RESUMEN
Cell elongation during seedling development is antagonistically regulated by light and gibberellins (GAs). Light induces photomorphogenesis, leading to inhibition of hypocotyl growth, whereas GAs promote etiolated growth, characterized by increased hypocotyl elongation. The mechanism underlying this antagonistic interaction remains unclear. Here we report on the central role of the Arabidopsis thaliana nuclear transcription factor PIF4 (encoded by PHYTOCHROME INTERACTING FACTOR 4) in the positive control of genes mediating cell elongation and show that this factor is negatively regulated by the light photoreceptor phyB (ref. 4) and by DELLA proteins that have a key repressor function in GA signalling. Our results demonstrate that PIF4 is destabilized by phyB in the light and that DELLAs block PIF4 transcriptional activity by binding the DNA-recognition domain of this factor. We show that GAs abrogate such repression by promoting DELLA destabilization, and therefore cause a concomitant accumulation of free PIF4 in the nucleus. Consistent with this model, intermediate hypocotyl lengths were observed in transgenic plants over-accumulating both DELLAs and PIF4. Destabilization of this factor by phyB, together with its inactivation by DELLAs, constitutes a protein interaction framework that explains how plants integrate both light and GA signals to optimize growth and development in response to changing environments.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/efectos de los fármacos , Arabidopsis/efectos de la radiación , Forma de la Célula/efectos de los fármacos , Forma de la Célula/efectos de la radiación , Giberelinas/farmacología , Luz , Arabidopsis/citología , Arabidopsis/metabolismo , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/química , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Tamaño de la Célula/efectos de los fármacos , Tamaño de la Célula/efectos de la radiación , ADN de Plantas/metabolismo , Hipocótilo/genética , Hipocótilo/crecimiento & desarrollo , Hipocótilo/metabolismo , Proteínas Nucleares/química , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Fitocromo B/genética , Fitocromo B/metabolismo , Hojas de la Planta/metabolismo , Unión Proteica , Plantones/metabolismo , Transducción de Señal/efectos de los fármacos , Nicotiana/metabolismo , Triazoles/farmacología , Técnicas del Sistema de Dos HíbridosRESUMEN
Expression levels of vaccine antigens in transgenic plants have important consequences in their use as edible vaccines. The major structural protein VP60 from the rabbit haemorrhagic disease virus (RHDV) has been produced in transgenic plants using different strategies to compare its accumulation in plant tissues. The highest expressing plants were those presenting stable, complex, high-density structures formed by VP60, suggesting the importance of multisubunit structures for the stability of this protein in plant cells. Mice fed with leaves of transgenic plants expressing VP60 were primed to a subimmunogenic baculovirus-derived vaccine single dose. This indicates that plants expressing VP60 antigen may be a new means for oral RHDV immunization.
Asunto(s)
Anticuerpos Antivirales/sangre , Virus de la Enfermedad Hemorrágica del Conejo/inmunología , Inmunización , Proteínas Estructurales Virales/genética , Proteínas Estructurales Virales/inmunología , Vacunas Virales/inmunología , Administración Oral , Animales , Ratones , Hojas de la Planta/genética , Plantas Modificadas Genéticamente , Biosíntesis de Proteínas , Pliegue de Proteína , Conejos , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/inmunología , Transformación Genética , Vacunas Comestibles/genética , Vacunas Sintéticas/inmunología , Vacunas Virales/genéticaRESUMEN
It has recently been discovered that glutathione-dependent formaldehyde dehydrogenase (FALDH) exhibits a strong S-nitrosoglutathione reductase activity. Plants use NO and S-nitrosothiols as signaling molecules to activate defense mechanisms. Therefore, it is interesting to investigate the regulation of FALDH by mechanical wounding and plant hormones involved in signal transduction. Our results show that the gene encoding FALDH in Arabidopsis (ADH2) is down-regulated by wounding and activated by salicylic acid (SA). In tobacco, FALDH levels and enzymatic activity decreased after jasmonate treatment, and increased in response to SA. This is the first time that regulation of FALDH in response to signals associated with plant defense has been demonstrated.