Moez Hanin

This study investigated Serratia bockelmanii sp. 201 (strain C2), a bacterium isolated from the rhizosphere of Opuntia ficus-indica. This strain d

Drought is a major constraint on the productivity of durum wheat across Mediterranean and North African regions. To elucidate the mechanisms underlying drought resilience, we employed a combination of scenario-controlled phenomics and flag leaf transcriptomics across ten durum wheat genotypes. These included the Tunisian landraces Chili and Mahmoudi, seven breeding lines, and the reference cultivar Svevo. The plants were grown to maturity under well-watered or long-term drought conditions in pots and rhizotrons, enabling a comprehensive assessment of growth, yield components, root architecture, physiological traits, and reaction norm plasticity. Drought markedly reduced performance, yet Chili and Mahmoudi consistently maintained superior biomass, grain number and intrinsic water use efficiency (iWUE). This was supported by balanced C/N allocation, strong osmotic adjustment, and the ability to sustain robust root systems under stress, albeit through partly divergent physiological strategies. Transcriptomic profiling revealed highly genotype specific responses, with drought tolerance unrelated to the number of differentially expressed genes. Instead, the landraces displayed distinct regulatory programs involving mainly photosynthesis protection, ABA-related transporters, osmotic adjustment pathways, and stress-responsive transcription factors. These mechanistic insights identify actionable physiological and molecular determinants of drought plasticity and provide high value targets for accelerating the breeding of climate resilient durum wheat. Highlights: Integrated phenomics and transcriptomics revealed landrace-specific physiological and molecular mechanisms enabling superior drought resilience and identifying actionable targets for durum wheat improvement.

Seed vigor and germination efficiency, which are essential traits for achieving proper plant growth and yield, are negatively impacted by seed dormancy and inadequate environmental conditions. These traits are under multiple genetic determinants controlling redox status. Our current research aims to evaluate germination parameters and seedling growth alongside the accumulation of reactive oxygen species (ROS), phenolic compounds, and antioxidants in three evolutionary divergent plant species: durum wheat (Triticum durum L.), and fenugreek (Trigonella foenum-graecum L.) as glycophytes, and Atriplex halimus L. as a halophyte representative. Our results revealed a significant variation among these genotypes in germination performance and seedling growth. Fenugreek and Atriplex exhibited lower ROS accumulation and higher antioxidant potential compared to wheat. Principal Component Analysis (PCA) illustrates these differentiating traits, by clustering Fenugreek and Atriplex into distant groups far from wheat. Remarkably, high-performance liquid chromatography analysis of total seed phenolic compounds showed that Atriplex had the most diverse repertoire of antioxidants (i.e. quercetin and scutellarin) highlighting differential pathways that might have evolved for stress adaptation. Altogether, these findings advance our understanding of seed metabolic adaptability and highlight potential targets for enhancing crop stress resilience.

Plant growth-promoting rhizobacteria (PGPR) enhance plant growth and development through diverse mechanisms, including phytohormone production, nutrient acquisition, and stress mitigation. This study describes the isolation and characterization of two bacterial strains, DT1 and S10, from the rhizospheres of Diplotaxis tenuifolia and Cynodon dactylon , respectively capable of solubilizing phosphate and zinc, fix nitrogen and produce indole acetic acid (IAA) and siderophores. Using whole genome sequencing and taxonomic analyses, these two strains were identified as Acinetobacter calcoaceticus (DT1) and Citrobacter braakii (S10). Functional genomic annotation revealed numerous genes associated with key plant growth-promoting traits, including those involved in indole-3-acetic acid (IAA) ( trpABCDE , ipdC ), cytokinin ( miaABE ), and riboflavin biosynthesis, confirmed by targeted metabolomics. In addition, genes associated with nitrogen metabolism ( nirB , narGHI ) and phosphate solubilization ( gcd , phoARP , pstABCS , pqqEFG ) were identified and supported by phenotypic assays. Interestingly, biosynthetic gene clusters for the secondary metabolites enterobactin, bacillibactin, and staphyloferrin B, known to contribute to plant growth promotion, were identified in both genomes. Both strains also harbored genes encoding ACC deaminase, an enzyme known to enhance plant tolerance to abiotic stress. Furthermore, non-targeted metabolomic analysis revealed that DT1 and S10 produced a range of intracellular and extracellular metabolites associated with plant growth promotion and stress resilience, including cadaverine, biotin, arginine, and GABA. Collectively, these findings position DT1 and S10 as promising bioinoculant candidates, offering an integrative genomic and metabolic foundation for their application in next-generation sustainable agricultural strategies.

Type 1 protein phosphatases (PP1s) are crucial in various plant cellular processes. Their function is controlled by regulators known as PP1-interacting proteins (PIPs), often intrinsically disordered, such as Inhibitor 2 (I2), conserved across kingdoms. The durum wheat TdRL1 acts as a positive regulator of plant stress tolerance, presumably by inhibiting PP1 activity. In this work, co-immunoprecipitation and bimolecular fluorescence complementation (BiFC) assays demonstrate that the durum wheat TdPP1 interacts with both TdRL1 and At-I2 in vivo. YFP fluorescence restored after TdRL1-TdPP1 interaction decorated specifically the microtubular network of the tobacco co-infiltrated cells. In vitro phosphatase assays revealed that TdRL1 inhibited the activity of wild-type TdPP1 and two mutant forms (T243M and H135A) in a concentration-dependent manner, showing a novel and potent inhibition mechanism. Structural modeling of the TdPP1-inhibitor complexes suggested that both At-I2 and TdRL1 bind to TdPP1 by wrapping their flexible C-terminal tails around it, blocking access to the active site. Remarkably, the model showed that TdRL1 differs from At-I2 in its interaction with TdPP1 by trapping the phosphatase with its N-terminal tail. These findings provide important insights into the regulatory mechanisms governing the activity of PP1s in plants and highlight the potential for targeted inhibition to modulate plant stress responses.

Simple physico-chemical techniques can be used to evaluate the composition, structure, and characteristics of plant seeds to determine their viability, quality, and possible uses in agriculture. Advanced analytical techniques, including thermo gravimetric analysis (TGA), electron paramagnetic resonance (EPR), and high-pressure liquid chromatography (HPLC), provide completely new insights and more precise information. They can be integrated to build up seed quality profiles, with great advantage to assess water content, organic compounds, and inorganic metals without the need to carry out many extraction procedures, as requested by more conventional methods. In this study, seed lots from three different plant species such as Triticum turgidum L. subsp. durum (wheat), Trigonella foenum graecum L. (trigonella or fenugreek), and Atriplex halimus L. (saltbush or sea orach) have been used to test the potential of TGA, EPR, and HPLC to discriminate between seed-specific features. A key finding of this study is that HPLC is essential in Principal Component Analysis (PCA) because various seeds (from the same species or other species) may contain compounds with varying polarity groups. The reported data confirm the efficacy of this approach. These data, fully available for other users, are coherently constructed and provide a proof of concept for future seed quality control studies.

Phosphorus (P) is the second most important macro-element for plant growth, and its low availability in soil is a major obstacle to crop production. Inorganic phosphate (Pi) is the least available form in the soil, while organic phosphate (Po) is the most dominant one, up to 80% of which exists as inositol hexakisphosphate, also known as phytic acid (PA) that cannot be absorbed by plant roots unless hydrolyzed by microbial phytases. Similar to phosphate-solubilizing bacteria, many plant growth-promoting rhizobacteria (PGPR) can play a relevant role in phosphate turnover. In our study, we screened a series of PGPR strains for phytase activities using PA as a sole source of P. Three strains (named C2, N4, and S10) with relatively high phytase activities ranging from 42.84 to 100.55 Units g⁻¹ were selected for barley growth assays. When barley plants grown in poor sandy soil and irrigated with a PA-containing solution were inoculated with each of these PGPR isolates, a significant growth enhancement was observed. This positive effect was well illustrated by an increase in root growth, plant height, and chlorophyll contents. In addition, the inoculated barley plants accumulated significantly higher Pi contents in leaves and roots compared to non-inoculated plants. Finally, the expression of a number of high-affinity Pi transporter genes (PHT1.1, PHT1.4, PHT1.8, and PHT1.6) in inoculated barley plants was downregulated especially in roots, compared to non-inoculated plants. This difference is most likely due to the bacterial phytases that change the P availability in the rhizosphere. In summary, these three strains can improve barley growth under phosphate-limited conditions and should be considered in developing eco-friendly biofertilizers as an alternative to conventional P fertilizers.

Plant catalases (CAT) are involved in the cellular scavenging of the reactive oxygen species during developmental processes and in response to abiotic and biotic stresses. However, little is known about the regulation of the CAT activity to ensure efficient antioxidant function. Using bioinformatic analyses, we showed that durum wheat catalase 1 (TdCAT1) harbors highly conserved cation-binding and calmodulin binding (CaMBD) domains which are localized at different positions of the protein. As a result, the catalytic activity of TdCAT1 is enhanced in vitro by the divalent cations Mn²⁺ and Fe²⁺ and to a lesser extent by Cu²⁺, Zn²⁺, and Mg²⁺. Moreover, the GST-pull down assays performed here revealed that TdCAT1 bind to the wheat CaM (TdCaM1.3) in a Ca²⁺-independent manner. Furthermore, the TdCaM1.3/Ca²⁺ complex is stimulated in a CaM-dose-dependent manner by the catalytic activity of TdCAT1, which is further increased in the presence of Mn²⁺ cations. The catalase activity of TdCAT1 is enhanced by various divalent cations and TdCaM1.3 in a Ca-dependent manner. Such effects are not reported so far and raise a possible role of CaM and cations in the function of CATs during cellular response to oxidative stress.