Fusarium head blight (FHB), caused by Fusarium graminearum, is one of the most devastating diseases of wheat (Triticum aestivum) and other cereal crops worldwide. Improving FHB resistance has been a major focus in many wheat genetics and breeding programs globally. However, only a few major loci have been effectively deployed, limiting progress in breeding for FHB resistance. To expand the genetic basis of resistance, we developed a modified nested association mapping (NAM) panel comprising four synthetic hexaploid wheat (SHW) lines, ten hard red spring wheat (HRSW) varieties/lines, and 276 BC1-derived progenies. The panel was genotyped using the 90 K SNP (single nucleotide polymorphism) Infinium array and evaluated for Type II FHB resistance across six environments. The disease evaluations revealed that 15 resistant lines, primarily derived from backcrossing SHW line SW183 (T. dicoccum PI 191091/Aegilops tauschii CIae 26) with HRSW ‘Linkert’ or ‘Glenn,’ exhibited resistance levels comparable to the well-known FHB resistance source, Sumai 3. A genome-wide association study (GWAS) identified 19 significant marker–trait associations (MTAs) for FHB resistance. Of these, three SNPs carried resistance alleles from SHW, two from HRSW, and 14 from both parental sources. Sixteen MTAs co-localized with previously reported quantitative trait loci (QTLs) linked to FHB resistance, while three, located on the short arms of chromosomes 1D, 2B, and 4A, appear to be associated with novel resistance loci. The resistant lines developed in this study could serve as new sources for FHB resistance, and their associated resistance loci can be further validated and incorporated into breeding programs. Three potentially novel loci and sixteen loci overlapping with previously reported regions for Fusarium head blight resistance were identified in a mapping panel derived from synthetic and bread wheat germplasm.

Wheat production is challenged by biotic and abiotic stresses. Alien gene transfer is an effective approach to tackle such challenges. We previously showed that sea wheatgrass (SWG; Thinopyrum junceiforme (2n = 2x = 28; J1J2) is an untapped resource possessing resistance to an array of pests and abiotic stress. However, the transfer of these important traits has been hindered by the lack of genomic resources and a clear picture of its genome constitution. Using multi-color genomic in situ hybridization, we distinguished the SWG sub-genomes and corroborated that the J1 sub-genome is closely related to the E genome of Th. elongatum and the J genome of Th. bessarabicum and the J2 sub-genome to the V genome of Dasypyrum villosum. Meanwhile, we developed a draft SWG genome assembly and 127 SWG-specific DNA markers covering the 14 SWG chromosomes. Screening a population of 466 BC2F1 and BC2F2 individuals, derived from backcrosses of wheat-SWG amphiploid to wheat, by the SWG-specific markers led to selection of 72 plants putatively carrying one or two SWG chromosomes. The genome painting analysis of the 72 plants eventually identified a set of 37 wheat-SWG chromosome addition lines covering all the 14 pairs of SWG chromosomes and two compensating Robertsonian translocations (RobTs). While the wheat-SWG chromosome addition lines and RobTs are invaluable genetic resources for wheat improvement via chromosome engineering, our results showed the power of genome-specific markers in combination with genome painting in dissection of a polyploid genome and implicated the origin of a group of important polyploid grasses.

Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe, is one of the most devastating diseases in wheat (Triticum aestivum L.). The synthetic hexaploid wheat line Largo was developed from a cross between the durum wheat [T. turgidum ssp. durum (Desf.) Husn.] variety Langdon and the Aegilops tauschii Cosson accession PI 268210, and it was previously found to have a moderate level of FHB resistance. This study was conducted to identify quantitative trait loci (QTL) associated with FHB resistance using a population of 188 recombinant inbred lines (RILs) from a cross between Largo and the susceptible wheat line ND495. The RILs were evaluated for Type II resistance in two greenhouse and two field environments. The disease severity and 90K single-nucleotide polymorphism marker data were used for QTL analysis, which revealed six QTL on chromosomes 1D, 2D, 5B, and 7D. Four QTL (QFhb.rwg-1D, QFhb.rwg-5B, QFhb.rwg-7D.1, and QFhb.rwg-7D.3) from Largo had minor effects, whereas two QTL (QFhb.rwg-2D and QFhb.rwg-7D.2) from ND495 showed large effects on FHB resistance. The result suggested that ND495 may possess suppressor or susceptibility gene(s) suppressing or masking FHB resistance controlled by the resistance QTL. Among these QTL, four coincided with previously reported QTL, including Fhb9, and two (QFhb.rwg-1D and QFhb.rwg-7D.1) are likely novel QTL. From the six QTL regions, 10 Kompetitive allele-specific PCR markers were developed and validated for marker-assisted selection. The QTL detected from the resistant and susceptible parents enhance our understanding of FHB resistance expression and provide new resources for improving FHB resistance in wheat.

AbstractFusarium head blight (FHB), mainly caused by Fusarium graminearum and Fusarium culmorum, is a major wheat disease. Significant efforts have been made to improve resistance to FHB in bread wheat (Triticum aestivum), but more work is needed for durum wheat (Triticum turgidum spp. durum). Bread wheat has ample genetic variation for resistance breeding, which can be readily exploited, while durum wheat is characterized by higher disease susceptibility and fewer valuable resistance sources. The Wheat Initiative – Expert Working Group on Durum Wheat Genomics and Breeding has promoted a scientific discussion to define the key actions that should be prioritized for achieving resistance in durum wheat comparable to that found in bread wheat. Here, a detailed state of the art and novel tools to improve FHB resistance in durum are presented, together with a perspective on the next steps forward. A meta‐analysis grouping all quantitative trait loci (QTL) associated with FHB resistance in both bread and durum wheat has been conducted to identify hotspot regions that do not overlap with Rht alleles, which are known to negatively correlate with FHB resistance. A detailed list of QTL related to FHB resistance and deoxynivalenol contamination and durum lines carrying different sources of FHB resistance are provided as a strategic resource. QTL, closely linked markers and durum wheat lines carrying the useful alleles, can be selected to design an effective breeding program. Finally, we highlight the priority actions that should be implemented to achieve satisfactory resistance to FHB in durum wheat.

Four durum wheat (Triticum turgidum ssp. durum) lines Rusty-KLB (Reg. no. GP-1098, PI 705448), Rusty-14803 (Reg. no. GP-1097, PI 705447), Rusty-ST464C1 (Reg. no. GP-1099, PI 705449), and CAT-A1 (Reg. no. GP-1096, PI 705446), which carry stem rust resistance gene Sr13 alleles Sr13a, Sr13b, Sr13c, and Sr13d, respectively, are released by USDA-ARS. These alleles originated from cultivated emmer wheat (T. turgidum ssp. dicoccum) landrace Khapli (CItr 4013), T. turgidum ssp. polonicum accession CItr 14803, durum landrace ST464 (PI 191365), and durum line Camadi Abdu tipo #103 (PI 192168), respectively. Rusty-KLB, Rusty-14803, and Rusty-ST464C1 are near-isogenic lines with the pedigrees Rusty*7/KL-B, Rusty*4/3/Rusty/CItr 14803//2*Rusty, and Rusty*7/ST464-C1, respectively. KL-B, ST464-C1, and CAT-A1 are monogenic lines with the pedigrees Marruecos 9623//Khapli/Marruecos 9623, Marruecos 9623*2/ST464, and Marruecos 9623*2/Camadi Abdu tipo #103, respectively. Sr13 can be detected by perfect markers including Kompetitive allele specific polymerase chain reaction (KASP) marker KASPSr13 and semi-thermal asymmetric reverse polymerase chain reaction (STARP) markers rwgsnp37. Specific alleles can be identified via STARP markers rwgsnp38, rwgsnp39, and rwgsnp40. The Sr13 alleles provide a moderate level of resistance, typically an infection type 2, to a broad spectrum of stem rust races. Sr13c was effective against all 15 stem rust races tested while Sr13a was ineffective only against race TCMJC. Sr13b was ineffective against JRCQC, QCCJC, QFCSC, and TTRTF. Sr13d is notable in being the only Sr13 allele ineffective to TTKSK (Ug99) and TKTTF. These lines are useful for studying the host-stem rust pathogen interactions, identifying new genes, and breeding durum and bread wheat cultivars with stem rust resistance.

Fusarium head blight (FHB) is a devastating disease lowering yield and quality of wheat. Intensive use of limited allelic pools critically affects wheat resistance, while advances pathogenic alleles. This study presents new alleles raised from moderate rather than elite crosses. ‘Parshall’ has indigenous moderate resistance that was crossed with the moderate susceptible ‘Reeder’ and developed the 110 RIL population (noted as PR) that was tested across three states and years under field and greenhouse conditions. Heading- and FHB-related traits of incidence, severity, and index were assessed. A genetic map (1417cM) of SNP/DArT markers was generated. Composite interval mapping produced 45 QTL. Permutated LOD assessment identified two consistent QTL (4AL and 4BL) of type I and II resistance. Significant markers at the 4A QTL showed correlation with previous FHB resistance, while at the 4B QTL with pathogen responsive regions. The 1- and 2-D genome scan identified 16 QTL and six pairs of interacting resistance markers; respectively, with additive effects between 0.17% and 2.19%. Additionally, additive×environment interaction was between 0.04% and 3.18% confirming the high environmental effect. Three pairs of QTL with additive×additive effects between 0.15% and 0.30% were revealed by FHB epistasis. However, the additive×additive environmental interaction at these three loci was varied between 0.03% and 1%, confirming the G×E effect on FHB resistance. Our results have broadened the allelic pool of wheat resistance. PR-alleles can help breeders to develop lines mitigating epidemic environments and changeable climates, to boost yield facing hanger, food scarce, and unsecure worldwide penurious economies.

KEY MESSAGE:Yield and quality tests of wheat lines derived from RWG35 show they carry little, or no linkage drag and are the preferred source of Sr47 for stem rust resistance. Three durum wheat (Triticum turgidum L. subsp. durum) lines, RWG35, RWG36, and RWG37 carrying slightly different Aegilops speltoides introgressions, but each carrying the Sr47 stem rust resistance gene, were backcrossed to three durum and three hard red spring (HRS) wheat (Triticum aestivum L.) cultivars to produce 18 backcross populations. Each population was backcrossed to the recurrent parent six times and prepared for yield trials to test for linkage drag. Lines carrying the introgression (S-lines) were compared to euploid sibling lines (W-lines) and their parent. Yield trials were conducted from 2018 to 2021 at three locations. Three agronomic and several quality traits were studied. In durum, lines derived from RWG35 had little or no linkage drag. Lines derived from RWG36 and RWG37 still retained linkage drag, most notably involving yield and thousand kernel weight, but also test weight, falling number, kernel hardness index, semolina extract, semolina protein content, semolina brightness, and peak height. In HRS wheat, the results were more complex, though the general result of RWG35 lines having little or no linkage drag and RWG36 and RWG37 lines retaining linkage drag still applied. But there was heterogeneity in the Glenn35S lines, and Linkert lines had problems combining with the Ae. speltoides introgressions. We concluded that introgressions derived from RWG35 either had eliminated linkage drag or any negative effects were minor in nature. We recommend that breeders who wish to incorporate Sr47 into their cultivars should work exclusively with germplasm derived from RWG35.

Durum wheat [Triticum turgidum L. ssp. durum (Desf.)] is mainly used for the production of pasta, couscous, and bulgur. Spring durum wheat cultivar 'ND Grano' (Reg. no. CV-1186, PI 687795) was released in 2017 and is adapted to North Dakota and surrounding regions. It was developed by the durum breeding program at North Dakota State University and released by the North Dakota Agricultural Experiment Station. ND Grano was tested as D09557 in the yield trials and has the pedigree D00752/DH01146. In field trials, ND Grano showed high grain yield potential, disease resistance, excellent end-use qualities, and low cadmium uptake. Based on data from 34 location-years of testing in the Uniform Regional Durum Nursery, the average grain yield of ND Grano was 4,008 kg ha(-1), compared with 3,867 kg ha(-1) for 'Divide' and 3,978 kg ha(-1) for 'Joppa'. ND Grano has very strong dough mixing characteristics and a high gluten index. Fusarium head blight (FHB) tolerance of ND Grano is similar to Divide. ND Grano is also resistant to predominant races of stem rust.

Understanding the genetics of drought tolerance can expedite the development of drought-tolerant cultivars in wheat. In this study, we dissected the genetics of drought tolerance in spring wheat using a recombinant inbred line (RIL) population derived from a cross between a drought-tolerant cultivar, 'Reeder' (PI613586), and a high-yielding but drought-susceptible cultivar, 'Albany.' The RIL population was evaluated for grain yield (YLD), grain volume weight (GVW), thousand kernel weight (TKW), plant height (PH), and days to heading (DH) at nine different environments. The Infinium 90 k-based high-density genetic map was generated using 10,657 polymorphic SNP markers representing 2,057 unique loci. Quantitative trait loci (QTL) analysis detected a total of 11 consistent QTL for drought tolerance-related traits. Of these, six QTL were exclusively identified in drought-prone environments, and five were constitutive QTL (identified under both drought and normal conditions). One major QTL on chromosome 7B was identified exclusively under drought environments and explained 13.6% of the phenotypic variation (PV) for YLD. Two other major QTL were detected, one each on chromosomes 7B and 2B under drought-prone environments, and explained 14.86 and 13.94% of phenotypic variation for GVW and YLD, respectively. One novel QTL for drought tolerance was identified on chromosome 2D. In silico expression analysis of candidate genes underlaying the exclusive QTLs associated with drought stress identified the enrichment of ribosomal and chloroplast photosynthesis-associated proteins showing the most expression variability, thus possibly contributing to stress response by modulating the glycosyltransferase (TraesCS6A01G116400) and hexosyltransferase (TraesCS7B01G013300) unique genes present in QTL 21 and 24, respectively. While both parents contributed favorable alleles to these QTL, unexpectedly, the high-yielding and less drought-tolerant parent contributed desirable alleles for drought tolerance at four out of six loci. Regardless of the origin, all QTL with significant drought tolerance could assist significantly in the development of drought-tolerant wheat cultivars, using genomics-assisted breeding approaches.

Summary This research was conducted to determine the effect of milling and pasta making on yellow pigment content, soluble brown pigment content, polyphenol oxidase (PPO) activity and peroxidase (POD) activity in semolina and pasta derived from ten durum genotypes. Results showed that pasta colour was impacted more by the milling than by pasta making. The loss of yellow pigment content, POD activity, PPO activity and soluble brown pigment content due to milling was 1.3×, 4.4×, 6.2× and 17.5×, respectively, greater than losses due to pasta making. Dry pasta contained 62%, 31%, 16% and 25% of the original yellow pigment content, brown pigment content and PPO activity and POD activity in the grain, respectively. Semolina yellow pigment content had a positive effect on pasta colour while semolina protein content, ash content and speck count had negative effects. These results indicate the importance of selecting genotypes that have high yellow pigment content and excellent milling qualities.

Leaf rust, caused by Puccinia triticina ( Pt ), stripe rust caused by Puccinia striiformis f. sp. tritici ( Pst ), and stem rust caused by Puccinia graminis f. sp. tritici ( Pgt ) are major diseases to wheat production globally. Host resistance is the most suitable approach to manage these fungal pathogens. We investigated the phenotypic and genotypic structure of resistance to leaf rust, stem rust, and stripe rust pathogen races at the seedling stage in a collection of advanced durum wheat breeding lines and cultivars adapted to Upper Mid-West region of the United States. Phenotypic evaluation showed that the majority of the durum wheat genotypes were susceptible to Pt isolates adapted to durum wheat, whereas all the genotypes were resistant to common wheat type- Pt isolate. The majority of genotypes were resistant to stripe rust and stem rust pathogen races. The durum panel genotyped using Illumina iSelect 90 K wheat SNP assay was used for genome-wide association mapping (GWAS). The GWAS revealed 64 marker-trait associations (MTAs) representing six leaf rust resistance loci located on chromosome arms 2AS, 2AL, 5BS, 6AL, and 6BL. Two of these loci were identified at the positions of Lr52 and Lr64 genes, whereas the remaining loci are most likely novel. A total of 46 MTAs corresponding to four loci located on chromosome arms 1BS, 5BL, and 7BL were associated with stripe rust response. None of these loci correspond to designated stripe rust resistance genes. For stem rust, a total of 260 MTAs, representing 22 loci were identified on chromosome arms 1BL, 2BL, 3AL, 3BL, 4AL, 5AL, 5BL, 6AS, 6AL, 6BL, and 7BL. Four of these loci were located at the positions of known genes/alleles ( Sr7b , Sr8155B1 , Sr13a , and Sr13b ). The discovery of known and novel rust resistance genes and their linked SNPs will help diversify rust resistance in durum wheat.

Abstract Durumwheat [Triticum turgidum L. ssp. durum (Desf.)] production is constrained by fungal diseases including stripe rust caused by Puccinia striiformis Westend. f. sp. tritici Erikss. (Pst). Continuous mining of germplasm for the discovery and deployment of stripe rust resistance (Yr) genes is needed to counter the impact of this disease. In this study, we evaluated a worldwide collection of 432 durum wheat accessions to seven U.S. Pst races that carry diverse virulence and avirulence combinations on wheat Yr genes. We found that 47–82% of the durum wheat accessions were susceptible to each of the tested Pst races. A total of 32 accessions were resistant to all seven races. Genome‐wide association studies (GWAS) using over 97,000 single‐nucleotide polymorphism markers generated from genotyping‐by‐sequencing of 364 accessions identified 56 quantitative trait loci (QTL) associated with all‐stage stripe rust resistance located on all 14 durum wheat chromosomes. Six of these QTL were associated with resistance to 2–4 Pst races, and none were associated with resistance to all seven races. The remaining 50 QTL were race specific. Eighteen of the 56 identified QTL had relatively large effects against at least one of the races. A map‐based comparison of the discovered QTL in this study with previously published Yr genes and QTL showed that 29 were previously identified, whereas the remaining 27 QTL appeared to be novel. This study reports effective sources of stripe rust resistance to contemporary races in the United States and shows that this durum wheat collection is abundant in novel resistance loci that can be transferred into adapted durum cultivars.

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)(2013)(2014)(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.

Understanding the genetics of drought tolerance in hard red spring wheat (HRSW) in northern USA is a prerequisite for developing drought-tolerant cultivars for this region. An association mapping (AM) study for drought tolerance in spring wheat in northern USA was undertaken using 361 wheat genotypes and Infinium 90K single-nucleotide polymorphism (SNP) assay. The genotypes were evaluated in nine different locations of North Dakota (ND) for plant height (PH), days to heading (DH), yield (YLD), test weight (TW), and thousand kernel weight (TKW) under rain-fed conditions. Rainfall data and soil type of the locations were used to assess drought conditions. A mixed linear model (MLM), which accounts for population structure and kinship (PC+K), was used for marker–trait association. A total of 69 consistent QTL involved with drought tolerance-related traits were identified, with p ≤ 0.001. Chromosomes 1A, 3A, 3B, 4B, 4D, 5B, 6A, and 6B were identified to harbor major QTL for drought tolerance. Six potential novel QTL were identified on chromosomes 3D, 4A, 5B, 7A, and 7B. The novel QTL were identified for DH, PH, and TKW. The findings of this study can be used in marker-assisted selection (MAS) for drought-tolerance breeding in spring wheat.

The resistance gene Sr13 is one of the most important genes in durum wheat for controlling stem rust caused by Puccinia graminis f. sp. tritici (Pgt). The Sr13 functional gene CNL13 has haplotypes R1, R2 and R3. The R1/R3 and R2 haplotypes were originally designated as alleles Sr13a and Sr13b, respectively. To detect additional Sr13 alleles, we developed Kompetitive allele specific PCR (KASP™) marker KASPSr13 and four semi-thermal asymmetric reverse PCR markers, rwgsnp37-rwgsnp40, based on the CNL13 sequence. These markers were shown to detect R1, R2 and R3 haplotypes in a panel of diverse tetraploid wheat accessions. We also observed the presence of Sr13 in durum line CAT-A1, although it lacked any of the known haplotypes. Sequence analysis revealed that CNL13 of CAT-A1 differed from the susceptible haplotype S1 by a single nucleotide (C2200T) in the leucine-rich repeat region and differed from the other three R haplotypes by one or two additional nucleotides, confirming that CAT-A1 carries a new (R4) haplotype. Stem rust tests on the monogenic, transgenic and mutant lines showed that R1 differed from R3 in its susceptibility to races TCMJC and THTSC, whereas R4 differed from all other haplotypes for susceptibility to TTKSK, TPPKC and TCCJC. Based on these differences, we designate the R1, R3 and R4 haplotypes as alleles Sr13a, Sr13c and Sr13d, respectively. This study indicates that Sr13d may be the primitive functional allele originating from the S1 haplotype via a point mutation, with the other three R alleles probably being derived from Sr13d through one or two additional point mutations.

Fusarium head blight (FHB) is a major disease of wheat in many wheat-growing regions affecting wheat yield and quality. Glenn is arguably the most FHB-resistant spring wheat cultivar in the USA. To decipher the genetics of FHB resistance in Glenn, a population of 112 recombinant inbred lines was developed from the cross Glenn × MN00261-4 and evaluated for various FHB related traits at multiple locations in two states (North Dakota and Minnesota) over 3 years. Quantitative trait loci (QTL) analysis detected 15 QTL for FHB resistance related traits and heading date (HD). One QTL for FHB incidence (INC; type I resistance), six QTL for FHB severity (SEV; type II resistance), one QTL for Fusarium damaged kernels (FDK; type IV resistance), four QTL for disease index (DI), and three QTL for HD were detected. Major QTL defined as those consistent across multiple environments and explaining > 10% of the phenotypic variation were detected on chromosomes 5BL, 6BS, and 7AS. They were associated with multiple FHB variables and HD. The stable 6BS QTL with a large effect for FHB SEV resistance corresponded to the Fhb2 gene in Sumai 3. In addition, potentially novel QTL were identified on 1AS, 5BL and 7DS. Our study showed that FHB resistance in the GM population was contributed by loci other than Fhb1. The major QTL detected for FHB resistance have potential for use in marker-assisted breeding for FHB resistance.

White mold caused by Sclerotinia sclerotiorum is an important constraint to field pea (Pisum sativum L.) production worldwide. To transfer white mold resistance into an adapted background, and study the genetics of the disease, two recombinant inbred line (RIL) populations (PRIL17 and PRIL19) were developed by crossing two partially resistant plant introductions with two susceptible pea cultivars. PRIL17 (Lifter × PI240515), and PRIL19 (PI169603 × Medora) were evaluated for resistance to white mold by measuring lesion expansion inhibition (LEI) and nodal transmission inhibition (NTI) at 3, 7, and 14 days post inoculation (dpi) under controlled environmental conditions. Lesion expansion inhibition percentage (LEIP), survival rate (SR), and area under disease progress curves (AUDPC) were also calculated accordingly. Because of a positive correlation between LEI and NTI with height, short and long internode individuals of each population were analyzed separately to avoid any confounding effect of height to pathogen response. A total of 22 short genotypes demonstrated partial resistance based on at least two Porter's resistance criteria. Only two pea genotypes with partial resistance to white mold (PRIL19-18 and PRIL19-124) had both semi-leafless (afila) and short internode traits. Both the RIL populations were genotyped using genotyping by sequencing (GBS). For PRIL17 and PRIL19, genetic maps were constructed from a total of 1,967 and 1,196 single nucleotide polymorphism (SNP) and spanned over 1,494 cM and 1,415 cM representing seven and nine linkage groups, respectively. A consensus map constructed using data from both populations, had 1,486 unique SNPs over 2,461 cM belonging to seven linkage groups. Inclusive composite interval mapping (ICIM) identified thirteen quantitative trait loci (QTL) associated with white mold resistance traits in both populations. Three of them were co-located with height genes (a morphological trait that reduces infection risk and acts as disease avoidance) and the other ten QTL were associated with two forms of physiological resistance (seven for LEI and three for NTI) with LOD and r2 ranging from 3.0 to 28.5 and 5.1 to 64.3, respectively. The development of resistance lines, genetic dissection and identification of markers associated will help accelerate breeding efforts for white mold resistance using molecular breeding approaches.

Eight advanced durum-breeding lines were treated with 5-methyl-azacytidine to test the feasibility of generating sources of Fusarium head blight (FHB) resistance. Of the 800 treated seeds, 415 germinated and were advanced up to four (M4) generations by selfing. Thirty-two of the resulting 415 M4 lines were selected following preliminary screening and were further tested for FHB resistance for three years at two field locations, and in the greenhouse. Five of the 32 M4 lines showed less than 30% disease severity, as compared to the parental lines and susceptible checks. Fusarium-damaged kernels and deoxynivalenol analyses supported the findings of the field and greenhouse disease assessments. Two of the most resistant M4 lines were crossed to a susceptible parent, advanced to third generation (BC1:F3) and were tested for stability and inheritance of the resistance. About, one third of the BC1:F3 lines showed FHB resistance similar to their M4 parents. The overall methylation levels (%) were compared using FASTmC method, which did not show a significant difference between M4 and parental lines. However, transcriptome analysis of one M4 line revealed significant number of differentially expressed genes related to biosynthesis of secondary metabolites, MAPK signaling, photosynthesis, starch and sucrose metabolism, plant hormone signal transduction and plant-pathogen interaction pathways, which may have helped in improved FHB resistance.