RESUMO
Integration of environmental signals and interactions among photoreceptors and transcriptional regulators is key in shaping plant development. TANDEM ZINC-FINGER PLUS3 (TZP) is an integrator of light and photoperiodic signaling that promotes flowering in Arabidopsis thaliana Here we elucidate the molecular role of TZP as a positive regulator of hypocotyl elongation. We identify an interacting partner for TZP, the transcription factor ZINC-FINGER HOMEODOMAIN 10 (ZFHD10), and characterize its function in coregulating the expression of blue-light-dependent transcriptional regulators and growth-promoting genes. By employing a genome-wide approach, we reveal that ZFHD10 and TZP coassociate with promoter targets enriched in light-regulated elements. Furthermore, using a targeted approach, we show that ZFHD10 recruits TZP to the promoters of key coregulated genes. Our findings not only unveil the mechanism of TZP action in promoting hypocotyl elongation at the transcriptional level but also assign a function to an uncharacterized member of the ZFHD transcription factor family in promoting plant growth.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas , Hipocótilo/crescimento & desenvolvimento , Regiões Promotoras Genéticas , Transativadores/metabolismo , Fatores de Transcrição/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Núcleo Celular/genética , Núcleo Celular/metabolismo , Hipocótilo/genética , Fotoperíodo , Transativadores/genética , Fatores de Transcrição/genética , Transcrição Gênica , Dedos de ZincoRESUMO
Ultraviolet-B (UV-B) irradiation (280-320 nm) is an integral part of sunlight and a pivotal environmental cue that triggers various plant responses, from photoprotection to photomorphogenesis and metabolic processes. UV-B is perceived by ULTRAVIOLET RESISTANCE 8 (UVR8), which orchestrates UV-B signal transduction and transcriptional control of UV-B-responsive genes. However, there is limited information on the molecular mechanism underlying the UV-B- and UVR8-dependent regulation of flowering time in plants. Here, we investigate the role of UV-B and UVR8 in photoperiodic flowering in Arabidopsis thaliana. Our findings suggest that UV-B controls photoperiodic flowering in an ecotype-specific manner and that UVR8 acts as a negative regulator of UV-B-induced flowering. Overall, our research shows that UV-B modulates flowering initiation through the action of UVR8 at the transcriptional level.
RESUMO
⢠Signalling by ubiquitination is implicated in diverse aspects of the plant lifecycle, and enzymes of ubiquitin metabolism are overrepresented in the Arabidopsis genome compared with other model eukaryotes. Despite the importance of ubiquitination in the regulation of signalling, little is known about deubiquitinating enzymes, which reverse the process of ubiquitination. ⢠Transgenic RNA interference-based cosuppression and the isolation of Atubp12/13 double mutants collectively provides the first report that AtUBP12 and AtUBP13 are functionally redundant and are required for immunity against virulent Pseudomonas syringae pv tomato in Arabidopsis. The Solanaceous AtUBP12 orthologue NtUBP12 was identified. Viral-induced gene silencing and transient gain-of-function assays were employed to establish that the NtUBP12 protein functions as a negative regulator of the Cf-9-triggered hypersensitive response. ⢠Here, we demonstrate that NtUBP12 and AtUBP12 are bona fide deubiquitinating enzymes capable of cleaving lysine-48-linked ubiquitin chains. AtUBP12 and NtUBP12 are functionally interchangeable and their deubiquitinating activity is required to suppress plant cell death. ⢠Overall, our data implicate AtUBP12- and NtUBP12-dependent deubiquitination in the stabilization of common substrates across Solanaceae and Brassicaceae which regulate disease resistance.
Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/enzimologia , Endopeptidases/fisiologia , Nicotiana/enzimologia , Proteínas de Plantas/fisiologia , Sequência de Aminoácidos , Arabidopsis/imunologia , Arabidopsis/microbiologia , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Endopeptidases/química , Endopeptidases/genética , Endopeptidases/metabolismo , Imunidade Inata/genética , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Dados de Sequência Molecular , Mutação , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Pseudomonas syringae/imunologia , Interferência de RNA , Alinhamento de Sequência , Transdução de Sinais , Nicotiana/imunologia , Nicotiana/microbiologia , Proteases Específicas de Ubiquitina , UbiquitinaçãoRESUMO
Light regulates major plant developmental transitions by orchestrating a series of nuclear events. This study uncovers the molecular function of the natural variant, TZP (Tandem Zinc-finger-Plus3), as a signal integrator of light and photoperiodic pathways in transcriptional nuclear foci. We report that TZP acts as a positive regulator of photoperiodic flowering via physical interactions with the red-light receptor phytochrome B (phyB). We demonstrate that TZP localizes in dynamic nuclear domains regulated by light quality and photoperiod. This study shows that phyB is indispensable not only for localizing TZP to transcriptionally active nuclear photobodies, but also for recruiting TZP on the promoter of the floral inducer FLOWERING LOCUS T (FT). Our findings signify a unique transcriptional regulatory role to the highly enigmatic plant nuclear photobodies, where TZP directly activates FT gene expression and promotes flowering.