Arabidopsis VQ motif-containing proteins VQ1 and VQ10 interact with plastidial 1-deoxy-D-xylulose-5-phosphate synthase.

VQ1 and VQ10 are largely unstructured homologous proteins with a significant potential for protein-protein interactions. Yeast two-hybrid (Y2H) analysis confirmed that both proteins interact not only with themselves and each other but also with other VQ and WRKY proteins. Screening an Arabidopsis Y2H library with VQ1 as bait identified 287 interacting proteins.

Enhanced meristem development, tolerance to oxidative stress and hyposensitivity to nitric oxide in the hypermorphic vq10-H mutant in AtVQ10 gene.

Nitric oxide (NO) and reactive oxygen are common factors in multiple plant responses to stress, and their involvement in hypoxia-triggered responses is key to ensure growth under adverse environmental conditions. Here, we analyse the regulatory functions exerted by hypoxia-, NO- and oxidative stress-inducible Arabidopsis gene coding for the VQ motif-containing protein 10 (VQ10). A hypermorphic vq10-H mutant allowed identifying VQ10-exerted regulation on root and shoot development as well as its role in regulating responses to NO and oxidative stress.

Thioredoxin TRXo1 is involved in ABA perception via PYR1 redox regulation.

Abscisic acid (ABA) plays a fundamental role in plant growth and development processes such as seed germination, stomatal response or adaptation to stress, amongst others. Increases in the endogenous ABA content is recognized by specific receptors of the PYR/PYL/RCAR family that are coupled to a phosphorylation cascade targeting transcription factors and ion channels. Just like other receptors of the family, nuclear receptor PYR1 binds ABA and inhibits the activity of type 2C phosphatases (PP2Cs), thus avoiding the phosphatase-exerted inhibition on SnRK2 kinases, positive regulators which phosphorylate targets and trigger ABA signalling.

NIN-like protein7 and PROTEOLYSIS6 functional interaction enhances tolerance to sucrose, ABA, and submergence.

Nitrate (NO3) assimilation and signaling regulate plant growth through the relevant function of the transcription factor NIN-like Protein7 (NLP7). NO3 is also the main source for plants to produce nitric oxide (NO), which regulates growth and stress responses. NO-mediated regulation requires efficient sensing via the PROTEOLYSIS6 (PRT6)-mediated proteasome-triggered degradation of group VII of ethylene response transcription factors through the Cys/Arg N-degron pathway.

Valine-Glutamine Proteins in Plant Responses to Oxygen and Nitric Oxide.

Multigene families coding for valine-glutamine (VQ) proteins have been identified in all kind of plants but chlorophytes. VQ proteins are transcriptional regulators, which often interact with WRKY transcription factors to regulate gene expression sometimes modulated by reversible phosphorylation. Different VQ-WRKY complexes regulate defense against varied pathogens as well as responses to osmotic stress and extreme temperatures.

Post-Translational Modifications of Nitrate Reductases Autoregulates Nitric Oxide Biosynthesis in Arabidopsis.

Nitric oxide (NO) is a regulator of growth, development, and stress responses in living organisms. Plant nitrate reductases (NR) catalyze the reduction of nitrate to nitrite or, alternatively, to NO. In plants, NO action and its targets remain incompletely understood, and the way NO regulates its own homeostasis remains to be elucidated.

Nitrite Reductase 1 Is a Target of Nitric Oxide-Mediated Post-Translational Modifications and Controls Nitrogen Flux and Growth in Arabidopsis.

Plant growth is the result of the coordinated photosynthesis-mediated assimilation of oxidized forms of C, N and S. Nitrate is the predominant N source in soils and its reductive assimilation requires the successive activities of soluble cytosolic NADH-nitrate reductases (NR) and plastid stroma ferredoxin-nitrite reductases (NiR) allowing the conversion of nitrate to nitrite and then to ammonium. However, nitrite, instead of being reduced to ammonium in plastids, can be reduced to nitric oxide (NO) in mitochondria, through a process that is relevant under hypoxic conditions, or in the cytoplasm, through a side-reaction catalyzed by NRs.

Nitric oxide deficiency decreases C-repeat binding factor-dependent and -independent induction of cold acclimation.

Plant tolerance to freezing temperatures is governed by endogenous components and environmental factors. Exposure to low non-freezing temperatures is a key factor in the induction of freezing tolerance in the process called cold acclimation. The role of nitric oxide (NO) in cold acclimation was explored in Arabidopsis using triple nia1nia2noa1-2 mutants that are impaired in the nitrate-dependent and nitrate-independent pathways of NO production, and are thus NO deficient.

Nitric oxide responses in Arabidopsis hypocotyls are mediated by diverse phytohormone pathways.

Plants are often exposed to high levels of nitric oxide (NO) that affects development and stress-triggered responses. However, the way in which plants sense NO is still largely unknown. Here we combine the analysis of early changes in the transcriptome of plants exposed to a short acute pulse of exogenous NO with the identification of transcription factors (TFs) involved in NO sensing.

Nitric Oxide Controls Constitutive Freezing Tolerance in Arabidopsis by Attenuating the Levels of Osmoprotectants, Stress-Related Hormones and Anthocyanins.

Plant tolerance to freezing temperatures is governed by endogenous constitutive components and environmental inducing factors. Nitric oxide (NO) is one of the endogenous components that participate in freezing tolerance regulation. A combined metabolomic and transcriptomic characterization of NO-deficient nia1,2noa1-2 mutant plants suggests that NO acts attenuating the production and accumulation of osmoprotective and regulatory metabolites, such as sugars and polyamines, stress-related hormones, such as ABA and jasmonates, and antioxidants, such as anthocyanins and flavonoids.

Nitric oxide triggers a transient metabolic reprogramming in Arabidopsis.

Nitric oxide (NO) regulates plant growth and development as well as responses to stress that enhanced its endogenous production. Arabidopsis plants exposed to a pulse of exogenous NO gas were used for untargeted global metabolomic analyses thus allowing the identification of metabolic processes affected by NO. At early time points after treatment, NO scavenged superoxide anion and induced the nitration and the S-nitrosylation of proteins.

FYVE1/FREE1 Interacts with the PYL4 ABA Receptor and Mediates Its Delivery to the Vacuolar Degradation Pathway.

Recently, we described the ubiquitylation of PYL4 and PYR1 by the RING E3 ubiquitin ligase RSL1 at the plasma membrane of This suggested that ubiquitylated abscisic acid (ABA) receptors might be targeted to the vacuolar degradation pathway because such ubiquitylation is usually an internalization signal for the endocytic route. Here, we show that FYVE1 (previously termed FREE1), a recently described component of the endosomal sorting complex required for transport (ESCRT) machinery, interacted with RSL1-receptor complexes and recruited PYL4 to endosomal compartments. Although the ESCRT pathway has been assumed to be reserved for integral membrane proteins, we show the involvement of this pathway in the degradation of ABA receptors, which can be associated with membranes but are not integral membrane proteins.

Inactivation of PYR/PYL/RCAR ABA receptors by tyrosine nitration may enable rapid inhibition of ABA signaling by nitric oxide in plants.

Abscisic acid (ABA) is a phytohormone that inhibits growth and enhances adaptation to stress in plants. ABA perception and signaling rely on its binding to receptors of the pyrabactin resistance1/PYR1-like/regulatory components of ABA receptors (PYR/PYL/RCAR) family, the subsequent inhibition of clade A type 2C protein phosphatases (PP2Cs), and the phosphorylation of ion channels and transcription factors by protein kinases of the SnRK2 family. Nitric oxide (NO) may inhibit ABA signaling because NO-deficient plants are hypersensitive to ABA.

Identification of transcription factors potentially involved in the juvenile to adult phase transition in Citrus.

Background And Aims: The juvenile to adult transition (JAT) in higher plants is required for them to reach reproductive competence. However, it is a poorly understood process in woody plants, where only a few genes have been definitely identified as being involved in this transition. This work aims at increasing our understanding of the mechanisms regulating the JAT in citrus.