RESUMO
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.
Assuntos
Adaptação Biológica/fisiologia , Agricultura/métodos , Beta vulgaris/fisiologia , Evolução Biológica , Flores/fisiologia , Genes Reguladores/genética , Proteínas de Plantas/genética , Adaptação Biológica/genética , Sequência de Aminoácidos , Análise do Polimorfismo de Comprimento de Fragmentos Amplificados , Sequência de Bases , Beta vulgaris/genética , Mapeamento Cromossômico , Cromossomos Artificiais Bacterianos/genética , Clonagem Molecular , Primers do DNA/genética , Flores/genética , Marcadores Genéticos/genética , Haplótipos/genética , Immunoblotting , Modelos Biológicos , Dados de Sequência Molecular , Fenótipo , Fotoperíodo , Filogenia , Estações do Ano , Seleção Genética , Alinhamento de Sequência , Análise de Sequência de DNARESUMO
The consumption of fructans as a low caloric food ingredient or dietary fibre is rapidly increasing due to health benefits. Presently, the most important fructan source is chicory, but these fructans have a simple linear structure and are prone to degradation. Additional sources of high-quality tailor-made fructans would provide novel opportunities for their use as food ingredients. Sugar beet is a highly productive crop that does not normally synthesize fructans. We have introduced specific onion fructosyltransferases into sugar beet. This resulted in an efficient conversion of sucrose into complex, onion-type fructans, without the loss of storage carbohydrate content.
