Wheat Landraces Research Articles

Pathogenicity of Puccinia striiformis f. sp. tritici and quantitative traits on bread wheat landraces in Ethiopia

AbstractBread wheat (Triticum aestivum L.) is severely affected by stripe rust caused by Puccinia striiformis Westend. f. sp. tritici (Pst). This study was conducted to investigate pathogenicity of Pst isolates to bread wheat landraces grown in Ethiopia, establish stripe rust yield loss models and estimate variability in bread wheat quantitative traits. A greenhouse pot experiment was setup to assess seedling stage responses of landraces to Pst and a field study was conducted for adult plant stage evaluation. Among dominant isolates of Pst, Kubsa was the most virulent. Apart from the detection of resistance at the seedling stage study, a broad range of adult‐stage resistance was also observed which can confer durable resistance. Among single‐point models, the onset of severe infection at the development of heading stage causes significant yield loss by stripe rust. The integral yield loss model predicted a strong negative linear relationship between agronomic traits and stripe rust. Hierarchical analysis revealed the presence of three distinct clusters of bread wheat landraces, each forming different stripe rust resistance groups. With the exception of the harvest index and the growth stage parameter of days to heading, all agronomic traits were significantly different for the various landraces. This suggests the presence of diverse genetic resources, which might have also led to different responses to the stripe rust in these materials. This work clarifies the many ways in which landraces of bread wheat react to Pst infection, revealing a range of resistance mechanisms that can be used for efficient disease management.

Fine mapping of powdery mildew resistance gene PmXNM in a Chinese wheat landrace Xiaonanmai.

Powdery mildew resistance gene PmXNM, originated from the Chinese wheat landrace Xiaonanmai, was delimited to a 300.7-kb interval enriched with resistance genes. Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a globally devastating disease threatening the yield and quality of wheat worldwide. The use of broad-spectrum disease resistance genes from wheat landraces is an effective strategy to prevent this pathogen. Chinese wheat landrace Xiaonanmai (XNM) was immune to 23 tested Bgt isolates at the seedling stage. The F1, F2, and F2:4 progenies derived from the cross between XNM and Chinese Spring (CS) were used in this study. Genetic analysis revealed that powdery mildew resistance in XNM was controlled by a single dominant gene, temporarily designated PmXNM. Bulked segregant analysis and molecular mapping delimited PmXNM to the distal terminal region of chromosome 4AL flanked by markers caps213923 and kasp511718. The region carrying the PmXNM locus was approximately 300.7kb and contained nine high-confidence genes according to the reference genome sequence of CS. Five of these genes, annotated as disease resistance RPP13-like proteins 1, were clustered in the target region. Haplotype analysis using the candidate gene-specific markers indicated that the majority of 267 common wheat accessions (75.3%) exhibited extensive gene losses at the PmXNM locus, as confirmed by aligning the targeted genome sequences of CS with those of other sequenced wheat cultivars. Seven candidate gene-specific markers have proven effective for marker-assisted introgression of PmXNM into modern elite cultivars.

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.

Resistance of old winter bread wheat landraces to tan spot

Background. The most effective and environmentally safe way to combat wheat diseases is to produce cultivars resistant to their pathogens. For this purpose, old landraces are often used as genetically diverse sources of traits important for breeding. In the process of wheat breeding for resistance to tan spot caused by the fungus Pyrenophora tritici-repentis (Died.) Drechs. (abbr. Ptr), selection is carried out against the dominant allele of Tsn1, the gene of sensitivity to the toxin Ptr ToxA, which induces necrosis and represents the main pathogenicity factor of Ptr controlled by the ToxA gene. The aim of the study was to characterize a set of bread wheat (Triticum aestivum L.) accessions from the VIR collection for resistance to various Ptr populations, genotype these accessions using Xfcp623 – a DNA marker of the Tsn1 gene, and identify sources of tan spot resistance.Materials and methods. Sixty-seven accessions of winter bread wheat landraces were studied. Seedling resistance to two Ptr populations was assessed using a 5-point scale adopted at VIZR. The allelic state of Tsn1 was identified by PCR.Results. Dominant alleles of Tsn1 were found for 55% of the studied accessions. Seventeen accessions were resistant or moderately resistant to two Ptr populations and an isolate from Krasnodar Territory previously used for their characterization. Nine of them had the tsn1tsn1 genotype, and 8 had Tsn1Tsn1. The accessions mainly belonged to three agroecological groups proposed by N. I. Vavilov: “steppe winter bread wheat (Banatka wheats)”, “North European forest awnless bread wheats (Sandomirka wheats)”, and “Caucasian mountain winter bread wheat”.Conclusion. The identified 17 accessions resistant to Ptr are potential breeding sources of resistance. In the studied set of accessions, no significant relationship was found between the allelic state of the Tsn1 gene in the accession and its response to the infection with pathogen populations, including isolates with the ToxA gene.

Wheat landraces as sources of high grain quality and nutritional properties

Background. Improving the grain quality of modern spring bread wheat cultivars is a highly relevant task of breeding. To solve this problem, old and local wheat varieties (landraces) are of considerable interest. A rich collection of them is available among the plant genetic resources preserved at VIR. With this in view, the aim of this research was to identify sources of high protein, gluten, macro- and micronutrient content out of the landraces from the VIR collection for improvement of wheat grain quality through breeding.Materials and methods. Field and laboratory research were conducted in the experimental field of Omsk State Agrarian University under the conditions of the southern forest-steppe of Western Siberia in 2020–2021. Sowing was carried out on fallow on conventional sowing dates. Mineral composition in the grain of the studied landraces was analyzed at the Kurchatov Genomic Center, Novosibirsk, using atomic absorption spectrometry techniques.Results. The research results showed that landraces from different regions of Russia, Kazakhstan, Tajikistan, and Kyrgyzstan were characterized by high levels of protein (18.4–18.8%) and gluten (35.9–36.0%) in grain. Landraces from Kazakhstan had low Zn content (on average 38.3 mg/kg), while those from Kyrgyzstan, on the contrary, had high content of Zn (41.9 mg/kg) and Fe (55.1 mg/kg), and landraces from Tajikistan had high K content (3820 mg/kg). A positive relationship between the concentrations of Mg, Mn, Fe, and Zn was found in the grain of wheat landraces.Conclusion. Wheat landraces are of interest as genetic resources for the development of high-protein cultivars with improved nutritional value of grain for the milling and breadmaking industries.

Genetic variation, genetic advance, heritability and correlation analysis of phenotypic traits in tetraploid wheat (Triticum turgidum spp.) landraces and some improved cultivars of Ethiopia

AbstractTetraploid wheat species from Ethiopia hold ample genetic variation, which could provide a source for improvement of wheat. A total of 196 Ethiopian tetraploid wheat (Triticum turgidum spp.) accessions, including 174 landraces and 22 improved cultivars, were evaluated at Sinana and Debrezeit to assess morphological variation, genetic advance, heritability and correlation based on 11 phenotypic traits. Except for spike length, highly significant variation (P < 0.001) among genotypes for all traits was observed. The observed mean and range values of the phenotypic traits revealed high variability in the accessions. Phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) values were high for grain yield, biomass yield and harvest index. Seed yield showed highly significant (P < 0.001) negative correlation with days to booting and days to maturity and positive correlation with all traits. The estimates of heritability (H2) for grain yield and the number of spikelets per spike respectively ranged from 41.78 to 84.62%. The genetic advance as a percentage of mean was low for the number of seeds per spikelet, days to booting and days to maturity; intermediate for plant height, thousand kernel weight and spike length and high for the number of spikelets per spike, the number of effective tillers per plant, grain yield, biomass yield and harvest index, respectively. The number of spikelets per spike gave a high value of genetic advance and heritability implying high genetic gain from its selection.

Identification of candidate regulators of the response to early heat stress in climate-adapted wheat landraces via transcriptomic and co-expression network analyses.

Climate change is likely to lead to not only increased global temperatures but also a more variable climate where unseasonal periods of heat stress are more prevalent. This has been evidenced by the observation of spring-time temperatures approaching 40°C in some of the main spring-wheat producing countries, such as the USA, in recent years. With an optimum growth temperature of around 20°C, wheat is particularly prone to damage by heat stress. A warming climate with increasingly common fluctuations in temperature therefore threatens wheat crops and subsequently the lives and livelihoods of billions of people who depend on the crop for food. To futureproof wheat against a variable climate, a better understanding of the response to early heat stress is required. Here, we utilised DESeq2 to identify 7,827 genes which were differentially expressed in wheat landraces after early heat stress exposure. Candidate hub genes, which may regulate the transcriptional response to early heat stress, were identified via weighted gene co-expression network analysis (WGCNA), and validated by qRT-PCR. Two of the most promising candidate hub genes (TraesCS3B02G409300 and TraesCS1B02G384900) may downregulate the expression of genes involved in the drought, salinity, and cold responses-genes which are unlikely to be required under heat stress-as well as photosynthesis genes and stress hormone signalling repressors, respectively. We also suggest a role for a poorly characterised sHSP hub gene (TraesCS4D02G212300), as an activator of the heat stress response, potentially inducing the expression of a vast suite of heat shock proteins and transcription factors known to play key roles in the heat stress response. The present work represents an exploratory examination of the heat-induced transcriptional change in wheat landrace seedlings and identifies several candidate hub genes which may act as regulators of this response and, thus, may be targets for breeders in the production of thermotolerant wheat varieties.

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 Variability and Association Studies in Germplasm Accessions and Land Races of Wheat (Triticum aestivum L.)

Wheat (Triticum aestivum L.) is described as the ‘King of Cereals’ is a leading cereal crop which plays a crucial role in feeding the hungry world and improving global food security. Understanding the contribution of yield components to the variation of grain yield is essential for designing breeding programs and increasing grain production. A diversity panel of 200 genotypes including 145 accessions and 55 landraces of wheat were evaluated in Augmented Design for genetic variability and correlation between grain yield and yield related components. Analysis of variance revealed significant differences among the genotypes for all the traits except chlorophyll fluorescence. The highest phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) were recorded for effective number of tillers metre-1 followed by biological yield row-1, flag leaf length, grain yield row-1. Heritability coupled with genetic advance percent of mean was high for effective number of tillers metre-1, followed by biological yield row-1, flag leaf length, grain yield row-1. Association studies revealed a highly significant and positive association of grain yield row-1 with biological yield row-1 (0.805), 1000-grain weight (0.476), effective number of tillers metre-1 (0.328), flag leaf width (0.137) and harvest index (0.133) whereas, it showed a significant negative association with days to maturity (-0.304) and days to 50% heading, (-0.291). The study revealed that days to maturity, days to heading, 1000-grain weight and effective number of tillers metre-1 could be considered the most appropriate traits for improvement and selection of trait to achieve stable and high yielding early wheat genotypes.

Polyethylene Glycol (PEG) Induced Changes in Germination, Seedling Growth, Water Relation and α-β Amylase of some Hungarian Wheat Landraces Varieties

Wheat productivity has been steadily declining over the past few years, and abiotic stresses are responsible for more than half of all yield losses. Stress from drought is one of the most significant factors that can impede plant growth and production wherever in the world. The main goal of this study was to examine how low water potential, which was caused by polyethylene glycol (PEG 6000), on the germination and biochemical parameters of Hungarian wheat landraces. Seven Hungarian wheat landraces varieties (Szentesi; Nyirádi; Kiszombori; Háromfai; Tapiószelei; Nagykállói, and Szajlai) were tested for germination characteristics; seedling parameters; water relative content; tolerance index; and enzyme activities in the presence of different five concentrations of water stress (0; 5; 10; 15 and 20%) of polyethylene glycol (PEG 6000). At the Research Institute of Nyiregyhaza in Hungary, a laboratory experiment using Factorial Experiment in Randomized Completely Design (RCD) was carried out in four replicates. According to the data, the Háromfai landrace outperformed all other landraces under research and recorded the highest values of all analyzed features, followed by Tapiószelei; Kiszombori; Szajlai; Nyirádi; Szentesi and Nagykállói landraces varieties. All characteristics under study were significantly decreased as water stress concentrations (PEG 6000) were increased from 0 up to 20%. In comparison to other wheat landraces, Háromfai and Tapiószelei landraces varieties had the highest water relative content (WRC), tolerance index (TI), and α as well β-amylase amylase activities, and were able to induce better drought tolerance. These results suggest that these landraces could be a good resource for breeding programs and cultivation under drought stress conditions. Furthermore, the results of correlation analysis did not neither positive nor negative correlation between the Hungarian wheat landraces varieties and all of analyzed traits. On contrary, the correlation analysis results show negative correlation between the drought stress levels and studied traits.

Wheat stripe rust resistance locus YR63 is a hot spot for evolution of defence genes – a pangenome discovery

BackgroundStripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), poses a threat to global wheat production. Deployment of widely effective resistance genes underpins management of this ongoing threat. This study focused on the mapping of stripe rust resistance gene YR63 from a Portuguese hexaploid wheat landrace AUS27955 of the Watkins Collection.ResultsYR63 exhibits resistance to a broad spectrum of Pst races from Australia, Africa, Asia, Europe, Middle East and South America. It was mapped to the short arm of chromosome 7B, between two single nucleotide polymorphic (SNP) markers sunCS_YR63 and sunCS_67, positioned at 0.8 and 3.7 Mb, respectively, in the Chinese Spring genome assembly v2.1. We characterised YR63 locus using an integrated approach engaging targeted genotyping-by-sequencing (tGBS), mutagenesis, resistance gene enrichment and sequencing (MutRenSeq), RNA sequencing (RNASeq) and comparative genomic analysis with tetraploid (Zavitan and Svevo) and hexaploid (Chinese Spring) wheat genome references and 10+ hexaploid wheat genomes. YR63 is positioned at a hot spot enriched with multiple nucleotide-binding and leucine rich repeat (NLR) and kinase domain encoding genes, known widely for defence against pests and diseases in plants and animals. Detection of YR63 within these gene clusters is not possible through short-read sequencing due to high homology between members. However, using the sequence of a NLR member we were successful in detecting a closely linked SNP marker for YR63 and validated on a panel of Australian bread wheat, durum and triticale cultivars.ConclusionsThis study highlights YR63 as a valuable source for resistance against Pst in Australia and elsewhere. The closely linked SNP marker will facilitate rapid introgression of YR63 into elite cultivars through marker-assisted selection. The bottleneck of this study reinforces the necessity for a long-read sequencing such as PacBio or Oxford Nanopore based techniques for accurate detection of the underlying resistance gene when it is part of a large gene cluster.

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.

Genome wide association in Spanish bread wheat landraces identifies six key genomic regions that constitute potential targets for improving grain yield related traits

Key messageAssociation mapping conducted in 189 Spanish bread wheat landraces revealed six key genomic regions that constitute stable QTLs for yield and include 15 candidate genes.Genetically diverse landraces provide an ideal population to conduct association analysis. In this study, association mapping was conducted in a collection of 189 Spanish bread wheat landraces whose genomic diversity had been previously assessed. These genomic data were combined with characterization for yield-related traits, including grain size and shape, and phenological traits screened across five seasons. The association analysis revealed a total of 881 significant marker trait associations, involving 434 markers across the genome, that could be grouped in 366 QTLs based on linkage disequilibrium. After accounting for days to heading, we defined 33 high density QTL genomic regions associated to at least four traits. Considering the importance of detecting stable QTLs, 6 regions associated to several grain traits and thousand kernel weight in at least three environments were selected as the most promising ones to harbour targets for breeding. To dissect the genetic cause of the observed associations, we studied the function and in silico expression of the 413 genes located inside these six regions. This identified 15 candidate genes that provide a starting point for future analysis aimed at the identification and validation of wheat yield related genes.

GGE biplot analysis of biofortification traits in relation to grain yield in landraces of tetraploid wheat (Triticum turgidum ssp. dicoccum)

GGE biplot analysis of biofortification traits in relation to grain yield in landraces of tetraploid wheat (Triticum turgidum ssp. dicoccum)

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.

Mapping of a Stripe Rust Resistance Gene Yr72 in the Common Wheat Landraces AUS27506 and AUS27894 from the Watkins Collection.

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is among the major threats to global wheat production. The common wheat landraces AUS27506 and AUS27894 displayed stripe rust resistance against several commercially prevailing Pst pathotypes. These genotypes were crossed with a stripe-rust-susceptible landrace AUS27229 to understand the inheritance of resistance and to determine the genomic location(s) of underlying gene(s). F3 generations of crosses AUS27506/AUS27229 and AUS27894/AUS27229 showed monogenic segregation for stripe rust resistance under greenhouse conditions. The absence of segregation for stripe rust response among the AUS27506/AUS27894-derived F3 population suggested that both genotypes carry the same gene. The stripe rust resistance gene carried by AUS27506 and AUS27894 was tentatively named YrAW4. A bulked segregant analysis placed YrAW4 in the long arm of chromosome 2B. The AUS27506/AUS27229 F3 population was enhanced to develop an F6 recombinant inbred line (RIL) population for detailed mapping of chromosome 2BL. DArT-based SSR, STS and SNP markers were employed to enrich the 2BL map. DArT-based STS markers sun481 and SNP marker IWB12294 flanked YrAW4 proximally (1.8 cM) and distally (1.2 cM), respectively. Deletion mapping placed sun481 in the deletion bin 2BL-5. All stripe rust resistance genes, previously located on chromosome 2BL, neither express an infection type like YrAW4, nor are they mapped in the deletion bin 2BL-5. Hence, YrAW4 represented a new locus and was formally named Yr72. The usefulness of the markers IWB12294 and sun481 in marker-assisted selection was demonstrated by the amplification of alleles that are different to that linked with Yr72 in 19 common wheat and two durum wheat cultivars.

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 < 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.

Evaluating agromorphological traits of Greek wheat landraces and exploring their potential for bread and pasta making based on seed physical properties

Physical and morphological characteristics of Greek wheat landrace and cultivar seeds were evaluated, aiming to assess their bread- and pasta-making quality. Furthermore, the plant agromorphological traits of wheat landraces and cultivars were measured and correlated with seed physical properties. Fifteen Triticum spp. accessions, out of which four cultivars (two Triticum aestivum and two T. durum), nine landraces (two T. durum, five T. aestivum, one T. dicoccum and one T. polonicum) and two T. durum of unknown status were studied. Seventeen morphological plant and seed traits were measured based on UPOV descriptors. Ear emergence was earlier in cultivars than in landraces. The plant weight of the landraces was, in some cases, almost twice the cultivars’. Seed firmness (62.96–194.85N) was positively correlated with thousand kernel weight and volume (0.840 and 0.791, P < 0.05, respectively). Based on the agromorphological traits, cluster analysis clearly separated the species and the cultivars from the landraces, and the unknown status accessions were grouped with the cultivars. Cluster analysis with all measured traits set the wheat accessions in the following distinct groups: (1) T. durum cultivars including the unknown status accessions, (2) T. aestivum cultivars, and (3) T. aestivum and T. durum landraces. T. polonicum and T. dicoccum each formed a separate group. Seed physical properties of the analyzed Greek landraces indicated their suitability for bread and/or pasta making.

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.