V-ATPases and amino acid catabolism are strongly disturbed in the roots of autophagy mutants in Arabidopsis, impacting water use efficiency and tricarboxylic acid metabolism.

Autophagy is essential for homeostasis and nutrient recycling. Its activity increases with aging and in response to deficiencies. The effects of defective autophagy on root metabolism have not yet been described.

A Brassica napus water soluble chlorophyll binding protein (WSCP1) delays chlorophyll degradation and inhibits serine proteases during dark-induced leaf senescence in Arabidopsis thaliana.

This preliminary study shows that Brassica napus WSCP1 delays chlorophyll degradation and inhibits serine proteases during dark-induced leaf senescence in Arabidopsis. In Brassica napus L., one of the levers for improving Nitrogen Remobilization Efficiency (NRE) consists to delay senescence onset, which prolongs leaf lifespan and reduces the asynchronism between the nitrogen emptying period in these source organs and the filling period of seeds.

BdNRT2A and BdNRT3.2 Are the Major Components of the High-Affinity Nitrate Transport System in .

An efficient nitrate uptake system contributes to the improvement of crop nitrogen use efficiency under low nitrogen availability. The High Affinity nitrate Transport System (HATS) in plants is active in low range of external nitrate and is mediated by a two-component system (high affinity transporters NRT2 associated to a partner protein NRT3 (NAR2)). In Brachypodium, the model plant for C3 cereals, we investigated the role of and through various experimental approaches.

Lack or excess of autophagy leads to premature leaf senescence probably due to unbalanced nutrient management.

Background And Aims: Macroautophagy is essential for the degradation and recycling of various macromolecules in eukaryote cells. In plants, autophagy is involved in the degradation of damaged chloroplasts in response to stress. Autophagy is a key player in nitrogen management at the whole-plant level, and autophagy mutants display strong defects in nitrogen remobilization and early leaf senescence phenotypes especially under nitrogen source limitation.

Evidence of the specific roles of autophagy in senescent leaves and maturing seeds.

In plants, a large part of the nutrients used to generate seed lipid and protein reserves is derived from both the degradation of macromolecules in source leaves and the transfer of small catabolic molecules like amino acids from the senescing leaves to the seeds. Studies of autophagy mutants in is showed that autophagy is a master player controlling 60% of the remobilization of nitrogen from senescing leaf tissues to developing seeds, and strongly impacting reserve deposition, especially in the protein to lipid ratio. Since autophagy is largely enhanced in leaves during senescence and in the seeds during maturation, we investigated the roles of autophagy in these sources and sink tissues, to identify checkpoints controlling seed filling and quality.

Nitrate activates an MKK3-dependent MAPK module via NLP transcription factors in Arabidopsis.

Plant responses to nutrient availability are critical for plant development and yield. Nitrate, the major form of nitrogen in most soils, serves as both a nutrient and signaling molecule. Nitrate itself triggers rapid, major changes in gene expression, especially via nodule inception (NIN)-like protein (NLP) transcription factors, and stimulates protein phosphorylation.

A tissue-specific rescue strategy reveals the local roles of autophagy in leaves and seeds for resource allocation.

Autophagy is a vesicular mechanism that plays a fundamental role in nitrogen remobilization from senescing leaves to seeds. The Arabidopsis (Arabidopsis thaliana) autophagy (atg) mutants exhibit early senescence, reduced biomass, and low seed yield. The atg seeds also exhibit major changes in N and C concentrations.

Phytochrome-interacting factors PIF4 and PIF5 directly regulate autophagy during leaf senescence in Arabidopsis.

During leaf senescence, autophagy plays a critical role by removing damaged cellular components and participating in nutrient remobilization to sink organs. However, how AUTOPHAGY (ATG) genes are regulated during natural leaf senescence remains largely unknown. In this study, we attempted to identify upstream transcriptional regulator(s) of ATG genes and their molecular basis during leaf senescence in Arabidopsis through the combined analyses of promoter binding, autophagy flux, and genetic interactions.

Multi-scale phenotyping of senescence-related changes in roots of rapeseed in response to nitrate limitation.

Root senescence remains largely unexplored. In this study, the time-course of the morphological, metabolic, and proteomic changes occurring with root aging were investigated, providing a comprehensive picture of the root senescence program. We found novel senescence-related markers for the characterization of the developmental stage of root tissues.

Natural variation in response to combined water and nitrogen deficiencies in Arabidopsis.

Understanding plant responses to individual stresses does not mean that we understand real-world situations, where stresses usually combine and interact. These interactions arise at different levels, from stress exposure to the molecular networks of the stress response. Here, we built an in-depth multiomic description of plant responses to mild water (W) and nitrogen (N) limitations, either individually or combined, among 5 genetically different Arabidopsis (Arabidopsis thaliana) accessions.

A cellulose synthesis inhibitor affects cellulose synthase complex secretion and cortical microtubule dynamics.

P4B (2-phenyl-1-[4-(6-(piperidin-1-yl) pyridazin-3-yl) piperazin-1-yl] butan-1-one) is a novel cellulose biosynthesis inhibitor (CBI) discovered in a screen for molecules to identify inhibitors of Arabidopsis (Arabidopsis thaliana) seedling growth. Growth and cellulose synthesis inhibition by P4B were greatly reduced in a novel mutant for the cellulose synthase catalytic subunit gene CESA3 (cesa3pbr1). Cross-tolerance to P4B was also observed for isoxaben-resistant (ixr) cesa3 mutants ixr1-1 and ixr1-2.

Discovery of the biostimulant effect of asparagine and glutamine on plant growth in .

Protein hydrolysates have gained interest as plant biostimulants due to their positive effects on plant performances. They are mainly composed of amino acids, but there is no evidence of the role of individual of amino acids as biostimulants. In this study we carried out experiments to monitor the development of Arabidopsis seedlings on amino acid containing media in order to analyze the biostimulant properties of the twenty individual proteinogenic amino acids.

The Root-Colonizing Endophyte Supports Nitrogen-Starved Seedlings with Nitrogen Metabolites.

The root-colonizing endophytic fungus promotes the root and shoot growth of its host plants. We show that the growth promotion of leaves is abolished when the seedlings are grown on media with nitrogen (N) limitation. The fungus neither stimulated the total N content nor did it promote NO uptake from agar plates to the leaves of the host under N-sufficient or N-limiting conditions.

The Arabidopsis Target of Rapamycin kinase regulates ammonium assimilation and glutamine metabolism.

In eukaryotes, a target of rapamycin (TOR) is a well-conserved kinase that controls cell metabolism and growth in response to nutrients and environmental factors. Nitrogen (N) is an essential element for plants, and TOR functions as a crucial N and amino acid sensor in animals and yeast. However, knowledge of the connections between TOR and the overall N metabolism and assimilation in plants is still limited.

Impairment of sugar transport in the vascular system acts on nitrogen remobilization and nitrogen use efficiency in Arabidopsis.

Carbon (C) and nitrogen (N) metabolisms have long been known to be coupled, and this is required for adjusting nitrogen use efficiency (NUE). Despite this intricate relationship, it is still unclear how deregulation of sugar transport impacts N allocation. Here, we investigated in Arabidopsis the consequences of the simultaneous downregulation of the genes coding for the sugar transporters SWEET11, SWEET12, SWEET16, and SWEET17 on various anatomical and physiological traits ranging from the stem's vascular system development to plant biomass production, seed yield, and N remobilization and use efficiency.

Proton exchange by the vacuolar nitrate transporter CLCa is required for plant growth and nitrogen use efficiency.

Nitrate is a major nutrient and osmoticum for plants. To deal with fluctuating nitrate availability in soils, plants store this nutrient in their vacuoles. Chloride channel a (CLCa), a 2NO3-/1H+ exchanger localized to the vacuole in Arabidopsis (Arabidopsis thaliana), ensures this storage process.

Modulation of plant nitrogen remobilization and postflowering nitrogen uptake under environmental stresses.

Plants are sessile organisms that take up nitrogen (N) from the soil for growth and development. At the postflowering stage, N that plants require for seed growth and filling derives from either root uptake or shoot remobilization. The balance between N uptake and N remobilization determines the final carbon (C) and N composition of the seed.

Corrigendum: Genotypic Variation of Nitrogen Use Efficiency and Amino Acid Metabolism in Barley.

[This corrects the article DOI: 10.3389/fpls.2021.

Genotypic Variation of Nitrogen Use Efficiency and Amino Acid Metabolism in Barley.

Owing to the large genetic diversity of barley and its resilience under harsh environments, this crop is of great value for agroecological transition and the need for reduction of nitrogen (N) fertilizers inputs. In the present work, we investigated the diversity of a North African barley genotype collection in terms of growth under limiting N (LN) or ample N (HN) supply and in terms of physiological traits including amino acid content in young seedlings. We identified a Moroccan variety, Laanaceur, accumulating five times more lysine in its leaves than the others under both N nutritional regimes.

ACCELERATED CELL DEATH 6 Acts on Natural Leaf Senescence and Nitrogen Fluxes in .

As the last step of leaf development, senescence is a molecular process involving cell death mechanism. Leaf senescence is trigged by both internal age-dependent factors and environmental stresses. It must be tightly regulated for the plant to adopt a proper response to environmental variation and to allow the plant to recycle nutrients stored in senescing organs.

OsASN1 Overexpression in Rice Increases Grain Protein Content and Yield under Nitrogen-Limiting Conditions.

Nitrogen (N) is a major limiting factor affecting crop yield in unfertilized soil. Thus, cultivars with a high N use efficiency (NUE) and good grain protein content (GPC) are needed to fulfill the growing food demand and to reduce environmental burden. This is especially true for rice (Oryza sativa L.

Concurrent activation of OsAMT1;2 and OsGOGAT1 in rice leads to enhanced nitrogen use efficiency under nitrogen limitation.

Nitrogen (N) is a major factor for plant development and productivity. However, the application of nitrogenous fertilizers generates environmental and economic problems. To cope with the increasing global food demand, the development of rice varieties with high nitrogen use efficiency (NUE) is indispensable for reducing environmental issues and achieving sustainable agriculture.

Transcriptional Plasticity of Autophagy-Related Genes Correlates with the Genetic Response to Nitrate Starvation in .

In eukaryotes, autophagy, a catabolic mechanism for macromolecule and protein recycling, allows the maintenance of amino acid pools and nutrient remobilization. For a better understanding of the relationship between autophagy and nitrogen metabolism, we studied the transcriptional plasticity of autophagy genes () in nine Arabidopsis accessions grown under normal and nitrate starvation conditions. The status of the N metabolism in accessions was monitored by measuring the relative expression of 11 genes related to N metabolism in rosette leaves.