Biology subjects

Bouzid, M.

Publications and source records attributed to Bouzid, M..

7 recordsLinked to original sources

bioRxiv2026

Boosting NADP-malic enzyme 1 enhances seed vigor and longevity in Arabidopsis thaliana

Seed longevity is a key determinant of crop establishment, productivity, and germplasm conservation. During storage and germination, reactive oxygen species accumulate and contribute to seed aging through oxidative damage and loss of viability. The maintenance of redox homeostasis therefore relies on NADPH-dependent antioxidant systems, which require a continuous supply of reducing power. NADP-dependent malic enzyme 1 (NADP-ME1), represents a source of NADPH supporting antioxidant defense during seed aging. Here, we show that enhanced expression of NADP-ME1 positively contributes to seed vigor and longevity in Arabidopsis thaliana. NADP-ME1 overexpression lines exhibited faster germination and higher overall germination after accelerated aging, whereas knockout mutants showed markedly reduced germination performance. Enhanced post-aging vigor in the overexpression lines was associated with reduced oxidative damage as indicated by lower malondialdehyde and hydrogen peroxide accumulation, along with preservation of specific polyunsaturated fatty acids, and increased {gamma}-tocopherol levels in aged dry seeds. Enhanced expression of NADP-ME1 reshapes the transcriptome of germinated seeds under fresh conditions compared with the wild type, while only minimal differences between genotypes are detected in aged seeds. These results suggest that NADP-ME1 contributes to the establishment of a transcriptional state associated with enhanced seed vigor and improved post-aging germination. Finally, co-immunoprecipitation coupled to mass spectrometry and bimolecular fluorescence complementation identified aspartate aminotransferase 2 as a NADP-ME1 interactor, pointing to a link between malate metabolism and amino acid-related metabolic adjustment. Together, these results identify NADP-ME1 as a determinant of seed resilience to aging and a potential target for improving seed quality.

plant biology↗

bioRxiv2026

NADP-malic enzyme 1 couples ABA signaling to ROS-auxin patterning to restrict Arabidopsis root growth

Abscisic acid (ABA) restricts primary root growth by reshaping reactive oxygen species (ROS) dynamics and hormone signaling at the root apex, yet how cellular reductant supply for redox homeostasis is integrated into this response remains unclear. Here, we show that the cytosolic NADP-dependent malic enzyme 1 (NADP-ME1) is required for full ABA inhibition of Arabidopsis primary root elongation after germination. Three independent me1 loss-of-function mutants retained significant elongation of primary roots under ABA compared with wild type. In wild type, ABA induced an asymmetric auxin response at the root tip, whereas me1 roots failed to establish this auxin asymmetry and instead accumulated superoxide, indicating disrupted ROS balance. Pharmacological perturbation of auxin transport and ethylene biosynthesis/signaling attenuated the mutant phenotype, linking NADP-ME1 function to auxin-ethylene interactions during ABA-regulated growth. NADP-ME1 loss amplifies ABA-dependent transcriptional rewiring, including induction of oxidative stress and depression of growth-associated hormone modules. Co-immunoprecipitation coupled with bimolecular fluorescence complementation identified ascorbate peroxidase 1 (APX1) and major latex protein-like 34 (MLP34) as NADP-ME1 interaction partners, suggesting functional coupling between NADPH production and ROS detoxification. Together, our results support a model in which NADP-ME1 shapes the superoxide/H2O2 balance to control auxin patterning at the root tip and thereby execute ABA-mediated growth inhibition.

plant biology↗

bioRxiv2023

Natural variation in Arabidopsis thaliana identifies GlyoxalaseI;2 as key for the detoxification of glucose-derived reactive carbonyl species

Reactive carbonyl species (RCS) are toxic byproducts of normal metabolism that become more prevalent under oxidative stress. Here, we show that Arabidopsis thaliana ecotypes exhibit natural variation in their ability to detoxify glucose-derived RCS. We identified the IP-Pal-0 ecotype showing enhanced tolerance to glucose-derived RCS via upregulation of the glyoxalase system. In particular, the Viridiplantae-specific isoforms GLXI;2, GLXII;4, and GLXII;5 are highly expressed in IP-Pal-0 when plants are grown in the presence of 2-keto-D-glucose (KDG; glucosone) or methylglyoxal, and protein extracts from these plants display enhanced GLXI activity on KDG than other ecotypes. We identified specific motif/cis-regulatory elements in the GLXI;2 promoter regions of Col-0 and IP-Pal-0 that may underlie the differential expression of GLXI;2 associated with KDG detoxification. IP-Pal-0 GLXI;2 contains two different amino acids compared to Col-0, but these do not affect the basic kinetics of the protein. Interestingly, we found that the simultaneous change of these amino acids also occurs together in the GLXI proteins of some other organisms, suggesting a convergence in the simultaneous change of both amino acid residues. Our findings underscore the importance of Viridiplantae-specific glyoxalase isoforms in detoxifying glucose-derived RCS, particularly KDG, and highlight the promise of harnessing natural genetic diversity in the glyoxalase pathway to enhance plant stress tolerance.

plant biology↗

bioRxiv2020

Cis-regulatory evolution spotlights species differences in the adaptive potential of gene expression plasticity

Phenotypic plasticity is the variation in phenotype that a single genotype can produce in different environments and, as such, is an important component of individual fitness. However, whether the effect of new mutations, and hence evolution, depends on the direction of plasticity remains controversial. Here, we identify the cis-acting modifications that have reshaped gene expression in response to dehydration stress in three Arabidopsis species. Our study shows that the direction of effects of most cis-regulatory variants differentiating the response between A. thaliana and the sister species A. lyrata and A. halleri depends on the direction of pre-existing plasticity in gene expression. A comparison of the rate of cis-acting variant accumulation in each lineage indicates that the selective forces driving adaptive evolution in gene expression favors regulatory changes that magnify the stress response in A. lyrata. The evolutionary constraints measured on the amino-acid sequence of these genes support this interpretation. In contrast, regulatory changes that mitigate the plastic response to stress evolved more frequently in A. halleri. Our results demonstrate that pre-existing plasticity can be a stepping stone for adaptation, but its selective remodeling differs between lineages.

evolutionary biology↗

bioRxiv2019

Actin modulates shape and mechanics of tubular membranes

The actin cytoskeleton shapes cells and also organizes internal membranous compartments. In particular, it interacts with membranes in intracellular transport of material in mammalian cells, yeast or plant cells. Tubular membrane intermediates, pulled along microtubule tracks, are involved during these processes, and destabilize into vesicles. While the role of actin in this destabilization process is still debated, literature also provide examples of membranous structures stabilization by actin. To directly address this apparent contradiction, we mimic the geometry of tubular intermediates with preformed membrane tubes. The growth of an actin sleeve at the tube surface is monitored spatio-temporally. Depending on network cohesiveness, actin is able to stabilize, or maintain membrane tubes under pulling. Indeed, on a single tube, thicker portions correlate with the presence of actin. Such structures relax over several minutes, and may provide enough time and curvature geometries for other proteins to act on tube stability.

biophysics↗

bioRxiv2019

A rapid and simple method for assessing and representing genome sequences relatedness

AO_SCPLOWBSTRACTC_SCPLOWCoherent genomic groups are frequently used as a proxy for bacterial species delineation through computation of overall genome relatedness indices (OGRI). Average nucleotide identity (ANI) is a widely employed method for estimating relatedness between genomic sequences. However, pairwise comparisons of genome sequences based on ANI is relatively computationally intensive and therefore precludes analyses of large datasets composed of thousands of genome sequences. In this work we proposed a workflow to compute and visualize relationships between genomic sequences. A dataset containing more than 3,500 Pseudomonas genome sequences was successfully classified with an alternative OGRI based on k-mer counts in few hours with the same precision as ANI. A new visualization method based on zoomable circle packing was employed for assessing relationships among the 350 groups generated. Amendment of databases with these Pseudomonas groups greatly improved the classification of metagenomic read sets with k-mer-based classifier. The developed workflow was integrated in the user-friendly KI-S tool that is available at the following address: https://iris.angers.inra.fr/galaxypub-cfbp.

genomics↗

bioRxiv2018

Arabidopsis species deploy distinct strategies to cope with drought stress

O_LIBackground and Aims Water limitation is an important determinant of the distribution, abundance and diversity of plant species. Yet, little is known about how the response to limiting water supply changes among closely related plant species with distinct ecological preferences. Comparison of the model annual species A. thaliana to its close perennial relatives A. lyrata and A. halleri, can help disentangle the molecular and physiological changes contributing to tolerance and avoidance mechanisms, because these species must maintain tolerance and avoidance mechanisms to increase long-term survival, but they are exposed to different levels of water stress and competition in their natural habitat.\nC_LIO_LIMethods We conducted a dry-down experiment that mimics a period of missing precipitation. We quantified the covariation of progressive decrease in soil water content (SWC) with various physiological and morphological plant traits across a set of representative genotypes in Arabidopsis thaliana, A. lyrata and A. halleri. To quantify the degree of plant stress, transcriptome changes were also monitored.\nC_LIO_LIKey Results The analysis of trait co-variation demonstrates that the three species differ in the strategies they deploy to respond to drought stress. A. thaliana showed drought avoidance reaction but failed to survive wilting. A. lyrata efficiently combined avoidance and tolerance mechanisms. By contrast, A. halleri showed some degree of tolerance to wilting but it did not seem to protect itself from the stress imposed by drought. Transcriptome data collected just before plant wilting and after recovery corroborated the phenotypic analysis, with A. lyrata and A. halleri showing a stronger activation of recovery- and stress-related genes, respectively.\nC_LIO_LIConclusions We conclude that these three Arabidopsis species have evolved distinct strategies to face drought stress, and discuss the extent to which these strategic differences reflect their respective ecological priorities.\nC_LI

plant biology↗