Production of aneuhaploid and euhaploid sporocytes by meiotic restitution in fertile hybrids between durum wheat Langdon chromosome substitution lines and Aegilops tauschii

Fertile F1 hybrids were obtained between durum wheat （Triticum durum Desf.） Langdon （LDN） and its 10 disomic substitution （LDN DS） lines with Aegilops tauschii accession AS60 without embryo rescue. Selfed seedset rates for hybrids of LDN with AS60 were 36.87% and 49.45% in 2005 and 2006, respectively. Similar or higher selfed seedset rates were observed in the hybrids of 1D （1A）, 1D （1B）, 3D （3A）, 4D （4B）, 7D （7A）, and 2D （2B） with AS60, while lower in hybrids of 3D （3B） ＋ 3BL, 5D （5A） ＋ 5AL, 5D （5B） ＋ 5B and 6D （6B） ＋ 6BS with AS60 compared with the hybrids of LDN with AS60. Observation of male gametogenesis showed that meiotic restitution, both first-division restitution （FDR） and single-division meiosis （SDM） resulted in the formation of functional unreduced gametes, which in turn produced seeds. Both euhaploid and aneuhaploid gametes were produced in F1 hybrids. This suggested a strategy to simultaneously transfer and locate major genes from the ancestral species T. turgidum or Ae. tauschii. Moreover, there was no significant difference in the aneuhaploid rates between the F1 hybrids of LDN and LDN DS lines with AS60, suggesting that meiotic pairing between the two D chromosomes in the hybrids of LDN DS lines with AS60 did not promote the formation of aneuhaploid gametes.

Effect of Lead Toxicity on Germination and Enzymatic Activity of Durum Wheat Triticum durum Desf.

The aim of this work is to identify the effect of lead on germinal parameters and the antioxidant enzyme activities （lipase, peroxidase and catalase） in durum wheat Triticum durum Desf. cv （waha, vitron and gta） exposed to the concentrations of 0, 0.15, 0.25 and 0.3 g/L of Pb （NO3）2 during germination process. The obtained results showed that lead reduced the germination, root and aerial biomass. The concentration of 0.3 g/L inhibited completely the germination of the three varieties. It also slowed lipase activity, the degradation of lipids of the seed＇s reserves and disrupted the metabolism of peroxidase and catalase. Concerning the behavior of the three varieties studied, it appears that the Vitron is the best predisposed variety to stand against lead stress by its strong antioxidant defense system.

The Effect of Weather and Agronomic Practice on Deoxynivalenol Mycotoxin in Durum Wheat

Deoxynivalenol （DON） produced by Fusarium graminearum and F. culmorum in durum wheat （Triticum turgidum L. var. durum） is an important food safety issue for the cereal chain. A number of agronomic practices are known to affect the infection and mycotoxin production by these Fusarium species in cereal grains. A field study was conducted to compare the natural occurrence of DON in durum wheat grown under conventional （n = 67 samples） and organic （n = 50） farming conditions during two consecutive crop years. DON mean levels were 95 and 194 μg/kg in conventional and organic durum wheat, respectively. The incidence and levels of DON were higher in the second crop year due to higher rainfall （〉 100 mm） during flowering. Overall, organically managed farming system may provide Lsome reduction in DON levels in durum wheat, which could be attributable to the lower intensity of cultivation in addition to the different system of cropping rotation. However, favourable weather conditions are likely to be more important for DON contamination than crop system.

Effect of Weather on Grain Quality Traits of Durum Wheat Grown in the Northern Plains of USA

The objective of this research was to determine the effect of genotype and growing environment, particularly weather, on grain quality traits of durum wheat using nine genotypes (Alkabo, Carpio, Divide, Grenora, Joppa, Maier, Mountrail, Pierce, and Tioga) grown in four years (2012-2015) at six locations in North Dakota, USA. The results of this research indicated that grain test weight, 1000-kernel weight, protein content, kernel vitreousness, and falling number were affected more by environment than by genotype. However, genotypes within an environment differed in the magnitude of their response and this difference could be used to select genotypes in a breeding program to improve quality. For a given quality trait, the magnitude of the response reflects the stability of the trait to changes in the environment. In general, the quality of durum wheat grown in the northern plains of USA was favored by warm daytime temperature, low night temperature, and low relative humidity. Growing locations with high maximum air temperature and a high number of days with temperature ≥ 30°C had a positive effect on grain protein content and falling number, while a high number of days with night time temperature ≤ 13°C were ideal for 1000-kernel weight. Low rainfall and low relative humidity promoted a high falling number and vitreous kernel content. The results of this study suggested that genotypes could be selected based on their overall quality and their stability across environments. Trait stability could be an important consideration when growers select genotypes for planting in their fields.

Durum Wheat Bread： Old Sicilian Varieties and Improved Ones

In Mediterranean countries and particularly in Southern Italy, durum wheat （Triticum durum Desf.） is traditionally used for bread production. Market globalization has created, also in these regions, the spread of bread made with soft wheat flour （Triticum aestivum L.） standardizing this product flattening consumers＇ taste. With the aim of re-evaluating the old Sicilian local varieties, some landraces, chosen from the genebank of the institute, have been multiplied on farmers＇ fields to have enough material for making bread and for comparing this product with bread made by improved new varieties. Before milling in the pilot plant, the different wheats were characterized for their merceological indexes. The semolina obtained was analyzed for its chemical parameters. Rheological tests were conducted on dough and, finally, using standardized methods, one-variety breads were produced. On the bread slices, computerized image analysis was performed to measure colour and morphological parameters of crumb and crust. Sensory analysis, achieved through a descriptive profiling test, was conducted with trained judges using touch, fragrance and taste attributes for the different bread types. The different merceological, chemical and theological properties of raw material, grain and semolina were reflected in the breads prepared using old or improved varieties. Finally, the data obtained pointed out that the bread prepared with old and improved varieties can be clearly distinguished both by objective morphological parameters （image analysis） and by sensorial evaluations, for a potential traceability of typical product.

Interpreting genotype × environment interactions for grain yield of rainfed durum wheat in Iran

Clustering genotype × environment(GE) interactions and understanding the causes of GE interactions are among the most important tasks in crop breeding programs. Pattern analysis(cluster and ordination techniques) was applied to analyze GE interactions for grain yield of 24 durum wheat(Triticum turgidum L. var. durum) genotypes(breeding lines and old and new cultivars) along with a popular bread wheat(Triticum aestivum) cultivar grown in 21 different rainfed environments during the 2010–2013 cropping seasons. To investigate the causes of GE interaction, several genotypic and environmental covariables were used. In a combined ANOVA, environment was the predominant source of variation,accounting for 81.2% of the total sum of squares(TSS), and the remaining TSS due to the GE interaction effect was almost seven times that of the genetic effect. Cluster analysis separated the environments into four groups with similar discriminating ability among genotypes, and genotypes into five groups with similar patterns in yield performance.Pattern analysis confirmed two major environmental clusters(cold and warm), and allowed the discrimination and characterization of genotype adaptation. Within the cold-environment cluster, several subclusters were identified. The breeding lines were most adapted to moderate and warm environments, whereas the old varieties were adapted to cold environments. The results indicated that winter rainfall and plant height were among the environmental and genotypic covariables, respectively, that contributed most to GE interaction for grain yield in rainfed durum wheat.

Mapping of dwarfing gene Rht14 in durum wheat and its effect on seedling vigor, internode length and plant height

Short coleoptiles associated with GA-insensitive Rht-1 alleles in wheat reduces yield due to poor seedling establishment under dry, or stubble-retained conditions. Hence there is a need for alternative dwarfing genes for wheat improvement programs. GA-sensitive dwarfing gene Rht14 confers semidwarf stature in wheat while retaining longer coleoptiles and early seedling vigor. Two RIL populations were used to identify the map position of Rht14 and to estimate its effect on plant height, coleoptile length, seedling shoot length,spike length and internode length. Rht14 on chromosome 6 A was mapped in the genomic region 383–422 Mbp flanked by GA2oxA9 and wmc753 in a Bijaga Yellow/Castelporziano RIL population. Recombination events between Rht14 and GA2oxA9 in the RIL population indicated that Rht14 might not be allelic to GA2oxA9. The conserved DNA sequence of GA2oxA9 and its flanking region in Castelporziano also suggested that the point of mutation responsible for the Rht14 allele must be a few Mbp away from GA2oxA9. The dwarfing effects of Rht14 on plant height, internode length and seedling vigor were compared with those of Rht-B1 b in an HI 8498/Castelporziano RIL population. Both genes significantly reduced plant height and internode length. Rht-B1 b conferred a significant reduction in coleoptile length and seedling shoot length, whereas Rht14 reduced plant height, but not coleoptile and seedling shoot length. Therefore, Rht14 can be a used as an alternative to Rht-B1 b for development of cultivars suitable for deeper sowing in dry environments and in conditions of conservation agriculture where crop residues are retained.

Planting Date, Seeding Rate, and Cultivar Impact Agronomic Traits and Semolina of Durum Wheat

Durum wheat (Triticum durum Desf.) is a market class of wheat subject to price discounts in the marketplace if quality standards are not met. This study was conducted in order to determine how certain agronomic practices might impact durum wheat quality. The effects of planting date (PD), cultivar, and seeding rate on agronomic and semolina quality traits were investigated in field trials conducted near Hettinger and Minot, ND in 2014 and 2015. The interaction of PD and cultivar was significant for many of the traits evaluated. There was a significant PD X cultivar interaction or PD and cultivar effect for yield in all environments. Planting date X cultivar interacted for test weight at all environments. In general, a delay in PD resulted in a significant decrease in yield and test weight for all cultivars. However, Carpio yielded more than other cultivars in high yielding environments while the yield and test weight of Joppa was more adversely affected by delays in PD. Seeding rate did not have a consistent effect on any agronomic or quality trait. Protein content, kernel yellow pigment content, falling number (FN), and vitreous kernels were more dependent on cultivar, regardless of PD and environment. Semolina extraction, gluten index (GI), and wet gluten (WG) values tended to decrease with a delay in PD. These data continue to support cultivar selection as a critical component for obtaining high-yielding, high-quality durum wheat. However, PD and environment can impact certain agronomic and end-use traits, regardless of cultivar grown.

Sensitivity of durum wheat (Triticum turgidum) to various postemergence herbicides

There are a limited number of herbicide options available for durum wheat production in Ontario, Canada. Four field studies were conducted in Ontario, Canada over a three year period (2008, 2009 and 2010) to evaluate the sensitivity of spring planted durum wheat to post-emergence (POST) applications of dichlorprop/2,4-D, dicamba/ MCPA/mecoprop, clopyralid, bromoxynil/MCPA, pyrasulfotole/bromoxynil, thifensulfuron/tribenuron + MCPA amine, fluroxypyr + MCPA ester, tralkoxydim and fenoxaprop-p-ethyl/safener at the manufacturers’ recommended dose and twice that dose. Visible injury in durum wheat were 0 to 2.4% with dichlorprop/2,4-D, 0 to 6% with dicamba/MCPA/mecoprop, 0 to 0.4% injury with clopyralid, 0 to 1.4% injury with bromoxynil/MCPA, 0 to 3.5% with pyrasulfotole/bromoxynil, 0 to 5% with thifensulfuron/tribenuron + MCPA amine, 0 to 2.6% with fluroxypyr + MCPA ester, 0 to 5% with tralkoxydim and 0.4% to 8% with fenoxaprop-pethyl/safener at various evaluation dates (1, 2, 3 and 4 weeks after treatment). Durum wheat height was decreased as much as 5% with dicamba/ MCPA/mecoprop, 4% with pyrasulfotole/bromoxynil and 6% with fenoxaprop-pethyl/safener but was not affected with other herbicides evaluated. There was no decrease in durum wheat yield with the herbicides evaluated.

Field evaluation of durum wheat landraces for prevailing abiotic and biotic stresses in highland rainfed regions of Iran

Biotic and abiotic stresses are major limiting factors for high crop productivity worldwide. A landrace collection consisting of 380 durum wheat(Triticum turgidum L. var. durum) entries originating in several countries along with four check varieties were evaluated for biotic stresses:yellow rust(Puccinia striiformis Westendorf f. sp. tritici) and wheat stem sawfly(WSS) Cephus cinctus Norton(Hymenoptera: Cephidae), and abiotic stresses: cold and drought. The main objectives were to(i) quantify phenotypic diversity and identify variation in the durum wheat landraces for the different stresses and(ii) characterize the agronomic profiles of landraces in reaction to the stresses. Significant changes in reactions of landraces to stresses were observed.Landraces resistant to each stress were identified and agronomically characterized.Percentage reduction due to the stresses varied from 11.4%(yellow rust) to 21.6%(cold stress) for 1000-kernel weight(TKW) and from 19.9(yellow rust) to 91.9%(cold stress) for grain yield. Landraces from Asia and Europe showed enhanced genetic potential for both grain yield and cold tolerance under highland rainfed conditions of Iran. The findings showed that TKW and yield productivity could be used to assess the response of durum wheat landraces to different stresses. In conclusion, landraces showed high levels of resistance to both biotic and abiotic stresses, and selected landraces can serve in durum wheat breeding for adaptation to cold and drought-prone environments.

Mapping QTLs for Yield Stability in Durum Wheat Grown under Different Water Regimes

Among the most important Mediterranean annual crops, durum wheat is widely grown in drought-prone areas. Therefore, improving water-use effi ciency (WUE) of durum wheat represents a major breeding goal. IDu-

Morphological and Physiological Traits of Assistance in the Selection of High Yielding Varieties of Durum Wheat (<i>Triticum turgidum</i>L. spp. Durum) for the Rainfed Mediterranean Environments of Central Chile

Chile has high potential to produce quality durum wheat;however, it is not self-sufficient. It is necessary to increase durum grain yield in the Mediterranean rainfed areas which are characterized by adverse environmental conditions, mainly, water deficit. The criteria normally used by breeders to select varieties of wheat for these environments are yield under stress and early flowering. The objective of this monograph is to propose that the selection of high yielding genotypes of durum wheat, under Chilean Mediterranean rainfed conditions, be assisted by morphological and physiological traits associated with yield in order to increase its heritability.

Composition and Molecular Weight Distribution of Albumin and Globulin Protein Isolates from Durum Wheat Genotypes

This paper attempts to evaluate the banding patterns of non-gluten protein isolates from the grain of durum wheat varieties. Under reduced condition, polyacrylamide-gel electrophoresis has revealed a number of different sized albumin and globulin protein bands. The electrophoretic pattern of globulin showed more polymorphisms than that of albumin. High polymorphism, both in band intensity and occurrence, was observed between 15 kDa and 35 kDa. Most of the protein bands were scored in the range of 10 kDa and 85 kDa in the two protein fractions. At a cutoff point 2.5, cluster analysis based on the SDS-PAGE of globulin proteins classified the durum wheat varieties into three major family groups. Generally, the experiment showed the suitability and usefulness of globulin protein fractions as a genetic marker in discriminating durum wheat genotypes.

Using Bayesian and Eigen approaches to study spatial genetic structure of Moroccan and Syrian durum wheat landraces

The Mediterranean durum wheat landraces are genetically diverse and important sources for improving resistance to abiotic and biotic stresses and developing adapted and productive durum wheat varieties in the Mediterranean region. To study the diversity two distant countries (MoroccoandSyria) durum landraces were studied. Fifty-one microsatellites were used as molecular markers tool to determine the genetic structure and spatial adaptation of these landraces. We used two spatially-explicit methods (Bayesian and Eigen) to determine the genetic diversity and structure of a population composed of Moroccan (98) and Syrian (90) durum wheat landraces. Non-spatial methods were also applied for comparison. A significant genetic difference was detected between the landraces originated from Morocco and Syria. Six subpopulations were revealed for each country using the Bayesian method and the Eigenanalysis, which generated PC1 and sPC1, showed similar structure. Eigenanalysis exhibited a significant global genetic structure for both countries landraces;and showed that neighboring landraces tend to have close genetic profile. The two first axes of PC1 and sPC1 had discriminated four out of the six subpopulations revealed by the Bayesian methodology. Also, our study detected the close relationship between the durum landraces from the coastal areas of Syria and the Moroccan landraces from the Atlantic coastal regions where the Phoenicians/Carthaginians had settled in Morocco. These results demonstrate the importance of using the spatial models in genetic analysis of durum wheat landraces;and also recommend the use of the easily usable Eigenanalysis to analyze the genetic diversity and structure.

Gene expression and physiological responses to salinity and water stress of contrasting durum wheat genotypes

Elucidating the relationships between gene expression and the physiological mechanisms remains a bottleneck in breeding for resistance to salinity and drought. This study related the expression of key target genes with the physiological performance of durum wheat under different combinations of salinity and irrigation. The candidate genes assayed included two encoding for the DREB（dehydration responsive element binding） transcription factors Ta DREB1 A and Ta DREB2 B, another two for the cytosolic and plastidic glutamine synthetase（Ta GS1 and Ta GS2）, and one for the specific Na^＋/H^＋ vacuolar antiporter（Ta NHX1）. Expression of these genes was related to growth and different trait indicators of nitrogen metabolism（nitrogen content, stable nitrogen isotope composition, and glutamine synthetase and nitrate reductase activities）, photosynthetic carbon metabolism（stable carbon isotope composition and different gas exchange traits） and ion accumulation. Significant interaction between genotype and growing conditions occurred for growth, nitrogen content, and the expression of most genes.In general terms, higher expression of Ta GS1, Ta GS2,Ta DREB2 B, and to a lesser extent of Ta NHX1 were associated with a better genotypic performance in growth, nitrogen, and carbon photosynthetic metabolism under salinity and water stress. However, Ta DREB1 A was increased in expression under stress compared with control conditions, with tolerant genotypes exhibiting lower expression than susceptible ones.

Epidemiological factors of septoria tritici blotch(Zymoseptoria tritici)in durum wheat(Triticum turgidum)in the highlands of Wollo,Ethiopia

Background:Septoria tritici blotch(STB)(Zymoseptoria tritici)is a major disease of durum wheat,an economic crop grown in the highlands of Wollo in Ethiopia.Methods:To determine the status of this disease,we conducted surveys in five districts of Wollo(Meket,Woreilu,Wadila,Jama,and Dessie Zuria)during the 2015 cropping season.We visited 75 farm plots to determine the prevalence,incidence,and severity of STB.Results:STB prevalence varied among locations,genotypes,planting dates,growth stages,previous crops,plant population,weed population,and soil types.Similarly,disease intensity also varied along all independent variables.The level of incidence was high in all the visited districts,and the level severity ranged from 9.9 to 59.3%while the incidence varied from 50 to 100%.The mean differences in incidence and severity within the districts’variable classes,altitude,varieties,growth stage,plant population,planting date,previous crop,weed population,and soil type were high.The independent variables,districts,altitude,varieties,growth stage,plant population,planting date,previous crops,weed population,and soil type,were significantly associated with high incidence and severity of STB as single predictor in the logistic regression model.A reduced multiple variable model was fitted using districts,altitude,varieties,growth stage,plant population,planting date,previous crop,weed population,and soil type as independent variables.High incidence(>50%)and severity(>25%)had a high probability of association to all independent variables,except previous crop.Low disease incidence(≤50%)and low disease severity(≤25%)had high probability of association to the previous crop.Conclusion:Environmental variables,cultivation practice,and responses were important for the development of STB.Therefore,these factors must be considered in designing strategies for the effective management of STB.

High-resolution genetic mapping and identification of candidate genes for the wheat stem rust resistance gene Sr8155B1

Stem rust,caused by Puccinia graminis f.sp.tritici(Pgt),threatens global wheat production.Development of cultivars with increased resistance to stem rust by identification,mapping,and deployment of resistance genes is the best strategy for controlling the disease.In this study,we performed fine mapping and characterization of the all-stage stem rust resistance(Sr)gene Sr8155B1 from the durum wheat line 8155-B1.In seedling tests of biparental populations,Sr8155B1 was effective against six Chinese Pgt races tested.In a segregating population of 5060 gametes,Sr8155B1 was mapped to a 0.06-cM region flanked by markers Pku2772 and Pku43365,corresponding to 1.5-and 2.7-Mb regions in the Svevo and Chinese Spring reference genomes.Both regions include several typical nucleotide-binding leucine-rich repeat(NLR)and protein kinase genes that represent candidate genes.Among them,three NLR genes and three receptor-like protein kinases were highly polymorphic between the parental lines and their transcripts were upregulated in the homozygous resistant line TdR2 relative to its susceptible sister line TdS4.Four markers(Pku2772,Pku43365,Pku2950,and Pku3721)developed in this study,together with seedling resistance responses,correctly predicted Sr8155B1 absence or presence in 78 tetraploid wheat genotypes tested.The presence of Sr8155B1 in tetraploid wheat accessions CItr 14916,PI 197492,and PI 197493 was confirmed by mapping in three F_(2)populations.The genetic map and linked markers developed in this study may accelerate the deployment of Sr8155B1-mediated resistance in wheat breeding programs.

Development of soft kernel durum wheat

Kernel texture(grain hardness) is a fundamental and determining factor related to wheat(Triticum spp.) milling, baking and flour utilization.There are three kernel texture classes in wheat: soft and hard hexaploid(T.aestivum), and very hard durum(T.turgidum subsp.durum).The genetic basis for these three classes lies with the Puroindoline genes.Phenotypically, the easiest means of quantifying kernel texture is with the Single Kernel Characterization System(SKCS), although other means are valid and can provide fundamental material properties.Typical SKCS values for soft wheat would be around 25 and for durum wheat≥80.Soft kernel durum wheat was created via homeologous recombination using the ph1b mutation, which facilitated the transfer of ca.28 Mbp of5 DS that replaced ca.21 Mbp of 5 BS.The 5 DS translocation contained a complete and intact Hardness locus and both Puroindoline genes.Expression of the Puroindoline genes in durum grain resulted in kernel texture and flour milling characteristics nearly identical to that of soft wheat, with high yields of break and straightgrade flours, which had small particle size and low starch damage.Dough water absorption was markedly reduced compared to durum flour and semolina.Dough strength was essentially unchanged and reflected the inherent gluten properties of the durum background.Pasta quality was essentially equal-to-or-better than pasta made from semolina.Agronomically, soft durum germplasm showed good potential with moderate grain yield and resistance to a number of fungal pathogens and insects.Future breeding efforts will no doubt further improve the quality and competitiveness of soft durum cultivars.

基于BSR-Seq分析筛选Y1499条锈病抗性相关基因

条锈病是危害小麦生产安全的重要病害之一,而携带不同抗病基因小麦品种的利用与合理布局是降低病害威胁最经济可靠的途径。为挖掘和丰富小麦条锈病抗性相关基因资源,本研究以筛选到的抗条锈病硬粒小麦种质Y1499和感病材料Gaza为亲本构建遗传群体,在室内对其进行苗期抗性鉴定和统计分析;利用衍生后代中选择的F 3∶4群体构建混池,进行RNA测序,对测序数据进行相关分析。结果表明,Y1499对CYR32的抗性由两个主效基因互补遗传控制。利用BSR-Seq关联分析在鉴定到3个小麦材料Y1499中条锈病抗性基因候选区间。GO富集结果显示,F 3∶4抗感池间差异表达基因涉及多个过氧化物酶等抗氧化反应相关基因。KEGG富集结果表明,显著差异表达基因主要富集于谷胱甘肽代谢和苯丙烷类生物合成等代谢通路。

Isolation and Analysis of α-Gliadin Gene Coding Sequences from Triticum durum

Three coding sequences of gliadins genes, designed as Gli2_Dul, Gli2_Du2 and Gli2_Du3, were isolated from the genomic DNA of Triticum durum accessions CItr5083. Gli2_Dul and Gli2_Du2 contain 945 and 864 bp, encoding the mature proteins with 314 and 287 amino acid residues, respectively. Gli2_Du3 is recognized as a pseudogene due to the stop codon occurring in the coding region. The pseudogenes, commonly occurring in gliadins family, are attributed to the single base change C→T. The amino acid sequences deduced from these gene sequences were characterized with the typical structure of α-gliadin proteins, including the toxic sequences （PSQQQP）. The peptide fraction PF（Y）PP（Q）is thought to be an extra unit of repetitive domain, slightly diverging from the previous report. Six cysteine residues were observed within two unique domains. Phylogenetic analysis showed Gli2_Du2 and Gli2_Du3 were closely related to the genes on chromosome 6A, whereas Gli2_Dul seems to be more homologous with the genes on chromosome 6B.