MIR164B ensures robust Arabidopsis leaf development by compensating for compromised POLYCOMB REPRESSIVE COMPLEX2 function.

Robustness is pervasive throughout biological systems, enabling them to maintain persistent outputs despite perturbations in their components. Here, we reveal a mechanism contributing to leaf morphology robustness in the face of genetic perturbations. In Arabidopsis (Arabidopsis thaliana), leaf shape is established during early development through the quantitative action of the CUP-SHAPED COTYLEDON2 (CUC2) protein, whose encoding gene is negatively regulated by the co-expressed MICRORNA164A (MIR164A) gene.

A transcriptomic dataset for investigating the Arabidopsis Unfolded Protein Response under chronic, proteotoxic endoplasmic reticulum stress.

The Unfolded Protein Response (UPR) is a retrograde, ER-to-nucleus, signalling pathway which is conserved across kingdoms. In plants, it contributes to development, reproduction, immunity and tolerance to abiotic stress. This RNA sequencing (RNA-seq) dataset was produced from 14-day-old seedlings challenged by tunicamycin (Tm), an antibiotic inhibiting Asn-linked glycosylation in the endoplasmic reticulum (ER), causing an ER stress and eventually activating the UPR.

A New Role for SAG12 Cysteine Protease in Roots of .

Senescence associated gene (SAG) 12, which encodes a cysteine protease is considered to be important in nitrogen (N) allocation to seeds. A decrease in the yield and N content of the seeds was observed in the Arabidopsis SAG12 knockout mutants () relative to the wild type (Col0) under limited nitrogen nutrition. However, leaf senescence was similar in both lines.

Three cytosolic glutamine synthetase isoforms localized in different-order veins act together for N remobilization and seed filling in Arabidopsis.

Glutamine synthetase (GS) is central for ammonium assimilation and consists of cytosolic (GS1) and chloroplastic (GS2) isoenzymes. During plant ageing, GS2 protein decreases due to chloroplast degradation, and GS1 activity increases to support glutamine biosynthesis and N remobilization from senescing leaves. The role of the different Arabidopsis GS1 isoforms in nitrogen remobilization was examined using 15N tracing experiments.

The Arabidopsis TOR Kinase Specifically Regulates the Expression of Nuclear Genes Coding for Plastidic Ribosomal Proteins and the Phosphorylation of the Cytosolic Ribosomal Protein S6.

Protein translation is an energy consuming process that has to be fine-tuned at both the cell and organism levels to match the availability of resources. The target of rapamycin kinase (TOR) is a key regulator of a large range of biological processes in response to environmental cues. In this study, we have investigated the effects of TOR inactivation on the expression and regulation of Arabidopsis ribosomal proteins at different levels of analysis, namely from transcriptomic to phosphoproteomic.

OCTOPUS Negatively Regulates BIN2 to Control Phloem Differentiation in Arabidopsis thaliana.

The phloem is a vascular strand that conducts photoassimilates and systemic signals throughout the plant to coordinate growth. To date, few molecular genetic determinants have been identified to control both specification and differentiation of this tissue [1-3]. Among them, OCTOPUS (OPS) protein was previously identified as a polarly localized plasma membrane-associated protein of unknown biochemical function whose broad provascular expression becomes restricted to the phloem upon differentiation [2].

Physiological and metabolic consequences of autophagy deficiency for the management of nitrogen and protein resources in Arabidopsis leaves depending on nitrate availability.

Autophagy is present at a basal level in all plant tissues and is induced during leaf ageing and in response to nitrogen (N) starvation. Nitrogen remobilization from the rosette to the seeds is impaired in autophagy mutants. This report focuses on the role of autophagy in leaf N management and proteolysis during plant ageing.

Sugar metabolism and the plant target of rapamycin kinase: a sweet operaTOR?

In eukaryotes, the ubiquitous TOR (target of rapamycin) kinase complexes have emerged as central regulators of cell growth and metabolism. The plant TOR complex 1 (TORC1), that contains evolutionary conserved protein partners, has been shown to be implicated in various aspects of C metabolism. Indeed Arabidopsis lines affected in the expression of TORC1 components show profound perturbations in the metabolism of several sugars, including sucrose, starch, and raffinose.

Arabidopsis thaliana ASN2 encoding asparagine synthetase is involved in the control of nitrogen assimilation and export during vegetative growth.

We investigated the function of ASN2, one of the three genes encoding asparagine synthetase (EC 6.3.5.

Mutations in the Arabidopsis homolog of LST8/GβL, a partner of the target of Rapamycin kinase, impair plant growth, flowering, and metabolic adaptation to long days.

The conserved Target of Rapamycin (TOR) kinase forms high molecular mass complexes and is a major regulator of cellular adaptations to environmental cues. The Lethal with Sec Thirteen 8/G protein β subunit-like (LST8/GβL) protein is a member of the TOR complexes, and two putative LST8 genes are present in Arabidopsis thaliana, of which only one (LST8-1) is significantly expressed. The Arabidopsis LST8-1 protein is able to complement yeast lst8 mutations and interacts with the TOR kinase.

PII is induced by WRINKLED1 and fine-tunes fatty acid composition in seeds of Arabidopsis thaliana.

The PII protein is an integrator of central metabolism and energy levels. In Arabidopsis, allosteric sensing of cellular energy and carbon levels alters the ability of PII to interact with target enzymes such as N-acetyl-l-glutamate kinase and heteromeric acetyl-coenzyme A carboxylase, thereby modulating the biological activity of these plastidial ATP- and carbon-consuming enzymes. A quantitative reverse transcriptase-polymerase chain reaction approach revealed a threefold induction of the AtGLB1 gene (At4g01900) encoding PII during early seed maturation.

The cytosolic glutamine synthetase GLN1;2 plays a role in the control of plant growth and ammonium homeostasis in Arabidopsis rosettes when nitrate supply is not limiting.

Glutamine synthetase (EC 6.3.1.

Nitrogen recycling and remobilization are differentially controlled by leaf senescence and development stage in Arabidopsis under low nitrogen nutrition.

Five recombinant inbred lines (RILs) of Arabidopsis (Arabidopsis thaliana), previously selected from the Bay-0 x Shahdara RIL population on the basis of differential leaf senescence phenotypes (from early senescing to late senescing) when cultivated under nitrogen (N)-limiting conditions, were analyzed to monitor metabolic markers related to N assimilation and N remobilization pathways. In each RIL, a decrease of total N, free amino acid, and soluble protein contents with leaf aging was observed. In parallel, the expression of markers for N remobilization such as cytosolic glutamine synthetase, glutamate dehydrogenase, and CND41-like protease was increased.