Fusarium head blight (FHB), caused by Fusarium graminearum, is a serious disease of wheat and barley that has caused several billion dollars in crop losses over the last decade in the United States. Spores of F. graminearum are released from corn and small grain residues left-over from the previous growing season and are transported long distances in the atmosphere before being deposited.  Current risk assessment tools consider environmental conditions favorable for disease development, but do not include spore transport. Long distance transport models have been proposed for a number of plant pathogens, but many of these models have not been experimentally validated. In order to predict the atmospheric transport of F. graminearum, the potential source strength (Qpot) of inoculum must be known.  We conducted a series of laboratory and field experiments to estimate Qpot from a field-scale source of inoculum of F. graminearum.  Perithecia were generated on artificial (carrot agar) and natural (corn stalk) substrates.  Artificial substrate (carrot agar) produced 15±0.4 perithecia cm-2, and natural substrate (corn stalk) produced 44±2 perithecia cm-2.  Individual perithecia were excised from both substrate types and allowed to release ascospores every 24 hours.  Perithecia generated from artificial (carrot agar) and natural (corn stalk) substrates released a mean of 104±5 and 276±16 ascospores, respectively.  A volumetric spore trap was placed inside a 3,716 m2 clonal source of inoculum in 2011 and 2012.  Results indicated that ascospores were released under field conditions predominantly (>90%) during the night (1900 to 0700 hours).  Estimates of Qpot for our field-scale sources of inoculum were approximately 4 billion ascospores per 3,716 m2.  Release-recapture studies were conducted from a clonal field-scale source of F. graminearum in 2011 and 2012. Microsatellites were used to identify the released clone of F. graminearum at distances up to 1 km from the source. Dispersal kernels for field observations were compared to results predicted by a Gaussian dispersal-based spore transport model.  In 2011 and 2012, dispersal kernel shape coefficients were similar for both results observed in the field and predicted by the model, with both being dictated by a power law function, indicating that turbulence was the dominant transport factor on the scale we studied (~ 1 km).  Model predictions had a stronger correlation with the number of spores being released when using a time varying q0 emission rate (r= 0.92 in 2011 and r= 0.84 in 2012) than an identical daily pattern q0 emission rate (r= 0.35 in 2011 and r= 0.32 in 2012).  The actual numbers of spores deposited were 3 and 2000 times lower than predicted if Qpot were equal to the actual number of spores released in 2011 and 2012, respectively. Future work should address estimating the actual number of spore released from an inoculated field during any given season, to improve prediction accuracy of the model.  This work should assist in improving current risk assessment tools for FHB and contribute to the development of early warning systems for the spread of F. graminearum. / Ph. D.

La fusariose des épis, causée majoritairement par le champignon pathogène Fusarium graminearum (Fg), est une des principales maladies du blé tendre (Triticum aestivum). Pendant son cycle infectieux, l’agent pathogène produit des mycotoxines appartenant principalement aux trichothécènes de type B, tel que le déoxynivalénol (DON), qui sont toxiques pour l’homme et l’animal. Plusieurs loci à caractère quantitatif (QTLs) impliqués dans la résistance à la fusariose des épis ont été identifiés. Certains ont été corrélés avec une détoxication de la mycotoxine, principalement par conjugaison du DON en DON-3-O-glucose (D3G), une réaction enzymatique catalysée par des UDP-glucosyltransferases (UGT). Néanmoins, peu d’études ont conduit des analyses fonctionnelles dans des plantes hôtes de la maladie afin de relier directement la glucosylation de la mycotoxine avec la résistance à la maladie in planta, et aucune d’entre elles n'a été effectuée sur des gènes de détoxication du blé tendre. Notre équipe, à l'aide de la céréale modèle Brachypodium distachyon, a démontré que l'UGT Bradi5g03300 est capable de conférer une tolérance au DON par glucosylation en DON 3-O-glucose et qu’elle est impliquée dans l'établissement précoce d'une résistance quantitative à la fusariose des épis. Le présent travail avait pour objectif de transférer les analyses fonctionnelles menées sur la céréale modèle Brachypodium distachyon au blé tendre. Dans une première approche, le gène Bradi5g03300 a été introduit dans la variété de blé Apogée, sensible à la fusariose. Les analyses phénotypiques effectuées sur les lignées de blé transgéniques exprimant constitutivement le gène Bradi5g03300, montrent une résistance plus élevée à la maladie ainsi qu'une tolérance à la mycotoxine par rapport à la lignée contrôle. Parallèlement, en utilisant une approche de synténie entre les génomes de B. distachyon et du blé tendre, nous avons identifié un gène de blé, orthologue au gène Bradi5g03300.La transformation de l’écotype de B. distachyon sensible à la fusariosepar ce gène candidat a été effectuée pour déterminer rapidement sa capacité à conjuguer le DON in planta et son implication dans la résistance à la fusariose. En conclusion, ce projet contribue à accroître les connaissances concernant la relation fonctionnelle entre la glucosylation DON et la résistance à la fusariose dans le blé tendre et à fournir des gènes candidats à inclure dans les processus de sélection. / Fusarium head blight (FHB) caused by fungi of the Fusarium genus is a widespread disease of wheat (Triticum aestivum) and other small-grain cereal crops. The main causal agent of FHB, Fusarium graminearum, can produce mycotoxins mainly belonging to type B trichothecenes, such as deoxynivalenol (DON) that can negatively affect humans, animals and plants. Several quantitative trait loci (QTLs) for resistance to FHB have been identified some of which have been correlated with efficient DON detoxification, mainly through the conjugation of DON into DON-3-O-glucose (D3G), a reaction catalyzedby UDP-glucosyltransferases (UGTs). Nevertheless, only few studies have conducted functional analyses to directly correlate DON glucosylation and resistance in planta and none were performed on wheat UGT gene(s). Our team, using the model cereal species Brachypodium distachyon, has recently demonstrated that the Bradi5g03300 UGT is able to confer tolerance to DON following glucosylation of DON into DON 3-O-glucose and is involved in the early establishment of quantitative resistance to FHB. In the present work, we transferred the functional analyses conducted on the model species Brachypodium distachyon to bread wheat. In a first approach the B. distachyon Bradi5g03300 gene has been introduced through biolistic-mediated transformation in the wheat variety Apogee, susceptible to FHB. The phenotypic analyses conducted on homozygous transgenic wheat constitutively expressing the Bradi5g03300 gene showed that they exhibit higher resistance to FHB as well as increased root tolerance to DON compared to the control line. In parallel, using a synteny approach between B. distachyon and bread wheat genomes we identified a wheat candidate gene orthologous to the B. distachyon Bradi5g03300 gene. This wheat gene after validation through gene expression pattern during wheat infection, was introduced by transformation into B. distachyon to rapidly determine its ability to conjugate DON into D3G in planta and its involvement in FHB resistance. In conclusion, this project contributes to increase the knowledge concerning the functional relationship between DON glucosylation and FHB resistance in wheat and provide candidate genes to include in selection processes.

No description available.

Fusarium head blight (FHB) is one of the most economically important diseases of small grains and continues to impact crops when environmental conditions are favorable to Gibberella zeae (Fusarium graminearum), the causal agent of the disease. Corn residues are considered to be primary sources of inoculum for epidemics of FHB. Therefore, knowledge of the movement of Gibberella zeae from a local source of infested corn residue is critical to the management of FHB in wheat and barley. Previous research made significant progress in defining the spatial dissemination of inoculum sources of G. zeae within agricultural fields, but was unable to clearly distinguish between within-field and background sources. Using amplified fragment length polymorphism, released clones of G. zeae were tracked within wheat and barley fields. This strategy allowed the distinction between the contributions of released clones to FHB, compared to that of background inocula. Corn residue infested with clones of G. zeae was placed into small replicated plots in winter wheat fields in New York and Virginia in 2007 and 2008 and wheat spikes were collected at 0, 3, 6, and ≥24 m from the inoculum sources. Recovery of released clones decreased an average of 90% between 3 and 6 m from inoculum sources. Various amounts of corn residue infested with a single clone of G. zeae were placed into small replicated plots in winter wheat and barley fields in Virginia from 2008 to 2010. The use of minimal or conventional tillage and a moderately resistant cultivar of wheat or barley may reduce the contribution of within-field inocula to FHB; however, environmental conditions play an important role in the effectiveness of these management strategies. With the increase of corn production due to incentives for ethanol-based fuel, overwintering sites for G. zeae on corn residue are likely to increase. Our work contributes to an increased understanding of the influence of overwintered corn residue to FHB which will also direct future research on how to reduce the inoculum potential from within-field sources. / Ph. D.

Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe, is a devastating fungal disease that affects barley production worldwide through damaged kernels, low yields, and production of mycotoxins. The most effective means of control is through the use of FHB resistant cultivars that are developed through gene pyramiding and incorporation of various sources of resistance. Resistance identified in winter barley cultivar Eve has been identified in Virginia Tech's Small Grains Breeding Program. The objectives of this study are to validate resistance and identify additional resistance QTL, and identify tightly linked and diagnostic markers for use in MAS programs. A population of F5:7 RILs derived from the cross Eve/Doyce were evaluated for FHB resistance. FHB incidence (Inc), FHB severity (Sev), Fusarium damaged kernels (FDK), and deoxynivalenol (DON) were assessed over 2014-15 and 2015-16 at Blacksburg, VA, Mount Holly, VA, Kinston, NC, and Lexington, KY. A QTL on chromosome 6H associated with FHB Sev, FDK, and DON was identified. The QTL accounted for as high as 14.5% of the phenotypic variation for DON accumulation, 8.3% for FHB Sev, and 11.87% to 17.63% for FDK. The QTL marker region spans 56.5 to 66.6 cM with flanking markers SCRI_RS_147342 and Bmag0613. QTL for morphological traits, heading date and height, were found in the same region as the FHB resistance traits. Diagnostic SNP makers associated with the FHB resistance QTL identified can be used for FHB resistance identification in MAS breeding programs to incorporate and pyramid resistance QTL and genes into other plant material. / Master of Science

Phenotypic and genotypic characterization of hulled and hulless winter barley (Hordeum vulgare L.) is necessary for improvement using traditional and molecular breeding techniques.  Identification of genomic regions conferring resistance to Fusarium head blight (caused by Fusarium graminearum), leaf rust (caused by Puccinia hordei G. Otth), powdery mildew [caused by Blumeria graminis (DC.) E.O. Speer f. sp. hordei Em. Marchal], net blotch (caused by Pyrenophora teres) and spot blotch [caused by Cochliobolus sativus (Ito & Kuribayashi) Drechsler ex Dastur] will greatly aid in breeding for improved resistance.  Determining factors that contribute to yield differences between hulled and hulless genotypes, and identification of markers associated with yield and yield related traits will greatly aid in improvement of hulled and hulless genotypes.  The hulled cultivar Nomini, hulless cultivar Eve, and hulless line VA06H-48 were consistently resistant to Fusarium head blight (FHB) and had low deoxynivalenol (DON) accumulation.  Screening with molecular markers on chromosomes 2H and 6H for FHB and DON identified quantitative trait loci (QTL) which may confer resistance in Virginia Tech germplasm.  Evaluation of hulled and hulless full-sibs from four populations indicated  that  grain volume weight and protein concentration were significantly (P d 0.05) higher for hulless genotypes, while seedling emergence and grain ash concentration were significantly (P d 0.05) higher for hulled genotypes.  In linear regression analysis, none of the assessed traits explained yield variation in all populations and environments.  Identification of hulless genotypes having yield potentials similar to those of their hulled sibs should be possible after adjusting for hull weight.  A genome wide association study was used to identify chromosome regions governing traits of importance in six-rowed winter barley germplasm and to identify single nucleotide polymorphisms (SNPs) markers for use in a marker-assisted breeding program. Significant SNPs associated with previously described QTL or genes were identified for heading date, test weight, yield, grain protein, polyphenol oxidase activity, and resistance to leaf rust, powdery mildew, net blotch, and spot blotch.  Novel QTL also were identified for agronomic, quality, and disease resistance traits.  These SNP-trait associations provide the opportunity to directly select for QTL contributing to multiple traits in breeding programs. / Ph. D.

Fusarium Head Blight (FHB) is a devastating fungal disease of wheat (Triticum aestivum L.) and results in significant economic losses due to reductions in grain yield and the accumulation of mycotoxins, such as deoxynivalenol (DON) and nivalenol (NIV). As a result, breeding programs have been working to identify resistance genes in wheat varieties known to be resistant to FHB. Some of the major quantitative trait loci (QTL) for FHB resistance identified to date have been from exotic sources such as 'Sumai3' and the Chinese landrace Wangshuibai, and native resistance has been identified in North American cultivars such as Ernie and Truman which are being used in breeding programs. This study was conducted to characterize and map QTL for resistance to FHB in the soft red winter wheat cultivar Jamestown and to identify tightly linked DNA markers associated with those QTL so that marker-assisted selection (MAS) can be used in pyramiding these and other known QTL into elite backgrounds. Types of resistance assessed in this study include: Type I (resistance to initial infection; incidence), Type II (resistance to spread in wheat spike; severity), and decreases in mycotoxin accumulation (DON) and percentage of Fusarium damaged kernels (FDK). A population composed of 186 F5:7 recombinant-inbred lines (RILs) from the cross Pioneer Brand '25R47'/Jamestown were used to evaluate these traits in six environments (MD, NC, and VA in 2011 and 2012). This study identified a QTL for resistance to DON accumulation and FHB severity on the wheat chromosome 1B. The QTL accounted for 12.7% to 13.3% of the phenotypic variation in DON accumulation and 26.1% of the phenotypic variation in FHB severity. The most diagnostic marker for the QTL on chromosome 1B associated with resistance to FHB severity and DON accumulation is Xwmc500.6 located 7.2 cM from the QTL peak and flanked by markers Xwmc500.7 and Xgwm273.2 (28.2 cM interval). / Master of Science

Foram realizados experimentos em laboratório, casa-de-vegetação e campo visando os seguintes objetivos: (i) avaliar a eficiência de diferentes métodos de detecção do fungo Fusarium graminearum em sementes de trigo (Triticum aestivum L.); (ii) estudar o efeito do patógeno na germinação das sementes, bem como na emergência de plântulas e verificar a sua transmissão da semente para a plântula; (iii) avaliar o efeito de diferentes doses de nitrogênio (0, 30, 60, 90, 120 e 180 kg.ha-1), cultivares (IAC - 24, IAC - 350 e IAC - 370), aplicação de mistura de fungicidas (triciclazole + tebuconazol: três aplicações de 0,75 L.ha-1) na parte aérea das plantas na incidência de F. graminearum; (iv) avaliar o efeito do tratamento de sementes de trigo na incidência do patógeno empregando, individualmente, os seguintes fungicidas com as respectivas dosagens (g i.a.100 kg-1 de sementes): captana (150,0), tiofanato metílico (75,0), triflumizole (45,0), triticonazole (45,0), triadimenol (13,5), tolyfluanida (75,0), tebuconazole (5,0), fludioxonil (5,0), difeconazole (30,0) e thiabendazole (30,0). Na detecção de F. graminearum em sementes de trigo da cultivar BR 23 foram utilizados os seguintes métodos: meio semi-seletivo (MSS); MSS + 2,4- D (0,02%); MSS + KCl (-0,8MPa); papel de filtro (PF) com e sem o congelamento das sementes; PF + 2,4 - D (0,02%); restritores hídricos (KCl, NaCl, manitol e sacarose) nos potenciais osmóticos de -0,4, -0,6, -0,8 e -1,0 MPa. A maior incidência do patógeno foi observada com a utilização de MSS + 2,4 - D e a menor percentagem de sementes germinadas foi observada com o uso de PF com congelamento. A germinação de 30 diferentes genótipos de trigo foi significativamente influenciada pela quantidade de sementes mortas com a presença de F. graminearum, contudo não foi encontrada correlação entre a incidência do patógeno e a germinação das sementes. Também foi constatado que o fungo não afeta a emergência das plântulas, contudo verificou-se que a sua taxa de transmissão para diferentes partes da plântula (raiz, colo e haste) é variável de acordo com a com o genótipo infectado. O inóculo da semente pode contribuir para o desenvolvimento de epidemias no campo. Verificou-se que maiores doses de N promovem o aumento da incidência do patógeno nas sementes, enquanto que a aplicação da mistura de fungicidas promove a redução. Não houve diferenças significativas entre as cultivares IAC - 250, IAC - 350 e IAC - 370 na incidência do patógeno. No tratamento químico de sementes de trigo da cultivar BR 18 Terena, as menores incidências do fungo foram observadas empregando-se os fungicidas tiofanato metílico e tebuconazole. Não houve influência dos fungicidas tanto na germinação quanto na emergência e velocidade de emergência de plântulas. Por outro lado, fungicidas como o captana, triticonazole, tebuconazole e triadimenol afetaram negativamente a altura de plântulas, interferindo no desempenho das mesmas. / Experiments were carried out in laboratory, green house and field aiming at the following objectives: (i) to evaluate the efficiency of different methods of detection of Fusarium graminearum; (ii) to study the effect of the pathogen in the germination of wheat seeds, as well as in the emergence of seedlings and to verify the transmission of the seed to the seedling; (iii) to evaluate the effect of different dosages of nitrogen (0, 30, 60, 90, 120 and 180 kg.ha-1), in the incidence of cultivars (IAC - 24, IAC - 350 and IAC - 370) and the application of a mixture of fungicides (triciclazole + tebuconazol: three applications of 0,75 L.ha-1) in the aerial part of the plants in the incidence of F. graminearum; (iv) to evaluate the effect of the treatment of wheat seeds in the incidence of the pathogen employed individually, the following fungicides, with the respective dosages (g i.a.100 kg-1 of seeds): captana (150,0), methylic tiophanate (75,0), triflumizole (45,0), triticonazole (45,0), triadimenol (13,5), tolyfluanida (75,0), tebuconazole (5,0), fludioxonil (5,0), difeconazole (30,0) and thiabendazole (30,0). In the detection of F. graminearum in wheat seeds of the cultivar BR 23 the following methods were used: semiselective media (MSS); MSS + 2,4-D (0,02%); MSS + KCl (-0,8MPa); blotter (PF) with and without the freezing of the seeds; 2,4 PF + - D (0,02%); hidric restrictors (KCl, NaCl, manitol and sacarose) in the osmotic potentials of -0,4, -0,6, -0,8 and -1,0 MPa. The highest incidence of the pathogen was observed with the use of MSS + 2,4 - D and the lowest percentage of germinated seeds was observed with the use deep freezing blotter method of PF with freezing. The germination of 30 different wheat genotypes was significantly influenced by the quantity of dead seeds with the presence of F. graminearum. However, correlation between the incidence of the pathogen and the germination of the seeds was not found. It was found that the fungus does not affect the emergence of seedlings, however it was verified that its rate of transmission for different parts of seedling is variable in accordance with the infected genotype. It was also verified that higher doses of N promote the increase of the incidence of the pathogen in the seeds, and that the application of the mixture of fungicides promotes the reduction. There was no effect of cultivars IAC - 250, IAC - 350 e IAC - 370 on the incidence of pathogen. Regarding the chemical treatment of wheat seeds of cultivar BR 18 Terena, the lowest incidences of the fungus were observed using the fungicides methylic tiophanate and tebuconazole. There was no effect of fungicides both on the germination and on the seedlings emergence and emergence velocity. On the other hand, fungicides such as the captan, triticonazole, tebuconazole and triadimenol affected the height of plântulas negatively, interfering with their performance.

Phytopathogene <i>Fusarium</i> spp.treten weltweit in landwirtschaftlichen Kulturen auf und führen häufig zur Ertragsreduktion, Verschlechterung der Produktqualität sowie Kontaminationen der Erntegüter mit toxischen Sekundärmetaboliten, sog. Mykotoxinen. Die durch <i>Fusarium spp.</i> hervorgerufene partielle Taubährigkeit (FHB) des Weizens und anderer Getreidearten sowie die <i>Fusarium</i> Kolbenfäule an Mais sind aus ökonomischer Sicht von besonderer Bedeutung. Im Rahmen dieser Arbeit wurde die Verwendung von volatilen organischen Verbindungen (VOCs) zur Detektion von Fusariosen an Sommerweizen und Hybridmais unter Gewächshausbedingungen untersucht. Maiskolben wurden mit <i>F. graminearum</i>, <i>F. verticillioides</i> und <i>F. subglutinans</i> infiziert, während Weizenähren mit Sporensuspensionen von <i>F. graminearum</i>, <i>F. avenaceum</i> und <i>F. poae</i> inokuliert wurden. Auch Mischinfektionen wurden durchgeführt. Für die Sammlung der VOCs wurde ein statisches Verfahren (Festphasenmikroextraktion, SPME) sowie ein dynamisches Verfahren (open-loop stripping, OLS) eingesetzt. Die Analyse erfolgte in beiden Fällen mittels GC-MS. Ein nichtparametrischer Test (Kruskal-Wallis) wurde zur Identifikation von spezifischen volatilen Markern herangezogen. Auf diese Weise konnte an Mais ein Set aus 27 volatilen Biomarkern für die Infektion mit <i>Fusarium</i> spp. ermittelt werden. Die Kombination der VOCs ermöglichte hier die Unterscheidung zwischen Infektionen mit <i>F. graminearum</i> und <i>F. verticillioides</i>. An Weizen konnte ein Set aus 13 charakteristischen VOCs für den <i>Fusarium</i> Befall ermittelt werden. Die selektierten volatilen Marker beinhalteten sowohl einfache Moleküle mit 5 bis 8 Kohlenstoffatomen (C₅ - C₈), welche häufig von Pflanzen und Mikroorganismen emittiert werden, als auch infektionsspezifische Sesquiterpene (C₁₅H₂₄). In Zeitreihenversuchen konnte gezeigt werden, dass ein Großteil der relevanten VOCs bereits nach kurzer Zeit emittiert wird. So waren in Mais volatile Biomarker detektierbar, bevor Symptome am Kolben erkennbar waren (4 – 8 Tage nach der Inokulation). Ein Monitoring von VOC Profilen im Hinblick auf volatile Marker könnte eine schnelle und nicht-destruktive Detektion von <i>Fusarium</i> Infektionen (ggf. auch Risikoabschätzung zur Mykotoxinbelastung), z.B. im Feld oder Lager, ermöglichen. Hierfür stehen transportable Detektoren zur Verfügung. Das makrozyklische Lacton Zearalenon (ZEN) wird von mehreren <i>Fusarium</i> spp. produziert und besitzt eine östrogene Wirkung auf den menschlichen und tierischen Organismus. Schweine gelten diesbezüglich als besonders anfällig. ZEN wird in gemäßigten Klimazonen regelmäßig in Lebens- und Futtermitteln nachgewiesen. Bislang wurden zahlreiche Bioassays für die Detektion von ZEN beschrieben. Sie basieren meist auf den menschlichen Östrogenrezeptoren α und β und reagieren unspezifisch auf eine Vielzahl von östrogenen Substanzen (z.B. Genistein, 17β-Estradiol). Die vorliegende Arbeit beschreibt erstmalig ein Bioassay zur spezifischen Detektion von ZEN sowie dem kritischen Metabolit α-Zearalenol (α-ZOL). Das Assay basiert auf einer <i>zes2::gfp</i> Mutante des Mykoparasiten <i>Gliocladium roseum</i> und ermöglicht eine Detektion von ZEN in Feldproben (z.B. kontaminierter Mais). Schritte zur Probenvorbereitung und Extraktion, einschließlich Aufreinigung mit Immunoaffinitätssäulen, sowie die Kultur des Inditaktorstammes wurden optimiert. Das Assay eignet sich für die qualitative Detektion von ZEN in einem weiten Konzentrationsbereich sowie für eine quantitative ZEN Bestimmung in kontaminierten Mais Feldproben im Bereich zwischen 0,9 mg kg^-1 und 90 mg kg^-1. Neben der Detektion in Feldproben, konnte das Bioassay erfolgreich für ein Screening von Pilzstämmen zur Identifikation von ZEN-Produzenten eingesetzt werden. Das hier beschriebene <i>G. roseum zes2::gfp</i> Bioassay kann mit einer einfachen Laborausstattung durchgeführt werden und eignet sich möglicherweise für die Anwendung in Entwicklungsländern.

Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe [telomorph: Gibberella zeae Schwein.(Petch)], is recognized as one of the most destructive diseases of wheat (Triticum aestivum L. and T. durum L.) and barley (Hordeum vulgare L.) worldwide. Breeding for FHB resistance must be accompanied by selection for desirable agronomic traits. Donor parents with two FHB resistance quantitative trait loci (QTL) Fhb1 (chromosome 3BS) and QFhs.nau-2DL (chromosome 2DL) were crossed to four adapted SRW wheat lines to generate backcross and forward cross progeny. F2 individuals were genotyped and assigned to 4 different groups according to presence/ absence of one or both QTL. The effectiveness of these QTL in reducing FHB in F2 derived lines was assessed in a misted, inoculated scab nursery. Resistance alleles and the interaction among FHB resistance QTL have distinct behavior in different genetic backgrounds in wheat. Fhb1 showed an average disease reduction of 12%, however it did not result in significant improvement of FHB resistance in all populations. In general, for the four backgrounds studied, the QFhs.nau-2DL QTL as more effective reducing FHB (19% average reduction). The combination of Fhb1 and QFhs.nau-2DL is not necessary, but recommended and it improved resistance in all populations. Backcross derived (BC) progeny from four genetic backgrounds were planted in replicated plots (2011 and 2012) and in the scab nursery in 2012. Population 2 had its progeny characterized by 961 DArT markers distributed throughout the genome. Several high-quality polymorphic markers were identified and listed as good predictors of phenotypic traits like disease resistance, and improved agronomic and quality characteristics. Backcross and forward cross derived progenies were tested for FHB resistance and agronomic and baking quality performance for 4 different populations sharing the same donor parent for resistance QTL. The results confirmed that F2 populations were effective indicators of expression levels of QTL prior to extensive backcrossing. The QTL Fhb1 and QFhs.nau-2DL increased FHB resistance without detriments on agronomic and quality traits on wheat populations investigated. BC populations were assessed as breeding populations and established as being rewarding tools for derivation of inbred lines in a breeding program, being BC2 the most recommended from our results.