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Black point disease is a serious concern in wheat production worldwide. In this study, we aimed to identify the major quantitative trait loci (QTL) for resistance to black point caused by Bipolaris sorokiniana and develop molecular markers for marker-assisted selection (MAS). A recombinant inbred line (RIL) population derived from a cross between PZSCL6 (highly susceptible) and Yuyou1 (moderately resistant) was evaluated for black point resistance at four locations under artificial inoculation with B. sorokiniana . Thirty resistant and 30 susceptible RILs were selected to form resistant and susceptible bulks, respectively, which were genotyped by the wheat 660 K SNP array. Two hundred and four single-nucleotide polymorphisms (SNPs) were identified, among which 41(20.7%), 34 (17.2%), 22 (11.1%), and 22 (11.1%) were located on chromosomes 5A, 5B, 4B, and 5D, respectively. The genetic linkage map for the RIL population was constructed using 150 polymorphic SSR and dCAPS markers. Finally, five QTL were detected on chromosomes 5A, 5B, and 5D, designated QBB.hau-5A , QBB.hau-5B . 1 , QBB.hau-5B . 2 , QBB.hau-5D.1 , and QBB.hau-5D .2, respectively. All resistance alleles were contributed by the resistant parent Yuyou1. QBB.hau-5D . 1 is likely to be a new locus for black point resistance. The markers Xwmc654 and Xgwm174 linked to QBB.hau-5A and QBB.hau-5D . 1 , respectively, have potential utility in MAS-based breeding.

Fungi associated with black point were isolated from three highly susceptible wheat genotypes in the North China Plain. The 21 isolates represented 11 fungal genera. The most prevalent genera were Alternaria (isolation frequency of 56.7%), Bipolaris (16.1%), and Fusarium (6.0%). The other eight genera were Curvularia, Aspergillus, Cladosporium, Exserohilum, Epicoccum, Nigrospora, Penicillium, and Ulocladium; their isolation frequencies ranged from 0.8 to 4.8%. The pathogenicity of the isolates was individually assessed in the greenhouse by inoculating wheat plants with spore suspensions. Ten of the 21 isolates caused significantly higher incidences of black point than that the controls. These isolates belonged to eight fungal species (A. alternata, B. sorokiniana, B. crotonis, B. cynodontis, C. spicifera, F. equiseti, E. rostratum, and E. sorghinum) based on morphological traits and phylogenetic analysis. The average incidences of black point in the eight fungal species were 32.4, 54.3, 43.0, 41.9, 37.2, 38.8, 50.1, and 34.1%, respectively. B. sorokiniana and A. alternata were determined to be the most important pathogens in the North China Plain based on fungal prevalence and symptom severity. This study is the first to identify E. rostratum as a major pathogen causing black point in wheat.

Black point (BP) disease affects wheat (Triticum aestivum) production worldwide, and identifying BP resistance genes is essential for developing resistant cultivars. We previously detected QBB.hau-4A, a major QTL for BP resistance, using the fungal pathogen Bipolaris sorokiniana with a recombinant inbred line (RIL) population from a cross between wheat lines Wanyuanbai 1 and SN4143. Here, we fine mapped QBB.hau-4A using secondary F2 and F2:3 populations derived from resistant and susceptible RILs. Using 14 dCAPS markers, the QTL was delimited to a 1.36 Mb interval. With gene-specific markers, we narrowed this interval to a 1.06 Mb region between markers BP-100-d1 and BP-4A-d34 (40.87–41.93 Mb), containing six high-confidence genes in the Chinese Spring reference genome. Based on parental expression patterns and sequence polymorphisms, we identified four candidate genes for QBB.hau-4A: TraesCS4A02G050400, TraesCS4A02G050500, TraesCS4A02G050700, and TraesCS4A02G050800. Of these, TraesCS4A02G050800 is the most likely candidate for QBB.hau-4A. We developed BP-800-d1, a gene-specific marker for TraesCS4A02G050800 based on a SNP and an InDel distinguishing the resistant and susceptible parents. This marker was subsequently validated in two F2 populations and a diverse panel of 412 wheat accessions. To our knowledge, this study represents one of the first efforts to identify candidate genes associated with BP resistance. In addition to offering valuable information for understanding the complex genetic basis of BP resistance, it provides molecular markers for breeders.

Wheat is among the ten top and most widely grown crops in the world. Several diseases cause losses in wheat production in different parts of the world. Bipolaris sorokiniana (teleomorph, Cochliobolus sativus ) is one of the wheat pathogens that can attack all wheat parts, including seeds, roots, shoots, and leaves. Black point, root rot, crown rot and spot blotch are the main diseases caused by B. sorokiniana in wheat. Seed infection by B. sorokiniana can result in black point disease, reducing seed quality and seed germination and is considered a main source of inoculum for diseases such as common root rot and spot blotch. Root rot and crown rot diseases, which result from soil-borne or seed-borne inoculum, can result in yield losses in wheat. Spot blotch disease affects wheat in different parts of the world and cause significant losses in grain yield. This review paper summarizes the latest findings on B. sorokiniana , with a specific emphasis on management using genetic, chemical, cultural, and biological control measures.

Mycotoxins in small grains are a significant and long-standing problem. These contaminants may be produced by members of several fungal genera, including Alternaria, Aspergillus, Fusarium, Claviceps, and Penicillium. Interventions that limit contamination can be made both pre-harvest and post-harvest. Many problems and strategies to control them and the toxins they produce are similar regardless of the location at which they are employed, while others are more common in some areas than in others. Increased knowledge of host-plant resistance, better agronomic methods, improved fungicide management, and better storage strategies all have application on a global basis. We summarize the major pre- and post-harvest control strategies currently in use. In the area of pre-harvest, these include resistant host lines, fungicides and their application guided by epidemiological models, and multiple cultural practices. In the area of post-harvest, drying, storage, cleaning and sorting, and some end-product processes were the most important at the global level. We also employed the Nominal Group discussion technique to identify and prioritize potential steps forward and to reduce problems associated with human and animal consumption of these grains. Identifying existing and potentially novel mechanisms to effectively manage mycotoxin problems in these grains is essential to ensure the safety of humans and domesticated animals that consume these grains.

Black point is a cereal disease caused by complex pathogens, of which the pathogenicity of Bipolaris sorokiniana is the most serious in wheat. Resistance to black point is quantitative in nature, and thus the mechanism is poorly understood. We conducted a comparative transcriptome analysis to identify differentially expressed genes (DEGs) in black point-slightly susceptible and -highly susceptible wheat lines at different timepoints following B. sorokiniana inoculation. DEGs associated with photosynthesis were upregulated in black point-slightly susceptible lines. The top Gene Ontology enrichment terms for biological processes were oxidation–reduction, response to cold, salt stress, oxidative stress, and cadmium ion; terms for cellular component genes were mainly involved in plasma membrane and cytoplasmic membrane-bounded vesicle, whereas those for molecular function were heme binding and peroxidase activity. Moreover, activities of antioxidant enzymes superoxide dismutase, catalase, and peroxidase were higher in slightly susceptible lines than those in highly susceptible lines (except peroxidase 12–24 days post-inoculation). Thus, resistance to B. sorokiniana -caused black point in wheat was mainly related to counteracting oxidative stress, although the specific metabolic pathways require further study. This study presents new insights for understanding resistance mechanisms of selected wheat lines to black point.

In bread wheat, a literature search gave 228 QTLs for six traits, including resistance against spot blotch and the following five other related traits: (i) stay green; (ii) flag leaf senescence; (iii) green leaf area duration; (iv) green leaf area of the main stem; and (v) black point resistance. These QTLs were used for metaQTL (MQTL) analysis. For this purpose, a consensus map with 72,788 markers was prepared; 69 of the above 228 QTLs, which were suitable for MQTL analysis, were projected on the consensus map. This exercise resulted in the identification of 16 meta-QTLs (MQTLs) located on 11 chromosomes, with the PVE ranging from 5.4% (MQTL7) to 21.8% (MQTL5), and the confidence intervals ranging from 1.5 to 20.7 cM (except five MQTLs with a range of 36.1–57.8 cM). The number of QTLs associated with individual MQTLs ranged from a maximum of 17 in MQTL3 to 8 each in MQTL5 and MQTL8 and 5 each in MQTL7 and MQTL14. The 16 MQTLs, included 12 multi-trait MQTLs; one of the MQTL also overlapped a genomic region carrying the major spot blotch resistance gene Sb1 . Of the total 16 MQTLs, 12 MQTLs were also validated through marker-trait associations that were available from earlier genome-wide association studies. The genomic regions associated with MQTLs were also used for the identification of candidate genes (CGs) and led to the identification of 516 CGs encoding 508 proteins; 411 of these proteins are known to be associated with resistance against several biotic stresses. In silico expression analysis of CGs using transcriptome data allowed the identification of 71 differentially expressed CGs, which were examined for further possible studies. The findings of the present study should facilitate fine-mapping and cloning of genes, enabling Marker Assisted Selection.

Alternaria species are important fungal pathogens occurring worldwide in wheat, causing both productive and qualitative losses, and posing a toxicological risk to human health due to the production of their mycotoxins in kernels. This study aimed to investigate the occurrence of Alternaria species and their mycotoxins in 48 wheat grain samples collected from the northeast to the southeast of Algeria. Seventy-two representative Alternaria strains were molecularly analyzed using a multi-locus sequence approach and evaluated for their capability to produce mycotoxins under in vitro conditions. Alternaria alternata, representing 42% of the strains, was the dominant species, followed to a lesser extent by species included in the Infectoriae section (26%). In addition, three species not previously reported in Algerian wheat, A. eureka, A. consortialis and A. tellustris, were identified, accounting for 5% of the total strains. Mycotoxin analyses showed high contamination of grains with alternariol monomethyl ether, alternariol and tenuazonic acid, occurring in 75, 69 and 35% of the samples, respectively. Moreover, 41 out of 48 samples showed the co-occurrence of multiple Alternaria mycotoxins. This study provides, for the first, time a clear picture of the occurrence and the distribution of Alternaria species on wheat in Algeria. Finally, the extensive monitoring activities carried out revealed the great biodiversity of Alternaria species able to colonize wheat grains. Moreover, findings on mycotoxin contamination raise concerns about the significant mycotoxigenic risk in Algerian wheat, emphasizing the need for strict monitoring and regulatory measures on Alternaria mycotoxins in food and feed.

Bipolaris sorokiniana is a prevalent fungal pathogen that resides in the soil and affects various parts of wheat, leading to diseases such as spot blotch, common root rot, head blight and black point. The genetic mechanisms that confer resistance in wheat against this pathogen are not completely known. In this research, 1302 wheat germplasms from around the world were evaluated for resistance to spot blotch at the seedling stage, and it was found that merely 3.8% displayed moderate or better resistance. A genome‐wide association study (GWAS) employing high‐density 660K single‐nucleotide polymorphism (SNP) data pinpointed a segment on chromosome 1BL (621.2–674.0 Mb) containing nine SNPs that are significantly linked to spot blotch resistance, named Qsb.hebau‐1BL. RNA sequencing and reverse transcription‐quantitative PCR analyses demonstrated that the gene TraesCS1B02G410300, which codes for nicotinamide‐adenine dinucleotide phosphate‐binding oxidoreductase (TaNADPO), was markedly upregulated by B. sorokiniana. Five SNP variations were identified in the promoter region of TaNADPO in wheat lines with or without Qsb.hebau‐1BL. Wheat lines that overexpressed TaNADPO exhibited increased resistance to spot blotch and higher accumulation of reactive oxygen species (ROS). In contrast, knockout EMS mutants of Triticum turgidum TdNADPO (tdnadpo‐K2561, Gln125*) and TaNADPO (tanadpo‐J10516796, splice donor variant) showed diminished resistance and lower ROS levels. In conclusion, TaNADPO is a key gene for resistance against B. sorokiniana, providing essential information for the development of spot blotch‐resistant wheat varieties through molecular breeding techniques. Spot blotch resistance locus Qsb.hebau‐1BL was identified by a genome‐wide association study, revealing TaNADPO upregulation drives resistance to Bipolaris sorokiniana in wheat, guiding molecular breeding.

Black point is a fungal disease of wheat, mainly associated with mycotoxigenic Alternaria species. Affected wheat kernels are characterized by dark brown discolouration of the embryo region and reduction of grain quality. Potential risk is the possible accumulation of Alternaria mycotoxins, alternariol (AOH), alternariol-monomethyl ether (AME), tenuazonic acid (TA), and altenuene (ALT), provided by haemato-toxic, genotoxic, and mutagenic activities. One hundred and twenty durum wheat samples belonging to 30 different genotypes grown in Bologna and Modena areas, in Italy, showing black point symptoms, were analyzed for Alternaria species and their mycotoxin contamination. Alternariol was selected as an indicator of the capability of the Alternaria species to produce mycotoxin in vivo in field conditions. The data showed that Alternaria species occurred in 118 out of 120 wheat kernels samples, with the incidence of infected kernels ranging between 1% and 26%. Moreover, AOH was detected by using a HPLC with a diode array detector (LC-DAD) in 98 out of 120 samples with values ranging between 24 and 262 µg Kg−1. Ninety-two Alternaria representative strains, previously identified morphologically, were identified at species/section level using gene sequencing, and therefore were analyzed for their mycotoxin profiles. Eighty-four strains, phylogenetically grouped in the Alternaria section, produced AOH, AME, and TA with values up to 8064, 14,341, and 3683 µg g−1, respectively, analyzed by using a LC-DAD. On the other hand, eight Alternaria strains, included in Infectoriae Section, showed a very low or no capability to produce mycotoxins.