RESUMO
Stomata are pores that regulate the gas and water exchange between the environment and aboveground plant tissues, including hypocotyls, leaves, and stems. Here, we show that mutants of Arabidopsis thaliana LLM-domain B-GATA genes are defective in stomata formation in hypocotyls. Conversely, stomata formation is strongly promoted by overexpression of various LLM-domain B-class GATA genes, most strikingly in hypocotyls but also in cotyledons. Genetic analyses indicate that these B-GATAs act upstream of the stomata formation regulators SPEECHLESS(SPCH), MUTE, and SCREAM/SCREAM2 and downstream or independent of the patterning regulators TOO MANY MOUTHS and STOMATAL DENSITY AND DISTRIBUTION1 The effects of the GATAs on stomata formation are light dependent but can be induced in dark-grown seedlings by red, far-red, or blue light treatments. PHYTOCHROME INTERACTING FACTOR(PIF) mutants form stomata in the dark, and in this genetic background, GATA expression is sufficient to induce stomata formation in the dark. Since the expression of the LLM-domain B-GATAs GNC(GATA, NITRATE-INDUCIBLE, CARBON METABOLISM-INVOLVED) and GNC-LIKE/CYTOKININ-RESPONSIVE GATA FACTOR1 as well as that of SPCH is red light induced but the induction of SPCH is compromised in a GATA gene mutant background, we hypothesize that PIF- and light-regulated stomata formation in hypocotyls is critically dependent on LLM-domain B-GATA genes.
Assuntos
Arabidopsis/genética , Citocininas/metabolismo , Fatores de Transcrição GATA/metabolismo , Transdução de Sinal Luminoso , Reguladores de Crescimento de Plantas/metabolismo , Arabidopsis/citologia , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Escuridão , Fatores de Transcrição GATA/genética , Regulação da Expressão Gênica de Plantas , Genes Reporter , Hipocótilo/citologia , Hipocótilo/genética , Hipocótilo/crescimento & desenvolvimento , Hipocótilo/fisiologia , Luz , Mutação , Folhas de Planta/citologia , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Caules de Planta/citologia , Caules de Planta/genética , Caules de Planta/crescimento & desenvolvimento , Caules de Planta/fisiologia , Estômatos de Plantas/citologia , Estômatos de Plantas/genética , Estômatos de Plantas/crescimento & desenvolvimento , Estômatos de Plantas/fisiologia , Plantas Geneticamente Modificadas , Domínios Proteicos , Plântula/citologia , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/fisiologiaRESUMO
The strawberry fruit allergens Fra a 1.01E, Fra a 1.02 and Fra a 1.03 belong to the group of pathogenesis-related 10 (PR-10) proteins and are homologs of the major birch pollen Bet v 1 and apple allergen Mal d 1. Bet v 1 related proteins are the most extensively studied allergens but their physiological function in planta remains elusive. Since Mal d 1-Associated Protein has been previously identified as interaction partner of Mal d 1 we studied the binding of the orthologous Fra a 1-Associated Protein (FaAP) to Fra a 1.01E/1.02/1.03. As the C-terminal sequence of FaAP showed strong auto-activation activity in yeast 2-hybrid analysis a novel time resolved DNA-switching system was successfully applied. Fra a 1.01E, Fra a 1.02, and Fra a 1.03 bind to FaAP with KD of 4.5 ± 1.1, 15 ± 3, and 11 ± 2 nM, respectively. Fra a 1.01E forms a dimer, whereas Fra a 1.02 and Fra a 1.03 bind as monomer. The results imply that PR-10 proteins might be integrated into a protein-interaction network and FaAP binding appears to be essential for the physiological function of the Fra a 1 proteins.
Assuntos
Antígenos de Plantas/química , Fragaria/química , Proteínas de Plantas/química , Sequência de Aminoácidos/genética , Antígenos de Plantas/genética , Antígenos de Plantas/metabolismo , Humanos , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Ligação Proteica , Mapas de Interação de Proteínas/genéticaRESUMO
Leu-Leu-Met (LLM)-domain B-GATAs are a subfamily of the 30-membered GATA transcription factor family from Arabidopsis. Only two of the six Arabidopsis LLM-domain B-GATAs, i.e. GATA, NITRATE-INDUCIBLE, CARBON METABOLISM-INVOLVED (GNC) and its paralog GNC-LIKE/CYTOKININ-RESPONSIVE GATA FACTOR1 (GNL), have already been analyzed with regard to their biological function. Together, GNC and GNL control germination, greening, flowering time, and senescence downstream from auxin, cytokinin (CK), gibberellin (GA), and light signaling. Whereas overexpression and complementation analyses suggest a redundant biochemical function between GNC and GNL, nothing is known about the biological role of the four other LLM-domain B-GATAs, GATA15, GATA16, GATA17, and GATA17L (GATA17-LIKE), based on loss-of-function mutant phenotypes. Here, we examine insertion mutants of the six Arabidopsis B-GATA genes and reveal the role of these genes in the control of greening, hypocotyl elongation, phyllotaxy, floral organ initiation, accessory meristem formation, flowering time, and senescence. Several of these phenotypes had previously not been described for the gnc and gnl mutants or were enhanced in the more complex mutants when compared to gnc gnl mutants. Some of the respective responses may be mediated by CK signaling, which activates the expression of all six GATA genes. CK-induced gene expression is partially compromised in LLM-domain B-GATA mutants, suggesting that B-GATA genes play a role in CK responses. We furthermore provide evidence for a transcriptional cross regulation between these GATAs that may, in at least some cases, be at the basis of their apparent functional redundancy.
Assuntos
Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Citocininas/farmacologia , Arabidopsis/efeitos dos fármacos , Sequência Conservada , Evolução Molecular , Flores/anatomia & histologia , Flores/efeitos dos fármacos , Flores/fisiologia , Flores/efeitos da radiação , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Genes de Plantas , Hipocótilo/efeitos dos fármacos , Hipocótilo/crescimento & desenvolvimento , Hipocótilo/efeitos da radiação , Luz , Mutagênese Insercional/genética , Mutação/genética , Fotoperíodo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/efeitos da radiação , Domínios ProteicosRESUMO
The transcription of the Arabidopsis (Arabidopsis thaliana) GATA transcription factors GATA, NITRATE-INDUCIBLE, CARBON METABOLISM-INVOLVED (GNC) and GNC-LIKE (GNL)/CYTOKININ-RESPONSIVE GATA FACTOR1 is controlled by several growth regulatory signals including light and the phytohormones auxin, cytokinin, and gibberellin. To date, GNC and GNL have been attributed functions in the control of germination, greening, flowering time, floral development, senescence, and floral organ abscission. GNC and GNL belong to the 11-member family of B-class GATA transcription factors that are characterized to date solely by their high sequence conservation within the GATA DNA-binding domain. The degree of functional conservation among the various B-class GATA family members is not understood. Here, we identify and examine B-class GATAs from Arabidopsis, tomato (Solanum lycopersicon), Brachypodium (Brachypodium distachyon), and barley (Hordeum vulgare). We find that B-class GATAs from these four species can be subdivided based on their short or long N termini and the presence of the 13-amino acid C-terminal leucine-leucine-methionine (LLM) domain with the conserved motif LLM. Through overexpression analyses and by complementation of a gnc gnl double mutant, we provide evidence that the length of the N terminus may not allow distinguishing between the different B-class GATAs at the functional level. In turn, we find that the presence and absence of the LLM domain in the overexpressors has differential effects on hypocotyl elongation, leaf shape, and petiole length, as well as on gene expression. Thus, our analyses identify the LLM domain as an evolutionarily conserved domain that determines B-class GATA factor identity and provides a further subclassification criterion for this transcription factor family.