Targeted and Untargeted Metabolomics Profiling of Wheat Reveals Amino Acids Increase Resistance to Fusarium Head Blight

Fusarium head blight (FHB), a notorious plant disease caused by Fusarium graminearum (F. graminearum), is severely harmful to wheat production, resulting in a decline in grain quality and yield. In order to develop novel control strategies, metabolomics has been increasingly used to characterize more comprehensive profiles of the mechanisms of underlying plant-pathogen interactions. In this research, untargeted and targeted metabolomics were used to analyze the metabolite differences between two wheat varieties, the resistant genotype Sumai 3 and the susceptible genotype Shannong 20, after F. graminearum inoculation. The untargeted metabolomics results showed that differential amino acid metabolic pathways existed in Sumai 3 and Shannong 20 after F. graminearum infection. Additionally, some of the amino acid contents changed greatly in different cultivars when infected with F. graminearum. Exogenous application of amino acids and F. graminearum inoculation assay showed that proline (Pro) and alanine (Ala) increased wheat resistance to FHB, while cysteine (Cys) aggravated the susceptibility. This study provides an initial insight into the metabolite differences of two wheat cultivars under the stress of F. graminearum. Moreover, the method of optimization metabolite extraction presents an effective and feasible strategy to explore the understanding of the mechanisms involved in the FHB resistance.

A Ricin B-like lectin protein physically interacts with TaPFT and is involved in resistance to Fusarium head blight in wheat

Fusarium head blight (FHB), mainly caused by Fusarium graminearum, has become one of the most serious diseases that damage wheat. The TaPFT (pore-forming toxin-like) and TaHRC (histidine rich calcium-binding protein) genes at the quantitative trait locus (QTL) Fhb1 were identified to confer resistance to FHB in the wheat cultivar Sumai 3. Here, a wheat ricin B-like lectin gene (designated TaRBL) that interacted with TaPFT was isolated by a yeast two-hybrid screen of a wheat cDNA library. A yeast two-hybrid and bimolecular fluorescence complementation study further verified that TaRBL interacted with TaPFT but not with TaHRC. Gene expression studies showed upon F. graminearum infection, TaRBL expression was upregulated in resistant cultivars but downregulated in susceptible cultivars. Furthermore, knockdown of TaRBL expression by barley stripe mosaic virus-induced gene silencing significantly reduced the resistance of wheat to FHB in both the resistant cultivar Sumai 3 and the susceptible cultivar Jimai 22. Thus, we conclude that TaRBL encodes a Ricin B-like lectin protein that interacts with TaPFT and is involved in resistance to FHB in wheat.

A Novel QTL Controlling Flag Leaf Width Located on Chromosome Arm 7AS in Bread Wheat (Triticum Aestivum L.)

Background: Wheat is an important cereal crop and improving wheat production is essential for meeting the food demand from the growing population worldwide. Flag leaf width (FLW) is an important trait affecting plant architecture and contributing to grain yield. To detect loci conferring FLW, we assessed a population of recombinant inbred lines (RILs) from a cross of EGA Wylie/Sumai 3 in different environments.Results: A total of six QTL were detected from the population. Two of them located on chromosome 2B and the other four located on chromosomes 2D, 4B, 7A, and 7B, respectively. The percentage of phenotypic variation (PEV) explained by these loci ranged from 14.6% to 33.8%, with LOD scores varying from 3.01 to 7.81. Of them, the locus located on chromosome arm 7AS is likely novel. Significant effects of this locus were detected in multiple trials conducted and the PEV explained by this QTL varied from 14.6% to 19.8% among the different trials. An orthologous analysis based on rice and Arabidopsis identified 3 putative genes underlying this potentially novel locus.Conclusion: This study identified a stable potentially novel QTL in multiple environments and predicted three candidate genes of it, which laid the foundation for further fine-mapping and cloning the gene(s) underlying QFlw.WS-7A with the contribution to grain yield.

Effectiveness of multigenerational transfer of Sumai 3 Fusarium head blight resistance in hard red spring wheat breeding populations

Several quantitative trait loci (QTL) have been identified for Fusarium head blight (FHB) resistance in the cultivar Sumai 3. Wheat breeders need to know which Sumai 3 loci are present in derived lines used as parents for effective marker-assisted selection for genetic improvement. This study was conducted to identify the loci in Sumai 3 derived parents that contribute FHB resistance in breeding populations. Three doubled haploid (DH) populations utilizing Sumai 3 derived parents, ND3085, ND744, and Alsen, were evaluated during 2007 and 2008 in FHB nurseries near Carman, MB, Ottawa, ON and Charlottetown, PE. The percentage of incidence, severity, Fusarium-damaged kernels (FDK), and deoxynivalenol (DON) accumulation were measured, and FHB index calculated. DNA markers at six FHB resistance loci detected in Sumai 3 were evaluated on the populations. For each trait, a t test was applied to means of observations pooled by parental type of each marker to determine which loci contributed to resistance. The alleles at 3BS and 5AS most frequently contributed to Type I and Type II FHB resistance, as well as to reduced FDK and DON in all three populations. Markers revealed resistance on 3BS and 5AS in Alsen, ND3085, and ND744, on 3BSc, 4D, and 6BS in ND744, on 4D in ND3085, and on 6BS in Alsen. In some environments, the susceptible parent Infinity contributed minor QTL on 2D, 3BSc, and 6BS. Likewise, Helios contributed minor QTL on 5AS and 6BS.

Genetics of Fusarium head blight resistance in three wheat genotypes

Fusarium head blight (FHB) is global concern as recent outbreaks reported in Canada, Europe, Asia, Australia and South America. The disease has emerged as one of the most important plant diseases worldwide in 21st century. One of the major threats posed by FHB fungus is the mycotoxin production which is harmful to human and animal health. Development of disease resistant cultivars is the only effective method for managing the disease. Control of these pathogen / Fusarium spp. is also challenging due to limited sources of known resistance. The famous Chinese wheat cultivar Sumai 3 and Frontana are the main sources of resistance to this disease. For genetic analysis and incorporation of FHB resistance into recently released high yielding wheat cultivars, HD 2967 and DPW 621-50, crosses were made with Sumai 3, Frontana and Aldan. The F2 plants from the crosses HD 2967/Frontana (140), HD 2967/Aldan (150), HD 2967/Sumai 3 (169) and DPW 621-50/Sumai 3 (182) were screened for resistance under controlled conditions. Disease score was recorded to identify resistant, moderately resistant and susceptible plants. The genetic ratios for resistance to FHB indicated a complex nature of resistance in all the three donors.

Molecular Mapping of Fusarium Head Blight Resistance in the Spring Wheat Line ND2710

ND2710 is a hard red spring wheat line with a very high level of resistance to Fusarium head blight (FHB). It was selected from the progeny of a cross between ND2603 (an advanced breeding line derived from the Sumai 3/Wheaton cross) and Grandin (a spring wheat cultivar). The FHB resistance of ND2710 is presumably derived from Sumai 3 because the other parents (Grandin and Wheaton) are very susceptible to FHB. To identify and map the quantitative trait loci (QTL) for FHB resistance in ND2710, we developed a mapping population consisting of 233 recombinant inbred lines (RILs) from the cross between ND2710 and the spring wheat cultivar Bobwhite. These RILs along with their parents and checks were evaluated for reactions to FHB in three greenhouse experiments and one field experiment during 2013 to 2014. The population was also genotyped with the wheat 90K iSelect single-nucleotide polymorphism (SNP) assay, and a genetic linkage map was developed with 1,373 non-cosegregating SNP markers, which were distributed on all 21 wheat chromosomes spanning 914.98 centimorgans of genetic distance. Genetic analyses using both phenotypic and genotypic data identified one major QTL (Qfhb.ndwp-3B) on the short arm of chromosome 3B, and three minor QTL (Qfhb.ndwp-6B, Qfhb.ndwp-2A, and Qfhb.ndwp-6A) on 6B, 2A, and 6A, respectively. The major QTL on 3B was detected in all experiments and explained 5 to 20% of the phenotypic variation, while the three minor QTL on 6B, 2A, and 6A explained 5 to 12% phenotypic variation in at least two experiments, except for Qfhb.ndwp-2A, which was only detected in the field experiment. Qfhb.ndwp-3B and Qfhb.ndwp-6B were mapped to the genomic regions containing Fhb1 and Fhb2, respectively, confirming that they originated from Sumai 3. The additive effect of the major and minor QTL may contribute to the high level of FHB resistance in ND2710. The SNP markers closely linked to the FHB resistance QTL will be useful for marker-assisted selection of FHB resistance in wheat breeding programs.

Molecular Characterization and Expression of PFT, an FHB Resistance Gene at the Fhb1 QTL in Wheat

Fusarium head blight (FHB) is a destructive fungal disease in wheat worldwide. Efforts have been carried out to combat this disease, and the pore-forming toxin-like (PFT) gene at the quantitative trait locus (QTL) Fhb1 was isolated and found to confer resistance to FHB in Sumai 3. In this study, we characterized PFT in 348 wheat accessions. Four haplotypes of PFT were identified. The wild haplotype of PFT had higher resistance than other haplotypes and explained 13.8% of phenotypic variation in FHB resistance by association analysis. PFT was highly expressed during early flowering and increased after Fusarium graminearum treatment in Sumai 3. Analysis of the 5′ flanking sequence of PFT predicted that the cis elements of the PFT promoter were related to hormones and biological defense responses. However, PFT existed not only in the FHB-resistant accessions but also in some susceptible accessions. These results suggested that FHB resistance in a diverse range of wheat genotypes is partially conditioned by PFT. The profiling of FHB resistance and the PFT locus in this large collection of wheat germplasm may prove helpful for incorporating FHB resistance into wheat breeding programs, although more work is needed to reveal the exact role of the QTL Fhb1 in conferring resistance to fungal spread.

Androgenic response of wheat genotypes resistant to fusariosis

The objective of this work was to assess the androgenic response, via microspore culture, of wheat genotypes with different levels of resistance to Gibberella zeae. The number of androgenic embryos per spike, and of green and albino plants was counted for the BRS 179 (moderately resistant), Frontana and Sumai 3 (resistant), and BRS 194, Embrapa 27, and Fielder (susceptible) genotypes. The degree of interference by the Fielder, Pavon 76, and Sumai 3 ovary-donor genotypes, used for co-culture with the microspore cells, was also assessed regarding androgenic response. Induction efficiency ranged from 0.33 embryo per spike for Embrapa 27 to 109.8 embryos for Frontana. Sumai 3 presented the second best response, and Embrapa 27 behaved as highly recalcitrant. The co-culture of ovaries from the Fielder genotype stands out from the others and positively interferes in the embryo induction rate. No significant differences were observed for the regeneration frequency of green plants; however, for albino plants, BRS 194 produced the highest rate. Frontana and Sumai 3 present the highest androgenic response rates and can be used in breeding programs for the rapid development of cultivars resistant to Gibberella zeae.