The wheat pathogenesis-related protein (TdPR1.2) enhanced tolerance to abiotic and biotic stresses in transgenic Arabidopsis plants.

In plants, the pathogenesis-related (PR) proteins have been identified as important regulators of biotic and abiotic stresses. PR proteins branch out into 19 different classes (PR1-PR19). Basically, all PR proteins display a well-established method of action, with the notable exception of PR1, which is a member of a large superfamily of proteins with a common CAP domain. We have previously isolated and characterized the first PR1 from durum wheat, called TdPR-1.2. In the current research work, TdPR1.2 gene was used to highlight its functional activities under various abiotic (sodium chloride (100 mM NaCl) and oxidative stresses (3 mM H2O2), hormonal salicylic acid (SA), abscisic acid (ABA) and jasmonic acid (JA), and abiotic stresses (Botrytis cinerea and Alternaria solani). Enhancement survival index was detected in Arabidopsis transgenic plants expressing TdPR1.2 gene. Moreover, quantitative real-time reverse transcription PCR (qRT-PCR) analysis demonstrated induction of antioxidant enzymes such as catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD). It equally revealed a decrease of malondialdehyde (MDA) as well as hydrogen peroxide (H2O2) levels in transgenic Arabidopsis plants compared to control lines, confirming the role of TdPR1.2 in terms of alleviating biotic and abiotic stresses in transgenic Arabidopsis plants. Eventually, RT-qPCR results showed a higher expression of biotic stress-related genes (PR1 and PDF1.2) in addition to a downregulation of the wound-related gene (LOX3 and VSP2) in transgenic lines treated with jasmonic acid (JA). Notably, these findings provide evidence for the outstanding functions of PR1.2 from durum wheat which can be further invested to boost tolerance in crop plants to abiotic and biotic stresses.

Deciphering Physio-Biochemical Basis of Tolerance Mechanism for Sesame (Sesamum indicum L.) Genotypes under Waterlogging Stress at Early Vegetative Stage.

Waterlogging represents a substantial agricultural concern, inducing harmful impacts on crop development and productivity. In the present study, 142 diverse sesame genotypes were examined during the early vegetative phase to assess their response under waterlogging conditions. Based on the severity of symptoms observed, 2 genotypes were classified as highly tolerant, 66 as moderately tolerant, 69 as susceptible, and 5 as highly susceptible. Subsequent investigation focused on four genotypes, i.e., two highly tolerant (JLT-8 and GP-70) and two highly susceptible (R-III-F6 and EC-335003). These genotypes were subjected to incremental stress periods (0 h, 24 h, 48 h, 72 h, and 96 h) to elucidate the biochemical basis of tolerance mechanisms. Each experiment was conducted as a randomized split-plot design with three replications, and the statistical significance of the treatment differences was determined using the one-way analysis of variance (ANOVA) followed by the Fisher least significant difference (LSD) test at p ≤ 0.05. The influence of waterlogging stress on morphological growth was detrimental for both tolerant and susceptible genotypes, with more severe consequences observed in the latter. Although adventitious roots were observed in both sets of genotypes above flooding levels, the tolerant genotypes exhibited a more rapid and vigorous development of these roots after 48 h of stress exposure. Tolerant genotypes displayed higher tolerance coefficients compared to susceptible genotypes. Furthermore, tolerant genotypes maintained elevated antioxidant potential, thereby minimizing oxidative stress. Conversely, susceptible genotypes exhibited higher accumulation of hydrogen peroxide (H2O2) and malondialdehyde content. Photosynthetic efficiency was reduced in all genotypes after 24 h of stress treatment, with a particularly drastic reduction in susceptible genotypes compared to their tolerant counterparts. Tolerant genotypes exhibited significantly higher activities of anaerobic metabolism enzymes, enabling prolonged survival under waterlogging conditions. Increase in proline content was observed in all the genotypes indicating the cellular osmotic balance adjustments in response to stress exposure. Consequently, the robust antioxidant potential and efficient anaerobic metabolism observed in the tolerant genotypes served as key mechanisms enabling their resilience to short-term waterlogging exposure. These findings underscore the promising potential of specific sesame genotypes in enhancing crop resilience against waterlogging stress, offering valuable insights for agricultural practices and breeding programs.

Assessing suboptimal health status in the Saudi population: Translation and validation of the SHSQ-25 questionnaire.

Background: Suboptimal Health Status (SHS) is realised as a vital feature for improving global health. However, the Arabian world does not have a validated instrument for screening SHS in their population. Therefore, the study aimed to evaluate the psychometric properties of Arabic-translated SHS (ASHSQ-25) in the Saudi Arabian population. Methods: We conducted a cross-sectional study among the conveniently sampled 1590 participants from the Saudi population (with a 97.4% response rate). The data was gathered through an online survey and then exported into SPSS and AMOS version 26.0 for analysis. Mann-Whitney and Kruskal-Wallis tests were used to identify the median difference between demographic groups. The one-tailed 90% upper limit of SHS scores was chosen as the cut-off criteria for SHS. Reliability and confirmatory analysis were performed for the psychometric evaluation of ASHSQ-25 in the Saudi Arabian context. Results: This study demonstrates that the ASHSQ-25 has good internal consistency, interclass correlation coefficient (ICC) = 0.92; 95% confidence interval (CI) = 0.91-0.93) and reliability (Cronbach's α = 0.92). The confirmatory factor analysis (CFA) results indicated a good fit of the databased on the CMIN/degrees of freedom (df) = 4.461, comparative fit index (CFI) = 0.94, Tucker Lewis index (TLI) = 0.93, and Root Mean Square Error of Approximation (RMSEA) = 0.05. The result factor loadings for each item were high (≥ 0.55), except for one item from the immune system subscale. The SHS cut-off point for ASHSQ-25 was 33, leading to a 23.7% prevalence of SHS. Conclusions: This study reveals that ASHSQ-25 has appropriate internal consistency and structural validity to assess SHS in an Arabic-speaking population; therefore, it is recommended.

Genome-Wide Investigation and Expression Analysis of the Catalase Gene Family in Oat Plants (Avena sativa L.).

Through the degradation of reactive oxygen species (ROS), different antioxidant enzymes, such as catalase (CAT), defend organisms against oxidative stress. These enzymes are crucial to numerous biological functions, like plant development and defense against several biotic and abiotic stresses. However, despite the major economic importance of Avena sativa around the globe, little is known about the CAT gene's structure and organization in this crop. Thus, a genome-wide investigation of the CAT gene family in oat plants has been carried out to characterize the potential roles of those genes under different stressors. Bioinformatic approaches were used in this study to predict the AvCAT gene's structure, secondary and tertiary protein structures, physicochemical properties, phylogenetic tree, and expression profiling under diverse developmental and biological conditions. A local Saudi oat variety (AlShinen) was used in this work. Here, ten AvCAT genes that belong to three groups (Groups I-III) were identified. All identified CATs harbor the two conserved domains (pfam00199 and pfam06628), a heme-binding domain, and a catalase activity motif. Moreover, identified AvCAT proteins were located in different compartments in the cell, such as the peroxisome, mitochondrion, and cytoplasm. By analyzing their promoters, different cis-elements were identified as being related to plant development, maturation, and response to different environmental stresses. Gene expression analysis revealed that three different AvCAT genes belonging to three different subgroups showed noticeable modifications in response to various stresses, such as mannitol, salt, and ABA. As far as we know, this is the first report describing the genome-wide analysis of the oat catalase gene family, and these data will help further study the roles of catalase genes during stress responses, leading to crop improvement.

Genome-Wide Identification and Expression Profiling of Pathogenesis-Related Protein 1 (PR-1) Genes in Durum Wheat (Triticum durum Desf.).

Pathogen-related proteins (PRs) are diversified proteins with a low molecular weight implicated in plant response to biotic and abiotic stress as well in regulating different functions in plant maturation. Interestingly, no systematical study has been conducted in durum wheat (Triticum turgidum subsp. durum). In the present study, 12 PR-1 genes encoding a CAP superfamily domain were identified in the genome of Triticum turgidum subsp. durum, which is an important cereal, using in silico approaches. Additionally, phylogenetic analysis showed that the PR-1 genes were classified into three groups based on their isoelectric point and the conserved motif domain. Moreover, our analysis showed that most of the TdPR-1 proteins presented an N-terminal signal peptide. Expression patterns analysis showed that the PR-1 gene family presented temporal and spatial specificity and was induced by different abiotic stresses. This is the first report describing the genome-scale analysis of the durum wheat PR-1 gene family, and these data will help further study the roles of PR-1 genes during stress responses, leading to crop improvement.

Methicillin-Resistant Staphylococcus aurous: Epidemiology, Transmission and New Alternative Therapies: A Narrative Review.

Over the last decade, we were facing medical struggle by the emergence of multi-resistant bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA). MRSA infections are still causing a growing global concern due to the rapid adaptive multidrug resistance to conventional antibiotics in human, community and veterinary medicine. Here we provide an overview about MRSA epidemiology, transmission and alternative potential treatments particularly new discovered phytochemicals with biological activity. In this narrative review, bibliographic data was collected from literature search databases: Google Scholar, web of science and PubMed/MEDLINE during recent years (2016 to 2021). MRSA is responsible of wide spectrum life threatening infections such us septicemia, endocarditis, and wound infections. It has epidemic potential in hospitals, that is responsible of most nosocomial infections leading to mortality and constitute a real burden for the healthcare systems. Effective preventive strategies for management of MRSA are highly required moreover, the identification and development of novel drugs or active biomolecules through phytochemicals are time challenging to face new resistant strains.

Identification of a putative kinase interacting domain in the durum wheat catalase 1 (TdCAT1) protein.

Catalases are crucial antioxidant enzymes that regulate plants responses to different biotic and abiotic stresses. It has been previously shown that the activities of durum wheat catalase proteins (TdCAT1) were stimulated in the presence of divalent cations Mn2+, Mg2+, Fe2+, Zn2+, and Ca2+. In addition, TdCAT1s can interact with calmodulins in calcium-independent manner, and this interaction stimulates its catalytic activity in a calcium-dependent manner. Moreover, this activity is further enhanced by Mn2+ cations. The current study showed that wheat catalase presents different phosphorylation targets. Besides, we demonstrated that catalase is able to interact with Mitogen Activated Proteins kinases via a conserved domain. This interaction activates wheat catalase independently of its phosphorylation status but is more promoted by Mn2+, Fe2+ and Ca2+ divalent cations. Interestingly, we have demonstrated that durum wheat catalase activity is differentially regulated by Mitogen Activated Proteins kinases and Calmodulins in the presence of calcium. Moreover, the V0 of the reaction increase gradually following the increasing quantities of Mn2+ divalent cations. Such results have never been described before and suggest i) complex regulatory mechanisms exerted on wheat catalase, ii) divalent cations (Mn2+; Mg2+; Ca2+ and Fe2+) act as key cofactors in these regulatory mechanisms.

Catalase Gene Family in Durum Wheat: Genome-Wide Analysis and Expression Profiling in Response to Multiple Abiotic Stress Conditions.

Catalase (CAT) is an antioxidant enzyme expressed by the CAT gene family and exists in almost all aerobic organisms. In fact, the CAT enzyme modulates the hydrogen peroxide (H2O2) contents in cells by translating this toxic compound into water (H2O) and O2- to reduce reactive oxygen species (ROS) contents in cells. ROS are produced as a result of biotic and abiotic environmental stressors. To avoid ROS toxicity, plants are armed with different enzymatic and non-enzymatic systems to decompose ROS. Among the enzymatic system, CAT proteins are well studied. CAT not only controls growth and development in plants but is also involved in plant defense against different stresses. So far, the CAT gene family has not been reported in durum wheat (Triticum turgidum ssp. durum L.). Therefore, a genome-wide comprehensive analysis was conducted to classify the CAT genes in the durum wheat genome. Here, six TdCAT genes were identified. Based on phylogenetics, the TdCAT genes belong to three groups (Groups I-III) which is explainable by their comparable structural characteristics. Using bio-informatic analysis, we found that the secondary and tertiary structures were conserved among plants and present similar structures among durum wheat CATs. Two conserved domains (pfam00199 and pfam06628) are also present in all identified proteins, which have different subcellular localizations: peroxisome and mitochondrion. By analyzing their promoters, different cis-elements were identified, such as hormone-correlated response and stress-related responsive elements. Finally, we studied the expression pattern of two catalase genes belonging to two different sub-classes under different abiotic stresses. Expression profiling revealed that TdCAT2 and TdCAT3 presented a constitutive expression pattern. Moreover, both genes are induced in response to salt, mannitol, cold, heat and ABA. Thus, we speculate that those genes are activated by different stresses, such as oxygen deficiency, light, cold, abscisic acid and methyl jasmonate. Further, this study will help in understanding the behavior of CAT genes during environmental stress in durum wheat and in Triticeae species in general.

Genome-Wide Identification and Expression Analysis of Catalase Gene Families in Triticeae.

Aerobic metabolism in plants results in the production of hydrogen peroxide (H2O2), a significant and comparatively stable non-radical reactive oxygen species (ROS). H2O2 is a signaling molecule that regulates particular physiological and biological processes (the cell cycle, photosynthesis, plant growth and development, and plant responses to environmental challenges) at low concentrations. Plants may experience oxidative stress and ultimately die from cell death if excess H2O2 builds up. Triticum dicoccoides, Triticum urartu, and Triticum spelta are different ancient wheat species that present different interesting characteristics, and their importance is becoming more and more clear. In fact, due to their interesting nutritive health, flavor, and nutritional values, as well as their resistance to different parasites, the cultivation of these species is increasingly important. Thus, it is important to understand the mechanisms of plant tolerance to different biotic and abiotic stresses by studying different stress-induced gene families such as catalases (CAT), which are important H2O2-metabolizing enzymes found in plants. Here, we identified seven CAT-encoding genes (TdCATs) in Triticum dicoccoides, four genes in Triticum urartu (TuCATs), and eight genes in Triticum spelta (TsCATs). The accuracy of the newly identified wheat CAT gene members in different wheat genomes is confirmed by the gene structures, phylogenetic relationships, protein domains, and subcellular location analyses discussed in this article. In fact, our analysis showed that the identified genes harbor the following two conserved domains: a catalase domain (pfam00199) and a catalase-related domain (pfam06628). Phylogenetic analyses showed that the identified wheat CAT proteins were present in an analogous form in durum wheat and bread wheat. Moreover, the identified CAT proteins were located essentially in the peroxisome, as revealed by in silico analyses. Interestingly, analyses of CAT promoters in those species revealed the presence of different cis elements related to plant development, maturation, and plant responses to different environmental stresses. According to RT-qPCR, Triticum CAT genes showed distinctive expression designs in the studied organs and in response to different treatments (salt, heat, cold, mannitol, and ABA). This study completed a thorough analysis of the CAT genes in Triticeae, which advances our knowledge of CAT genes and establishes a framework for further functional analyses of the wheat gene family.

The Life Cycle of the Xylophagous Beetle, Steraspis speciosa (Coleoptera, Buprestidae), Feeding on Acacia Trees in Saudi Arabia.

The xylophagous beetle, Steraspis speciosa, has infected Acacia forests in Saudi Arabia, causing significant damage and even leading to the death of several trees. In the Ha'il region, in the north of Saudi Arabia, an investigation of 13 study sites shows that the Acacia population is mainly composed of three species: A. gerrardii (90.3%), A. ehrenbergiana (7.5%), and A. raddiana (2.2%) and that 21.7% of this population was infected by S. speciosa. The age of the tree (young, adult, old) and environment habitat (Dam, Wadi, Plateau) effects, and insect life-cycle were studied in the protected Machar National Park. Infection in the park, estimated at 25.4%, mainly affects the oldest trees (20.1%) more than the youngest ones (2.3%), while the driest environments (Plateau, 38.8%) are more vulnerable to infection than humid habitats (Dam, 9.4%). The life cycle of S. speciosa lasts about two years, with four stages to complete metamorphosis: mating and eggs (≈3 months), larvae (≈16 months), pupae (≈3 months), and emergency and adults (≈3 months). The larvae stage with many metamorphic instars was the most harmful for tree and takes the longest. The female beetle lays its eggs on weak stem parts. Steraspis speciosa larvae feed on the stems of Acacia trees, and the instar larvae were gathered under the bark of infected stems, harming most of the phloem and a large portion of the xylem. When combined with a prolonged period of drought, S. speciosa causes the withering of numerous branches and, in extreme cases, kills the entire tree.

Identification and Expression Profiling of Two Saudi Arabia Catalase Genes from Wheat and Barley in Response to Abiotic and Hormonal Stresses.

Catalase is a crucial enzyme in antioxidant defense systems protecting eukaryotes from oxidative stress. These proteins are present in almost all living organisms and play important roles in controlling plant responses to biotic and abiotic stresses by catalyzing the decomposition of H2O2. Despite their importance, little is known about their expression in the majority of monocotyledonous species. Here, we isolated and characterized two novel catalase genes from Triticum turgidum and Hordeum vulgare, designated as TtCAT1 and HvCAT1, respectively. Phylogenetic analysis revealed that TtCAT1 and HvCAT1 presented 492 aa and shared an important identity with other catalase proteins belonging to subfamily 1. Using bioinformatic analysis, we predicted the 3D structure models of TtCAT1 and HvCAT1. Interestingly, analysis showed that the novel catalases harbor a peroxisomal targeting signal (PTS1) located at their C-terminus portion, as shown for other catalase proteins. In addition, this motif is responsible for the in silico peroxisomal localization of both proteins. Finally, RT-qPCR analysis showed that TtCAT1 and HvCAT1 are highly expressed in leaves in normal conditions but faintly in roots. Moreover, both genes are upregulated after the application of different stresses such as salt, osmotic, cold, heavy metal, and hormonal stresses. The positive responses of TtCAT1 and HvCAT1 to the various stimuli suggested that these proteins can help to protect both species against environmental stresses.

Isolation and Characterization of a Novel Pathogenesis-Related Protein-1 Gene (AvPR-1) with Induced Expression in Oat (Avena sativa L.) during Abiotic and Hormonal Stresses.

Pathogenesis-related protein-1 (PR-1) plays crucial roles in regulating plant responses to biotic and abiotic stresses. This study aimed to isolate and characterize the first PR-1 (AvPR-1) gene in oat (Avena sativa L.). AvPR-1 presented conserved signal peptide motifs and core amino acid composition in the functional protein domains as the protein sequence of AvPR-1 presented 98.28%, 97.7%, and 95.4% identity with known PR1 proteins isolated from Triticum aestivum PRB1-2-like, Triticum dicoccoides PRB1-2-like, and Aegilops tauschii subsp. tauschii, respectively. Bioinformatic analysis showed that the AvPR-1 protein belongs to the CAP superfamily (PF00188). Secondary and 3D structure analyses of the AvPR-1 protein were also conducted, confirming sequence conservation of PR-1 among studied species. The AvPR-1 protein harbors a calmodulin-binding domain located in its C-terminal part as previously shown for its wheat homolog TdPR1.2. Moreover, gene expression analysis showed that AvPR-1 was induced in response to many abiotic and hormonal stresses especially in leaves after treatment for 48 h. This is the first study exhibiting the expression profiles of the AvPR-1 gene under different stresses in oat.

The Putative Auto-Inhibitory Domain of Durum Wheat Catalase (TdCAT1) Positively Regulates Bacteria Cells in Response to Different Stress Conditions.

Catalase is a crucial enzyme in the antioxidant defense system protecting organisms from oxidative stress. Proteins of this kind play important roles in controlling plant response to biotic and abiotic stresses by catalyzing the decomposition of H2O2. The durum wheat catalase 1, TdCAT1, has been previously isolated and characterized. Here, using bio-informatic analysis, we showed that durum wheat catalase 1 TdCAT1 harbors different novel conserved domains. In addition, TdCAT1 contains various phosphorylation residues and S-Nitrosylation residues located at different positions along the protein sequence. TdCAT1 activity decreased after treatment with λ-phosphatase. On the other hand, we showed that durum wheat catalase 1 (TdCAT1) exhibits a low CAT activity in vitro, whereas a deleted form of TdCAT1 has better activity compared to the full-length protein (TdCAT460), suggesting that TdCAT1 could present a putative autoinhibitory domain in its C-terminal portion. Moreover, we showed that TdCAT1 positively regulates E. coli cells in response to salt, ionic and osmotic stresses as well as heavy metal stress in solid and liquid mediums. Such effects had not been reported and lead us to suggest that the durum wheat catalase 1 TdCAT1 protein could play a positive role in response to a wide array of abiotic stress conditions.

The Activity of the Durum Wheat (Triticum durum L.) Catalase 1 (TdCAT1) Is Modulated by Calmodulin.

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.

Role of jasmonic acid in plants: the molecular point of view.

KEY MESSAGE: Recent updates in JA biosynthesis, signaling pathways and the crosstalk between JA and others phytohormones in relation with plant responses to different stresses. In plants, the roles of phytohormone jasmonic acid (JA), amino acid conjugate (e.g., JA-Ile) and their derivative emerged in last decades as crucial signaling compounds implicated in stress defense and development in plants. JA has raised a great interest, and the number of researches on JA has increased rapidly highlighting the importance of this phytohormone in plant life. First, JA was considered as a stress hormone implicated in plant response to biotic stress (pathogens and herbivores) which confers resistance to biotrophic and hemibiotrophic pathogens contrarily to salicylic acid (SA) which is implicated in plant response to necrotrophic pathogens. JA is also implicated in plant responses to abiotic stress (such as soil salinity, wounding and UV). Moreover, some researchers have recently revealed that JA controls several physiological processes like root growth, growth of reproductive organs and, finally, plant senescence. JA is also involved in the biosynthesis of various metabolites (e.g., phytoalexins and terpenoids). In plants, JA signaling pathways are well studied in few plants essentially Arabidopsis thaliana, Nicotiana benthamiana, and Oryza sativa L. confirming the crucial role of this hormone in plants. In this review, we highlight the last foundlings about JA biosynthesis, JA signaling pathways and its implication in plant maturation and response to environmental constraints.

Pathogenesis Related Proteins (PRs): From Cellular Mechanisms to Plant Defense.

Many unfavorable stress conditions, such as wounding, drought, extreme temperatures, salinity and pathogen attacks, control growth, development and plant yield. To survive in such environments, plants have developed many strategies. They are able to induce the expression of a large number of genes that encode effectors, receptors, as well as signaling proteins and protective molecules. Among all, pathogenesis-related proteins (PRs) were found to be activated in response to different biotic and abiotic threats. Those proteins have a wide range of functions; acting as chitinases, peroxidases, anti-microbial agents, hydrolases, protease inhibitors, and other activities. Activation of PR proteins has been demonstrated in different plant families as a response to different stresses. In this review, we have summarized the structural, biological and functional characteristics of the different PRs families in plants, their regulation, as well as their roles in plant defense against abiotic and biotic stresses.

Differential regulation of the durum wheat Pathogenesis-related protein (PR1) by Calmodulin TdCaM1.3 protein.

In plants, pathogenesis-related 1 protein (PR1) is considered as important defense protein. The production and accumulation of PR proteins in plants are one of the important responses to several biotic and abiotic stresses. In this regard, PR1 gene was isolated from Triticum turgidum ssp durum and was named as TdPR1.2. The amino acid sequence of TdPR1.2 protein showed 100%, 97.13%, and 44.41% with known PR1 proteins isolated from Triticum aestivum TdPR1-18, PRB1.2 of Aegilops tauschii subsp. tauschii and Arabidopsis thaliana respectively. qRT-PCR showed that TdPR1.2 was induced specially in leaves of durum wheat treated with Salicylic acid for 48 h. Besides, bioinformatic analysis showed that the durum wheat TdPR1.2 harbors a calmodulin binding domain located in it's C-terminal part and that this domain is conserved among different PR1 proteins isolated so far. However, no information is available about the regulation of PR genes by calmodulin and Ca2+ complex (CaM/Ca2+). Here, we showed that TdPR1.2 gene exhibits an antibacterial effect as revealed by the in vitro tests against 8 different bacteria and against the fungi Septoria tritici. In addition, we demonstrate for the first time that PR1 proteins are able to bind to CaM in a Ca2+-dependent manner via a GST-Pull down assay. Finally, in presence of Mn2+ cations, CaM/Ca2+ complex stimulated the antimicrobial effect of TdPR1.2. Such effects were not reported so far, and raise a possible role for CaM/Ca2+ complex in the regulation of plant PRs during cellular response to external signals.

Highlight on the expression and the function of a novel MnSOD from diploid wheat (T. monococcum) in response to abiotic stress and heavy metal toxicity.

Superoxide dismutases (SODs) play a pivotal role in improving abiotic stress tolerance in plant cells. A novel manganese superoxide dismutase gene, denoted as TmMnSOD, was identified from Triticum monococcum. The encoded protein displayed high sequence identity with MnSOD family members and was highly homologous to TdMnSOD from durum wheat. Furthermore, the 3D structure analysis revealed that TmMnSOD displayed homotetramer subunit organization, incorporating four Mn2+ ions. Notably, TmMnSOD structure contains predominantly alpha helices with three beta sheets. On the other hand, under stress conditions, TmMnSOD transcript level was significantly up-regulated by salt, oxidative and heavy metal stresses. At the functional level, TmMnSOD imparts tolerance of yeast and E. coli cells under diverse stresses. Promoter analysis of TmMnSOD gene showed the presence of a great number of salt and pathogen-responsive cis-regulatory elements, highlighting the interest of this gene in breeding programs towards improved tolerance to salt stress in wheat.

Differential regulation of the durum wheat MAPK phosphatase 1 by calmodulin, bivalent cations and possibly mitogen activated protein kinase 3.

MAPK phosphatases (MKPs) are relevant negative regulators of MAPKs in eukaryotes as they mediate the feedback control of MAPK cascades in multiple cellular processes. Despite their relevance, our knowledge on the role of cereal MKPs in stress tolerance is scarce and TMKP1 remains today the only studied MKP in wheat. TMKP1 was previously reported to be involved in plant salt stress tolerance. Moreover, TMKP1 was shown to interact with calmodulin (CaM), 14-3-3 and TMPK3/TMPK6 proteins, which regulate its catalytic activity. To further understand the functional properties of TMKP1, we investigate here the contribution of its phosphorylation status, and of TMPK3 together with CaM and bivalent cations on the catalytic activity. In-gel kinase assays revealed that TMKP1 can be phosphorylated by similar wheat and Arabidopsis MAPKs, including most likely MPK3 and MPK6. In addition, we provide evidence for the capacity of wheat TMPK3 to bind to TMKP1 via a conserved Kinase Interacting Domain (KID) located on its C-terminal part. This interaction leads to a stimulation of TMKP1 activity in the presence of Mn2+ or Mg2+ ions, but to its inhibition in the presence of Ca2+ ions. However, the phosphorylation status of TMKP1 seems to be dispensable for TMKP1 activation by TMPK3. Remarkably, in assays combining TMPK3 with CaM/Ca2+ complex, we registered rather an inhibition of TMKP1 activity which however can be suppressed by Mn2+ cations. Our data are in favor of complex differential regulation of TMKP1 by its MPK substrates, metallic cations that might help in fine-tuning the plant cellular responses to various stresses.

Regulation of the wheat MAP kinase phosphatase 1 by 14-3-3 proteins.

Plant MAP kinase phosphatases (MKPs) are major regulators of MAPK signaling pathways and play crucial roles in controlling growth, development and stress responses. The presence of several functional domains in plant MKPs such as a dual specificity phosphatase catalytic domain, gelsolin, calmodulin-binding and serine-rich domains, suggests that MKPs can interact with distinct cellular partners, others than MAPKs. In this report, we identified a canonical mode I 14-3-3-binding motif (574KLPSLP579) located at the carboxy-terminal region of the wheat MKP, TMKP1. We found that this motif is well-conserved among other MKPs from monocots including Hordeum vulgare, Brachypodium distachyon and Aegilops taushii. Using co-immunoprecipitation assays, we provide evidence for interaction between TMKP1 and 14-3-3 proteins in wheat. Moreover, the phosphatase activity of TMKP1 is increased in a phospho-dependent manner by either Arabidopsis or yeast 14-3-3 isoforms. TMKP1 activation by 14-3-3 proteins is enhanced by Mn2+, whereas in the presence of Ca2+ ions, TMKP1 activation was limited to Arabidopsis 14-3-3φ (phi), an isoform harboring an EF-hand motif. Such findings strongly suggest that 14-3-3 proteins, in conjunction with specific divalent cations, may stimulate TMKP1 activity and point-out that 14-3-3 proteins bind and regulate the activity of a MKP in eukaryotes.