RESUMEN
FT/TFL1 family members have been known to be involved in the development and flowering in plants. In rose, RoKSN, a TFL1 homologue, is a key regulator of flowering, whose absence causes continuous flowering. Our objectives are to functionally validate RoKSN and to explore its mode of action in rose. We complemented Arabidopsis tfl1 mutants and ectopically expressed RoKSN in a continuous-flowering (CF) rose. Using different protein interaction techniques, we studied RoKSN interactions with RoFD and RoFT and possible competition. In Arabidopsis, RoKSN complemented the tfl1 mutant by rescuing late flowering and indeterminate growth. In CF roses, the ectopic expression of RoKSN led to the absence of flowering. Different branching patterns were observed and some transgenic plants had an increased number of leaflets per leaf. In these transgenic roses, floral activator transcripts decreased. Furthermore, RoKSN was able to interact both with RoFD and the floral activator, RoFT. Protein interaction experiments revealed that RoKSN and RoFT could compete with RoFD for repression and activation of blooming, respectively. We conclude that RoKSN is a floral repressor and is also involved in the vegetative development of rose. RoKSN forms a complex with RoFD and could compete with RoFT for repression of flowering.
Asunto(s)
Flores/crecimiento & desarrollo , Proteínas de Plantas/metabolismo , Proteínas Represoras/metabolismo , Rosa/crecimiento & desarrollo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Flores/fisiología , Regulación del Desarrollo de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Genes de Plantas/genética , Prueba de Complementación Genética , Inflorescencia/genética , Inflorescencia/crecimiento & desarrollo , Mutación/genética , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente , ARN Mensajero/genética , ARN Mensajero/metabolismo , Proteínas Represoras/genética , Reproducción , Rosa/genéticaRESUMEN
The role of gibberellins (GAs) during floral induction has been widely studied in the annual plant Arabidopsis thaliana. Less is known about this control in perennials. It is thought that GA is a major regulator of flowering in rose. In spring, low GA content may be necessary for floral initiation. GA inhibited flowering in once-flowering roses, whereas GA did not block blooming in continuous-flowering roses. Recently, RoKSN, a homologue of TFL1, was shown to control continuous flowering. The loss of RoKSN function led to continuous flowering behaviour. The objective of this study was to understand the molecular control of flowering by GA and the involvement of RoKSN in this inhibition. In once-flowering rose, the exogenous application of GA(3) in spring inhibited floral initiation. Application of GA(3) during a short period of 1 month, corresponding to the floral transition, was sufficient to inhibit flowering. At the molecular level, RoKSN transcripts were accumulated after GA(3) treatment. In spring, this accumulation is correlated with floral inhibition. Other floral genes such as RoFT, RoSOC1, and RoAP1 were repressed in a RoKSN-dependent pathway, whereas RoLFY and RoFD repression was RoKSN independent. The RoKSN promoter contained GA-responsive cis-elements, whose deletion suppressed the response to GA in a heterologous system. In summer, once-flowering roses did not flower even after exogenous application of a GA synthesis inhibitor that failed to repress RoKSN. A model is presented for the GA inhibition of flowering in spring mediated by the induction of RoKSN. In summer, factors other than GA may control RoKSN.
Asunto(s)
Florigena/metabolismo , Flores/genética , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Giberelinas/genética , Rosa/genética , Agrobacterium tumefaciens/genética , Florigena/farmacología , Flores/crecimiento & desarrollo , Flores/metabolismo , Regulación del Desarrollo de la Expresión Génica/efectos de los fármacos , Genes de Plantas/efectos de los fármacos , Giberelinas/metabolismo , Giberelinas/farmacología , Proteínas Fluorescentes Verdes/metabolismo , Microscopía Confocal , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/crecimiento & desarrollo , Plantas Modificadas Genéticamente/metabolismo , Regiones Promotoras Genéticas/efectos de los fármacos , ARN de Planta/genética , ARN de Planta/metabolismo , Rosa/crecimiento & desarrollo , Rosa/metabolismo , Estaciones del Año , Alineación de Secuencia , Análisis de Secuencia de ADN , Nicotiana/genética , Regulación hacia ArribaRESUMEN
TERMINAL FLOWER1 (TFL1) was named from knockout Arabidopsis thaliana mutants in which the inflorescence abnormally terminates into a flower. In wild type plants, the expression of TFL1 in the center of the inflorescence meristem represses the flower meristem identity genes LEAFY (LFY) and APETALA1 (AP1) to maintain indeterminacy. LFY and AP1 are activated by flowering signals that antagonize TFL1. Its characterization in numerous species revealed that the TFL1-mediated regulation of meristem fate has broader impacts on plant development than originally depicted in A. thaliana. By blocking floral transition, TFL1 genes participate in the control of juvenility, shoot growth pattern, inflorescence architecture, and the establishment of life history strategies. Here, we contextualize the role of the TFL1-mediated protection of meristem indeterminacy throughout plant development.