Turgidum Var Research Articles

Growth, yield and grain quality responses of Durum Wheat (Triticum turgidum var. durum) cultivars to irrigated and rain-fed production systems at Debre Zeit, central Ethiopia

Growth, yield and grain quality responses of Durum Wheat (Triticum turgidum var. durum) cultivars to irrigated and rain-fed production systems at Debre Zeit, central Ethiopia

Portable optical spectroscopy and machine learning techniques for quantification of the biochemical content of raw food materials

BackgroundAccuracy in determining food authenticity, possible contamination, content analysis, and even geographical origin is of considerable scientific and economic value. The aim of this study is to facilitate quantitative evaluation of protein content in the seeds of cereals (Triticum turgidum var. durum and Tritordeum genotypes) and ripening pomegranate fruits (Wonderful cultivar).MethodsTwo species of wheat were evaluated in this study: durum wheat, Triticum turgidum var. durum, and Tritordeum (durum wheat × wild barley) together with pomegranate fruits of the variety Wonderful. Two different portable Near InfraRed (NIR) spectrometers have been used: a prototype developed in the PhasmaFood project and the commercial SCiO™ molecular sensor.ResultsConsidering the specific samples, the obtained results of the classification models indicate a validation mean absolute error of 0.8% (percentage of total protein content in dry matter) for two species of wheat using Convolutional Neural Network following normalization procedures and 0.32% using Partial Least Square (PLS) analysis applied to Tritordeum samples; visible reflectance spectra have been used to discriminate the two cereal species. A Root Mean Square Error (RMSE) of 1.25 was obtained for the determination of total soluble solids (TSS) over a 2-year period for pomegranate fresh fruits of Wonderful cultivar, which is commonly harvested with TSS values of 16–17.ConclusionsThe application of portable sensors using NIR spectroscopy can be a valid and rapid alternative to the use of destructive laboratory techniques for the assessment of protein content in intact wheat seeds and ripeness grade (TSS) in intact pomegranates.

Identification of Novel Broad-Spectrum Leaf Rust Resistance Sources from Khapli Wheat Landraces.

Wheat leaf rust caused by Puccinia triticina Eriks is an important disease that causes yield losses of up to 40% in susceptible varieties. Tetraploid emmer wheat (T. turgidum ssp. Dicoccum), commonly called Khapli wheat in India, is known to have evolved from wild emmer (Triticum turgidum var. dicoccoides), and harbors a good number of leaf rust resistance genes. In the present study, we are reporting on the screening of one hundred and twenty-three dicoccum wheat germplasm accessions against the leaf rust pathotype 77-5. Among these, an average of 45.50% of the germplasms were resistant, 46.74% were susceptible, and 8.53% had mesothetic reactions. Further, selected germplasm lines with accession numbers IC138898, IC47022, IC535116, IC535133, IC535139, IC551396, and IC534144 showed high level of resistance against the eighteen prevalent pathotypes. The infection type varied from “;”, “;N”, “;N1” to “;NC”. PCR-based analysis of the resistant dicoccum lines with SSR marker gwm508 linked to the Lr53 gene, a leaf rust resistance gene effective against all the prevalent pathotypes of leaf rust in India and identified from a T. turgidum var. dicoccoides germplasm, indicated that Lr53 is not present in the selected accessions. Moreover, we have also generated 35K SNP genotyping data of seven lines and the susceptible control, Mandsaur Local, to study their relationships. The GDIRT tool based on homozygous genotypic differences revealed that the seven genotypes are unique to each other and may carry different resistance genes for leaf rust.

Creation and breeding value of introgressive forms, obtained by hybridizations of Triticum Spelta L. × Triticum turgidum subsp. dicoccum (Schrank ex Schübl.) Thell.

The aim of the research was to expand the genetic diversity of spelt wheat by introgression of genetic material of the species Triticum turgidum subsp. dicoccum (Schrank ex Schübl.) Thell. and to create on this basis new source material. Materials and methods. The study was conducted during 2016–2022 in the conditions of Uman National University of Horticulture, located in the zone of the Right-Bank Forest-Steppe of Ukraine, in the subzone of unstable moisture. The source material was winter spelt wheat variety Zoria Ukrainy (maternal form) and the sample Triticum turgidum subsp. dicoccum (Schrank ex Schübl.) Thell. (pollinator). The research used the common technology of growing winter cereals. Sowing was carried out in the optimal time for the zone – the third decade of September. All records and observations were performed in accordance with generally accepted methods. In work was used a systematic method of plot placement with four repetitions. Results. As a result of the conducted researches a number of introgressive lines of spelled wheat with different level of manifestation of morphological and economically valuable features was created. The created samples according to the morphology of the ear are divided into morphotypes of spelt, emmer and intermediate forms. Conclusions. As a result of the conducted researches the technology of creation of initial breeding material at distant hybridization of Triticum spelta L. × Triticum turgidum var. dicoccoides. Valuable high-yielding samples were obtained using introgressive breeding. It was found that the highest frequency of transgression in the second and third generations was recor­ded by the weight of grain from the ear (19.1–20.0%). Materials with a yield (535.2 g/m2) and a weight of 1000 grains (44.8 g) significantly exceeded the standard (sample 230), as well as protein (20.4%) and gluten (44.0%) significantly exceeded the standard (sample 227). The selected samples will be used by donors of genes of econo­mically valuable traits in breeding schemes for the creation source material of spelt wheat.

Fine mapping of powdery mildew resistance gene MlWE74 derived from wild emmer wheat (Triticum turgidum ssp. dicoccoides) in an NBS-LRR gene cluster.

Powdery mildew resistance gene MlWE74, originated from wild emmer wheat accession G-748-M, was mapped in an NBS-LRR gene cluster of chromosome 2BS. Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a globally devastating disease. Wild emmer wheat (Triticum turgidum var. dicoccoides) is a valuable genetic resource for improving disease resistance in common wheat. A powdery mildew resistance gene was transferred to hexaploid wheat line WE74 from wild emmer accession G-748-M. Genetic analysis revealed that the powdery mildew resistance in WE74 is controlled by a single dominant gene, herein temporarily designated MlWE74. Bulked segregant analysis (BSA) and molecular mapping delimited MlWE74 to the terminal region of chromosome 2BS flanking by markers WGGBD412 and WGGBH346 within a genetic interval of 0.25cM and corresponding to 799.9kb genomic region in the Zavitan reference sequence. Sequence annotation revealed two phosphoglycerate mutase-like genes, an alpha/beta-hydrolases gene, and five NBS-LRR disease resistance genes that could serve as candidates for map-based cloning of MlWE74. The geographical location analysis indicated that MlWE74 is mainly distributed in Rosh Pinna and Amirim regions, in the northern part of Israel, where environmental conditions are favorable to the occurrence of powdery mildew. Moreover, the co-segregated marker WGGBD425 is helpful in marker-assisted transfer of MlWE74 into elite cultivars.

Effects of Blended Fertilizer Type and Rates of Application on Yield and Quality of Durum Wheat (<i>Triticum turgidum var. durum</i>) in Southeastern Ethiopia

There are several biotic and abiotic factors that hindered the yield and quality of durum wheat in Ethiopia. To solve the problem, the field experiment was conducted during the 2020/21 cropping season to determine the effect of blended fertilizer type and rate of fertilizer application on the yield and quality of durum wheat in South Eastern Ethiopia. The experiment was laid out in randomized complete block design (RCBD) with three replications in factorial arrangement of three different blended fertilizer type (NPS, NPSB and NPSZnB) and four different rates (50 kg/ha, 100 kg/ha, 150 kg/ha and 200 kg/ha) of fertilizer application and one control in each replication. The results indicated that straw yield, Gluten content and protein content were significantly (P>0.05) affected by the main effect of different blended fertilizer type and rates of fertilizer application significantly (P>0.05) whereas harvest index of the wheat are significantly affected only by the different rates of fertilizer application but the productive tiller number, number of seed per spike and spike length were non significantly (P>0.05) affected by the different blended fertilizer type and rates of fertilizer application. More over the interaction effect of different blended fertilizer type and rate of fertilizer application on wheat yield and quality was affects the plant height, biomass yield, thousand seed weight and Grain yield was significant difference (P>0.05) but all other parameters were not affected by the interaction of different fertilizer type and rates of fertilizer application. Therefore based on the result of yield and quality of the durum wheat sown with NPS had better protein quality than the other fertilizer applied. The interactive effect of NPSZnB with 200 kg ha^-1 fertilizer rate was superior for achieving higher yield in the study area. However, further study has to be done under different locations based on the soil test with a wide range of different micronutrients and rates of fertilizer application to exploit the tentative recommendation of the present study.

MORPHO-AGRONOMIC, CYTOGENETIC AND MOLECULAR CHARACTERIZATION OF SYNTHETIC WHEAT ACCESSIONS AS A POTENTIAL GERMPLASM FOR PLANT BREEDING

Synthetic hexaploid wheat (AABBDD) is produced by using the tetraploid Triticum turgidum var. durum (AABB) and the diploid Aegilops tauschii (DD) as parents. This cross has allowed genetic variability to be transferred from parental to other wheat hexaploid accessions, lines or cultivars. This transference may occur not only of variable disease resistance genes but also traits involving quality and tolerance to abiotic stresses. We evaluated and characterized the genetic diversity and stability of synthetic wheat accessions that can be used in breeding programs due to the presence of desirable characteristics. Fifty synthetic accessions were investigated regarding their morphological and agronomic characteristics, presence of micronuclei in tetrads and genetic similarity based on molecular markers. Four commercial cultivars were used as controls. Depending on their proposed use, some genotypes were characterised as suitable for breeding programs based on their morphological traits, genetic stability or genetic diversity, or because of a combination of these factors.

Assessment of flag leaf water status as drought tolerance discriminating trait in durum wheat (Triticum turgidum var durum L.)

Drought is a prominent limiting factor that impacts negatively durum wheat grain yield. Ten durum wheat breeding lines were evaluated under rainfall conditions at the Field Crop Institute Agricultural Experimental Station of Setif, Algeria, during the 2016/2017 cropping season. The investigation aimed to study the ability of flag leaf water status to discriminate among varieties for drought tolerance trait. Significant variability was observed among the tested varieties for leaf dry, wilted and turgid weights, leaf relative water content, water saturation deficit and excised water loss, after three wilting periods of 30, 60 and 90 minutes dehydration at 40°C. The assessed breeding lines were differentially categorized as drought tolerant and drought sensitive based on either relative water content or water saturation deficit or excised leaf water loss genotypic mean values. Correlation, principal components and cluster analyses indicated an unwanted significant association between excised leaf water loss and relative water content and water saturation deficit and classified the assessed entries into three clusters (CI, C2 and C3). Cluster C1 had high relative water content, low water saturation deficit but high excised water loss, while C3 had low relative water content, low excised leaf water but high-water saturation deficit, C2 being intermediate. Crosses between distant clusters (C1 vs C3) are proposed to generate more variability of the targeted traits in progeny population and to break undesirable linkage between alleles controlling leaf water status, allowing to select efficiently drought tolerant genotypes.

First report of blast of durum wheat in Bangladesh, caused by Magnaporthe oryzae pathotype Triticum

Durum wheat (Triticum turgidum var. durum Desf.) is an important cereal crop in many regions of the world. In March of 2018 and 2019, symptoms typical of blast were frequently observed on durum wheat plants under field conditions in Jashore, Bangladesh. The putative causal pathogen was isolated from infected wheat spike specimens onto potato dextrose agar and oatmeal agar, and was identified from mono-conidium cultures as Magnaporthe oryzae, based on morphological features. The pathotype of the fungus was identified as Triticum, based on comparative molecular analyses of ITS sequences and MoT3 specific markers. BLAST analysis revealed >99.8% similarity with M. oryzae/P. oryzae, retrieved from the NCBI Genebank. This was confirmed through amplification of the predicted products with MoT3 primers in PCR analysis. Pathogenicity was confirmed by inoculating healthy durum wheat seedling leaves and spikes with a conidium suspensions of M. oryzae isolate DuBWMRI1901.2A. The fungus produced similar symptoms on inoculated leaves and spikes as those observed in the field, and was subsequently re-isolated, fulfilling Koch’s postulates. This is the first report of blast of durum wheat caused by Magnaporthe oryzae pathotype Triticum in Bangladesh.

Improving Grain Micronutrient Content of Durum Wheat (Triticum turgidum var. durum) through Agronomic Biofortification to Alleviate the Hidden Hunger

Improvement of durum wheat grain quality through agronomic biofortification becomes a priority research area and an effective route to combat malnutrition. An experiment was conducted to evaluate the effect of micronutrient application to different varieties of durum wheat and seeding rate on final harvest grain quality under different growing locations. The treatments were arranged in split-split plot design where the varieties were assigned in the main plot, micronutrients into the subplots, and seeding rate into the sub-subplots. Each variety was sown at four levels of seeding rates and treated with ZnSO₄ and FeSO4 applied foliarly, both at a rate of 25 Kg ha−1 during flowering. Micronutrients were applied in the form of ZnSO₄ 7H2O and FeSO₄ 7H2O. The study confirmed that application of 25 Kg ha−1 ZnSO₄-containing fertilizer has increased mineral content from 33.04 mg Kg−1 to 56.73 mg kg−1. The tested durum wheat varieties significantly differ in their capacity to accumulate grain Zn and Fe concentrations. Higher amount of Zn (20 mg kg−1) and Fe (10 mg kg−1) were accumulated by the landrace 208304 than by Asassa, an improved commercial variety. Increasing seeding rate from 100–175 Kg ha−1 has reduced grain Zn and Fe concentrations. Grain mineral concentration was significantly lower at the Mekelle location than at the Melfa location. It can be concluded that foliar application of ZnSO₄ and FeSO4 to the landrace, acc.208304, combined with 125 Kg seeds ha−1 can produce better Zn and Fe denser durum wheat grain. This will help to combat the hidden hunger, especially in resource poor countries, where fortified foods are limited in access and unaffordable by small-scale farmers.

Characterization of Resistance to Cereal Cyst Nematode, Agronomic Performance, and End-Use Quality Parameters in Four Perennial Wheat-Thinopyrum intermedium Lines.

Perennial wheat is considered to be a practical way to increase the flexibility and profitability of sustainable agricultural system, as it can be either a forage grass or a grain crop. Four perennial wheat lines SX12-480, SX12-787, SX12-1150, and SX12-1269 were developed from a series of interspecific crosses between common wheat (Triticum aestivum, 2n = 42) or durum wheat (T. turgidum var. durum, 2n = 28) and the intermediate wheatgrass (Thinopyrum intermedium, 2n = 42). These lines were characterized by the vigorous regrowth for at least 3 years. The one- and 2-year-old plants had higher grain yield potential than the 3-year-old perennial plants. The decline of grain yield was associated with plant age-related effects on yield components. The perennial wheat lines were all resistant to both Heterodera avenae and H. filipjevi, the two distinct cereal cyst nematode species that occur in China, except that line SX12-787 exhibited moderate resistance only to H. avenae. The dual-purpose perennial wheat lines were evaluated for quality values of both defoliated grass and harvested grains in the form of amino acid profile, mineral concentration, and contents of protein and fiber. Difference in the quality profile was observed between the perennial lines. These perennial lines had an overall improved quality levels over those of the perennial wheat control Montana-2 (T. turgidum × Th. intermedium) and the annual wheat cultivar Jinchun 9. The amplification profiles of the molecular markers provided molecular evidence for the introgression of alien chromatin. Genomic in situ hybridization detected 16, 14, 14, and 12 Th. intermedium chromosomes in lines SX12-480 (2n = 48), SX12-787 (2n = 56), SX12-1150 (2n = 56), and SX12-1269 (2n = 54), respectively, in addition to either 32 or the complete set of wheat chromosomes. The four perennial wheat-Th. intermedium lines described here provide valuable sources of perennial wheat for the dual-purpose application of both grain and forage.

Profiles of wheat rhizobacterial communities in response to repeated glyphosate applications, crop rotation, and tillage

Due to widespread adoption of no-till management and use of glyphosate-resistant transgenic crops, glyphosate is the most widely used herbicide worldwide. However, its effect on soil microbial communities is inconsistent. We studied the effects of glyphosate, tillage, and crop rotation on the diversity and composition of soil bacterial communities in wheat (Triticum turgidum var. durum Desf.) rhizosphere after 6 and 7 yr of glyphosate applications. In a 2 × 2 × 2 factorial design, there were two crop rotation treatments: continuous wheat (W–W) and wheat in rotation with field pea (Pisum sativum L.) (P–W); two tillage treatments: minimum tillage (MT) and no-till (NT); and two glyphosate treatments: no application or pre-seeding application at the recommended rate. None of the treatments affected wheat rhizobacterial α-diversity or the relative abundances of most bacterial groups. The most abundant phyla were Proteobacteria (25.1% relative abundance), Actinobacteria (21.7%), Acidobacteria (8.7%), Bacteroidetes (5.9%), Firmicutes (1.4%), Armatimonadetes (1.3%), and Verrucomicrobia (1.2%). Glyphosate reduced the relative abundance of Alphaproteobacteria in W–W rotation but increased it in P–W rotation, and it reduced the relative abundance of Opitutus spp. The W–W rotation had greater relative abundances of the classes Bacilli (Firmicutes) and Gammaproteobacteria, and genera Bacillus and Opitutus (Verrucomicrobia), than the P–W rotation. Compared with MT, NT increased the relative abundance of the phylum candidate division WPS-1, but it reduced that of Phenylobacterium spp. in W–W rotation. These treatment effects probably had implications for soil functioning, including nutrient cycling and biological disease/pest control.

Variability among Ethiopian durum wheat genotypes grown under different climatic conditions of Tigray for some agronomic and grain-quality traits

ABSTRACT The lack of adaptable varieties is the major problem for durum wheat (Triticum turgidum var. durum) production in Ethiopia. The variability in 36 durum wheat genotypes was studied for key traits across locations to select genotypes possessing optimal grain quality and high grain yield for production in northern Ethiopia, using a simple lattice design. Variation attributable to genotypes (G), locations (L) and G × L interaction was significant for the studied traits (p < 0.001). Mean grain protein content (GPC) among genotypes ranged from 9.4% to 12.9%. Genotypes 208312 (G17) and 208168 (G22) had mean GPC of 12.9% and 12.8%, respectively. Grain with high GPC (12.7%–21.3%) was harvested from Beati-Maymesanu (BMM), a terminal drought-affected location, whereas the lowest GPC range (5.5%–10.5%) was recorded at Agarba. This implied that water stress during the reproductive growth stage of durum wheat could increase GPC. Similarly, high gluten index (GI) (68%–95%) was obtained at BMM, whereas the frequency of genotypes with low GI (<60%) was high (n = 14) at Agarba. Genotypes with higher GPC and GI tended to have lower grain yield (GY). This negative association constrains breeding efforts to combine high GY with high GPC and GI. However, some genotypes, mainly farmers' varieties (FVs), had combined high GY with the modest value of GPC and GI. FVs SSD2, 248478, 222426, and 208873 and the improved varieties Asassa and Quamy were suitable as parents for making crosses to generate new genotypes with high GY, GPC, and GI.

Phenolic compounds and allelopathic activities of ancient emmer wheats: perspective for non-chemical weed control scenarios

Phenolic compounds are natural phytotoxins which play role as chemical defense compounds in wheat species. However, the contribution and role of phenolic compounds in ancient and modern wheat genotypes for plant-to-plant interference are equivocal. Biological screening of seven wheat genotypes including five emmer wheat genotypes of Triticum turgidum ssp. dicoccum (Zarneh, Singerd, Shahrekord, Khoygan and Joneghan), one modern hexaploid wheat genotype (Triticum aestivum var. Roushan) and one modern tetraploid wheat genotype (Triticum turgidum var. Yavaroos) demonstrated that all wheat genotypes suppressed the seedling growth of Raphanus sativus L. by shoot aqueous extract in a dose–response bioassay. Modern hexaploid wheat genotypes along with ancient tetraploid emmer wheat genotypes possessed a high allelopathic capability. High-performance liquid chromatography diode array detection analysis of aqueous extracts indicated that the ability to synthesise polyphenolic compounds is different among genotypes. The total amount of polyphenolics and flavonoid compounds in shoot aqueous showed a significant correlation to the R. sativus growth suppression. These results suggest that the number of polyphenolics in general and syringic acid in particular may have contributed to the allelopathic effects of ancient tetraploid and modern hexaploid wheat genotypes. At the same time, results showed that ancient tetraploid emmer wheat may offer promising values for their unique composition of allelochemicals, indicating their potential in sustainable crop production systems.

Evaluation of genotype × environment interaction in durum wheat (Triticum turgidum var. durum L.) regional yield trials

Evaluation of genotype × environment interaction in durum wheat (Triticum turgidum var. durum L.) regional yield trials

Multi-Trait, Multi-Environment Genomic Prediction of Durum Wheat With Genomic Best Linear Unbiased Predictor and Deep Learning Methods.

Although durum wheat (Triticum turgidum var. durum Desf.) is a minor cereal crop representing just 5–7% of the world’s total wheat crop, it is a staple food in Mediterranean countries, where it is used to produce pasta, couscous, bulgur and bread. In this paper, we cover multi-trait prediction of grain yield (GY), days to heading (DH) and plant height (PH) of 270 durum wheat lines that were evaluated in 43 environments (country–location–year combinations) across a broad range of water regimes in the Mediterranean Basin and other locations. Multi-trait prediction analyses were performed by implementing a multi-trait deep learning model (MTDL) with a feed-forward network topology and a rectified linear unit activation function with a grid search approach for the selection of hyper-parameters. The results of the multi-trait deep learning method were also compared with univariate predictions of the genomic best linear unbiased predictor (GBLUP) method and the univariate counterpart of the multi-trait deep learning method (UDL). All models were implemented with and without the genotype × environment interaction term. We found that the best predictions were observed without the genotype × environment interaction term in the UDL and MTDL methods. However, under the GBLUP method, the best predictions were observed when the genotype × environment interaction term was taken into account. We also found that in general the best predictions were observed under the GBLUP model; however, the predictions of the MTDL were very similar to those of the GBLUP model. This result provides more evidence that the GBLUP model is a powerful approach for genomic prediction, but also that the deep learning method is a practical approach for predicting univariate and multivariate traits in the context of genomic selection.

Performance Evaluation and Adaptability Study of Durum Wheat (Triticum turgidum var. durum) Varieties in Moisture Stress Areas of East Hararghe, Oromia

Seven Durum wheat varieties were evaluated at Faddis Agricultural Research Center (FARC) at Boko research station during 2013/14 cropping season. The results revealed that the tested Durum wheat varieties differed significantly for grain yield, plant height, spike length and seed per spike. Among the varieties Mangudo, Ude, Dembi and Asassa produced higher grain yield (3387.5, 3345.8, 3112.5 and 3101.4kg ha-1, respectively). Durum wheat varieties Yerer recorded maximum spike length (6.5cm) variety Mangudo recorded minimum spike length (4.5cm) whereas variety Mangudo recorded maximum seed per spike followed by Ude (58 and 54 respectively). Among the tested varieties Mangudo, Ude and Dembi recorded higher grain yields and maximum seed per spike and were good performing varieties in the study area.

Wheat powdery mildew resistance gene Pm64 derived from wild emmer (Triticum turgidum var. dicoccoides) is tightly linked in repulsion with stripe rust resistance gene Yr5

Stripe rust and powdery mildew are both devastating diseases for durum and common wheat. Pyramiding of genes conferring resistance to one or more diseases in a single cultivar is an important breeding approach to provide broader spectra of resistances in wheat improvement. A new powdery mildew resistance gene originating from wild emmer (Triticum turgidum var. dicoccoides) backcrossed into common wheat (T. aestivum) line WE35 was identified. It conferred an intermediate level of resistance to Blumeria graminis f. sp. tritici isolate E09 at the seedling stage and a high level of resistance at the adult plant stage. Genetic analysis showed that the powdery mildew resistance in WE35 was controlled by a dominant gene designated Pm64. Bulked segregant analysis (BSA) and molecular mapping indicated that Pm64 was located in chromosome bin 2BL4-0.50–0.89. Polymorphic markers were developed from the corresponding genomic regions of Chinese Spring wheat and wild emmer accession Zavitan to delimit Pm64 to a 0.55 cM genetic interval between markers WGGBH1364 and WGGBH612, corresponding to a 15 Mb genomic region on Chinese Spring and Zavitan 2BL, respectively. The genetic linkage map of Pm64 is critical for fine mapping and cloning. Pm64 was completely linked in repulsion with stripe rust resistance gene Yr5. Analysis of a larger segregating population might identify a recombinant line with both genes as a valuable resource in breeding for resistance to powdery mildew and stripe rust.

The Hydrogen Isotope Composition δ2H Reflects Plant Performance.

The stable carbon (δ13C) and oxygen (δ18O) isotope compositions in plant matter reflect photosynthetic and transpirative conditions in plants, respectively. However, the nature of hydrogen isotope composition (δ2H) and what it reflects of plant performance is poorly understood. Using durum wheat (Triticum turgidum var durum), this study evaluated the effect of different water and nitrogen growing field conditions on transpiration and how this effect influenced the performance of δ2H in autotrophic (flag leaf), mixotrophic (ears), and heterotrophic (grains and roots) organs. Moreover, δ2H was compared with the δ13C and δ18O in the same organs. Isotope compositions were analyzed in dry matter, the water-soluble fraction, and in water from different tissues of a set of genotypes. Similar to δ13C, the δ2H correlated negatively with stomatal conductance, whereas no correlation was observed for δ18O. Moreover, δ2H was not only affected by changes in transpiration but also by photosynthetic reactions, probably as a consequence of NADPH formation in autotrophic organs. Compared with the δ2H of stem water, plant δ2H was strongly diminished in photosynthetic organs such as the flag leaves, whereas it strongly increased in heterotrophic organs such as grains and roots. In heterotrophic organs, δ2H was associated with postphotosynthetic effects because there are several processes that lead to 2H-enrichment of carbohydrates. In summary, δ2H exhibited specific features that inform about the water conditions of the wheat crop, together with the photosynthetic characteristics of the plant part considered. Moreover, correlations of δ2H with grain yield illustrate that this isotope can be used to assess plant performance under different growing conditions.

Genetic architecture of yellow and stem rust resistance in a durum wheat diversity panel

Winter durum (Triticum turgidum var. durum) growing is favored in Germany, Austria, and Hungary. With the invasion of the aggressive Warrior race with a wider virulence spectrum of the yellow rust (YR) causing pathogen, YR came into focus of durum breeders. Accordingly, a local epidemic of stem rust in winter wheat 2013 gained much attention. Therefore, we aimed to analyze the genetic architecture of resistance to YR and stem rust (SR) in a diversity panel of 328 durum lines genotyped by 12,550 mapped markers. Infections were successful in three environments for YR and one environment for SR. Additionally, cumulative ratings of leaf and ear health were conducted in five and three environments, respectively. The genome-wide association analysis revealed six to eight quantitative trait loci (QTL) per trait with an explained total genotypic variance of 42% (YR) to 75% (ear health). Sequence comparison with a reference genome indicated that three YR (Yr10, Yr51, YrH9014) and two SR (Sr56, Sr8155B1) resistance genes might be present in the diversity panel. Other QTL with explained genotypic variances ranging from 1.5 to 21% were detected. The difference between marker-assisted selection and genomic prediction was the highest for those traits with lower explained genetic variance (YR, leaf health) indicating that an array of non-detected QTL was used for genomic prediction. Genomics-assisted breeding could greatly help in achieving complex resistances in cultivars.