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Free keywords:
Adaptation, Biological/genetics/*physiology
Agriculture/*methods
Amino Acid Sequence
Amplified Fragment Length Polymorphism Analysis
Base Sequence
Beta vulgaris/genetics/*physiology
*Biological Evolution
Chromosome Mapping
Chromosomes, Artificial, Bacterial/genetics
Cloning, Molecular
DNA Primers/genetics
Flowers/genetics/*physiology
Genes, Regulator/*genetics
Genetic Markers/genetics
Haplotypes/genetics
Immunoblotting
Models, Biological
Molecular Sequence Data
Phenotype
Photoperiod
Phylogeny
Plant Proteins/*genetics
Seasons
Selection, Genetic
Sequence Alignment
Sequence Analysis, DNA
Abstract:
Life cycle adaptation to latitudinal and seasonal variation in photoperiod and temperature is a major determinant of evolutionary success in flowering plants. Whereas the life cycle of the dicotyledonous model species Arabidopsis thaliana is controlled by two epistatic genes, FLOWERING LOCUS C and FRIGIDA, three unrelated loci (VERNALIZATION) determine the spring and winter habits of monocotyledonous plants such as temperate cereals. In the core eudicot species Beta vulgaris, whose lineage diverged from that leading to Arabidopsis shortly after the monocot-dicot split 140 million years ago, the bolting locus B is a master switch distinguishing annuals from biennials. Here, we isolated B and show that the pseudo-response regulator gene BOLTING TIME CONTROL 1 (BvBTC1), through regulation of the FLOWERING LOCUS T genes, is absolutely necessary for flowering and mediates the response to both long days and vernalization. Our results suggest that domestication of beets involved the selection of a rare partial loss-of-function BvBTC1 allele that imparts reduced sensitivity to photoperiod that is restored by vernalization, thus conferring bienniality, and illustrate how evolutionary plasticity at a key regulatory point can enable new life cycle strategies.