Biology subjects

Masclaux-Daubresse, C.

Publications and source records attributed to Masclaux-Daubresse, C..

5 recordsLinked to original sources

bioRxiv2026

Redirecting vacuolar nitrate transport improves nitrogen use efficiency and seed protein content

Improving seed protein content without compromising carbon allocation or yield is a major challenge for enhancing nitrogen use efficiency. Here, we show that redirecting vacuolar nitrate transport through concurrent manipulation of tonoplast proteins controlling nitrate storage or export provides an effective lever to reprogram nitrogen allocation from leaves toward the seeds. Using Arabidopsis thaliana Ws lines disrupted for the vacuolar CLC-a nitrate importer and/or overexpressing the NRT2.7 tonoplast nitrate exporter, we show that plants combining the two modifications (35S::NRT2.7(clc-a)) integrate reduced nitrogen retention in vegetative tissues with increased nitrogen allocation to seeds. As a result, 35S::NRT2.7(clc-a) plants exhibit the strongest increase in seed protein content among all genotypes (approximately +25%) without affecting seed yield, carbon concentration, or lipid composition. Altered vacuolar nitrate fluxes in 35S::NRT2.7(clc-a) stimulate nitrate assimilation, enhance nitrate reductase activity and amino acid biosynthetic pathways, and drive coordinated reprogramming of nitrogen and carbon metabolisms. Through 15N pulse chase experiments, we confirmed that 35S::NRT2.7(clc-a) shows the highest nitrogen remobilization efficiency toward seeds. Overexpression of the barley NRT2.7 homolog HvNRT2.10 in Arabidopsis wild type and clc-a backgrounds reproduces the key features of 35S::NRT2.7 phenotype, demonstrating the conservation of NRT2.7 regulatory effects on plant metabolism across species. Together, these findings identify vacuolar nitrate transport as a promising target to modulate grain protein content in cereals through genetic strategies acting on nitrogen storage and remobilization.

plant biology↗

bioRxiv2026

OEP24.1 involved in carbon allocation is a receptor of piecemeal plastid autophagy in Arabidopsis

Macroautophagy is a conserved intracellular catabolic process in eukaryotes that participates in chloroplast degradation, through the selective breakdown of chloroplast components. Selective autophagy of membrane-bound organelles typically requires receptors that bridge organelle membranes and pre-autophagosomal structures. Here we identify OEP24.1 as a new receptor in the selective chloroplast piecemeal autophagy, supporting the degradation of stromal proteins. We found that the {beta}-barrel protein OEP24.1 is located at the outer membrane of plastid envelopes and on bodies budding off plastids into the cytosol and containing stroma proteins. OEP24.1 interacts physically with ATG8 autophagy proteins in a UIM dependent manner. OEP24.1-GFP and RFP-ATG8 colocalize with in mobile autophagosome-like puncta in the cytosol and in autophagic bodies within the vacuole. Delivery of OEP24.1 to vacuole lumen is dependent on active autophagy. OEP24.1 controls carbon allocation at the whole plant level, carbon concentrations in flowering stems and xylem composition. These phenotypes can be explained by the role of OEP24.1 in metabolite diffusion across the chloroplast envelope, and by its involvement in the facilitation of chloroplast quality control through piecemeal autophagy.

plant biology↗

bioRxiv2024

Multi-scale phenotyping of senescence-related changes in roots of rapeseed in response to nitrogen deficiency

Senescence related markers have been widely studied in leaves in many plant species. Root senescence is more difficult to characterize. The existence of two different root organs in B. napus, with a taproot that appear to be specifically dedicated to the storage and remobilization of nutrients, offered the possibility of analysing the temporality of the changes linked to aging, based on the degradation of the taproot reserves. Microscopic and biochemical analyses showed that taproot plays an important role in carbon and nitrogen storage as reflected by the large quantities of starch and proteins present at early development stages. The proteomic study associated to the description of biochemical, morphological and anatomic changes provides a comprehensive picture of the main events occurring in the taproot and in the lateral roots with aging. Master modifications as protein and cell wall degradation, amino acid catabolism versus synthesis, nucleic acid degradation are presented and senescence related markers specific or not of the root types were identified. Comparison with Arabidopsis public data facilitated the identification of markers common to root and leaf senescence. The analysis of protease changes provides a list of candidates that may play a role in nitrogen and carbohydrate remobilization from taproot to the shoot and flowering organs and that would deserve attention for further functional analyses.

plant biology↗

bioRxiv2023

Autophagic activity acts as a rheostat in the control of nitrogen transfer from Arabidopsis rosette leaves to the seeds according to a principle of communicating vessels

Macroautophagy is known for long as essential for the degradation and the recycling of different macromolecules in eukaryotes. However how important is autophagy for nitrogen management at the whole plant level and for plant biomass and yield productivity in unstressed and well feed plants needed further investigation. In this study, we used both autophagy knock-out mutants and autophagy over-expressors that constitutively produce numerous autophagosomes. These mutants and over-expressors were cultivated using hydroponic system to observe and compare their phenotypes under sufficient nitrate supply, and when submitted after a while to strict nitrate starvation. The shift from nitrate sufficient condition to nitrate starvation allowed us to determine how autophagy defective or stimulated lines can use their own nitrogen resources to complete their cycle. Unexpectedly we observed that irrespective of the nitrate conditions, both mutants and over-expressors exhibited early leaf senescence phenotypes relative to wild type. While autophagy mutants exhibited strong defect for N remobilisation and seed production irrespective of nitrate condition, the better performance of autophagy-over expressors for N remobilisation and seeds production was only significant under sufficient nitrate supply, i.e. when autophagy was not naturally stimulated by nitrate limitation. Interestingly, comparisons of genotypes showed that the nitrogen pool used for seed filling originated from rosette leaves, as if rosette and seeds were used as communicating vessels independently of the stem and pod connecting organs. Altogether, results show that autophagy is a master player in nitrogen management at the whole plant level that controls yield production and leaf senescence.

physiology↗

bioRxiv2018

Autophagy is essential for optimal Fe translocation to seeds in Arabidopsis

Micronutrient deficiencies affect a large part of the world population. They are mostly due to the consumption of grains with insufficient content of Fe or Zn. Both de novo uptake by roots and recycling from leaves may provide seeds with nutrients. Autophagy, which is a conserved mechanism for nutrient recycling in eukaryotes, was shown to be involved in nitrogen remobilization to seeds. Here, we have investigated the role of this mechanism in micronutrient translocation to seeds. We found that several Arabidopsis thaliana plants impaired in autophagy display defects in nutrient remobilization to seeds. In atg5-1 mutant, which is completely defective in autophagy, the efficiency of Fe translocation from vegetative organs to seeds was severely decreased even when Fe was provided during seed formation. Combining atg5-1 with sid2 mutation that counteracts premature senescence associated to autophagy deficiency and using 57Fe pulse labeling, we could propose a two-step mechanism in which iron taken up de novo during seed formation is first accumulated in vegetative organs and subsequently remobilized to seeds. Finally, we showed that translocations of zinc and manganese to seeds are also dependent on autophagy. Fine tuning autophagy during seed formation opens therefore new possibilities to improve micronutrient remobilization to seeds.

plant biology↗