Basal defense is enhanced in a wheat cultivar resistant to Fusarium head blight

Fusarium head blight(FHB),mainly caused by the fungal pathogen Fusarium graminearum,is one of the most destructive wheat diseases.Besides directly affecting the yield,the mycotoxin residing in the kernel greatly threatens the health of humans and livestock.Xinong 979(XN979)is a widely cultivated wheat elite with high yield and FHB resistance.However,its resistance mechanism remains unclear.In this study,we studied the expression of genes involved in plant defense in XN979 by comparative transcriptomics.We found that the FHB resistance in XN979 consists of two lines of defense.The first line of defense,which is constitutive,is knitted via the enhanced basal expression of lignin and jasmonic acid(JA)biosynthesis genes.The second line of defense,which is induced upon F.graminearum infection,is contributed by the limited suppression of photosynthesis and the struggle of biotic stress-responding genes.Meanwhile,the effective defense in XN979 leads to an inhibition of fungal gene expression,especially in the early infection stage.The formation of the FHB resistance in XN979 may coincide with the breeding strategies,such as selecting high grain yield and lodging resistance traits.This study will facilitate our understanding of wheat-F.graminearum interaction and is insightful for breeding FHB-resistant wheat.

Marker-assisted selection to pyramid Fusarium head blight resistance loci Fhb1 and Fhb2 in the high-quality soft wheat cultivar Yangmai 15

Fusarium head blight(FHB)is one of the most detrimental wheat diseases which greatly decreases the yield and grain quality,especially in the middle and lower reaches of the Yangtze River of China.Fhb1 and Fhb2 are two major resistance loci against Fusarium graminearum.Yangmai 15(YM15)is one of the most popular varieties in the middle and lower reaches of the Yangtze River,and it has good weak gluten characters but poor resistance to FHB.Here we used Fhb1 and Fhb2 to improve the FHB resistance of YM15 by a molecular marker-assisted selection(MAS)backcrossing strategy.The selection of agronomic traits was performed for each generation.We successfully selected seven introgressed lines which carry homozygous Fhb1 and Fhb2 with significantly higher FHB resistance than the recurrent parent YM15.Three of the introgressed lines had agronomic and quality characters that were similar to YM15.This study demonstrates that the pyramiding of Fhb1 and Fhb2 could significantly improve the FHB resistance in wheat using the MAS approach.

Elimination of the yellow pigment gene PSY-E2 tightly linked to the Fusarium head blight resistance gene Fhb7 from Thinopyrum ponticum

Fhb7 is a major gene that was transferred from Thinopyrum ponticum to chromosome 7D of wheat(Triticum aestivum)and confers resistance to both Fusarium head blight(FHB)and Fusarium crown rot(FCR).However,Fhb7 is tightly linked to the PSY-E2 gene,which causes yellow flour,limiting its application in breeding.To break this linkage,marker K-PSY was developed for tagging PSY-E2 and used with Fhb7 markers to identify recombination between the two genes.Screening 21,000 BC1F2 backcross progeny(Chinese Spring ph1bph1b*2/SDAU 2028)revealed two Fhb7^(+)wheat-Tp7el_(2)L lines,Shannong 2–16and Shannong 16–1,that carry a desired truncated Fhb7^(+)translocation segment without PSY-E2.The two lines show levels of resistance to FHB and FCR similar to those of the original translocation line SDAU 2028,but have white flour.To facilitate Fhb7 use in wheat breeding,STS markers were developed and used to isolate Fhb7 on a truncated Tp7el_(2) translocation segment.Near-isogenic lines carrying the Fhb7^(+)segment were generated in the backgrounds of three commercial cultivars,and Fhb7^(+)lines showed increased FHB and FCR resistance without yield penalty.The breakage of the tight linkage between Fhb7 and PSY-E2 via homoeologous recombination provides genetic resources for improvement of wheat resistance to FHB and FCR and permit the large-scale deployment of Fhb7 in breeding using marker-assisted selection.

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 Zhoumai16’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 withoutreducing yield potential by introgressing Fhb1 resistance allele into FHB-susceptible cultivars in the YHWZ.

Introduction of Several Methods to Control Fusarium Head Blight (FHB)

Fusarium head blight (FHB) is a worldwide destructive disease of wheat in the warm, semi-humid or humid regions, especially serious in China. The disease not only causes significant losses in yield and reduces grain quanlity, but also induces toxin to contaminated seeds, which is harmful to the healthy of human and livestocks, So it is important to control it. There are several methods to control Fusarium head blight (FHB). Such as using Crop rotation, Soil cultivation and Fertiliser, biological control, Fungicides control, transgenes, resistance to control Fusarium head blight (FHB). All of these methods gain some effect, but also exist their deficiency. Sometimes crop rotation had no significant effect on DON contamination of wheat grain, subsequent reductions in DON contamination were inconsistent when using Soil cultivation and Fertiliser, Unfortunately, under field conditions, the biological control achieved has been shown to be variable and in some tests has failed to give any control, The use of fungicides, however, have not been consistently effective in controlling FHB and in reducing DON formation, transgene-silencing at different generations is a problem to use transgenes, Information on location of QTL for FHB resistance should improve dramatically in the near future on resistance to control Fusarium head blight (FHB). Therefore, it is pressing to improve control methods, especially to DON.

A journey to understand wheat Fusarium head blight resistance in the Chinese wheat landrace Wangshuibai

Fusarium head blight(FHB) or scab caused by Fusarium graminearum is a major threat to wheat production in China as well as in the world. To combat this disease, multiple efforts have been carried out internationally. In this article, we review our long-time effort in identifying the resistance genes and dissecting the resistance mechanisms by both forward and reverse genetics approaches in the last two decades. We present recent progress in resistance QTL identification, candidate functional gene discovery, marker-assisted improvement of FHB resistant varieties, and findings in investigating association of signal molecules, such as Ca^(++),SA, JA, and ET, with FHB response, with the assistance from rapidly growing genomics platforms. The information will be helpful for designing novel and efficient approaches to curb FHB.

Breeding wheat for resistance to Fusarium head blight in the Global North: China, USA, and Canada

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 1950 s. 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.

Activity of the Fungicide JS399-19 Against Fusarium Head Blight of Wheat and the Risk of Resistance

This report reviews the characteristics of JS399-19, a novel cyanoacrylate fungicide. JS399-19 strongly inhibits the mycelial growth of the fungal plant pathogens of the genus Fusarium and exhibits great potential in controlling Fusarium head blight （FHB） on wheat and other cereals. The mode of action of JS399-19 is evidently different from that of benzimidazole （for example, carbendazim） and other sort of fungicides, making it a possible replacement for carbendazim in China to manage carbendazim-resistant subpopulations of Fusarium graminearum and F. asiaticum. JS399-t9 has excellent protective and curative activity against these pathogens. Incorrect use of this fungicide, however, is likely to select for resistance. Among JS399-19-resistant mutants of F. asiaticum induced in the laboratory, the resistant level of mutants was high and the phenotype of resistance against JS399-19 was conferred by a major gene by genetic analysis. The fitness of laboratory-induced JS399-19-resistant mutants of F. asiaticum was nearly equal to that of their parents. JS399-19 lacks cross resistance with other sort fungicides. To control FHB with JS399-19 and to delay the development of the fungicide-resistance, farmers should use tank mixtures containing JS399-19 and carbendazim, metconazole, tebuconazole, or prothioconazole.

Integration of meta-QTL discovery with omics: Towards a molecular breeding platform for improving wheat resistance to Fusarium head blight

Fusarium head blight(FHB) is a global wheat disease that devastates wheat production. Resistance to FHB spread within a wheat spike(type Ⅱ resistance) and to mycotoxin accumulation in infected kernel(type Ⅲ resistance) are the two main types of resistance. Of hundreds of QTL that have been reported, only a few can be used in wheat breeding because most show minor and/or inconsistent effects in different genetic backgrounds. We describe a new strategy for identifying robust and reliable meta-QTL(mQTL)that can be used for improvement of wheat FHB resistance. It involves integration of mQTL analysis with mQTL physical mapping and identification of single-copy markers and candidate genes. Using metaanalysis, we consolidated 625 original QTL from 113 publications into 118 genetic map-based mQTL(gmQTL). These gmQTL were further located on the Chinese Spring reference sequence map. Finally, 77 high-confidence mQTL(hcmQTL) were selected from the reference sequence-based mQTL(smQTL).Locus-specific single nucleotide polymorphism(SNP) and simple sequence repeat(SSR) markers and17 genes responsive to FHB were then identified in the hcmQTL intervals by combined analysis of transcriptomic and proteomic data. This work may lead to a comprehensive molecular breeding platform for improving wheat resistance to FHB.

Integration of QTL detection and marker assisted selection for improving resistance to Fusarium head blight and important agronomic traits in wheat

Fusarium head blight(FHB), caused by Fusarium graminearum, is one of the most destructive wheat(Triticum aestivum L.) diseases worldwide. Identification of quantitative trait loci(QTL) conferring FHB resistance followed by marker assisted selection(MAS) is an efficient approach to breed FHB-resistant varieties. In this study, 38 additive QTL and 18 pairs of epistatic QTL for FHB resistance were detected in four environments using a population of recombinant inbred lines(RILs) derived from varieties Neixiang 188 and Yanzhan 1. Six QTL clusters were located on chromosomes 2D, 4B, 4D, 5A, 5D and 7B, suggesting possible polytrophic functions. Six elite lines with good FHB resistance and agronomic traits were selected from the same population using the associated markers. Our results suggest that MAS of multiple QTL will be effective and efficient in wheat breeding.

An integrated pest management program for managing fusarium head blight disease in cereals

Fusarium head blight(FHB)is a worldwide devastating disease of small grain cereals and Fusarium graminearum species complex(FGSC)is the major pathogen causing the disease.The epidemics of FHB lead to the reduction of grain yield and economic losses.Additionally,mycotoxins produced by the FHB pathogens are hazardous to the health of human and livestock.In this review,we summarize the epidemiology of FHB,and introduce effects of this disease on economy,environment and food safety.We focus on the integrated management approaches for controlling FHB including agronomic practices,resistant cultivars,chemical control,and biocontrol.In addition,we also discuss the potential novel management strategies against FHB and mycotoxin.

Validation of EST-derived STS markers localized on Qfhs.ndsu-3BS for Fusarium head blight resistance in wheat using a‘Wangshuibai’derived population

A few EST-derived STS markers localized on Qfhs.ndsu-3BS, a major QTL for resistance to Fusarium head blight （FHB） in wheat, have been previously identified in the ＇Sumai 3＇/＇Stoa＇ population. In this study, we used a ＇Wangshuibai＇ （resistant）/＇Seri82＇ （susceptible） derived population, linkage group, QTL, and quantitative gene expression analysis to assess the genetic background dependence and stability of the EST-derived STS markers for use in marker aided selection to improve FHB resistance in wheat. Based on our results, a QTL in the map interval of Xsts3B-138_1-Xgwrn493 on chromosome 3BS was detected for FHB resistance, which accounted for up to 16% of the phenotypic variation. BLASTN analysis indicated that Xsts3B-138_1 sequence had significant similarity with the resistance gene analogue. Real-time quantitative PCR showed that the relative expression of Xsts3B-138_1 in ＇Wangshuibai＇ at 96 h after inoculation was 2.6 times higher than ＇Seri82＇. Our results underlined that EST-derived STS3B-138 markers could be predominantly used in marker aided selection to improve FHB resistance in wheat.

Expression of the N-terminal 99 Amino Acids of Yeast Ribosomal Protein L3 in Transgenic Wheat Confers Resistance to Fusarium Head Blight

Fusarium head blight (FHB) is a worldwide disease for wheat or barley. The contamination of important agricultural products with the trichothecene mycotoxins such as deoxynivalenol (DON) or 4,15-diacetoxyscirpe-

Detection of Genetic Markers of Am3 / Laizhou 953 Introgression Lines for Resistance to Fusarium Head Blight

Fusarium head blight （FHB） is a destructive disease widespread in warm humid and semi-humid areas, which not only causes yield and grain quality losses, but also produces myeatoxin deoxynivalenol, thus posing a serious threat to wheat production in the world. In this study, 15 introgression lines with signifi- cantly different levels of resistance to FHB were screened as experimental materials to detect the intmgressed fragments by SSR markers from BC4F5 progenies of Atrd/Laizhou 953. The results showed that the number of polymorphic markers detected on each chromosome varied greatly, and polymorphic markers detected on chromosomes 5D and 5A were more than on other chromosomes. Am3 fragment could be detected in 15 introgression lines with 38 pairs of primers; the number of detected introgressed fragments varied among different introgression lines. Among 21 linkage groups, no introgressed fragments were detected on chromosomes 1A, 6D and 7A; the largest number of intregressed fragments was detected on chromosomes 3D and 5B. In 15 intregression lines, three QTLs for plant height, spike length and disease index detected. Qdi-caas-5A, which was derived from Am3, might be related with Type III resistance.

Controlling fusarium head blight of wheat (triticum aestivum L.) with genetics

Fusarium head blight, one of the most destructive diseases of wheat (Triticum aestivum L.), results in significant economic losses from reduced grain yield and quality. In recent decades, the disease has been frequently recorded, especially under warm and wet climatic conditions. Genetic resistance has engaged plant breeders because the use of resistant cultivars is the most economical, effective, and environmentally friendly method of control. In the present paper, we summarize the research on resistance genetics of Fusarium head blight, suggest a new method for evaluating Fusarium head blight resistance, and recommend strategies for creating and developing new sources of resistance to Fusarium head blight through the use of alien genes and chromosomal segments.

Can effectoromics and loss-of-susceptibility be exploited for improving Fusarium head blight resistance in wheat?

Bread wheat(Triticum aestiuum L.),which provides about 20%of daily calorie intake,is the most widely cultivated crop in the world,in terms of total area devoted to its cultivation.Therefore,even small increases in wheat yield can translate into large gains.Reducing the gap between actual and potential grain yield in wheat is a crucial task to feed the increasing world population.Fusarium head blight(FHB)caused by the pathogenic fungus Fusaium graminearum and related Fusarium species is one of the most devastating wheat diseases throughout the world.This disease reduces not only the yield but also the quality by contaminating the grain with mycotoxins harmful for humans,animals and the environment.In recent years,remarkable achievements attained in omics"technologies have not only provided new insights into understanding of processes involved in pathogenesis but also helped develop effective new tools for practical plant breeding.Sequencing of the genomes of various wheat patho gens,including F.graminearum,as well as those of bread and durum wheat and their wild relatives,together with advances made in transcriptomics and bioinformatics,has allowed the identification of candidate pathogen effectors and corresponding host resistance(R)and susceptibility(S)genes.However,so far,FHB effectors and wheat susceptibility genes/factors have been poorly studied.In this paper,we first briefly highlighted recent examples of improving resistance against pathogens via new techniques in different host species.We then propose effective strategies towards developing wheat cultivars with improved resistance to FHB.We hope that the article will spur discussions and interest among researchers about novel approaches with great potential for improving wheat against FHB.

Efficacy of Biological Control and Cultivar Resistance on <i>Fusarium</i>Head Blight and T-2 Toxin Contamination in Wheat

Laboratory and green house experiments were carried out to evaluate the efficacy of fungicides, biological agents and host resistance in managing FHB and the associated T-2 toxin. In vitro activity of fungicides and antagonists was determined by paired culture method. Effect of microbial agents on FHB severity and mycotoxin content was determined by co-inoculating F. graminearum and F. poae with Alternaria spp., Epicoccum spp. and Trichoderma spp. Fungicides Pearl? (500 g/L carbendazim), Cotaf? (50 g/L hexaconacole), Thiovit? (micronised sulphur 80% w/w) and Folicur? (430 g/L tebuconazole) were the standard checks. Host resistance was determined by inoculating F. poae and F. graminearum to four wheat cultivars and fifteen lines in pot ex-periments. Fungicides resulted in 100% inhibition of pathogen radial growth in in vitro while microbial agents suppressed pathogen growth by up to 53%. Thiovit? and Trichoderma were the most effective in reducing FHB severity in green house pot experiments. The wheat cultivars and lines varied in susceptibility with cultivar Njoro BW II showing least susceptibility while line R1104, cv. Mbuni and cv. KIBIS were most susceptible. All the wheat cultivars and lines accumulated T-2 toxin by up to 5 to 28 μg/kg. The results indicated that neither fungicides nor antagonists can solely be relied on in managing FHB and toxin accumulation. Therefore, integration of biocontrol agents, fungicides and further breeding efforts to improve lines and cultivars with promising resistance to FHB and T2-toxin contamina-tion is recommended.

Progress of Intelligent Monitoring Technology for Wheat Fusarium Head Blight

Fusarium head blight is one of the most important diseases affecting wheat yield and quality.It is of great significance to carry out intelligent monitoring of wheat Fusarium head blight for high yield,high quality and sustainable development of wheat.On the basis of identifying the harms of wheat Fusarium head blight,this paper analyzed the monitoring technology of wheat Fusarium head blight based on satellite remote sensing,hyperspectral,near-infrared,Internet of things and photoelectric system,to provide a reference for the intelligent monitoring of wheat Fusarium head blight.

Multi-functional roles of TaSSI2 involved in Fusarium head blight and powdery mildew resistance and drought tolerance

The mutation of the gene encoding a stearoyl-acyl carrier protein fatty acid desaturase（ssi2） has been proved to enhance pathogen resistance in several plants, while it＇s potential to regulate biotic and abiotic stresses in wheat is still unclear. In this study, we cloned TaSSI2 gene in wheat and provided several evidences of its involvement in multiple biological functions. By using barley stripe mosaic virus（BSMV）-induced gene silencing（VIGS） in wheat, it was found that TaSSI2 negatively regulated both powdery mildew and Fusarium head blight（FHB） resistance, which was consistent with the phenotype observed in knock-out mutants of Kronos. The expression of TaSSI2 was down-regulated by in vitro treatments of methyl jasmonate（Me JA）, but positively regulated by salicylic acid（SA） and abscisic acid（ABA）, implying the cross-talk between different hormone signaling pathways involved in wheat to regulate biotic stresses is still to be elucidated. Furthermore, the up-regulated expression of PR4 and PR5 indicated that TaSSI2 probably regulated FHB resistance by depressing the SA signaling pathway in wheat. In addition, the over-expression of TaSSI2 increased the content of linolenic acid（18：3） and subsequently enhanced drought tolerance of transgenic Brachypodium. This phenomenon might be associated with its subcellular localization in the whole cytosol, partly overlapping with Golgi apparatus and the secreted vesicles. As a stearoyl-acyl carrier protein fatty acid desaturase, TaSSI2 was proposed to be involved in cell lipid metabolism and carried targets out of the cell from membrane or wax synthesis, resulting in enhanced drought tolerance in plant.

东北春小麦赤霉病抗性鉴定及抗病基因Fhb1检测

为明确东北春小麦赤霉病抗性水平和抗源分布,本研究对1592份东北春小麦品种/系进行赤霉病抗性鉴定和抗病基因Fhb1检测。赤霉病抗性鉴定结果发现:在供试材料中,赤霉病中抗材料仅29份,占1.82%;中感材料549份,占34.48%;高感材料1014份,占63.69%。分子标记结果显示:供试材料中未检测到赤霉病抗性基因Fhb1,推测29份材料抗性来源于其它抗性基因。东北春小麦抗性材料遗传基础不明,抗病基因Fhb1缺失。因此,挖掘当地小麦赤霉病抗性基因以及加强Fhb1基因的应用,对于提升东北春小麦赤霉病抗性水平十分重要。