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The objective of this paper is to review progress made in wheat breeding for Fusarium head blight (FHB) resistance in China, the United States of America (USA), and Canada. In China, numerous Chinese landraces possessing high levels of FHB resistance were grown before the 1950s. Later, pyramiding multiple sources of FHB resistance from introduced germplasm such as Mentana and Funo and locally adapted cultivars played a key role in combining satisfactory FHB resistance and high yield potential in commercial cultivars. Sumai 3, a Chinese spring wheat cultivar, became a major source of FHB resistance in the USA and Canada, and contributed to the release of more than 20 modern cultivars used for wheat production, including the leading hard spring wheat cultivars Alsen, Glenn, Barlow and SY Ingmar from North Dakota, Faller and Prosper from Minnesota, and AAC Brandon from Canada. Brazilian wheat cultivar Frontana, T. dicoccoides and other local germplasm provided additional sources of resistance. The FHB resistant cultivars mostly relied on stepwise accumulation of favorable alleles of both genes for FHB resistance and high yield, with marker-assisted selection being a valuable complement to phenotypic selection. With the Chinese Spring reference genome decoded and resistance gene Fhb1 now cloned, new genomic tools such as genomic selection and gene editing will be available to breeders, thus opening new possibilities for development of FHB resistant cultivars. Keywords: Fhb1, Fusarium head blight resistance, Fusarium graminearum, Triticum aestivum, Wheat breeding

Fusarium head blight (FHB) resistance of Yangmai wheat cultivars has been paid much attention, but the underlying genetic mechanism is unclear. In recent years, Yangmai 16 is a predominant wheat cultivar durably resistant to FHB in production. A population of 174 double haploid lines (DH) produced by crossing Yangmai 16 (YM16) with the susceptible cultivar Zhongmai 895 (ZM895) was evaluated for FHB response using point inoculation from 2017 to 2019. The DH population was genotyped with wheat 660K SNP array and a high-density genetic map was constructed. Six resistance QTLs were detected, and among them, five were from the resistant parent Yangmai 16 and one from Zhongmai 895. QFhb.yaas-4DS and QFhb.yaas-6AS were detected at least in two years, explaining 8.8% to 15.0% of the phenotypic variances, respectively. QFhb.yaas-2DL and QFhb.yaas-3BL were detected only in one year, accounting for 10.5% and 14.7% of the phenotypic variances. QFhb.yaas-5BL and QFhb.yaas-4BS were detected in one year, too, accounting for 6.4% and 8.3% of the phenotypic variances, respectively. Pyramiding of multiple resistant loci with large effects (>10%) is an effective approach to increase FHB resistance. The QTLs identified from Yangmai 16 in the present study will provide a starting point for genetic studies of other Yangmai cultivars, and the QTLs closely linked to markers will be useful for marker-assisted selection in wheat FHB improvement.

Fusarium head blight (FHB) is a destructive disease of wheat worldwide, particularly in China. To map genetic loci underlying FHB resistance, a doubled haploid (DH) population consisting of 174 lines was developed from a cross between widely grown Chinese cultivars Yangmai 16 and Zhongmai 895. The DH population and parents were evaluated in field nurseries at Wuhan in 2016 to 2017 and 2017 to 2018 crop seasons with both spray inoculation and natural infection, and at Jingzhou in 2017 to 2018 crop season with grain-spawn inoculation. The DH lines were genotyped with a wheat 660K SNP array. The FHB index, plant height, anther extrusion, and days to anthesis were recorded and used for quantitative trait loci (QTL) analysis. Seven QTL for FHB resistance were mapped to chromosome arms 3BL, 4AS, 4BS, 4DS, 5AL, 6AL, and 6BS in at least two environments. QFhb.caas-4BS and QFhb.caas-4DS co-located with semi-dwarfing alleles Rht-B1b and Rht-D1b, respectively, and were associated with anther extrusion. The other five QTL were genetically independent of the agronomic traits, indicating their potential value when breeding for FHB resistance. Based on correlations between FHB indices and agronomic traits in this population, we concluded that increasing plant height to some extent would enhance FHB resistance, that anther extrusion had a more important role in environments with less severe FHB, and that days to anthesis were independent of the FHB response when viewed across years. PCR-based markers were developed for the 3BL and 5AL QTL, which were detected in more than three environments. The InDel marker InDel_AX-89588684 for QFhb.caas-5AL was also validated on a wheat panel, confirming its effectiveness for marker-assisted breeding for improvements in FHB resistance.

The increasing severity and prevalence of powdery mildew aided by extensive use of semi-dwarf cultivars and high levels of nitrogenous fertilizers are causing significant yield losses in wheat. Resistant cultivars are the most cost-effective and environmentally friendly approach to manage the disease. The objective of this study was to identify quantitative trait loci (QTL) for powdery mildew resistance in a doubled haploid (DH) population from a cross between leading Chinese cultivars, Yangmai 16 and Zhongmai 895. A high-density genetic map comprising of 14,480 non-redundant markers (equal to 148,179 SNPs) in 21 wheat chromosomes was constructed by genotyping the population with the Wheat 660 K SNP array. The DH population was phenotyped for powdery mildew resistance at the adult plant stage in multiple field trials, including four environments in the 2016–2017 cropping season and two environments in 2017–2018. Composite interval mapping detected six stable QTL explaining 3.8–23.6% of the phenotypic variance across environments. QPmyz.caas-5DS, QPmyz.caas-6BL and QPmyz.caas-7BS, are probably new QTL for powdery mildew resistance. One SNP marker closely linked to QPmyz.caas-6BL, the most stable QTL, was converted into a Kompetitive Allele-Specific PCR marker (K_AX-94973433) and validated on 103 commercial wheat cultivars. Significantly lower maximum disease severities of cultivars with the resistance-associated allele than those with the susceptibility-associated allele at QPmyz.caas-6BL in some environments indicated partial effectiveness of the marker. The novel QTL and their closely linked markers identified in the present study should facilitate development of cultivars with improved powdery mildew resistance.

Fusarium head blight (FHB) is a devastating wheat disease worldwide. To decipher the genetic architecture of FHB resistance in Chinese germplasm, a Wheat Association Panel for Scab Research (WAPS) consisting of 240 leading Chinese wheat cultivars and elite lines was genotyped using the 90K single nucleotide polymorphism (SNP) arrays. The FHB response was evaluated in the field nurseries in Wuhan in Hubei Province over four consecutive years from 2014 to 2017. Five quantitative trait loci (QTL) were consistently identified on chromosome arms 1AS, 2DL, 5AS, 5AL, and 7DS using a mixed linear model (MLM), explaining 5.6, 10.3, 5.7, 5.4, and 5.6% of phenotypic variation, respectively. The QTL on 5AS, 5AL, and 7DS QTL are probably novel. The allelic frequency analysis indicated that cultivars from the Middle and Lower Yangtze River Valleys harbored more favorable alleles and were therefore more resistant than those from other regions. To facilitate in-house germplasm screening and marker-assisted selection (MAS), SNP-derived PCR markers were developed for the QTL regions on 1AS, 5AS, and 5AL QTL. In addition to the above five QTL, the WAPS population had a very low frequency of Fhb1, confirming that the gene is not widely used in Chinese wheat breeding programs. The resistant lines and molecular markers developed in this study are resources and information for enhancing FHB resistance in breeding populations by marker-assisted recurrent selection and gene stacking.

Wheat Avenin-like proteins (TaALP) are atypical storage proteins belonging to the Prolamin superfamily. Previous studies on ALPs have focused on the proteins’ positive effects on dough strength, whilst no correlation has been made between TaALPs and the plant immune system. Here, we performed genome-wide characterization of ALP encoding genes in bread wheat. In silico analyses indicated the presence of critical peptides in TaALPs that are active in the plant immune system. Pathogenesis-related nucleotide motifs were also identified in the putative promoter regions of TaALP encoding genes. RT-PCR was performed onTaALPand previously characterised pathogenesis resistance genes in developing wheat caryopses under control andFusarium graminearuminfection conditions. The results showed thatTaALPand NMT genes were upregulated uponF. graminearuminoculation. mRNA insitu hybridization showed thatTaALPgenes were expressed in the embryo, aleurone and sub-aleurone layer cells. SevenTaALPgenes were cloned for the expression of recombinant proteins inEscherichia coli, which displayed significant inhibitory function onF. graminearumunder anti-fungal tests. In addition, FHB index association analyses showed that allelic variations of two ALP genes on chromosome 7A were significantly correlated with FHB symptoms. Over-expression of an ALP gene on chromosome 7A showed an enhanced resistance to FHB. Yeast two Hybridization results revealed that ALPs have potential proteases inhibiting effect on metacaspases and beta-glucosidases. A vital infection process related pathogen protein,F. graminearumBeta-glucosidase was found to interact with ALPs. Our study is the first to report a class of wheat storage protein or gluten protein with biochemical functions. Due to its abundance in the grain and the important multi-functions, the results obtained in the current study are expected to have a significant impact on wheat research and industry.

Fusarium head blight (FHB), also known as head scab, is a devastating fungal disease of bread and durum wheat worldwide. It reduces yield, lowers seed germination, reduces grain quality, and renders grain unsuitable for human or animal consumption due to mycotoxin contamination. Use of host resistance in commercially cultivated wheat varieties is an economical, effective and environmentally friendly method to manage FHB. In order to map loci underlying FHB resistance in synthetic-derived bread wheat line SYN1, a doubled haploid (DH) population of 169 lines was developed through hybridizing SYN1 with FHB-susceptible line Ocoroni. The DH population was evaluated in spray-inoculated field nurseries in the 2010 and 2011 cropping seasons at the El Batan Experiment Station of the International Maize and Wheat Improvement Center, Mexico. Ten marked spikes from each plot were scored for disease response and an FHB index was subsequently calculated. The population was genotyped with 1391 genotyping by sequencing and 106 simple-sequence repeat (SSR) loci and 28 linkage groups were constructed. These linkage groups were anchored by SSRs to all chromosomes, except 4D, 5D and 6D. Using the inclusive composite interval mapping algorithm, three genomic regions were associated with FHB resistance, including a major QTL on chromosome 2D accounting for 25 % of the phenotypic variation explained (PVE) and two minor QTLs on chromosomes 1B (4.7 % PVE) and 7A (4.2 % PVE), with all favorable alleles contributed by SYN1. The average FHB index of lines with all three SYN1 alleles was substantially lower (61.4 %) than that of those with Ocoroni alleles.