators like CONSTANS (CO) and CONSTANS-LIKE (COL) genes identified in many LD and short-day (SD)-responsive plants have long been considered constituents and/or candidates for the B gene. Until now, the photoperiod response pathway of sugar beet (a Caryophyllid), diverged from the Rosids and Asterids has not been identified. Here, evidence supporting the existence of a COL gene family is provided and the presence of Group I, II, and III COL genes in sugar beet, as characterized by different zinc-finger (B-box) and CCT (CO, CO-like, TOC) domains is demonstrated. BvCOL1 is identified as a close-homologue of Group 1a (AtCO, AtCOL1, AtCOL2) COL genes, hence a good candidate for flowering time control and it is shown that it maps to chromosome II but distant from the B gene locus. The late-flowering phenotype of A. thaliana co-2 mutants was rescued by over-expression of BvCOL1 thereby suggesting functional equivalence with AtCO, and it is shown that BvCOL1 interacts appropriately with the endogenous downstream genes, AtFT and AtSOC1 in the transgenic plants. Curiously, BvCOL1 has a dawn-phased diurnal pattern of transcription, mimicking that of AtCOL1 and AtCOL2 while contrasting with AtCO. Taken together, these data suggest that BvCOL1 plays an important role in the photoperiod response of sugar beet.