Exploitation of the Genetic Variability of Diverse Metric Traits of Durum Wheat (Triticum turgidum L. ssp. durum Desf.) Cultivars for Local Adaptation to Semi-Arid Regions of Algeria.

Abiotic stresses pose significant challenges to wheat farming, yet exploiting the genetic variability within germplasm collections offers an opportunity to effectively address these challenges. In this study, we investigated the genetic diversity of key agronomic traits among twenty durum wheat cultivars, with the intention to pinpoint those better suited to semi-arid conditions. Field trials were conducted at the ITGC-FDPS Institute, Setif, Algeria, during the winter season of 2021/22. A completely randomized design was used with three replicates. Statistical analyses revealed significant variation among the genotypes for most of the studied traits, with some cultivars exhibiting a superior performance in a stressful environment. Notably, traits like the number of grains per spike (NGS) and the grain yield (GY) displayed high genotypic coefficients of variation (CVg). Except for membrane thermostability (MT) and biological yield (BY), the majority of the assessed traits exhibited moderate-to-high heritability estimates. Genotypic and phenotypic correlation studies have confirmed the importance of many yield-related traits in the expression of GY. The harvest index (HI) underscored the highest genotypic direct effect on GY, followed closely by spike number (SN), serving as consistent pathways through which most of the measured traits indirectly influenced GY. The cluster analysis categorized the durum wheat cultivars into seven distinct clusters. The largest inter-cluster distance was observed between clusters G3 and G4 (D2 = 6145.86), reflecting maximum dissimilarity between the individuals of these clusters. Hybridizing divergent clusters may benefit future breeding programs aiming to develop potential durum wheat varieties through cross combinations. This study's findings contribute to sustainable agriculture efforts by facilitating the selection of genotypes with enhanced resilience and productivity, particularly for cultivation in challenging semi-arid regions.

Genetic mapping of deoxynivalenol and fusarium damaged kernel resistance in an adapted durum wheat population.

BACKGROUND: Fusarium head blight (FHB) infection results in Fusarium damaged kernels (FDK) and deoxynivalenol (DON) contamination that are downgrading factors at the Canadian elevators. Durum wheat (Triticum turgidum L. var. durum Desf.) is particularly susceptible to FHB and most of the adapted Canadian durum wheat cultivars are susceptible to moderately susceptible to this disease. However, the durum line DT696 is less susceptible to FHB than commercially grown cultivars. Little is known about genetic variation for durum wheat ability to resist FDK infection and DON accumulation. This study was undertaken to map genetic loci conferring resistance to DON and FDK resistance using a SNP high-density genetic map of a DT707/DT696 DH population and to identify SNP markers useful in marker-assisted breeding. One hundred twenty lines were grown in corn spawn inoculated nurseries near Morden, MB in 2015, 2016 and 2017 and the harvested seeds were evaluated for DON. The genetic map of the population was used in quantitative trait locus analysis performed with MapQTL.6® software. RESULTS: Four DON accumulation resistance QTL detected in two of the three years were identified on chromosomes 1 A, 5 A (2 loci) and 7 A and two FDK resistance QTL were identified on chromosomes 5 and 7 A in single environments. Although not declared significant due to marginal LOD values, the QTL for FDK on the 5 and 7 A were showing in other years suggesting their effects were real. DT696 contributed the favourable alleles for low DON and FDK on all the chromosomes. Although no resistance loci contributed by DT707, transgressive segregant lines were identified resulting in greater resistance than DT696. Breeder-friendly KASP markers were developed for two of the DON and FDK QTL detected on chromosomes 5 and 7 A. Markers flanking each QTL were physically mapped against the durum wheat reference sequence and candidate genes which might be involved in FDK and DON resistance were identified within the QTL intervals. CONCLUSIONS: The DH lines harboring the desired resistance QTL will serve as useful resources in breeding for FDK and DON resistance in durum wheat. Furthermore, breeder-friendly KASP markers developed during this study will be useful for the selection of durum wheat varieties with low FDK and DON levels in durum wheat breeding programs.

Corrigendum: Characterization of Triticum turgidum sspp. durum, turanicum and polonicum grown in Central Italy in relation to technological and nutritional aspects.

[This corrects the article DOI: 10.3389/fpls.2023.1269212.].

Salt elicitation to enhance phytochemicals in durum wheat seedlings.

BACKGROUND: Salt has been identified as an elicitor that can increase the accumulation of phytochemicals in seedlings during the germination process. However, the salinity level required to maximize the yield of phytochemicals, particularly phenolic compounds, needs further investigation for several plant species. To address this issue, we imposed increasing levels of salinity (NaCl solutions) on the sprouting substrate of Triticum durum (var. Platone) grains, at concentrations of 0, 50, 100, 150, 200, 250, and 300 mM (0_S, 50_S, 100_S, 150_S, 200_S, 250_S, and 300_S, respectively). RESULTS: The highest NaCl doses (250_S and 300_S) significantly impacted germination performance and were excluded from further analysis. The seedlings harvested at 8 days after sowing exhibited different growth stages depending on the salinity level: wheatgrass for 0_S, early wheatgrass for 50_S, intermediate between sprout and wheatgrass for 100_S, sprout for 150_S, and very early sprout for 200_S. Furthermore, salinity induced the concentration of phenolic compounds (PhCs) in the seedlings' tissues (i.e., both roots and shoots) in a salinity-dependent manner. The highest values were observed at 200_S, with an increase of 187% of the total investigated PhCs in comparison with 0_S, averaged over shoots and roots. In particular, in 200_S, the accumulation of phenolic acids was up to fourfold higher in roots, and that of flavonoids was up to twofold higher in shoots. CONCLUSION: Our findings suggest that the use of 200 mM NaCl applied to the sprouting substrate is excessive for producing edible sprouts but may be suitable for phytochemical extraction purposes. © 2023 Society of Chemical Industry.

Characterization of endophytic bacteria isolated from root nodules of lentil in intercropping with durum wheat.

Legumes improve soil fertility by interacting symbiotically with nitrogen-fixing rhizobia allocated in root nodules. Some bacterial endophytes can coexist with rhizobia in nodules and might help legumes by enhancing stress tolerance, producing hormones stimulating plant growth, and increasing plant nutrient intake. Twenty-six bacterial endophytes from Lens culinaris root nodules cultivated in intercropping with Triticum durum were identified and characterized molecularly and biochemically. Potential plant growth-promoting strains have been selected according to the indole acetic acid and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase production, and for their inorganic phosphate solubilization ability. The presence of genes associated to ACC deaminase and nitrogenase was evaluated. Six selected strains were grown with varying NaCl and polyethylene glycol concentrations to test their salt and osmotic stress tolerance. Priestia megaterium 11NL3 and Priestia aryabhattai 19NL1, resulted to be tolerant to salinity and osmotic stress, were tested on four genotypes of T. durum seeds in different stress conditions. The effect of strain inoculation on seed germination, vigor, and root-to-shoot ratio varied depending on the type of stress and on the durum wheat genotypes. For future research, it will be necessary to test the selected bacterial strains at different plant phenological stages and to clarify the mechanisms involved in the different outcomes of plant-microbe interactions.

Mechanisms of Antioxidant Resistance in Different Wheat Genotypes under Salt Stress and Hypoxia.

Various stressors lead to an increase in ROS and damage to plant tissues. Plants have a powerful antioxidant system (AOS), which allows them to neutralize excess ROS. We detected an intense fluorescent glow of ROS in the cells of the cap, meristem, and elongation zones in the roots of wheat Triticum aestivum (Orenburgskaya 22 variety) and Triticum durum (Zolotaya variety). An increase in ROS was accompanied by DNA breaks in the nuclei of wheat root cells, the release of cytochrome c from mitochondria into the cytoplasm, and the translocation of phosphatidylserine into the outer layer of the plasma membrane under salt stress and hypoxia. The different resistances of the two wheat varieties to different abiotic stresses were revealed. The soft wheat variety Orenburgskaya 22 showed high resistance to salt stress but sensitivity to hypoxia, and the durum wheat variety Zolotaya showed tolerance to hypoxia but high sensitivity to salt stress. Different activations of AOS components (GSH, MnSOD, Cu/ZnSOD, CAT, PX, GPX, and GST) were revealed in different wheat genotypes. The basis for the tolerance of the Zolotaya variety to hypoxia is the high content of glutathione (GSH) and the activation of glutathione-dependent enzymes. One of the mechanisms of high resistance to salt stress in the Orenburgskaya 22 variety is a decrease in the level of ROS as a result of the increased activity of the MnSOD and Cu/ZnSOD genes. Identifying the mechanisms of plant tolerance to abiotic stress is the most important task for improving breeding varieties of agricultural plants and increasing their yield.

Characterization of Triticum turgidum sspp. durum, turanicum, and polonicum grown in Central Italy in relation to technological and nutritional aspects.

Introduction: Wheat is a staple food, with the two most common species being Triticum aestivum and Triticum turgidum ssp. durum. Moreover, the latter, T. turgidum, includes other tetraploid subspecies, among which the sspp. turanicum (Khorasan wheat) and polonicum (Polish wheat), whose importance has increased in the last decades, representing alternative crops for marginal areas, in addition to being a source of genetic diversity. Methods: In this work, different accessions of these three subspecies of T. turgidum have been grown in 2 years in the same environment and have been characterized for technological properties and factors affecting nutritional quality, such as fiber amount and the content of micro- and macro-nutrients in grains, and for root morphological traits. Results: These analyses allowed the identification, in particular, of a Polish wheat accession showing better technological performances, a higher amount of positive micro- and macro-elements, and a lower amount of toxic cadmium. The modern variety Svevo and the Polish Pol2 showed the lowest and the highest shoot:root ratio, respectively. The high shoot:root ratio in Pol2 was mainly attributable to the decrease in root growth. Although Pol2 had a lower root biomass, its particular root morphology made it more efficient for nutrient uptake, as evident from the greater accumulation of micro- and macro-nutrients. Discussion: These results underline that it is not possible to draw general conclusions about the difference between primitive and modern wheats, but rather a case-by-case approach should be chosen.

Growth Stimulation of Durum Wheat and Common Buckwheat by Non-Thermal Atmospheric Pressure Plasma.

The grains of durum wheat (Triticum durum Desf.) and achenes of common buckwheat (Fagopyrum esculentum Moench) were tested after treatment with two sources of non-thermal atmospheric pressure plasma (DCSBD, MSDBD) with different treatment times (0, 3, 5, 10, 20, 30, and 40 s). The effect of these treatments was monitored with regard to the seed surface diagnostics (water contact angle-WCA, chemical changes by Fourier transform infrared spectroscopy-FTIR); twenty parameters associated with germination and initial seed growth were monitored. A study of the wettability confirmed a decrease in WCA values indicating an increase in surface energy and hydrophilicity depending on the type of seed, plasma source, and treatment time. Surface analysis by attenuated total reflectance FTIR (ATR-FTIR) showed no obvious changes in the chemical bonds on the surface of the plasma-treated seeds, which confirms the non-destructive effect of the plasma on the chemical composition of the seed shell. A multivariate analysis of the data showed many positive trends (not statistically significant) in germination and initial growth parameters. The repeated results for germination rate and root/shoot dry matter ratio indicate the tendency of plants to invest in underground organs. Durum wheat required longer treatment times with non-thermal plasma (10 s, 20 s) for germination and early growth, whereas buckwheat required shorter times (5 s, 10 s). The responses of durum wheat grains to the two non-thermal plasma sources used were equal. In contrast, the responses of buckwheat achenes were more favorable to MSDBD treatment than to DCSBD.

Phenotypic evolution in durum wheat (Triticum durum Desf.) based on SNPs, morphological traits, UPOV descriptors and kernel-related traits.

Durum wheat is a worldwide staple crop cultivated mainly in the Mediterranean basin. Progress in durum wheat breeding requires the exploitation of genetic variation among the gene pool enclosed in landraces, old cultivars and modern cultivars. The aim of this study was to provide a more comprehensive view of the genetic architecture evolution among 123 durum wheat accessions (41 landraces, 41 old cultivars and 41 modern cultivars), grown in replicated randomized complete block in two areas, Metaponto (Basilicata) and Foggia (Apulia), using the Illumina iSelect 15K wheat SNP array and 33 plant and kernel traits including the International Union for the Protection of new Varieties of Plants (UPOV) descriptors. Through DAPC and Bayesian population structure five groups were identified according to type of material data and reflecting the genetic basis and breeding strategies involved in their development. Phenotypic and genotypic coefficient of variation were low for kernel width (6.43%) and for grain protein content (1.03%). Highly significant differences between environments, genotypes and GEI (Genotype x Environment Interaction) were detected by mixed ANOVAs for agro-morphological-quality traits. Number of kernels per spike (h2 = 0.02) and grain protein content (h2 = 0.03) were not a heritability character and highly influenced by the environment. Nested ANOVAs revealed highly significant differences between DAPC clusters within environments for all traits except kernel roundness. Ten UPOV traits showed significant diversity for their frequencies in the two environments. By PCAmix multivariate analysis, plant height, heading time, spike length, weight of kernels per spike, thousand kernel weight, and the seed related traits had heavy weight on the differentiation of the groups, while UPOV traits discriminated moderately or to a little extent. The data collected in this study provide useful resources to facilitate management and use of wheat genetic diversity that has been lost due to selection in the last decades.

Influence of Plant Growth-Promoting Rhizobacteria on the Formation of Apoplastic Barriers and Uptake of Water and Potassium by Wheat Plants.

The formation of apoplastic barriers is important for controlling the uptake of water and ions by plants, thereby influencing plant growth. However, the effects of plant growth-promoting bacteria on the formation of apoplastic barriers, and the relationship between these effects and the ability of bacteria to influence the content of hormones in plants, have not been sufficiently studied. The content of cytokinins, auxins and potassium, characteristics of water relations, deposition of lignin and suberin and the formation of Casparian bands in the root endodermis of durum wheat (Triticum durum Desf.) plants were evaluated after the introduction of the cytokinin-producing bacterium Bacillus subtilis IB-22 or the auxin-producing bacterium Pseudomonas mandelii IB-Ki14 into their rhizosphere. The experiments were carried out in laboratory conditions in pots with agrochernozem at an optimal level of illumination and watering. Both strains increased shoot biomass, leaf area and chlorophyll content in leaves. Bacteria enhanced the formation of apoplastic barriers, which were most pronounced when plants were treated with P. mandelii IB-Ki14. At the same time, P. mandelii IB-Ki14 caused no decrease in the hydraulic conductivity, while inoculation with B. subtilis IB-22, increased hydraulic conductivity. Cell wall lignification reduced the potassium content in the roots, but did not affect its content in the shoots of plants inoculated with P. mandelii IB-Ki14. Inoculation with B. subtilis IB-22 did not change the potassium content in the roots, but increased it in the shoots.

Rapid molecular assay for the evaluation of clove essential oil antifungal activity against wheat common bunt.

Common bunt of durum wheat (DW), Triticum turgidum L. ssp. durum (Desf.) Husn., is caused by the two closely related fungal species belonging to Tilletia genus (Tilletiales, Exobasidiomycetes, Ustilaginomycotina): Tilletia laevis Kühn (syn. T. foetida (Wallr.) Liro.) and T. caries (DC) Tul. (syn. T. tritici (Bjerk.) G. Winter). This is one of the most devastating diseases in wheat growing areas worldwide, causing considerable yield loss and reduction of wheat grains and flour quality. For these reasons, a fast, specific, sensitive, and cost-effective method for an early diagnosis of common bunt in wheat seedlings is urgent. Several molecular and serological methods were developed for diagnosis of common bunt in wheat seedlings but at late phenological stages (inflorescence) or based on conventional PCR amplification, with low sensitivity. In this study, a TaqMan Real Time PCR-based assay was developed for rapid diagnosis and quantification of T. laevis in young wheat seedlings, before tillering stage. This method, along with phenotypic analysis, was used to study conditions favoring pathogen infection and to evaluate the effectiveness of clove oil-based seed dressing in controlling the disease. The overall results showed that: i) the Real Time PCR assay was able to quantify T. laevis in young wheat seedlings after seed dressing by clove oil in different formulations, greatly reducing times of analysis. It showed high sensitivity, detecting up to 10 fg of pathogen DNA, specificity and robustness, allowing to directly analyze crude plant extracts and representing a useful tool to speed up the tests of genetic breeding for disease resistance; ii) temperature was a critical point for disease development when using wheat seeds contaminated by T. laevis spores; iii) at least one of the clove oil-based formulations tested was able to efficiently control wheat common bunt, suggesting that clove oil dressing could represent a promising tool for managing the disease, especially in sustainable farming.

Genomics-driven breeding for local adaptation of durum wheat is enhanced by farmers' traditional knowledge.

In the smallholder, low-input farming systems widespread in sub-Saharan Africa, farmers select and propagate crop varieties based on their traditional knowledge and experience. A data-driven integration of their knowledge into breeding pipelines may support the sustainable intensification of local farming. Here, we combine genomics with participatory research to tap into traditional knowledge in smallholder farming systems, using durum wheat (Triticum durum Desf.) in Ethiopia as a case study. We developed and genotyped a large multiparental population, called the Ethiopian NAM (EtNAM), that recombines an elite international breeding line with Ethiopian traditional varieties maintained by local farmers. A total of 1,200 EtNAM lines were evaluated for agronomic performance and farmers' appreciation in three locations in Ethiopia, finding that women and men farmers could skillfully identify the worth of wheat genotypes and their potential for local adaptation. We then trained a genomic selection (GS) model using farmer appreciation scores and found that its prediction accuracy over grain yield (GY) was higher than that of a benchmark GS model trained on GY. Finally, we used forward genetics approaches to identify marker-trait associations for agronomic traits and farmer appreciation scores. We produced genetic maps for individual EtNAM families and used them to support the characterization of genomic loci of breeding relevance with pleiotropic effects on phenology, yield, and farmer preference. Our data show that farmers' traditional knowledge can be integrated in genomics-driven breeding to support the selection of best allelic combinations for local adaptation.

Recent advances on genome-wide association studies (GWAS) and genomic selection (GS); prospects for Fusarium head blight research in Durum wheat.

PURPOSE: Wheat is an important cereal crop that is cultivated in different parts of the world. The biotic stresses are the major concerns in wheat-growing nations and are responsible for production loss globally. The change in climate dynamics makes the pathogen more virulent in foothills and tropical regions. There is growing concern about FHB in major wheat-growing nations, and until now, there has been no known potential source of resistance identified in wheat germplasm. The plant pathogen interaction activates the cascade of pathways, genes, TFs, and resistance genes. Pathogenesis-related genes' role in disease resistance is functionally validated in different plant systems. Similarly, Genomewide association Studies (GWAS) and Genomic selection (GS) are promising tools and have led to the discovery of resistance genes, genomic regions, and novel markers. Fusarium graminearum produces deoxynivalenol (DON) mycotoxins in wheat kernels, affecting wheat productivity globally. Modern technology now allows for detecting and managing DON toxin to reduce the risk to humans and animals. This review offers a comprehensive overview of the roles played by GWAS and Genomic selection (GS) in the identification of new genes, genetic variants, molecular markers and DON toxin management strategies. METHODS: The review offers a comprehensive and in-depth analysis of the function of Fusarium graminearum virulence factors in Durum wheat. The role of GWAS and GS for Fusarium Head Blight (FHB) resistance has been well described. This paper provides a comprehensive description of the various statistical models that are used in GWAS and GS. In this review, we look at how different detection methods have been used to analyze and manage DON toxin exposure. RESULTS: This review highlights the role of virulent genes in Fusarium disease establishment. The role of genome-based selection offers the identification of novel QTLs in resistant wheat germplasm. The role of GWAS and GS selection has minimized the use of population development through breeding technology. Here, we also emphasized the function of recent technological developments in minimizing the impact of DON toxins and their implications for food safety.

The Effects of Local Weed Species on Arbuscular Mycorrhizal Fungal Communities in an Organic Winter Wheat (Triticum durum L.) Field in Lebanon.

We examined the potential effects of weed species on the arbuscular mycorrhizal fungi (AMF) in an organic winter wheat (Triticum durum) field in Lebanon. In this agroecosystem, the field and its surroundings were covered with spontaneous vegetation corresponding to local weeds. The coexistence between wheat and weeds did not modify AM fungal community diversity and colonization in T. durum but changed their composition. We evidenced 22 operational taxonomic units (OTUs) specifically shared between wheat associated with weeds (Tdw) and weeds, regardless of their localization and 12 OTUs with an abundance of variation between wheat without neighboring weeds (Td) and Tdw. The number of AM propagules and total C and N contents were higher in soil covered with wheat associated with weeds (TdWsoil) vs. wheat without neighboring weeds (Tdsoil). In greenhouse experiments, the shoot biomass and root mycorrhizal intensity of Medicago sativa, used as a trap plant, were higher using TdWsoil vs. Tdsoil as the inoculum. Positive correlations were observed between soil AM propagule numbers and M. sativa shoot biomass, on the one hand and M. sativa mycorrhizal intensity, on the other hand. Weeds seemed to exert significant effects on root AM fungal composition in T. durum and these effects may contribute to enhanced AMF development in the field.

Differentiated Weed-Suppressive Ability of Modern and Old Durum Wheat Cultivars after Long-Term Cultivation under Semi-Arid Climate.

Durum wheat (Triticum turgidum spp. durum) is one of the most important grain crops cultivated across the Mediterranean Basin, where a strong return to local landraces cultivation is occurring to meet the market demand for high-quality food and low-input cropping systems. A characterisation of the long-term effect (10 years) of durum wheat landraces and modern cultivars on the potential and real weed flora is still lacking. Hence, a multilocation trial over 10 farms in Central-Eastern Sicily was carried out to investigate the repeated cultivation of several old landraces (OLD) and modern cultivars (MOD) on the abundance and diversity of weed flora. Overall, OLD was associated with a 47% reduction of the soil seedbank size and to -64% of the aboveground weed biomass compared to MOD. In addition, diversity indices pointed out a high similarity between MOD and OLD farm groups for the soil seedbank, while a lower diversity was found in OLD for aboveground weed communities. From the principal component analysis emerged that the species compositions of MOD and OLD were quite separated for both soil seedbank and real flora, with the latter showing few specific associations with major weeds. These findings demonstrated the indirect effect of durum wheat landraces in sustainably reducing weed pressure without the adoption of chemical weed control.

Minimal impacts on the wheat microbiome when Trichoderma gamsii T6085 is applied as a biocontrol agent to manage fusarium head blight disease.

Fusarium head blight (FHB) is a major fungal disease that causes severe yield and quality loss in wheat. Biological control can be integrated with other management strategies to control FHB. For this purpose, Trichoderma gamsii strain T6085 is a potential biocontrol agent to limit the infection of F. graminearum and F. culmorum in wheat. However, the possible impacts of T. gamsii T6085 on the broader microbiome associated with the wheat plant are not currently understood. Therefore, we identified bacteria and fungi associated with different wheat tissues, including assessment of their relative abundances and dynamics in response to the application of T6085 and over time, using amplicon sequencing. Residues of the prior year's wheat crop and the current year's wheat spikes were collected at multiple time points, and kernel samples were collected at harvest. DNA was extracted from the collected wheat tissues, and amplicon sequencing was performed to profile microbiomes using 16S v4 rRNA amplicons for bacteria and ITS2 amplicons for fungi. Quantitative PCR was performed to evaluate the absolute abundances of F. graminearum and T. gamsii in different wheat tissues. Disease progression was tracked visually during the growing season, revealing that FHB severity and incidence were significantly reduced when T6085 was applied to wheat spikes at anthesis. However, treatment with T6085 did not lessen the F. graminearum abundance in wheat spikes or kernels. There were substantial changes in F. graminearum abundance over time; in crop residue, pathogen abundance was highest at the initial time point and declined over time, while in wheat spikes, pathogen abundance increased significantly over time. The predominant bacterial taxa in wheat spikes and kernels were Pseudomonas, Enterobacter, and Pantoea, while Alternaria and Fusarium were the dominant fungal groups. Although the microbiome structure changed substantially over time, there were no community-scale rearrangements due to the T6085 treatment. The work suggests several other taxa that could be explored as potential biocontrol agents to integrate with T6085 treatment. However, the timing and the type of T6085 application need to be improved to give more advantages for T6085 to colonize and reduce the F. graminearum inoculum in the field.

A Metagenomic and Gene Expression Analysis in Wheat (T. durum) and Maize (Z. mays) Biofertilized with PGPM and Biochar.

Commodity crops, such as wheat and maize, are extremely dependent on chemical fertilizers, a practice contributing greatly to the increase in the contaminants in soil and water. Promising solutions are biofertilizers, i.e., microbial biostimulants that when supplemented with soil stimulate plant growth and production. Moreover, the biofertilizers can be fortified when (i) provided as multifunctional consortia and (ii) combined with biochar with a high cargo capacity. The aim of this work was to determine the molecular effects on the soil microbiome of different biofertilizers and delivery systems, highlight their physiological effects and merge the data with statistical analyses. The measurements of the physiological parameters (i.e., shoot and root biomass), transcriptomic response of genes involved in essential pathways, and characterization of the rhizosphere population were analyzed. The results demonstrated that wheat and maize supplemented with different combinations of selected microbial consortia and biochar have a positive effect on plant growth in terms of shoot and root biomass; the treatments also had a beneficial influence on the biodiversity of the indigenous rhizo-microbial community, reinforcing the connection between microbes and plants without further spreading contaminants. There was also evidence at the transcriptional level of crosstalk between microbiota and plants.

Pseudomonas and Curtobacterium Strains from Olive Rhizosphere Characterized and Evaluated for Plant Growth Promoting Traits.

Plant growth promoting (PGP) bacteria are known to enhance plant growth and protect them from environmental stresses through different pathways. The rhizosphere of perennial plants, including olive, may represent a relevant reservoir of PGP bacteria. Here, seven bacterial strains isolated from olive rhizosphere have been characterized taxonomically by 16S sequencing and biochemically, to evaluate their PGP potential. Most strains were identified as Pseudomonas or Bacillus spp., while the most promising ones belonged to genera Pseudomonas and Curtobacterium. Those strains have been tested for their capacity to grow under osmotic or salinity stress and to improve the germination and early development of Triticum durum subjected or not to those stresses. The selected strains had the ability to grow under severe stress, and a positive effect has been observed in non-stressed seedlings inoculated with one of the Pseudomonas strains, which showed promising characteristics that should be further evaluated. The biochemical and taxonomical characterization of bacterial strains isolated from different niches and the evaluation of their interaction with plants under varying conditions will help to increase our knowledge on PGP microorganisms and their use in agriculture.

Drought Stress Pre-Treatment Triggers Thermotolerance Acquisition in Durum Wheat.

Durum wheat is strongly affected by climatic constraints such as high temperatures and drought, which frequently lead to yield reduction. Damages due to high temperatures are related to plant thermotolerance, a trait determined by two components: basal and acquired thermotolerance. In this study, the effect of drought and heat stress imposed singularly or sequentially was investigated in ten durum wheat cultivars (cvs) at the physiological and molecular level. The traits analyzed were cell membrane stability, relative water content, proline content, and expression level of several genes for heat shock proteins (HSPs). Our results indicate that drought priming can induce the acquisition of thermotolerance in most cultivars already classified as able to acquire thermotolerance by heat pre-treatment. Proline accumulation was correlated to cell membrane stability, meaning that the most thermotolerant cvs were able to accumulate higher levels of proline. Acquired thermotolerance is also due to the activation of HSP gene expression; similarly, pre-treatment with water stress was able to activate HSPs expression. The results reported indicate that water stress plays an important role in inducing thermotolerance, comparable to mild heat stress pre-treatment. This is the first report on the effect of drought stress on the acquisition of thermotolerance.

Effects of Cadmium on Root Morpho-Physiology of Durum Wheat.

Durum wheat [Triticum turgidum L. subsp. durum (Desf.) Husn.] can accumulate a high level of Cd in grains with a significant variability depending on cultivars. Understanding how this toxic element is distributed in cereal tissues and grains is essential to improve the nutritional quality of cereal-based products. The main objective of this work was to investigate roots of durum wheat plants (cv. Iride) exposed to different Cd concentrations (0.5 and 5.0 µM) to identify the mechanisms involved in Cd management. Results showed that the root morphology was altered by Cd treatment both at macroscopic (increased number of tips and primary root length) and ultrastructural levels (cell membrane system damaged, cell walls thickened and enriched in suberin). On the other side, Cd was localized in vesicles and in cell walls, and the metal colocalized with the phytosiderophore nicotianamine (NA). Overall, data suggest that Cd is chelated by NA and then compartmentalized, through vesicular trafficking, in the root thickened walls reducing Cd translocation to the aerial organs of the plant.