Durum Wheat Lines Research Articles

Genetic dissection of agronomic and quality traits based on association mapping and genomic selection approaches in durum wheat grown in Southern Spain.

Climatic conditions affect the growth, development and final crop production. As wheat is of paramount importance as a staple crop in the human diet, there is a growing need to study its abiotic stress adaptation through the performance of key breeding traits. New and complementary approaches, such as genome-wide association studies (GWAS) and genomic selection (GS), are used for the dissection of different agronomic traits. The present study focused on the dissection of agronomic and quality traits of interest (initial agronomic score, yield, gluten index, sedimentation index, specific weight, whole grain protein and yellow colour) assessed in a panel of 179 durum wheat lines (Triticum durum Desf.), grown under rainfed conditions in different Mediterranean environments in Southern Spain (Andalusia). The findings show a total of 37 marker-trait associations (MTAs) which affect phenotype expression for three quality traits (specific weight, gluten and sedimentation indexes). MTAs could be mapped on the A and B durum wheat subgenomes (on chromosomes 1A, 1B, 2A, 2B and 3A) through the recently available bread wheat reference assembly (IWGSC RefSeqv1). Two of the MTAs found for quality traits (gluten index and SDS) corresponded to the known Glu-B1 and Glu-A1 loci, for which candidate genes corresponding to high molecular weight glutenin subunits could be located. The GS prediction ability values obtained from the breeding materials analyzed showed promising results for traits as grain protein content, sedimentation and gluten indexes, which can be used in plant breeding programs.

Effect of Glu‐D1 introgression on dough‐ and pasta‐making quality of durum wheat lines with different glutenin composition and amylose content

AbstractBackground and objectivesDurum wheat is mainly used for the production of pasta, but a significant amount is also used for bread and other products worldwide. However, leavened bread made from durum wheat flour or as blends results in bread with lower loaf volume compared to bread made from hexaploid wheat probably due to poor dough strength and/or extensibility. Durum wheat lacks the glutenin subunits important in bread making, in particular the Glu‐D1 subunit 5 + 10. Efforts are being made by researchers to introduce high molecular weight glutenin subunits (HMW‐GS), specifically 1, 2*, 17 + 18, 2 + 12, and 5 + 10 and combinations into durum wheat to improve baking quality. Typically, this work has not evaluated pasta‐making quality and dual purpose durum wheat is desirable. This work reports the effects of the addition of HMW‐GS 2 + 12 and 5 + 10 in various durum wheat backgrounds on dough‐ and pasta‐making quality.FindingsDurum wheats, Svevo, Svevo partial waxy (null 4A, null 7A, low amylose ~14%), and Lira biotypes 42/45 differing in their LMW‐GS as type 1, weak dough, and type 2, strong dough, respectively, were compared with lines having the Glu‐D1 subunit pair 2 + 12 or 5 + 10. For Svevo, the Glu‐B17 + 8 subunits were removed. The absence of 7 + 8 in Svevo reduced the over strong dough strengthening effect, especially from 5 + 10 but also 2 + 12 found previously when 7 + 8 is present. The weak gluten Lira42 genotype benefited from the improved dough strength from 2 + 12/5 + 10, and both Lira biotypes showed much larger effects on dough strength from the Glu‐D1 pairs than with Svevo, a better quality variety. The impacts on pasta were variable depending on the genotype. For Lira42, the presence of 2 + 12 lowered stickiness and cooking loss while stickiness was only reduced in Lira45 with 5 + 10. For Svevo (without 7 + 8), there was little to no impact on pasta quality from the presence of either 2 + 12 or 5 + 10. The very low amylose Svevo (SvLA) pasta quality was improved greatly by 5 + 10 improving firmness and reducing stickiness and cooking loss although still softer than Svevo.ConclusionsManipulation of the glutenin composition of durum wheat by introduction of Glu‐D1subunits 2 + 12 or 5 + 10 in various durum backgrounds had different effects. Generally, dough strength was improved more so in the weaker dough strength genotypes with these subunits and removing Glu‐B17 + 8 from Svevo provided a more balanced dough strength. Pasta firmness in Svevo and Lira with these subunits was not affected, and there were minimal changes in other pasta properties except an improvement in pasta stickiness in Lira. In the variable amylose Svevo genotypes, the 5 + 10 subunit pair improved pasta firmness of the overly soft low amylose waxy pasta and reduced stickiness.Significance and noveltyManipulation of the glutenin subunit composition of durum wheat by introduction of Glu‐D1 subunits affected dough properties, improving dough strength in genotypes with weak gluten. This study found minor impacts on pasta quality allowing the flexibility to develop durum with a better balance of glutenin subunits more suited to bread making without adversely affecting pasta‐making quality and acceptability.

The Plant-Transpiration Response to Vapor Pressure Deficit (VPD) in Durum Wheat Is Associated With Differential Yield Performance and Specific Expression of Genes Involved in Primary Metabolism and Water Transport.

The regulation of plant transpiration was proposed as a key factor affecting transpiration efficiency and agronomical adaptation of wheat to water-limited Mediterranean environments. However, to date no studies have related this trait to crop performance in the field. In this study, the transpiration response to increasing vapor pressure deficit (VPD) of modern Spanish semi-dwarf durum wheat lines was evaluated under controlled conditions at vegetative stage, and the agronomical performance of the same set of lines was assessed at grain filling as well as grain yield at maturity, in Mediterranean environments ranging from water stressed to good agronomical conditions. A group of linear-transpiration response (LTR) lines exhibited better performance in grain yield and biomass compared to segmented-transpiration response (STR) lines, particularly in the wetter environments, whereas the reverse occurred only in the most stressed trial. LTR lines generally exhibited better water status (stomatal conductance) and larger green biomass (vegetation indices) during the reproductive stage than STR lines. In both groups, the responses to growing conditions were associated with the expression levels of dehydration-responsive transcription factors (DREB) leading to different performances of primary metabolism-related enzymes. Thus, the response of LTR lines under fair to good conditions was associated with higher transcription levels of genes involved in nitrogen (GS1 and GOGAT) and carbon (RCBL) metabolism, as well as water transport (TIP1.1). In conclusion, modern durum wheat lines differed in their response to water loss, the linear transpiration seemed to favor uptake and transport of water and nutrients, and photosynthetic metabolism led to higher grain yield except for very harsh drought conditions. The transpiration response to VPD may be a trait to further explore when selecting adaptation to specific water conditions.

Identification of Stripe Rust Resistance in Ethiopian Durum Wheat by Phenotypic Screening and Kompetitive Allele Specific PCR (KASP) SNP Markers

Stripe (Yellow) rust caused by Puccinia striiformis f.sp. tritici (Pst) is one of the most devastating diseases of wheat in the highlands of Ethiopia. Improved cultivars often lose their resistance due to occurrence of new virulent races which overcome the genes and make the cultivars out of production. Therefore, identification of new sources of resistance genes helps in battling yellow rust and maximizes wheat production in Ethiopia. In this study, 300 durum wheat lines (landraces & cultivars) were screened with three virulent isolates (Pst_Is1, Pst_Is4 and Pst_Is8) for seedling resistance using Infection Type (IT) scoring method. The lines were also screened with 16 KASP-based SNP markers linked to 7 Yr genes already identified in various studies. Highly resistant infection type (IT: 0 -3) to Pst_Is1, Pst_Is4, and Pst_Is8 was exhibited by 59.3%; 67.3%; and 46.3% of the lines, respectively. 124 lines constantly exhibited high level of resistance to all three isolates. The majority (96.8%) of the resistant lines are landraces while four (3.2%) are commercial cultivars (Cocorit/71, Yerer, Obsa and Dire). In the molecular screening 12 of the markers gave clear amplifications in the controls and the tested lines. Yr7, Yr15 and YrSp were detected in 81.7%, 88.3% and 0.7% of the lines respectively while Yr1, Yr17 and Yr36 were not detected. Detection frequency was higher in landraces (58.7%) than in cultivars (32.8%). Gene combinations frequency was the highest (72.7%) for Yr7+Yr15 followed by Yr15+YrSp (0.3%). Overall, this study has resulted in detection of genes Yr15 and YrSp, which are potential candidates for marker assisted breeding for Pst resistance in wheat. Besides, it has shown that resistant source identification and detection of genes can be facilitated through combined application of phenotyping and molecular screening.

Gene-ecology of durum wheat HMW glutenin reflects their diffusion from the center of origin

The production of many food items processed from wheat grain relies on the use of high gluten strength flours. As a result, about 80% of the allelic variability in the genes encoding the glutenin proteins has been lost in the shift from landraces to modern cultivars. Here, the allelic variability in the genes encoding the high molecular weight glutenin subunits (HMW-GSs) has been characterized in 152 durum wheat lines developed from a set of landraces. The allelic composition at the two Glu-1 loci (Glu-A1 and -B1) was obtained at both the protein and the DNA level. The former locus was represented by three alleles, of which the null allele Glu-A1c was the most common. The Glu-B1 locus was more variable, with fifteen alleles represented, of which Glu-B1b (HMW-GSs 7 + 8), -B1d (6 + 8) and -B1e (20 + 20) were the most frequently occurring. The composition of HMW-GSs has been used to make inferences regarding the diffusion and diversification of durum wheat. The relationships of these allelic frequencies with their geographical distribution within the Mediterranean basin is discussed in terms of gene-ecology.

CENEB Oro C2017: nueva variedad de trigo duro para el noroeste de México

El cultivo de trigo cristalino o duro (Triticum durum L.) es una de las actividades agrícolas que genera mas riqueza en el estado de Sonora, porque este tipo de grano se comercializa en el mercado internacional. En el año 2017, dicho estado exportó este cereal por 176.3 millones de dólares, que representan 6.6% de las exportaciones agrícolas con destino a Sudamérica, Europa y África (SAGARHA, 2018). En respuesta a esta importancia del trigo cristalino y con base en las evaluaciones de rendimiento de grano llevado a en el Campo Experimental Norman E. Borlaug (CENEB), se propuso la liberación de la línea experimental de trigo duro CNDO/PRIMADUR//HAI-OU-17/3/SNITAN/4/JUPAREC2001/5/CNDO/PRIMADUR//HAIOU -17/3/SNITAN/6/RISSA/GAN//POHO-1/3/PLATA-3//CREX/ALLA*2/4/ARMENT//SRN-3/ NIGRIS-4/3/CANELO-9.1, como nueva variedad denominada “CENEB Oro C2017”. Su número de cruza e historial de selección es CDSS07Y00184S-099Y-099M-12Y-1M-04Y-0B. El estudio de progenitores, cruzamiento, selección de poblaciones segregantes y ensayos preliminares de rendimiento fueron realizados por el Centro Internacional de Mejoramiento de Maíz y Trigo y los ensayos de rendimiento evaluaciones de calidad, purificaciones y caracterización fenotípica fueron realizados por el Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias en el CENEB, localizado en el Valle del Yaqui, Sonora. Las comparaciones de rendimiento y calidad se efectuaron desde 2011 con respecto a CIRNO C2008, ha sido la variedad más sembrada en Sonora en los últimos años, pero perdió su resistencia a la roya de la hoja y carece de color en la sémola que produce. CENEB Oro C2017, fue registrada de acuerdo con la Ley Federal de Producción Certificación y Comercialización de Semillas vigente en México y cuenta con el registro definitivo TRI-146-231117 del Catálogo Nacional de Variedades Vegetales del Servicio Nacional de Inspección y Certificación de Semillas y el título de obtentor con número de registro 1897.

Haplotype Loci Under Selection in Canadian Durum Wheat Germplasm Over 60 Years of Breeding: Association With Grain Yield, Quality Traits, Protein Loss, and Plant Height.

Durum wheat was introduced in the southern prairies of western Canada in the late nineteenth century. Breeding efforts have mainly focused on improving quality traits to meet the pasta industry demands. For this study, 192 durum wheat lines were genotyped using the Illumina 90K Infinium iSelect assay, and resulted in a total of 14,324 polymorphic SNPs. Genetic diversity changed over time, declining during the first 20 years of breeding in Canada, then increased in the late 1980s and early 1990s. We scanned the genome for signatures of selection, using the total variance Fst-based outlier detection method (Lositan), the hierarchical island model (Arlequin) and the Bayesian genome scan method (BayeScan). A total of 407 outliers were identified and clustered into 84 LD-based haplotype loci, spanning all 14 chromosomes of the durum wheat genome. The association analysis detected 54 haplotype loci, of which 39% contained markers with a complete reversal of allelic state. This tendency to fixation of favorable alleles corroborates the success of the Canadian durum wheat breeding programs over time. Twenty-one haplotype loci were associated with multiple traits. In particular, hap_4B_1 explained 20.6, 17.9 and 16.6% of the phenotypic variance of pigment loss, pasta b∗ and dough extensibility, respectively. The locus hap_2B_9 explained 15.9 and 17.8% of the variation of protein content and protein loss, respectively. All these pleiotropic haplotype loci offer breeders the unique opportunity for further improving multiple traits, facilitating marker-assisted selection in durum wheat, and could help in identifying genes as functional annotations of the wheat genome become available.

Quantitative and Qualitative Aspects of Soluble and Ionically Wall-Bound Peroxidases of EMS-Mutagenized Durum Wheat Lines (Triticum durum), as Tested for Yield at Drought Conditions

In order to characterize the response to drought of 19 ethyl methanesulfonate (EMS)-mutagenized lines of durum wheat (Triticum durum Desf.) derived from the variety CHAM-1 and cultivated in Morocco, growth (plant height, PLH) and yield (grain number per spike, GNS) parameters were followed for different lines and CHAM-1 variety. All were cultivated under well-watered (C) and drought conditions (T). In parallel, quantitative and qualitative aspects of leaf peroxidases (EC 1.11.1.7) were analyzed. When compared with C plant lines, the corresponding T lines showed decreases of 9–38% and 1–78%, respectively, for PLH and GNS parameters. A positive correlation was found between PLH and the yield as GNS (r2 = 0.885). When expressed as units mg−1 proteins, soluble peroxidases (SPOX) were less represented than the ionically wall-bound peroxidases (IPOX) in all mutagenized wheat lines, with 22.1% and 46.2% as respective coefficients of variation for drought-stressed lines. Drought-induced reduction in grain yields for all lines correlated positively with percentages of IPOX exhibited by stressed plants (r2 = 0.68). In addition, Averages of drought-induced decreases in GNS, calculated for five groups of mutagenized lines, were found to be positively correlated with their respective percentages of IPOX (r2 = 0.906). Drought-adapted lines showed decreases in IPOX. When subjected to electrophoresis using 6–15% polyacrylamide gradient gels, resolved IPOX of cereal line groups of limited drought-induced reduction in GNS exhibited low reactivity on native gels. These data support the hypothesis that IPOX are indicators of the sensitivity of wheat lines to drought conditions. Possible mechanisms of POX involvement in wheat resistance to drought and developing appropriate biochemical tests to screen variability and drought adaptation of EMS mutants are discussed in this study.

Seedling resistance of selected Ethiopian bread and durum wheat lines against dominant stem rust races

Stem rust caused by Puccinia graminis f. sp. tritici (Pgt) is one of the most important diseases of wheat in Ethiopia. It has a reputation to cause yield losses reaching up to 100% on susceptible cultivars. A study was conducted to evaluate the infection responses of 34 bread and 20 durum wheat lines at the seedling stage against four major stem rust races; TKTTF (Digalu race), TTKSK (Ug99 race), TRTTF and JRCQC. Wheat lines were artificially inoculated with urediniospores of the four Pgt races at Ambo Plant Protection Research Center in 2017, under controlled environment. Diverse seedling resistance responses were observed against the tested Pgt races. Three durum wheat lines TD56, TD393 and TD402 showed low infection types against all the races while the great majority (73%) of the tested bread wheat lines was susceptible to at least three of the races. The resistant durum wheat lines identified in this study can be used as sources of resistance in wheat breeding program.

Phenotyping of isogenic chlorophyll-less bread and durum wheat mutant lines in relation to photoprotection and photosynthetic capacity.

In our experiments, we examined high light responses and photosynthetic capacity of chlorophyll-less isogenic mutant lines of hexaploid bread wheat (Triticum aestivum L.) and tetraploid durum wheat (Triticum durum L.) in comparison to parental lines representing the wild type (WT), in two growth phases and two environments. In young plants, we observed a typical yellow-green phenotype with low chlorophyll content, significantly lower CO2 assimilation rate, elevated chlorophyll a-to-b ratio and insufficient regulation of linear electron transport. In the mutants grown in a moderate light in the growth chamber, a typical "chlorina" phenotype almost disappeared or, at least, was significantly alleviated in later growth stages, including the values of CO2 assimilation and the majority of the measured parameters related to photoprotective responses. On the other hand, in the case of the mutant lines grown in direct sunlight and fluctuating environment, the chlorophyll-less phenotype was evident also in latter growth phases. The chlorophyll-less phenotype was more severe in the durum wheat mutant lines compared to the bread wheat. For example, the durum wheat mutant lines grown outdoors expressed lower flexibility of photoprotective responses, including lower non-photochemical quenching and low rate of cyclic electron flow compared to WT or bread wheat mutants. Based on the analyses, we have identified a set of parameters providing information on the specific photosynthetic traits typical for the chlorophyll-less phenotype. Thus, the proposed way of phenotyping may serve for efficient selection of mutant genotypes for future research or screening activities. As a general result, we observed that the decrease of the chlorophyll content due to mutation was always associated with improper regulation of linear electron transport and a limited ability to prevent over-reduction of PSI acceptor side, regardless of the genotype, environment, and growth stage. This can partly explain why the low chlorophyll mutants were not successful in the evolution of higher plants, despite the photosynthetic capacity observed is high enough and they are fully competitive with wild-type plants in non-fluctuating controlled environment.

A cytoplasmic male sterility (CMS) system in durum wheat

Cytoplasmic male sterility (CMS) systems are based in the incompatible interaction between nucleus and cytoplasm and are commonly used for hybrid seed production in many crop species. The msH1 CMS system in common wheat results from the incompatibility between the nuclear genome of wheat and the cytoplasm of Hordeum chilense. Fertility restoration of the CMS phenotype is associated with the addition of the short arm of chromosome 6Hch from H. chilense. In this work, we attempt to transfer the msH1 system to durum wheat and to evaluate its potential as a new source of CMS for the production of hybrid durum wheat. For that purpose, an alloplasmic durum wheat line was developed by substituting wheat cytoplasm by that from H. chilense. This line was completely male sterile. Also, the double translocation T6HchS·6DL was transferred from common wheat into durum wheat, to test its potential as a restorer line. Finally, the system was tested by using the double T6HchS·6DL translocation in durum wheat as pollen donor for the alloplasmic male sterile line, which confirmed the fertility restoration ability of 6HchS in durum wheat.

Investigation of Durum wheat (Triticum turgidum L. subsp. durum Desf) Lines for Tolerance to Aluminum Stress Condition

Investigation of Durum wheat (Triticum turgidum L. subsp. durum Desf) Lines for Tolerance to Aluminum Stress Condition

Small‐scale methods to assess the gluten properties of durum wheat

Background and objectivesDurum breeders are interested in being able to remove weak gluten genotypes from their crossing populations. Although numerous tests exist to measure gluten strength, methods that can be used in early generations, use minimal sample with little processing and have good discrimination are lacking. The purpose of this work was to evaluate several small‐scale methods to predict gluten strength in durum wheat with emphasis on the gluten aggregation behavior measured using a GlutoPeak device.FindingsUsing as little as 9 g of wholemeal (or semolina), a reproducible GlutoPeak aggregation curve is developed at the end of 5 min. Wholemeal gave higher precision than semolina and is more convenient to prepare when screening breeders’ material. The GlutoPeak Area and Peak Mixing Time (PMT) are good predictors of mixograph and gluten index (GI), which are traditional measures of gluten strength. Good correlations between these parameters were obtained using a diverse set of 145 durum genotypes. GlutoPeak Area gave the best prediction of GI from wholemeal samples allowing a breeder to remove weak‐moderate GI samples from a population using as little as 9 g of wholemeal. The GlutoPeak test showed higher correlations with mixograph and GI than the small‐scale biochemical methods, was easier to perform and uses no chemicals. However, GlutoPeak is not suitable when only mg quantities of sample are available.ConclusionsThe utility of the GlutoPeak device has been further validated in this work for screening durum wheat lines for gluten strength. Wholemeal is a suitable sample (9 g minimum) and provides good precision and reproducibility with a short analysis time of 5 min and requires minimal operator skill. It is suited to screening breeders’ populations for gluten strength and is preferred over SIG, HPLC determination of UPP and IP% determination using a turbidity assay.Significance and noveltyThe GlutoPeak can be used to effectively screen out low‐intermediate gluten strength in a durum wheat breeders’ population using 9 g of wholemeal with a 5 min run time.

ИЗУЧЕНИЕ СОРТОВ И ЛИНИЙ ОЗИМОЙ ТВЕРДОЙ ПШЕНИЦЫ В КОНКУРСНОМ СОРТОИСПЫТАНИИ

The study of the varieties and lines of winter durum wheat in competitive variety-testing The article presents the study results of 15 varieties and lines of winter durum wheat in the competitive variety-testing of 2016-2017 in the main economic-valuable properties and traits. All studied samples belong to low-height forms (81-90 sm). The standard variety “Donchanka” has 3.9 points in resistance to lodging. The varieties “Yubilyarka”, “Agat Donskoy”, “Teya”, “Yakhont” and the lines “993/12”, “840/11”, “840/12” have more than 4.5 points of resistance. On average the assessment of plant wintering ranges from 3.7 to 4.5 points. The varieties “Amazonka”, “Kristella”, “Oniks”, “Diona” and the line “840/12” have the maximum mark of 4.5 points. Frost tolerance of the variety “Donchanka” has been taken as 100%. The following varieties could preserve on 2.9-24.4% more alive plants during wintering than the standard variety: “Amazonka” (+24.4%), “Oniks” (+18.4%), “Diona” (+16.8%), “Lazurit” (+9.5%), “Teya” (+5.9%), “Yantarina” (+4.8%), “Agat Donskoy” (+2.9%). The lowest frost resistance has been shown by the lines “840/11” (83.2%), “840/12” (52.5%) and “993/12” (79.9%). On average the productivity ranged from 7.40 to 8.89 t/ha during the years of study. The productivity of the lines “840/12” (8.42 т/га), “993/12” (8.74 т/га), the varieties “Kristella” (8.62 т/га), “Lazurit” (8.76 т/га), “Yantarina” (8.89 т/га) had more than one ton of increase. All studied varieties and lines have high indexes of nature weight, vitreousness and protein content in grain. There have been determined positive correlations of productivity with plant height and nature weight of winter durum wheat grain (correlation coefficient of 0.65 and 0.59 respectively).

First production of wild hemmer (Triticum turgidum ssp. dicoccoides) transgenic plants

Plant genetic transformation and regeneration has become a valuable research tool for functional genomics. A successful transformation event involves the transfer of the target gene into a suitable explant, the integration and expression of the transgene into the host genome and the regeneration of the fertile transgenic plants from the transformed tissues. Wheat is considered as a recalcitrant species even if many efforts have been done in recent years to improve transformation efficiency. The transformation of its progenitors has never been attempted, even though the possibility to transform wild hemmer represents a valuable tool to evaluate structural and functional variability occurring in wild hemmer and explaining its higher adaptation to abiotic stresses. In this paper we report, as far as we know, for the first time, the microparticle transformation of immature embryos of the wild hemmer Triticum dicoccoides with the Tapgip1 gene. The transformation method was successfully transferred from durum wheat and several transgenic lines were obtained. Its application for the exploitation of wheat progenitors for molecular breeding is of great relevance for genomic and functional genomics studies. This result, indeed, opens new perspectives in complementation studies for the comprehension of durum and bread wheat adaptation mechanisms to stresses.

Expresión de cistatinas y su relación con la resistencia a Tilletia indica en trigo.

Desde el punto de vista económico, el mejoramiento genético es una de las mejores opciones para combatir al carbón parcial causado por el hongo Tilletia indica. Las cistatinas son una familia de proteínas inhibidoras de proteasas cuyos patrones de expresión podrían explicar un mecanismo eficaz de resistencia a carbón parcial. Los objetivos de este estudio fueron evaluar la resistencia/susceptibilidad de líneas de trigo harinero (Triticum aestivum) y cristalino (T. turgidum ssp. durum) a T. indica y determinar los niveles de expresión relativa de genes de cistatinas; así como determinar la correlación de dicha expresión con la resistencia fenotípica. Se estableció un ensayo con 9 líneas de trigo harinero y 9 líneas de trigo cristalino con diferentes grados de resistencia. Se inocularon 30 espigas por línea con esporidios alantoides y se determinó el porcentaje de infección. Los genes de cistatinas (Wheat Cystatin) WC1, WC3 y WC5 fueron amplificados mediante un protocolo de PCR en tiempo real para cuantificar la expresión normalizada (ΔCt) de cistatinas. Posteriormente se obtuvo el coeficiente de correlación para la expresión normalizada y el porcentaje de infección. Los porcentajes de infección estuvieron dentro de los rangos de 15.85% a 36.78% en trigo harinero y de 0.19% a 54.87% en trigo cristalino. Además, los niveles de expresión normalizada de cistatinas fueron comparativamente mayores en líneas resistentes (P>0.05). Se presentaron coeficientes de correlación significativos (P<0.05) de los genes WC3 y WC5 durante todas las etapas de muestreo, destacándose en estado vegetativo (0.969), embuche (0.841) y post-antesis (-0.789).

Evaluation of Claviceps purpurea isolates on wheat reveals complex virulence and host susceptibility relationships

Ergot of cereals, caused by Claviceps purpurea, results in yield loss and downgrading of infested grain because of toxic alkaloids in the sclerotia. Resistant wheat genotypes are known, but their effectiveness against different C. purpurea isolates over geographic regions has not been studied. The objective of this study was to examine the pathogenic variability among isolates of C. purpurea on wheat lines differing in resistance. Under controlled environmental conditions, 41 single spore isolates of C. purpurea were obtained from Canadian and UK collections and inoculated onto a set of wheat genotypes composed of durum wheat lines ‘Melita’, ‘Kyle’ and 9260B-173A, and hexaploid spring wheat lines ‘Cadillac’, ‘Vista’, ‘Kenya Farmer’, ‘Lee’ and HY630. Honeydew production and weight of sclerotia produced per spike were assessed. There were significant differences among the wheat genotypes for overall reactions to the pathogen isolates, and among pathogen isolates for geographic origin and host origin. Twenty virulence phenotypes were identified using the honeydew production data, and 23 virulence phenotypes identified using the sclerotial weight data from the 41 isolates. The existence of different virulence phenotypes indicates that variability in virulence exists in populations of C. purpurea, and knowledge of virulence phenotypes is necessary to effectively breed for resistant commercial lines.

Understanding the Effects of Genotype, Growing Year, and Breeding on Tunisian Durum Wheat Allergenicity. 2. The Celiac Disease Case.

The aim of this study was to compare immunogenic and toxic gluten peptides related to celiac disease (CD). 100 accessions of genotypes selected during the 20th century in Tunisia were in vitro digested and then analyzed by UPLC/ESI-MS technique using an isotopically labeled internal standard. The first MANOVA confirmed a high variability in the content of immunogenic and toxic peptides reflecting high genetic diversity in the germplasm released during the past century in Tunisia, consistently with PCA and clustering analysis results. Our finding showed also important variability in CD epitopes due to growing season's climate scenarios. Moreover, the second MANOVA revealed significant differences between abandoned and modern cultivars' CD-related peptide amounts. Although we could not conclude that there was an augment of allergens in newly selected durum wheat lines compared to abandoned ones, we demonstrated that modern genotype peptides were less sensitive to climate variation, which is a useful indicator for wheat breeders.

Genome-wide association mapping for seedling and field resistance to Puccinia striiformis f. sp. tritici in elite durum wheat

Genome-wide association analysis in tetraploid wheat revealed novel and diverse loci for seedling and field resistance to stripe rust in elite spring durum wheat accessions from worldwide. Improving resistance to stripe rust, caused by Puccinia striiformis f. sp. tritici, is a major objective for wheat breeding. To identify effective stripe rust resistance loci, a genome-wide association study (GWAS) was conducted using 232 elite durum wheat (Triticum turgidum ssp. durum) lines from worldwide breeding programs. Genotyping with the 90K iSelect wheat single nucleotide polymorphism (SNP) array resulted in 11,635 markers distributed across the genome. Response to stripe rust infection at the seedling stage revealed resistant and susceptible accessions present in rather balanced frequencies for the six tested races, with a higher frequency of susceptible responses to United States races as compared to Italian races (61.1 vs. 43.1% of susceptible accessions). Resistance at the seedling stage only partially explained adult plant resistance, which was found to be more frequent with 67.7% of accessions resistant across six nurseries in the United States. GWAS identified 82 loci associated with seedling stripe rust resistance, five of which were significant at the false discovery rate adjusted P value <0.1 and 11 loci were detected for the field response at the adult plant stages in at least two environments. Notably, Yrdurum-1BS.1 showed the largest effect for both seedling and field resistance, and is therefore considered as a major locus for resistance in tetraploid wheat. Our GWAS study is the first of its kind for stripe rust resistance in tetraploid wheat and provides an overview of resistance in elite germplasm and reports new loci that can be used in breeding resistant cultivars.

DURUM WHEAT RESISTANCE TO BLACK POINT

The search for effective sources of wheat immunity to common diseases in the Altai Region and the inclusion of the most valuable donors in breeding programs are the most important components of a strategy to create new varieties resistant to pathogens. The black point disease causing the darkening the grain germ is found in all regions where Triticum durum Desf. is cultivated. We studied 58 varieties and lines of spring durum wheat of different geographic origin for resistance to black point in the Priobskaya (the Ob River) forest-steppe of the Altai Region. A wide range of genotypes on the resistance to the disease was revealed. Growing season conditions were comparable with genotype contribution to the manifestation of black point: the proportion of the influence of "genotype" and "growing conditions" factors accounted for 45.8 and 41.1%, respectively. Interaction of the factors was 13.1%. Accessions with the lowest development of infection have been identified. Varieties from Altai Research Institute of Agriculture, Orenburg Research Institute of Agriculture, Donۥs Zonal Research Institute of Agriculture, Siberian Research Institute of Agriculture are characterized by a low level of black point damage (5.84 – 7.36%). The sources of resistance, according to the economic and biological evaluation have no negative characteristics and properties that prevent their using in programs for resistance to black point.