Durum Wheat Landraces Research Articles

From landraces to haplotypes, exploiting a genomic and phenomic approach to identify heat tolerant genotypes within durum wheat landraces

Dry and hot climates severely impact wheat yields, necessitating the development of innovative solutions to accelerate the breeding and selection of more adaptable durum wheat genotypes. The aim of this study was to identify new wheat ecotypes that can bridge the gap between commercial varieties and adaptability to ongoing climate change. In this study, advanced genomic and phenomic techniques were combined to characterize a set of durum wheat landraces derived from single seed descent (SSD). This approach enabled the identification of novel variability in the TdHsp26-A1 and -B1 genes. As a result, 38 durum wheat genotypes were analyzed using targeted enrichment PCR, leading to the identification of 17 novel haplotype combinations with SNPs in the TdHsp26 genes. The response of these SSD haplotypes to heat stress was characterized at both the seedling and tillering growth stages. Phenotypic analysis of contrasting genotypes led to the selection of two distinct genotypes: SSD69 and SSD397. During heat stress, SSD69 exhibited altered accumulation of H2O2 and MDA content under both growth conditions, providing new insights into the oxidative response to heat stress. Additionally, this work identifies phenotypic traits that are suitable for detecting differences between variants. The geographic distribution of the different alleles aligned with the spread of durum wheat from its center of origin.

Mapping and Candidate Gene Analysis of an All-Stage Stem Rust Resistance Gene in Durum Wheat Landrace PI 94701.

Puccinia graminis f. sp. tritici (Pgt), the causal agent of wheat stem rust, poses a significant threat to global wheat production. Genetic resistance offers a cost-effective and sustainable solution. The durum wheat landrace PI 94701 was previously hypothesized to carry two stem rust resistance (Sr) genes, but their chromosomal locations were unknown. In this study, we mapped and characterized an all-stage Sr gene in PI 94701, temporarily designated as SrPI94701. In seedling tests, SrPI94701 was effective against all six Pgt races tested. Using a large segregating population, we mapped SrPI94701 on chromosome arm 5BL within a 0.17-cM region flanked by markers pku69124 and pku69228, corresponding to 1.04 and 2.15 Mb genomic regions in the Svevo and Chinese Spring reference genomes. Within the candidate region, eight genes exhibited differential expression between the Pgt-inoculated resistant and susceptible plants. Among them, two nucleotide-binding leucine-rich repeat (NLR) genes, TraesCS5B03G1334700 and TraesCS5B03G1335100, showed high polymorphism between the parental lines and were upregulated in Pgt-inoculated resistant plants. However, the flanking and completely linked markers developed in this study could not accurately predict the presence of SrPI94701 in a survey of 104 wheat accessions. SrPI94701 is a promising resource for enhancing stem rust resistance in wheat breeding programs.

Lipids and Fatty Acid Composition Reveal Differences between Durum Wheat Landraces and Modern Cultivars.

Durum wheat (Triticum turgidum L. ssp. durum) landraces, traditional local varieties representing an intermediate stage in domestication, are gaining attention due to their high genetic variability and performance in challenging environments. While major kernel metabolites have been examined, limited research has been conducted on minor bioactive components like lipids, despite their nutritional benefits. To address this, we analyzed twenty-two tetraploid accessions, comprising modern elite cultivars and landraces, to (i) verify if the selection process for yield-related traits carried out during the Green Revolution has influenced lipid amount and composition; (ii) uncover the extent of lipid compositional variability, giving evidence that lipid fingerprinting effectively identifies evolutionary signatures; and (iii) identify genotypes interesting for breeding programs to improve yield and nutrition. Interestingly, total fat did not correlate with kernel weight, indicating lipid composition as a promising trait for selection. Tri- and di-acylglycerol were the major lipid components along with free fatty acids, and their relative content varied significantly among genotypes. In particular, landraces belonging to T. turanicum and carthlicum ecotypes differed significantly in total lipid and fatty acid profiles. Our findings provide evidence that landraces can be a genetically relevant source of lipid variability, with potential to be exploited for improving wheat nutritional quality.

Microbiological survey and physicochemical analysis of Moroccan durum, soft and red wheat landraces

Morocco possesses a significant genetic diversity of wheat cultivars in the form of landraces conserved by local farmers in several regions. This study aimed to evaluate the microbiological quality of refined flour and bran derived from 75 samples of Moroccan durum, soft, and red wheat landraces and to estimate their microbiological stability for controlling and preventing undesirable microbial proliferation. Various microbial and physicochemical parameters were evaluated according to ISO and AOAC standards, and results were interpreted based on Codex Alimentarius Commission regulation. Compliance of the analyzed refined flour and bran samples with current regulatory limits and satisfactory microbiological quality were observed. The phenotypic characterization revealed the identification of 16 yeast species belonging to the genera Trichosporon, Candida, Cryptococcus, Rhodotorula, and Saccharomyces, which had not been previously explored. Furthermore, the biodiversity of lactic acid bacteria is notably characterized by the predominance of Pediococcus acidilactici and Lactobacillus plantarum species. The analysis of moisture content and water activity exhibited values falling below the maximum limits defined by international standards, demonstrating the effectiveness of the implemented processing and storage practices. The neutral pH recorded confirms the absence of excessive proliferation of the assessed microbial contaminants. The abundant availability of carbohydrates, lipids, proteins, and minerals creates a favorable non-competitive environment essential for maintaining their functional stability in the analyzed samples. These findings hold significant implications for the agricultural and food industries, providing insights into preserving indigenous wheat varieties and producing safe wheat-based products with high nutritional quality.

Molecular screening of registered durum wheat (Triticum durum) varieties and landraces to common bunt disease in Türkiye

Common bunt caused by the basidiomycetes fungi Tilletia caries and Tilletia foetida is significant wheat disease, particularly following rust (Puccinia spp.) diseases. Seed treatment with fungicides has traditionally been the primary method for disease control. However recently its effectiveness has reduced. Growing resistant plant materials are therefore preferred to management of common bunt disease. In this regard, the current study was conducted to detect common bunt resistance genes (Bt8, Bt10, and Bt11) in a total of 61 registered durum wheat varieties and landraces using molecular techniques. In PCR assay, these plant materials were screened with SSR marker Xgwm114 to identify whether they carried any of the Bt resistance genes. According to the molecular results, most of the tested varieties and landraces were found in the Bt8 resistance gene (15 registered varieties and 5 landraces). Additionally, the results showed that none of the tested varieties and landraces had gene combinations. To sum up, this is the first molecular study to identify common bunt resistance genes in durum wheat varieties and landraces in Türkiye. Furthermore, these findings can be used in breeding programs to management with common bunt disease.

Nutrient and anti-nutrient composition of durum, soft and red wheat landraces: Implications for nutrition and mineral bioavailability

Morocco possesses a significant genetic diversity of wheat cultivars in the form of landraces conserved by local farmers in several regions. This study aimed to investigate the nutritional and antinutritional composition of 75 flour samples of durum, soft, and red wheat landraces cultivated in Morocco in order to determine their nutritional value. The analysis concerned the quantification of total carbohydrates, starch, lipid, fatty acids, protein, amino acids, minerals, and dietary fibers using AOAC standards, and phytic acid and polyphenols using spectrophotometric assays. The antiradical activity was evaluated using a DPPH assay based on the chelating properties of the free radicals against minerals. The bioavailability of minerals was also estimated using molar ratios. On a dry weight basis, soft wheat flour contains higher amounts of carbohydrates (80.307 ± 0.634 g/100 g), while durum (14.007 ± 0.569 g/100 g) and red (16.452 ± 0.141 g/100 g) wheat flours contain more proteins, predominantly represented by glutamic acid and leucine. The mineral analysis revealed the abundance of iron, zinc, and calcium in soft, red, and durum wheat flours. Concerning lipids, the flour samples showed relatively low concentrations with a distinct predominance of oleic, linoleic, and palmitic acids. The quantification of antinutrients revealed the richness of red wheat flour in dietary fibers (1.763 ± 0.103 g/100 g), total polyphenols (301.609 ± 0.169 μg GAE/g), and flavonoids (80.091 ± 0.121 μg QE/g), while durum and soft wheat flours contain more tannins (60.138 ± 0.751 μg CE/g) and phytic acid (9.182 ± 0.391 mg/g), respectively. The phenolic extract derived from red wheat flour demonstrated significant antiradical activity against DPPH, with an IC50 value of 121.683 ± 0.229 μg/mL. The calculated (PA:Fe), (PA:Zn), and (PA:Ca) were below the critical values, indicating a low bioavailability of iron, zinc, and calcium in the wheat flour samples. The results showed significant differences (p < 0.05) in the amounts of nutrients and antinutrients among the studied wheat cultivars, leading to variations in the bioavailability of their mineral contents. These quantitative differences could be used to more accurately guide dietary recommendations and develop focused strategies for optimizing the bioavailability of minerals in wheat flour-based products.

Phenotypic variability for early drought stress resistance in tetraploid wheat accessions correlates with terminal drought performance

AbstractDurum wheat (Triticum durum Desf.) is a fundamental staple food for the countries of the Mediterranean basin. Climate change is predicted to cause a trend of increasing drought severity in this region in the near future, necessitating the improvement of durum wheat's resilience to drought stress. Using polyethylene glycol to simulate water scarcity, early vigour parameters in germinating seeds are quickly, easily and affordably assessed. Many screenings, however, only consider the seedling stage; consequently, genotypes identified as promising for cultivation in drought scenarios, may not show such features if drought appears in later phenological phases, as happens in Mediterranean climatic areas, generally prone to terminal drought. The correlation between drought stress resistance during the seedling stage (early vigour) and later stages in the life cycle is elusive due to the lack of scientific efforts. Here we used polyethylene glycol screening to classify fifty‐five tetraploid wheat accessions into three clusters (susceptible, medium resistant and highly resistant to drought), based on morpho‐physiological traits. These accessions included durum wheat cultivars and landraces, as well as ancestors like durum emmer wheat and wild emmer wheat. The results of the screenings were combined with subsequent pot experiments using nine randomly selected accessions, imposing terminal drought, and evaluating their performance. Principal component analysis was performed on data for net photosynthesis, stomatal conductance, transpiration and grain yield. Notably, the genotypes that performed best in the pot experiments were also those that performed well in the screening. Highly resistant candidates had in fact higher physiological and performance parameters than susceptible candidates. In summary, polyethylene glycol screening of germinating seeds resulted to be suitable to predictively evaluate drought resistance in tetraploid wheat accessions under terminal drought conditions, typical of Mediterranean climate zones. The reported data, thus evidence of how this inexpensive and simple method might be efficiently applied for large‐scale phenotyping.

Evaluation of the industrial quality of Moroccan durum, soft and red wheat landraces

Wheat landraces are a treasure trove of genetic resources in Morocco and are very appreciated by farmers for their excellent grain quality. Therefore, an evaluation of the industrial quality of wheat landraces is necessary. The objective of this study was to determine the physico-chemical properties of three species of Moroccan wheat landraces (durum, soft and red) in order to evaluate the technological quality and to deduce the industrial value. For this purpose, seventy-five samples of the three species were collected from Moroccan farmers during the 2019-2020 agricultural season. The analyses concerned dimensional and physico-chemical characteristics, such as the 1000-kernel weight, specific weight, moisture, total ash and carotenoid pigment content. The results of the dimensional characterization showed that the three species have distinct physical structures. The agro-morphological characterization revealed exceptional values for red wheat. The moisture content recorded was lower than the maximum limit set by international standards (14.5%). The determination of the total ash content indicates that red wheat (3.25±0.64%) is ashier than durum (2.23±0.42%) and soft wheat (2.11±0.68%). The carotenoid pigment content recorded in red wheat (9.11±1.60 ppm) exceeds that of durum wheat (7.54±1.21 ppm), while soft wheat is low in carotenoid pigment (1.19±1.13 ppm). The results revealed that the three examined species meet the quality requirements of the semolina and the milling industries. This finding will promote national wheat production to reach international standards.

Evaluation of the durum wheat landrace genetic diversity using agro analysis and its benefit for human health

Ancient wheat and landraces (traditional varieties) are fascinating to the consideration of scientists who are re-evaluating the healthy and dietary properties attributed to them by popular tradition. Wheat (Triticum durum) is one of the most significant crops that is grown all over the world. In the present study, 19 landraces were analyzed for genetic diversity through morphological and SDS-PAGE analysis. The highest coefficient of variance (18.91%) was found for spike length, and the lowest for days to maturity (1.51%). The genotype Malakand and Dolram produced a maximum number of seeds (42 and 46 seeds per plant), and the genotypes Dogai and Rasool Banda were found to be the tallest (73 and 71 cm, respectively). The genotype Kamar Kotki was found to mature early (165 days) while Doagi was found to mature late (171 days). Spike length was found to be positively correlated with plant height, leaf width, and leaf length. Leaf width was significant with spike length and the internode distance. The cluster analysis divided all the genotypes into six sub-clusters where the Asban and the Shekhan were placed at the extreme of the dendrogram. Based on the total seed storage proteins analysis, 18 (85.71%) bands were polymorphic while 14.28% bands were found to be monomorphic. Using Ward’s methods, all the genotypes were divided into two main lineages at 25% Euclidian distance and five sub-clusters at 75% distance. Our findings have significance for understanding the variations and relationships between various durum wheat genotypes and could serve as a basis for local elite durum germplasm that has been regionally adapted.

Genetic diversity, linkage disequilibrium, and population structure of tetraploid wheat landraces originating from Europe and Asia

BackgroundDurum wheat is one of the most important crops, especially in the Mediterranean region. Insight into the genetic diversity of germplasm can improve the breeding program management in various traits. This study was done using single nucleotide polymorphisms (SNP) markers to characterize the genetic distinctiveness and differentiation of tetraploid wheat landraces collected from nine European and Asian countries. A sum of 23,334 polymorphic SNPs was detected in 126 tetraploid wheat landraces in relation to the reference genome.ResultsThe number of identified SNPs was 11,613 and 11,721 in A and B genomes, respectively. The highest and lowest diversity was on 6B and 6 A chromosomes, respectively. Structure analysis classified the landraces into two distinct subpopulations (K = 2). Evaluating the principal coordinate analysis (PCoA) and weighted pair-group method using arithmetic averages (WPGMA) clustering results demonstrated that landraces (99.2%) are categorized into one of the two chief subpopulations. Therefore, the grouping pattern did not clearly show the presence of a clear pattern of relationships between genetic diversity and their geographical derivation. Part of this result could be due to the historical exchange between different germplasms. Although the result did not separate landraces based on their region of origin, the landraces collected from Iran were classified into the same group and cluster. Analysis of molecular variance (AMOVA) also confirmed the results of population structure. Finally, Durum wheat landraces in some countries, including Turkey, Russia, Ukraine, and Afghanistan, were highly diverse, while others, including Iran and China, were low-diversity.ConclusionThe recent study concluded that the 126 tetraploid wheat genotypes and their GBS-SNP markers are very appropriate for quantitative trait loci (QTLs) mapping and genome-wide association studies (GWAS). The core collection comprises two distinct subpopulations. Subpopulation II genotypes are the most diverse genotypes, and if they possess desired traits, they may be used in future breeding programs. The degree of diversity in the landraces of countries can provide the ground for the improvement of new cultivars with international cooperation. linkage disequilibrium (LD) hotspot distribution across the genome was investigated, which provides useful information about the genomic regions that contain intriguing genes.

Valorizing Traditional Greek Wheat Varieties: Phylogenetic Profile and Biochemical Analysis of Their Nutritional Value

Research has highlighted the nutritional benefits of ancient grains, especially emmer (Triticum turgidum ssp. dicoccum) and einkorn (Triticum monococcum), compared to modern varieties of common and durum wheat, focusing on their higher levels of antioxidants and phytochemicals. In this study, grains from old Greek landraces of einkorn, emmer, durum and common wheat were compared to modern wheat cultivars, as well as barley, oats and rye grains, to investigate their unique genetic profile and nutritional properties. Genotyping of Triticum species was performed using SSR markers, which allowed differentiation up to cultivar level. Nutritional factors like the total content of bound and free polyphenols, flavonoids, antioxidant activity and fatty acid profile were assessed. The results showed that emmer and einkorn had the highest total polyphenol, flavonoid and mono-unsaturated fatty acids content, as well as higher antioxidant activity than common and durum wheat. Local landraces of common and durum wheat also exhibited higher values than commercial cultivars. The results of this study demonstrate the high nutritional value of ancient wheat varieties. Many of these cultivars have been put aside by more productive, yet with lower qualitative characteristics, commercial cultivars, underlining the importance of maintaining sustainable agricultural practices to ensure their continued cultivation.

Genome-wide association analysis of tan spot disease resistance in durum wheat accessions from Tunisia.

Background: Tunisia harbors a rich collection of unexploited durum wheat landraces (Triticum durum ssp. durum) that have been gradually replaced by elite cultivars since the 1970s. These landraces represent an important potential source for broadening the genetic background of elite durum wheat cultivars and for the introgression of novel genes for key traits, including disease resistance, into these cultivars. Methods: In this study, single nucleotide polymorphism (SNP) markers were used to investigate the genetic diversity and population structure of a core collection of 235 durum wheat accessions consisting mainly of landraces. The high phenotypic and genetic diversity of the fungal pathogen Pyrenophora tritici-repentis (cause of tan spot disease of wheat) in Tunisia allowed the assessment of the accessions for tan spot resistance at the adult plant stage under field conditions over three cropping seasons. A genome-wide association study (GWAS) was performed using a 90k SNP array. Results: Bayesian population structure analysis with 9191 polymorphic SNP markers classified the accessions into two groups, where groups 1 and 2 included 49.79% and 31.49% of the accessions, respectively, while the remaining 18.72% were admixtures. Principal coordinate analysis, the unweighted pair group method with arithmetic mean and the neighbor-joining method clustered the accessions into three to five groups. Analysis of molecular variance indicated that 76% of the genetic variation was among individuals and 23% was between individuals. Genome-wide association analyses identified 26 SNPs associated with tan spot resistance and explained between 8.1% to 20.2% of the phenotypic variation. The SNPs were located on chromosomes 1B (1 SNP), 2B (4 SNPs), 3A (2 SNPs), 3B (2 SNPs), 4A (2 SNPs), 4B (1 SNP), 5A (2 SNPs), 5B (4 SNPs), 6A (5 SNPs), 6B (2 SNPs), and 7B (1 SNP). Four markers, one on each of chromosomes 1B, and 5A, and two on 5B, coincided with previously reported SNPs for tan spot resistance, while the remaining SNPs were either novel markers or closely related to previously reported SNPs. Eight durum wheat accessions were identified as possible novel sources of tan spot resistance that could be introgressed into elite cultivars. Conclusion: The results highlighted the significance of chromosomes 2B, 5B, and 6A as genomic regions associated with tan spot resistance.

Unlocking the genetic potential of Ethiopian durum wheat landraces with high protein quality: Sources to be used in future breeding for pasta production

AbstractThe content and composition of the grain storage proteins in wheat determine to a high extent its end‐use quality for pasta and bread production. This study aimed to evaluate the content and composition of the grain storage proteins in Ethiopian landraces and cultivars to contribute to future breeding toward improved pasta quality. Thus, 116 landraces and 34 cultivars originating from Ethiopia were grown in three locations, and the protein parameters were analyzed using size exclusion‐high performance liquid chromatography (SE‐HPLC). A considerable variation in the amount of the analyzed protein parameters was found. The genotypes, environments, and interactions contributed significantly (p &lt; 0.001) to the differences obtained. The broad‐sense heritability was high (0.75–0.98) for all protein parameters except for unextractable small monomeric protein (uSMP). Using the principal component analysis (PCA) to evaluate the impact of protein parameters and using either PCA or unweighted pair group method with arithmetic mean (UPGMA) to assess the impact of the genetic composition, the cultivar group was found to form a separate cluster. This indicates that durum wheat improvement in Ethiopia has relied on exotic materials, which might result from a narrow genetic base. Unlike most landraces, most released cultivars showed a high and stable gluten strength across environments. Two landraces, G057 and G107, were found genetically distinct from the released cultivars but with high and stable gluten. The two selected landraces might be of extremely high value for future use in durum wheat breeding programs, as they might be adapted to wide‐ranging Ethiopian growing conditions, they might carry genes of relevance to withstand abiotic and biotic stresses, and they seem to hold essential protein properties, which might result in high‐quality grains for industrial processes.

Whole-genome resequencing-based characterization of a durum wheat landrace showing similarity to 'Senatore Cappelli'.

Durum wheat (Triticum turgidum spp. durum) is a major cereal adopted since antiquity to feed humans. Due to its use, dating back several millennia, this species features a wide genetic diversity and landraces are considered important repositories of gene pools which constitute invaluable tools for breeders. The aim of this work is to provide a first characterization of a wheat landrace, referred to as 'TB2018', that was collected in the Apulia region (Southern Italy). 'TB2018' revealed, through visual inspection, characters reminiscent of the traditional variety 'Senatore Cappelli', while exhibiting a distinctive trait, i.e., reduced stature. Indeed, the comparison with a set of Italian durum wheat cultivars conducted in this study, in which 24 CPVO plant descriptors were adopted, placed the 'TB2018' landrace in proximity to the 'Senatore Cappelli' cultivar. In addition, the close similarity between the two genotypes was confirmed by the analysis of the seed protein pattern. A relative reduction was detected for 'TB2018' root elongation in the early stages of plant growth. The 'TB2018' genome sequence, obtained through low-coverage resequencing and comparison to the reference 'Svevo' cultivar is also reported in this study, followed by a genome-wide comparison against 259 durum wheat accessions that placed 'TB2018' close to the 'Cappelli' reference. Hundreds of genes putatively affected by variants that possess Gene Ontology descriptors were detected, among which some were shown to be putatively linked to the morphological traits that distinguish 'TB2018' from 'Senatore Cappelli', Overall, this study poses the basis for a possible exploitation of 'TB2018' per se in cultivation or as a source of alternative alleles in the breeding of traditional cultivars. This work also presents a genomic methodology that exploits the information contained in a low-depth, whole-genome sequence to derive genotypic data useful for cross-platform (chip data) comparisons.

Evaluation of Agronomic Traits and Allele Specific DNA Markers Related to Some Disease and Quality Traits in Mutant Karakılçık M4 Individuals

Karakılçık (KK) is a landrace, of which both bread and durum wheat forms exist. This is the first study that reports mutation induction and detection with agronomic traits and allele specific markers on KK durum wheat landrace. In the study, KK landrace was induced with chemical mutation using sodium azide (NaN3) (3 mM) mutagen to improve agronomic traits. In the research, KK genotype and the 13 M4 individuals (KK-1 to KK-13) were used as plant materials. According to the results, the shortest mutant genotype was KK-10 (125.80 cm), with the highest protein ratio (18.50%) and wet gluten ratio (37.10%), while KK-9 genotype had the highest grain yield (4285.6 kg ha-1). The average polymorphism information content (PIC) was calculated as 0.97, while the average allele number was 15.2 per marker. Glu-B1 (Bx7OE primer) allele was determined on KK-11 and KK-13 genotypes. Wx-A1 allele was found on KK-1, KK-2, KK-4, KK-5 and KK-7 genotypes. Sr49 allele (Sun209) was determined on KK-5 genotype, while Yr45 allele (Xwgp118) was detected on KK-10 genotype. In addition, the high protein content allele Gpc-B1 (UHW89 primer) was found on KK-1, KK-2, KK-3 and KK-4 genotypes. Based on the principal component biplot analysis, it was determined that there was a positive relationship between grain yield (GY) with test weight (TW), grain number and weight per spike (GNS and GWS), and negative relationship with the other traits.

Evaluation of Drought Tolerance in Durum Wheat Landraces Using Grain Yield-Based Drought Selection Indices

Evaluation of Drought Tolerance in Durum Wheat Landraces Using Grain Yield-Based Drought Selection Indices

Genetic diversity of Ethiopian durum wheat (T. turgidum subsp. durum) landraces under water stressed and non stressed conditions

Ethiopia, being a major center of origin and diversity for durum wheat, possesses a highly variable genetic pool with diverse agroecological adaptations. Wheat landraces are an important source of genetic variation for breeding programs. This study was conducted to study the genotypic diversity of Ethiopian durum wheat genetic resources under two contrasting environments namely drought-stressed and non-stressed. It was carried out on 100 landraces and 4 local checks using an augmented design. Data were collected on 13 traits comprising yield and yield components, phenology, and canopy condition. The analysis of variance revealed significant differences between landraces for different traits with different sources of variation. Several landraces were found to outyield the checks at both environmental conditions. Intermediate to high estimates of the phenotypic coefficient of variation (PCV), genotypic coefficient of variation (GCV), heritability in a broad sense (h2b), and genetic advance in percent of the mean (GAPM) were observed for all the studied traits except for days to flowering at normal, thousands seed weight at stress, and days to maturity, leaf chlorophyll concentration measurement, and canopy temperature measurement at both conditions. The estimation of variability parameters showed that genotypic variation was higher than environmental variation for most traits. The number of tillers, spike length, kernel per spike, and grain yield indicated higher values for h2b and GAPM (74.42% and 20.86; 83.2% and 28.24; 70.79% and 28.0; and 89.54% and 74.71) at normal and (97.87% and 98.22; 71.27% and 28.51; 75.52% and 43.9; and 90.04% and 103.68) at the stressed condition, respectively. Spikelets per spike, kernel per spike, and thousands seed weight were positively correlated with grain yield. Grain yield exhibited a weak negative correlation with days to heading and days to maturity. Principal components analysis revealed that six traits were the major loadings on the first two principal components that describe 37.9% and 41.0% of the total morphological variance at normal and stressed conditions, respectively. Cluster analysis grouped the landraces into six clusters, with each cluster showing variation in performance for different traits under normal and stressed conditions. The intracluster distance was maximum in cluster I (D2 = 7.68) and (D2 = 8.19) at normal and stressed conditions respectively and the intercluster distance was found to be maximum between clusters I and IV (D2 = 11.02) and clusters I and II (D2 = 10.33) at normal and stressed conditions respectively. The presence of significant genetic variability among the evaluated durum wheat landraces suggests an opportunity for improvement of grain yield through the hybridization of genotypes from different clusters and subsequent selection. Genotypes with superior agronomic traits that outperform the best checks are identified as potential parents for yield improvement programs for moisture stress.

Estimating genetic diversity among durum wheat (Triticum durum desf.) landraces using morphological and SRAP markers

The durum wheat (Triticum turgidum L. ssp. durum Desf.) Landraces are a valuable source of natural germplasm for enhancing the genetic diversity of existing durum wheat cultivars. The study analyzed the genetic diversity of twenty-two durum wheat landraces including eight local Saudi landraces and fourteen introduced landraces using sixteen morphological descriptors and sequence-related amplified polymorphism (SRAP) markers. The results showed significant differences between the analyzed agro-morphological parameters and a large degree of genetic variation across the tested landraces. Principle components analysis (PCA) was used to determine agro-morphological relationships among different traits. The first six principal components (PCs) accounted for 78.47 % of the cumulative variability among 22 landraces. The PC1demonstrated variability in coleoptile anthocyanin coloration, straw pith, culm neck glaucosity, flag leaf glaucosity, ear glaucosity, and length of awn at tip relative to length of ear. Wheat landraces (L8, L14, L497, L569, L590, L594, L600, L601, and L602) showed increased diversity in dry region and contributed to PC1. A couple landraces had higher plant height (L12, L598, and L654), heading days (650, 656), and ear length (L12, L594, and L650) respectively. The dendrogram generated from the standardized morphological data separated the twenty-two durum wheat genotypes mainly into two clusters. The landraces 14, 600 and 602 grouped into separate cluster with strong correlation to ear glaucosity. Genetic diversity of these landraces was also evaluated using eight SRAP markers, with 482 amplified fragments and an average polymorphic information content (PIC) of 0.27. The dendrogram based on SRAP markers separated into two clusters with some diversified landraces (L8, 594, 602, 977, and L650). The Mantel test found no significant correlation (phenotypic or genetic) between 22 wheat durum landraces (r = 0.013, p = 0.84, =0.05). The results demonstrated the power of morphological and SRAP markers for detecting diversity among durum wheat landraces in the semi-arid region of Saudi Arabia. Thus, study provides insights into wheat diversity for better in-situ and ex-situ conservation and paves the road for their use in a Saudi durum wheat breeding program.

Unlocking the story of resistance to Zymoseptoria tritici in Tunisian old durum wheat germplasm based on population structure analysis

BackgroundSeptoria tritici blotch (STB) remains a significant obstacle to durum wheat cultivation on a global scale. This disease remains a challenge for farmers, researchers, and breeders, who are collectively dedicated to reduce its damage and improve wheat resistance. Tunisian durum wheat landraces have been recognized as valuable genetic ressources that exhibit resistance to biotic and abiotic stresses and therefore play a crucial role in breeding program aimed at creating new wheat varieties resistant to fungal diseases as STB, as well as adapted to climate change constraints.ResultsA total of 366 local durum wheat accessions were assessed for resistance to two virulent Tunisian isolates of Zymoseptoria tritici Tun06 and TM220 under field conditions. Population structure analysis of the durum wheat accessions, performed with 286 polymorphic SNPs (PIC > 0.3) covering the entire genome, identified three genetic subpopulations (GS1, GS2 and GS3) with 22% of admixed genotypes. Interestingly, all of the resistant genotypes were among GS2 or admixed with GS2.ConclusionsThis study revealed the population structure and the genetic distribution of the resistance to Z. tritici in the Tunisian durum wheat landraces. Accessions grouping pattern reflected the geographical origins of the landraces. We suggested that GS2 accessions were mostly derived from eastern Mediterranean populations, unlike GS1 and GS3 that originated from the west. Resistant GS2 accessions belonged to landraces Taganrog, Sbei glabre, Richi, Mekki, Badri, Jneh Khotifa and Azizi. Furthermore, we suggested that admixture contributed to transmit STB resistance from GS2 resistant landraces to initially susceptible landraces such as Mahmoudi (GS1), but also resulted in the loss of resistance in the case of GS2 susceptible Azizi and Jneh Khotifa accessions.

The Origin of Spanish Durum Wheat and Olive Tree Landraces Based on Genetic Structure Analysis and Historical Records

In this study, the origin of Spanish durum wheat and olive tree landrace collections (preserved in seed banks and ex situ field collections, respectively) was traced throughout different studies on genetic structure analysis of different landrace collections and historical records of plant material circulation of these two crops in the south and east of Spain (the main cultivation areas). Although there were several groups of Spanish durum wheat landraces, they did not cluster geographically and likely came from intense grain circulation within the country and abroad (due to a high seeding rate of about 100 kg/ha and an unstable production) from the 15 to 19th centuries (especially the Maghreb and Sicily). However, Spanish olive tree landraces experienced lower genetic circulation over time and space due to the longevity of the species and the large size of the reproductive material. They can be clearly divided into two groups: those from the south, of Maghrebi origin, which most likely originated during the Islamic expansion of the 8–15th centuries, and those from the east, arriving most likely during Roman times from Italy. The genetic circularity levels of the plant material of these two crops are different.