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QSbm.ubo - 2BS=Sbm2, a major QTL controlling the response to Soil - Borne Cereal Mosaic Virus (SB CMV) in durum wheat, was c haracterized in two recombinant inbred line populations, namely Meridiano (resistant, R) x Claudio (moderately susceptible, MS) and Simeto (susceptible, S) x Levante (R). B y means of meta - QTL analysis QSbm.ubo - 2BS was mapped as a unique QTL within a 2 cM - wide interval (LOD - 2) in the distal region of chromosome arm 2BS (Maccaferri et al., 2012) . The addition of the Illumina 90K SNPs array to the durum linkage maps allowed to identify 36 transcripts - associated SNPs tightly associated with the Mendelized QTL (Maccaferri et al., 2014) . Nine SNPs from the Illumina 90K wheat array were converted to KASP markers, which provided fluorescent high - throughput assays spanning the QTL region. Marker - assisted selection (MAS) was performed on ∼ 2,000 RILs from the Svevo (R) x Ciccio (S) population (Gadaleta et al., 2009) with two KAS P markers flanking the QTL interval , KUBO 9 and KUBO 13. MAS identified 291 lines recombinant between the two markers. These lines were characterized for SBCMV response in the 2016 field nursery under severe and uniform SBCMV infection. The lines were scor ed for symptom severity (SS) on a 0 to 4 scale , where 0 = very res istant and 4 = very susceptible (Vallega and Rubies Autonell, 1985). They were also genotyped with seven KASP markers distributed along the QTL interval ( KUBO 1 , KUBO 3 , KUBO 27 , KUBO 29 , KU BO 38, KUBO 40 and KUBO 41 ) and with the DArT marker wPt - 2106 , the marker most associated with the phenotype in the Meridiano x Claudio RIL population (Maccaferri et al., 2012). The bimodal distribution of SS reflects the segregation of the resistance trai t in the QTL interval: frequency peaks were observed around values of 1.7 and 3.8. The fine - mapping allowed to narrow the most probable support interval to 0,2 cM between KUBO 27 and KUBO 1 based on the Svevo x Ciccio RILs population. Work is in progress to analyze other - 1,000 RILs of the same population in order to confirm the results obtained with the first part of the study and to improve the ongoing fine - mapping of the gene responsible for the resistance.

According to the literature, in hexaploid wheat resistance to CSBMV is controlled by a few major genes. In field trials carried out for many years in Italy, most of the cultivars of hexaploid and durum wheat marketed in this country exhibited a consistent array of intermediate reactions to the virus, suggesting that, in these wheats, resistance to CSBMV is governed by numerous genes. A population consisting of 184 RILs (at the F7 generation) obtained by Produttori Sementi Bologna Spa, Italy, from a cross between the durum wheat cultivars Meridiano (classed as either resistant or moderately resistant to CSBMV in various seasons) and Claudio (repeatedly classed as moderately susceptible) was grown during the 2006–07 season in a field near Cadriano (Bologna) with natural inoculum sources of CSBMV and evaluated for resistance on the basis of both symptomatology (on a 0–4 scale) and virus Concentration (by ELISA). Disease pressure at the experimental site was severe, as testified by the relatively high percentage of lines (6%) with symptom severity scores equal or above 3.5. The results obtained showed that in the ‘Meridiano / Claudio’ cross, resistance to CSBMV is controlled by no less than four genes and that genotypes expressing more extreme reactions than either parent may be recovered (Tables 4 and 5). Our results also strongly suggested the presence of a further gene that, regardless of the symptomatology and virus concentration displayed on the first observation date, has a marked impact on the subsequent reaction to CSBMV of each line, i.e., a plus or minus effect of about 0.250 in terms of ELISA value and of about 0.2 in terms of symptom severity expression. The ‘Meridiano / Claudio’ population will be evaluated again for CSBMV-resistance in the same field during the 2007–08 season. Presently, the population is being profiled with SSR and DArT markers. Analysis of phenotypic and molecular data will allow us to identify the QTL involved in the control of CSBMV resistance.

Increasing temperatures, heat waves, and reduction of annual precipitation are all the expressions of climate change (CC), strongly affecting bread wheat (Triticum aestivum L.) grain yield in Southern Europe. Being temperature the major driving force of plants’ phenological development, these variations also have effects on wheat phenology, with possible consequences on grain quality, and gluten protein accumulation. Here, through a case study in the Bolognese Plain (North of Italy), we assessed the effects of CC in the area, the impacts on bread wheat phenological development, and the consequences on grain gluten quality. The increasing trend in mean annual air temperature in the area since 1952 was significant, with a breakpoint identified in 1989, rising from 12.7 to 14.1°C, accompanied by the signals of increasing aridity, i.e., increase in water table depth. Bread wheat phenological development was compared in two 15-year periods before and after the breakpoint, i.e., 1952–1966 (past period), and 2006–2020 (present period), the latest characterized by aridity and increased temperatures. A significant shortening of the chronological time necessary to reach the main phenological phases was observed for the present period compared to the past period, finally shortening the whole life cycle. This reduction, as well as the higher temperature regime, affected gluten accumulation during the grain-filling process, as emerged analyzing gluten composition in grain samples of the same variety harvested in the area both before and after the breakpoint in temperature. In particular, the proportion of gluten polymers (i.e., gliadins, high and low molecular weight glutenins, and their ratio) showed a strong and significant correlation with cumulative growing degree days (CGDDs) accumulated during the grain filling. Higher CGDD values during the period, typical of CC in Southern Europe, accounting for higher temperature and faster grain filling, correlated with gliadins, high molecular weight glutenins, and their proportion with low molecular weight glutenins. In summary, herein reported, data might contribute to assessing the effects of CC on wheat phenology and quality, representing a tool for both predictive purposes and decision supporting systems for farmers, as well as can guide future breeding choices for varietal innovation.

PubMedID: 30962619 The domestication of wild emmer wheat led to the selection of modern durum wheat, grown mainly for pasta production. We describe the 10.45 gigabase (Gb) assembly of the genome of durum wheat cultivar Svevo. The assembly enabled genome-wide genetic diversity analyses revealing the changes imposed by thousands of years of empirical selection and breeding. Regions exhibiting strong signatures of genetic divergence associated with domestication and breeding were widespread in the genome with several major diversity losses in the pericentromeric regions. A locus on chromosome 5B carries a gene encoding a metal transporter (TdHMA3-B1) with a non-functional variant causing high accumulation of cadmium in grain. The high-cadmium allele, widespread among durum cultivars but undetected in wild emmer accessions, increased in frequency from domesticated emmer to modern durum wheat. The rapid cloning of TdHMA3-B1 rescues a wild beneficial allele and demonstrates the practical use of the Svevo genome for wheat improvement. © 2019, The Author(s), under exclusive licence to Springer Nature America, Inc. Western Grains Research Foundation Ministry of Agriculture - Saskatchewan Israel Science Foundation: 1137/17 031A536 FP7 Food, Agriculture and Fisheries, Biotechnology: DROPS ID244347 Natural Sciences and Engineering Research Council of Canada InterOmics PB05 Genome Prairie United States-Israel Binational Science Foundation: 2015409 Genome Canada Saskatchewan Canola Development Commission 2819103915 PIR01_00017 3060-21000-038-00-D We acknowledge the funding support of: the Italian Ministry of Education and Research with projects CNR Flagship InterOmics PB05 (L.M., A.C., G.S.), PON ELIXIR CNR-BiOmics PIR01_00017 (L.M., M.G., M.Mo.) and PON ISCOCEM (P.D.); CREA project Interomics (L.C.); Fondazione in rete per la ricerca agroalimentare AGER project From Seed to Pasta (R.T.); FP7-KBBE Project DROPS ID244347 (R.T.); Genome Canada (A.G.S., C.P.); the Western Grain Research Foundation (A.G.S., C.P.); the Manitoba Wheat and Barley Commission (A.G.S., C.P.); the Saskatchewan Wheat Development Commission (A.G.S., C.P.); the Alberta Wheat Development Commission (A.G.S., C.P.); the Saskatchewan Ministry of Agriculture (A.G.S., C.P.); the administrative support of Genome Prairie (A.G.S., C.P.); Canadian Triticum Applied Genomics -CTAG2-(A.G.S., C.P.); Binational Science Foundation grant no. 2015409 (I.H., A.D.); Israel Science Foundation grant no. 1137/17 (A.D.); USDA-Agricultural Research Service Current Research Information System project 3060-21000-038-00-D (J.D.F., S.S.X.); German Federal Ministry of Food and Agriculture grant no. 2819103915 (N.S., K.F.X.M.); German Ministry of Education and Research grant no. 031A536 (K.F.X.M.); and Natural Sciences and Engineering Council of Canada grant nos. SPG 336119-06 and RGPIN 92787 (G.J.T., C.P.). The authors are grateful to E. Elias (North Dakota State University) for providing nine DW cultivars, included in the Global Tetraploid Wheat Collection and E. Scarpella (University of Alberta, Edmonton, Canada) for assistance with confocal microscopy.

Grain yield is a major goal for the improvement of durum wheat, particularly in drought-prone areas. In this study, the genetic basis of grain yield (GY), heading date (HD), and plant height (PH) was investigated in a durum wheat population of 249 recombinant inbred lines evaluated in 16 environments (10 rainfed and 6 irrigated) characterized by a broad range of water availability and GY (from 5.6 to 58.8 q ha−1). Among the 16 quantitative trait loci (QTL) that affected GY, two major QTL on chromosomes 2BL and 3BS showed significant effects in 8 and 7 environments, with R2 values of 21.5 and 13.8% (mean data of all 16 environments), respectively. In both cases, extensive overlap was observed between the LOD profiles of GY and PH, but not with those for HD. QTL specific for PH were identified on chromosomes 1BS, 3AL, and 7AS. Additionally, three major QTL for HD on chromosomes 2AS, 2BL, and 7BS showed limited or no effects on GY. For both PH and GY, notable epistasis between the chromosome 2BL and 3BS QTL was detected across several environments.

Although root architecture has been shown to play an important role in crop performance, particularly under drought conditions, no information is available on the genetic control of root traits in durum wheat, a crop largely grown in rainfed areas with low rainfall. In our study, a panel of 57 elite durum wheat accessions were evaluated under controlled conditions for root and shoot traits at the seedling stage. Significant genetic variability was detected for all the root and shoot traits that were investigated. Correlation analysis suggested that root and shoot features were only partially controlled by common sets of genes. The high linkage disequilibrium (up to 5 cM) present in the germplasm collection herein considered allowed us to use simple sequence repeat-based association mapping to identify chromosome regions with significant effects on the investigated traits. In total, 15 chromosome regions showed significant effects on one or more root architectural features. A number of these regions also influenced shoot traits and, in some cases, plant height measured in field conditions. Major effects were detected on chromosome arms 2AL (at Xgwm294), 7AL (at Xcfa2257 and Xgwm332) and 7BL (at Xgwm577 and Xcfa2040). The accessions with the most remarkable differences in root features will provide a valuable opportunity to assemble durum wheat mapping populations well suited for ascertaining the effects of root architecture on water use efficiency and grain yield.

A population consisting of 184 RILs obtained via single-seed descent by Produttori Sementi Bologna S.p.A., Italy, from a cross between the durum wheat cultivars Meridiano (resistant) and Claudio (moderately susceptible) was assayed during 2006–07 and 2007–08 in a field with natural inoculum sources of CSBMV at Cadriano (Bologna). In each season, the RILs, parents, and the cultivar Grazia (a susceptible control inserted at regular intervals) were evaluated for resistance on the basis of symptomatol¬ogy on four dates and ELISA absorbance on two dates. The plants were grown in 2.4-m2, solid-seeded plots distributed according to a randomized block design with two replicates. Symptoms were scored on a 0–4 scale. Virus concentration was estimated by DAS-ELISA, on leaf samples. Grain yield, kernel weight, and test weight also were measured. The data from the first season were reported (Ann Wheat Newlsett 54:76), those obtained in the 2007–08 trial are summarized in Table 1 and Table 2. Disease pressure was severe in both seasons, as testified by the mean symptom scores (3.8 in 2007 and 3.6 in 2008) recorded for Grazia at the time of maximum symptom expression. Analysis of symptom score and ELISA absorbance frequency distributions indicated a complex inheritance of CSBMV-resistance, involving no less than four major genes, various modifiers, and a dif¬ferent timeline of the expression of resistance. Transgressive segrega¬tion, moreover, indicated that both the resistant (Meridiano) and the moderately susceptible parents (Claudio) contributed favorable alleles. Despite the favorable genes contributed by the latter cultivar, however, RILs completely resistant to CSBMV were not recovered. Indeed, leaf samples from all the RILs assayed were found ELISA-positive on at least one of the four collection dates, and all except two RILs gave ELISA-positive results on at least two dates. Moreover, the only RIL that re¬mained symptom-free throughout the two seasons (i.e., on eight scoring dates) proved ELISA-positive on two out of collection dates. Eighteen of the 184 RILs assayed had overall mean symptom scores lower than the resistant parent; 15 of these RILs also showed lower overall mean ELISA absorbances; 9 produced higher grain yields; 10 showed higher test weights; and 11 showed higher kernel weights. Two RILs performed better than cultivar Meridiano in regard to all of the five parameters considered. Further trials are being set up to establish whether any of the above 18 RILs are indeed more resistant to CSBMV than cultivar Meridiano. The RILs also were profiled with molecular markers (158 SSRs), and an association map spanning 2,050 cM was obtained. Preliminary results indicate that at least four QTL accounted for most of the phenotypic variation observed. A major QTL was associated to Xwmc243 (distal telomeric region of chromosome arm 2BS),with the favorable allele contributed by Meridiano. The additional favorable QTL all located in the distal regions of the short and long arms of chromo¬some group 5 (particularly in chromosome 5A), were contributed by both parents. The QTL identified in the distal regions of 5AL (Xwmc524) and 5BL (Xbarc243) could represent the homoeologous copies of the major QTL identified in bread wheat (Sbm1).

A population of 181 recombinant inbred lines (RILs) derived from the cross Meridiano × Claudio was evaluated in five field trials varying for water and nitrogen regimes. A preliminary analysis carried out with 213 SSR and DArT markers evidenced two major QTL clusters for grain yield, yield components and several other traits on chrs. 4B and 5A. Favourable alleles were inherited from the parental cultivar Claudio at the 4B QTL region and from Meridiano at the 5A QTL. Additional markers with highly significant effects on grain yield were found on chrs. 2B, 3B, 5B and 7B, with favourable alleles contributed by both parents, thus accounting for the wide transgressive segregation observed among the RILs. Grain yield of the RILs was highly predictable based on the SSR alleles present at four key-chromosome regions.

The genetic basis of leaf rust (Puccinia triticina Eriks.) resistance was studied using 176 RILs from Colosseo × Lloyd and 62 advanced lines derived from multiple crosses. RILs were tested under field conditions with a mixture of leaf rust isolates and at the seedling stage with single isolates. In the field experiment, the percentage of infected leaf area was evaluated through the disease developmental cycle and the area under disease progress curve (AUDPC) was calculated. A major QTL (QLr.ubo-7B.2) for leaf rust resistance at both adult (field conditions) and seedling stages was identified on the distal region of chr. 7BL. In the field, the QTL showed an R2 of 72.9% and a peak LOD score of 44.5 for AUDPC. The presence of this major QTL was validated by a linkage disequilibrium-based test using field data of advanced lines from multiple crosses. The association results confirmed the QTL location between Xbarc340.2 and Xgwm344.2, with the corresponding AUDPC R2 values ranging from ca. 10 to ca. 35% depending on the year. QLr.ubo-7B.2 maps in a gene-dense region (7BL10-0.78-1.00) known to carry several genes/QTLs in wheat and barley for resistance to rusts and other major cereal fungal diseases, including Lr14a and Lr19, two major candidates for this gene.

A population consisting of 184 recombinant inbred lines (RILs) from a cross between durum wheat (Triticum durum Desf.) cvs. “Meridiano” (highly resistant) and “Claudio” (moderately susceptible) was grown during the 2006-07 season in a field with natural inoculum sources of SBCMV near Bologna, and evaluated for SBCMV-symptom severity expression and ELISA absorbance in extracts from leaves. Comparative analysis of symptom severity and ELISA absorbance values in time showed the presence of a sizeable temporal change in the relative degree of resistance of the lines in terms of symptom expression and virus concentration in leaves, responsible for marked changes in resistance ranking order among lines.