Improve Fusarium Head Blight Resistance Research Articles

Characterization of the Genetic Architecture for Fusarium Head Blight Resistance in Durum Wheat: The Complex Association of Resistance, Flowering Time, and Height Genes.

Durum wheat is an economically important crop for Canadian farmers. Fusarium head blight (FHB) is one of the most destructive diseases that threatens durum production in Canada. FHB reduces yield and end-use quality and most commonly contaminates the grain with the fungal mycotoxin deoxynivalenol, also known as DON. Serious outbreaks of FHB can occur in durum wheat in Canada, and combining genetic resistance with fungicide application is a cost effective approach to control this disease. However, there is limited variation for genetic resistance to FHB in elite Canadian durum cultivars. To explore and identify useful genetic FHB resistance variation for the improvement of Canadian durum wheat, we assembled an association mapping (AM) panel of diverse durum germplasms and performed genome wide association analysis (GWAS). Thirty-one quantitative trait loci (QTL) across all 14 chromosomes were significantly associated with FHB resistance. On 3BS, a stable QTL with a larger effect for resistance was located close to the centromere of 3BS. Three haplotypes of Fhb1 QTL were identified, with an emmer wheat haplotype contributing to disease susceptibility. The large number of QTL identified here can provide a rich resource to improve FHB resistance in commercially grown durum wheat. Among the 31 QTL most were associated with plant height and/or flower time. QTL 1A.1, 1A.2, 3B.2, 5A.1, 6A.1, 7A.3 were associated with FHB resistance and not associated or only weakly associated with flowering time nor plant height. These QTL have features that would make them good targets for FHB resistance breeding.

Epigenetic regulation of gene expression improves Fusarium head blight resistance in durum wheat

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.

Training Population Design With the Use of Regional Fusarium Head Blight Nurseries to Predict Independent Breeding Lines for FHB Traits.

Fusarium head blight (FHB) is a devastating disease in cereals around the world. Because it is quantitatively inherited and technically difficult to reproduce, breeding to increase resistance in wheat germplasm is difficult and slow. Genomic selection (GS) is a form of marker-assisted selection (MAS) that simultaneously estimates all locus, haplotype, or marker effects across the entire genome to calculate genomic estimated breeding values (GEBVs). Since its inception, there have been many studies that demonstrate the utility of GS approaches to breeding for disease resistance in crops. In this study, the Uniform Northern (NUS) and Uniform Southern (SUS) soft red winter wheat scab nurseries (a total 452 lines) were evaluated as possible training populations (TP) to predict FHB traits in breeding lines of the UK (University of Kentucky) wheat breeding program. DON was best predicted by the SUS; Fusarium damaged kernels (FDK), FHB rating, and two indices, DSK index and DK index were best predicted by NUS. The highest prediction accuracies were obtained when the NUS and SUS were combined, reaching up to 0.5 for almost all traits except FHB rating. Highest prediction accuracies were obtained with bigger TP sizes (300–400) and there were not significant effects of TP optimization method for all traits, although at small TP size, the PEVmean algorithm worked better than other methods. To select for lines with tolerance to DON accumulation, a primary breeding target for many breeders, we compared selection based on DON BLUES with selection based on DON GEBVs, DSK GEBVs, and DK GEBVs. At selection intensities (SI) of 30–40%, DSK index showed the best performance with a 4–6% increase over direct selection for DON. Our results confirm the usefulness of regional nurseries as a source of lines to predict GEBVs for local breeding programs, and shows that an index that includes DON, together with FDK and FHB rating could be an excellent choice to identify lines with low DON content and an overall improved FHB resistance.

Spike culture derived wheat (Triticum aestivum L.) variants exhibit improved resistance to multiple chemotypes of Fusarium graminearum.

Fusarium head blight (FHB) in wheat (Triticum aestivum L.), predominantly caused by Fusarium graminearum, has been categorized into three chemotypes depending on the major mycotoxin produced. The three mycotoxins, namely, 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivalenol (15-ADON) and nivalenol (NIV) also determine their aggressiveness and response to fungicides. Furthermore, prevalence of these chemotypes changes over time and dynamic changes in chemotypes population in the field have been observed. The objective of this study was to identify spike culture derived variants (SCDV) exhibiting resistance to multiple chemotypes of F. graminearum. First, the optimal volume of inoculum for point inoculation of the spikelets was determined using the susceptible AC Nanda wheat genotype. Fifteen μL of 105 macroconidia/mL was deemed optimal based on FHB disease severity assessment with four chemotypes. Following optimal inoculum volume determination, five chemotypes (Carman-NIV, Carman-705-2-3-ADON, M9-07-1-3-ADON, M1-07-2-15-ADON and China-Fg809-15-ADON) were used to point inoculate AC Nanda spikelets to confirm the mycotoxin produced and FHB severity during infection. Upon confirmation of the mycotoxins produced by the chemotypes, 55 SCDV were utilized to evaluate FHB severity and mycotoxin concentrations. Of the 55 SCDV, five (213.4, 244.1, 245.6, 250.2 and 252.3) resistant lines were identified with resistance to multiple chemotypes and are currently being utilized in a breeding program to develop wheat varieties with improved FHB resistance.

Comparing Genetic Variation within Red Winter Wheat Populations with and without Image-Based Optical Sorter Selection

Head scab is historically a devastating disease affecting not just all classes of wheat but also barley and other small grains around the world. Fusarium head blight (FHB), or head scab, is caused most often by Fusarium graminearum (Schwabe), (sexual stage – Gibberella zeae) although several Fusarium spp. can cause the disease. This study was conducted to determine the effect of mass selection for FHB resistance using an image-based optical sorter. lines were derived from the C0 and C2 of two populations to compare genetic variation within populations with and without sorter selection. Our overall hypothesis is that sorting grain results in improved Fusarium head blight resistance. Both of the used wheat derived line populations have genetic variation, and population 1 has more than population 17. They are significantly different from each other for fusarium damged kernel (FDK), deoxynivalenol (DON), and other FHB traits. Although both populations are suitable to be grown for bulks, population 1 seems better since it has more genetic variation as well as lower FDK and DON, and earlier heading date. Lines within each population were significantly different and some lines in each population had significantly lower FDK and DON after selection using an optical sorter. Some lines had significant reduction in both FDK and DON, and some others had either FDK or DON reduction. Lines of population 1 that had significant reduction, were more numerous than in population 17, and FDK and DON reduction were greater.

Comparing Genetic Variation within Red Winter Wheat Populations with and without Image-Based Optical Sorter Selection

Head scab is historically a devastating disease affecting not just all classes of wheat but also barley and other small grains around the world. Fusarium head blight (FHB), or head scab, is caused most often by Fusarium graminearum (Schwabe), (sexual stage – Gibberella zeae) although several Fusarium spp. can cause the disease. This study was conducted to determine the effect of mass selection for FHB resistance using an image-based optical sorter. lines were derived from the C0 and C2 of two populations to compare genetic variation within populations with and without sorter selection. Our overall hypothesis is that sorting grain results in improved Fusarium head blight resistance. Both of the used wheat derived line populations have genetic variation, and population 1 has more than population 17. They are significantly different from each other for fusarium damged kernel (FDK), deoxynivalenol (DON), and other FHB traits. Although both populations are suitable to be grown for bulks, population 1 seems better since it has more genetic variation as well as lower FDK and DON, and earlier heading date. Lines within each population were significantly different and some lines in each population had significantly lower FDK and DON after selection using an optical sorter. Some lines had significant reduction in both FDK and DON, and some others had either FDK or DON reduction. Lines of population 1 that had significant reduction, were more numerous than in population 17, and FDK and DON reduction were greater.

Harnessing Wheat Fhb1 for Fusarium Resistance.

Fusarium head blight (FHB), caused by the fungus Fusarium graminearum, is an economically devastating disease of wheat worldwide. Fhb1, a widely used genetic source of FHB resistance, originated in East Asia. The recent cloning of Fhb1 opens a new avenue to improve FHB resistance in wheat and potentially other crops.

A deletion mutation in TaHRC confers Fhb1 resistance to Fusarium head blight in wheat.

Fusarium head blight (FHB), which is mainly caused by Fusarium graminearum, is a destructive wheat disease that threatens global wheat production. Fhb1, a quantitative trait locus discovered in Chinese germplasm, provides the most stable and the largest effect on FHB resistance in wheat. Here we show that TaHRC, a gene that encodes a putative histidine-rich calcium-binding protein, is the key determinant of Fhb1-mediated resistance to FHB. We demonstrate that TaHRC encodes a nuclear protein conferring FHB susceptibility and that a deletion spanning the start codon of this gene results in FHB resistance. Identical sequences of the TaHRC-R allele in diverse accessions indicate that Fhb1 had a single origin, and phylogenetic and haplotype analyses suggest that the TaHRC-R allele most likely originated from a line carrying the Dahongpao haplotype. This discovery opens a new avenue to improve FHB resistance in wheat, and possibly in other cereal crops, by manipulating TaHRC sequence through bioengineering approaches.

Effects of the Fhb1 gene on Fusarium head blight resistance and agronomic traits of winter wheat

The gene Fhb1 has been used in many countries to improve wheat Fusarium head blight (FHB) resistance. To make better use of this gene in the Yellow-Huai River Valleys Winter Wheat Zone (YHWZ), the most important wheat-producing region of China, it is desirable to elucidate its effects on FHB resistance and agronomic traits in different genetic backgrounds. Based on a diagnostic marker for Fhb1, six BC2 populations were developed by crossing dwarf-male-sterile (DMS)-Zhoumai 16 to three Fhb1 donors (Ningmai 9, Ningmai 13, and Jianyang 84) and backcrossing to Zhoumai 16 and Zhoumai 16's derivative cultivars (Lunxuan 136 and Lunxuan 13) using marker-assisted backcross breeding. The progenies were assessed for FHB resistance and major agronomic traits. The Fhb1 alleles were identified using the gene-specific molecular marker. The plants with the Fhb1-resistant genotype (Fhb1-R) in these populations showed significantly fewer infected spikelets than those with the Fhb1-susceptible genotype (Fhb1-S). When Lunxuan 136 was used as the recurrent parent, Fhb1-R plants showed significantly fewer infected spikelets per spike than Fhb1-R plants produced using Lunxuan 13 as the recurrent parent, indicating that the genetic backgrounds of Fhb1 influence the expression of FHB resistance. Fhb1-R plants from the DMS-Zhoumai 16/Ningmai 9//Zhoumai 16/3/Lunxuan 136 population showed the highest FHB resistance among the six populations and a significantly higher level of FHB resistance than the moderately susceptible control Huaimai 20. No significant phenotypic differences between Fhb1-R and Fhb1-S plants were observed for the eight agronomic traits investigated. These results suggest that it is feasible to improve FHB resistance of winter wheat without reducing yield potential by introgressing Fhb1 resistance allele into FHB-susceptible cultivars in the YHWZ.

Fine-mapping of the Fusarium head blight resistance QTL Qfhs.ifa-5A identifies two resistance QTL associated with anther extrusion

Key messageFine-mapping separated Qfhs.ifa-5A into a major QTL mapping across the centromere and a minor effect QTL positioned at the distal half of 5AS. Both increase Fusarium resistance and anther extrusion.The Fusarium head blight (FHB) resistance QTL Qfhs.ifa-5A resides in the low-recombinogenic pericentromeric region of chromosome 5A making fine-mapping particularly arduous. Qfhs.ifa-5A primarily contributes resistance to fungal entry with the favorable allele descending from the highly Fusarium resistant cultivar Sumai-3. Fine-mapping a near-isogenic recombinant inbred line population partitioned the Qfhs.ifa-5A interval into 12 bins. Near-isogenic lines recombining at the interval were phenotyped for FHB severity, anther retention and plant height. Composite interval mapping separated the initially single QTL into two QTL. The major effect QTL Qfhs.ifa-5Ac mapped across the centromere and the smaller effect QTL Qfhs.ifa-5AS mapped to the distal half of 5AS. Although Qfhs.ifa-5Ac and Qfhs.ifa-5AS intervals were as small as 0.1 and 0.2 cM, their corresponding physical distances were large, comprising 44.1 Mbp and 49.2 Mbp, respectively. Sumai-3 alleles at either QTL improved FHB resistance and increased anther extrusion suggesting a pleiotropic effect of anthers on resistance. This hypothesis was supported by greenhouse experiments using the susceptible cultivar Remus and its resistant near-isogenic line NIL3 carrying the entire Qfhs.ifa-5A segment. By manually removing anthers prior to spray inoculation both, Remus and NIL3 became almost equally resistant in the early phase of the disease development and were significantly less diseased than variants without anther manipulation. At late time points the positive effect of the anther removal became smaller for Remus and disappeared completely for NIL3. Results affirm that absence of anthers enhanced resistance to initial infection but did not protect plants from fungal spreading within spikes.

Detection and validation of a novel major QTL for resistance to Fusarium head blight from Triticum aestivum in the terminal region of chromosome 7DL.

A novel QTL for FHB resistance was mapped on wheat 7DL, being effective in multiple genetic backgrounds and environments, and comparable to Fhb1 in effect magnitude. Fusarium head blight (FHB) is one of the major fungal diseases affecting wheat production in many countries. The wheat line AQ24788-83 (AQ) possesses FHB resistance. The American wheat cultivar Luke is FHB susceptible. A Luke × AQ population consisting of 1652 advanced recombinant inbred lines (RILs) was developed, from which 272 RILs were randomly sampled and used to construct a linkage map. Another 154 RILs were selected for homogeneity in plant height (PH) and flowering date (FD). This selection strategy was adopted to reduce possible confounding effects on FHB assessment due to variation in PH and FD. The 272 and 154 RILs were genotyped applying simple sequence repeat (SSR), diversity arrays technology (DArT) and single-nucleotide polymorphism (SNP) markers. The two sets of RILs were evaluated for FHB resistance applying point inoculation in greenhouses; the 154 RILs were also evaluated applying spray inoculation in multiple field environments. The linkage map consisted of 2088 SSR, DArT, and SNP markers. A FHB resistance quantitative trait locus (QTL), designated as QFhb.cau-7DL, was detected on chromosome arm 7DL; this QTL was closely linked to the SSR marker gwm428 ( http://www.wheat.pw.usda.gov/ggpages/SSR/ ). QFhb.cau-7DL was significantly effective (α = 0.01) in every test trial, and its effectiveness was validated using three additional wheat crosses. Sumai 3 (donor wheat of the FHB resistance gene Fhb1) was used in one of these crosses. QFhb.cau-7DL was comparable to Fhb1 in effect magnitude, providing a great potential for improving FHB resistance.

Cell wall features transferred from common into durum wheat to improve Fusarium Head Blight resistance

Durum wheat is naturally more susceptible to Fusarium graminerum infection in comparison to common wheat. The improvement of durum wheat resistance against F. graminearum is a challenge due to the lack of resistance sources in its gene pool. FHB-resistance factors were introduced in durum wheat by generating recombinant inbred lines (RILs), obtained by crossing the hexaploid resistant accession 02-5B-318 with the susceptible durum wheat cv. Saragolla. In this work we explored the possible contribution of cell wall (CW) in RILs with improved FHB resistance. We thoroughly studied CW components, mycotoxins content and the expression of related genes in different RILs selected for their extremely high and low resistance to FHB. Differences were found in resistant and susceptible lines in the degree of pectin methylesterification and in deoxynivalenol (DON) accumulation after fungal infection. Genes involved in biochemical modification of CW structure (WheatPme-1, Glu-1) and mycotoxins accumulation (ns-LTP-1) were analyzed as putative candidates for FHB resistance. Our results indicate that durum wheat plants with cell wall structure and gene response acquired from common wheat displayed an increased resistance to FHB.

Advantages and limitations of multiple-trait genomic prediction for Fusarium head blight severity in hybrid wheat (Triticum aestivum L.).

Predictabilities for wheat hybrids less related to the estimation set were improved by shifting from single- to multiple-trait genomic prediction of Fusarium head blight severity. Breeding for improved Fusarium head blight resistance (FHBr) of wheat is a very laborious and expensive task. FHBr complexity is mainly due to its highly polygenic nature and because FHB severity (FHBs) is greatly influenced by the environment. Associated traits plant height and heading date may provide additional information related to FHBr, but this is ignored in single-trait genomic prediction (STGP). The aim of our study was to explore the benefits in predictabilities of multiple-trait genomic prediction (MTGP) over STGP of target trait FHBs in a population of 1604 wheat hybrids using information on 17,372 single nucleotide polymorphism markers along with indicator traits plant height and heading date. The additive inheritance of FHBs allowed accurate hybrid performance predictions using information on general combining abilities or average performance of both parents without the need of markers. Information on molecular markers and indicator trait(s) improved FHBs predictabilities for hybrids less related to the estimation set. Indicator traits must be observed on the predicted individuals to benefit from MTGP. Magnitudes of genetic and phenotypic correlations along with improvements in predictabilities made plant height a better indicator trait for FHBs than heading date. Thus, MTGP having only plant height as indicator trait already maximized FHBs predictabilities. Provided a good indicator trait was available, MTGP could reduce the impacts of genotype environment [Formula: see text] interaction on STGP for hybrids less related to the estimation set.

The potential of genomic‐assisted breeding to improve Fusarium head blight resistance in winter durum wheat

AbstractDurum wheat is the most important tetraploid wheat mainly used for semolina and pasta production, but is notorious for its high susceptibility to Fusarium head blight (FHB). Our objectives were to identify and characterize quantitative trait loci (QTL) in winter durum and to evaluate the potential of genomic approaches for the improvement ofFHBresistance. Here, we employed an international panel of 170 winter and 14 spring durum lines, phenotyped forFusarium culmorumresistance at five environments. Heading date, plant height and meanFHBseverity showed significant genotypic variation with high heritabilities andFHBresistance was negatively correlated with both heading date and plant height. The dwarfing geneRht‐B1significantly affectedFHBresistance and the genome‐wide association scan identified eight additionalQTLaffectingFHBresistance, explaining between 1% and 14% of the genotypic variation. A genome‐wide prediction approach yielded only a slightly improved predictive ability compared to marker‐assisted selection based on the four strongestQTL. In conclusion,FHBresistance in durum wheat is a highly quantitative trait and in breeding programmes may best be tackled by classical high‐throughput recurrent phenotypic selection that can be assisted by genomic prediction if marker profiles are available.

High accuracy of predicting hybrid performance of Fusarium head blight resistance by mid-parent values in wheat.

Mid-parent values of Fusarium head blight (FHB) resistance tested across several locations are a good predictor of hybrid performance caused by a preponderance of additive gene action in wheat. Hybrid breeding is intensively discussed as one solution to boost yield and yield stability including an enhanced biotic stress resistance. Our objectives were to investigate (1) the heterosis for Fusarium head blight (FHB) resistance, (2) the importance of general (GCA) vs. specific combining ability (SCA) for FHB resistance, and (3) the possibility to predict the FHB resistance of the hybrids by the parental means. We re-analyzed phenotypic data of a large population comprising 1604 hybrids and their 120 female and 15 male parental lines evaluated in inoculation trials across seven environments. Mid-parent heterosis of FHB severity averaged -9%, with a range from -36 to +35%. Mean better parent heterosis was 2% and 78 of the hybrids significantly (P<0.05) outperformed the best commercial check variety included in our study. FHB resistance was not correlated with grain yield in healthy status for lines (r=0.01) and hybrids (r=0.09, P<0.01). While a preponderance of GCA variance (P<0.01) was found, SCA variance was not significantly different from zero. Accuracy to predict hybrid performance of FHB severity based on mid-parent values and on GCA effects was high (r=0.70 and 0.86, respectively; P<0.01). Similarly, line per se performance and GCA effects were significantly correlated (r=0.77; P<0.01). The substantial level of mid-parent heterosis in the desired direction of decreased susceptibility and the negligible better parent heterosis suggest that hybrids are an attractive alternative variety type to improve FHB resistance.

Hard white spring wheat line WS175 with a high level of resistance to Fusarium head blight

WS175 is a hard white spring wheat line with the parentage Snowbird/Sumai3 with a high level of resistance to Fusarium head blight (FHB) that was developed using marker-assisted selection. WS175 contains haplotypes similar to Sumai3 at the loci previously associated with FHB resistance, located on chromosomes 3B, 5A, and 6B. WS175 has similar maturity and protein content, but has lower grain yield, compared to Snowbird. The combination of white seed coat colour and very high level of FHB resistance will make WS175 a valuable parent for the improvement of FHB resistance in white spring wheat breeding programs.

00Ar134-1, a spring wheat line of intergeneric origin

00Ar134-1 is an intergeneric spring wheat line derived from Elymus repens (quack grass). The line was developed as a potentially new source of resistance to Fusarium head blight (FHB) in wheat. 00Ar134-1 is resistant to Fusarium head blight as well as leaf rust, stem rust, and common bunt. Although lower yielding and taller than commercial cultivars, this line is of similar maturity and kernel weight. 00Ar134-1 can potentially be used as a resistant parent for improving Fusarium head blight resistance in common wheat.

Identifying Rare FHB-Resistant Segregants in Intransigent Backcross and F2 Winter Wheat Populations.

Fusarium head blight (FHB), caused mainly by Fusarium graminearum Schwabe [telomorph: Gibberella zeae Schwein.(Petch)] in the US, is one of the most destructive diseases of wheat (Triticum aestivum L. and T. durum L.). Infected grain is usually contaminated with deoxynivalenol (DON), a serious mycotoxin. The challenge in FHB resistance breeding is combining resistance with superior agronomic and quality characteristics. Exotic QTL are widely used to improve FHB resistance. Success depends on the genetic background into which the QTL are introgressed, whether through backcrossing or forward crossing; QTL expression is impossible to predict. In this study four high-yielding soft red winter wheat breeding lines with little or no scab resistance were each crossed to a donor parent (VA01W-476) with resistance alleles at two QTL: Fhb1 (chromosome 3BS) and QFhs.nau-2DL (chromosome 2DL) to generate backcross and F2 progeny. F2 individuals were genotyped and assigned to 4 groups according to presence/ absence of resistance alleles at one or both QTL. The effectiveness of these QTL in reducing FHB rating, incidence, index, severity, Fusarium-damaged kernels (FDK) and DON, in F2-derived lines was assessed over 2 years. Fhb1 showed an average reduction in DON of 17.5%, and conferred significant resistance in 3 of 4 populations. QFhs.nau-2DL reduced DON 6.7% on average and conferred significant resistance in 2 of 4 populations. The combination of Fhb1 and QFhs.nau-2DL resistance reduced DON 25.5% across all populations. Double resistant lines had significantly reduced DON compared to double susceptible lines in 3 populations. Backcross derived progeny were planted in replicated yield trials (2011 and 2012) and in a scab nursery in 2012. Several top yielding lines performed well in the scab nursery, with acceptable DON concentrations, even though the average effect of either QTL in this population was not significant. Population selection is often viewed as an “all or nothing” process: if the average resistance level is insufficient, the population is discarded. These results indicate that it may be possible to find rare segregants which combine scab resistance, superior agronomic performance and acceptable quality even in populations in which the average effect of the QTL is muted or negligible.

A spontaneous segmental deletion from chromosome arm 3DL enhances Fusarium head blight resistance in wheat.

Much effort has been directed at identifying sources of resistance to Fusarium head blight (FHB) in wheat. We sought to identify molecular markers for what we hypothesized was a new major FHB resistance locus originating from the wheat cultivar 'Freedom' and introgressed into the susceptible wheat cultivar 'USU-Apogee'. An F2:3 mapping population from a cross between Apogee and A30, its BC4 near-isoline exhibiting improved FHB resistance, was evaluated for resistance. The distribution of FHB resistance in the population approximated a 1:3 moderately resistant : moderately susceptible + susceptible ratio. Separate disease evaluations established that A30 accumulated less deoxynivalenol and yielded a greater proportion of sound grain than Apogee. Molecular mapping revealed that the FHB resistance of A30 is associated with molecular markers on chromosome arm 3DL that exhibit a null phenotype in A30 but are present in both Apogee and Freedom, indicating a spontaneous deletion occurred during the development of A30. Aneuploid analysis revealed that the size of the deleted segment is approximately 19% of the arm's length. Our results suggest that the deleted interval of chromosome arm 3DL in Apogee may harbor FHB susceptibility genes that promote disease spread in infected spikes, and that their elimination increases FHB resistance in a novel manner.

Evaluation of Canadian barley breeding lines for Fusarium head blight resistance

He, X., Osman, M., Helm, J., Capettini, F. and Singh, P. K. 2015. Evaluation of Canadian barley breeding lines for Fusarium head blight resistance. Can. J. Plant Sci. 95: 923–929. Fusarium head blight (FHB) is a major challenge to the successful production of barley in Canada, as well as for end-users such as the malting and brewing industries. Due to the quantitative inheritance of FHB resistance, continuous effort is required to identify breeding lines with improved FHB resistance and incorporate them into crossing schemes to enhance FHB resistance. In the present study, 402 advanced breeding lines from Alberta, Canada, were evaluated in the FHB screening nursery at CIMMYT, Mexico. In 2011 and 2012, FHB incidence was measured on a scale of 1 to 4 to eliminate the most susceptible lines. In 2013 and 2014, 181 lines with the lowest disease scores in the previous 2 yr were tested in replicated experiments for field FHB index, Fusarium-damaged kernels, and deoxynivalenol content. Agronomic and morphological traits, specifically days to heading, plant height, and row and hull types were also evaluated in relations to FHB parameters. Correlation coefficients among the three FHB parameters in both 2013 and 2014 were all significant at P&lt;0.0001, ranging from 0.36 to 0.63. Additional correlation analysis showed that late-maturing, tall, and two-row lines tended to have lower disease, whereas hull type did not show a significant correlation with FHB. Several lines with high and stable FHB resistance similar to that of the resistant checks were identified. These could be used in breeding programs as resistance sources or be registered as new cultivars if their overall attributes meet commercial standards.