Disease Of Wheat Research Articles

Disease-driven yield losses in wheat (Triticum aestivum) crop under different agroclimatic locations of Punjab

The experiments were conducted during winter (rabi) seasons of 2021–22 and 2022–23 at Punjab Agricultural University, Ludhiana, Punjab to examine the yield losses due to diseases in wheat (Triticum aestivum L.) crop under different agroclimatic locations of Punjab. The experiment was conducted in split-plot design (SPD) having three dates of sowing (14th–15th October, 8th–9th November and 3rd–4th December) in main plots and wheat varieties, viz. PBW 725, HD 2967 and HD 3086 with two microclimate modification levels M1 (recommended irrigation) and M2 (additional water sprays) in sub plots, replicated four times. The yellow rust severity was maximum at Ludhiana (56.14%, 57.17%) and Gurdaspur (56.75%, 58.42%) in HD 2967 under early sown conditions in M2 treatment during 2021–22 and 2022–33, respectively. The Karnal bunt incidence was comparatively higher at Ludhiana (18.5% and 13.4%) and Gurdaspur (21.4% and 16.7%) in variety PBW 725 under normal sowing condition in M2 than other treatments during both the years of study, respectively. Grain yield during 2021–22 and 2022–23 was more in early sowing at Ludhiana (43.3 q/ha, 48.1 q/ha) and Gurdaspur (44.5 q/ha, 50.8 q/ha) than other dates of sowing. In variety × microclimate modification levels treatments, grain yield was maximum at Ludhiana (43.1 q/ha, 47.2 q/ha) and Gurdaspur (44.0 q/ha, 50.2 q/ha) in variety PBW 725 under M1 than other treatments during both the years of study. Early date of sowing recorded more yield losses followed by late and normal sowing and losses were more at Gurdaspur as compared to Ludhiana. Average yield losses during 2022–23 were higher i.e. 5.6% and 7.1% as compared to 1.6% and 2.3% during 2021–22 at Ludhiana and Gurdaspur, respectively.

Genome‐wide association study for powdery mildew resistance in CIMMYT's spring wheat germplasm

AbstractPowdery mildew (PM), caused by Blumeria graminis f. sp. tritici (Bgt), is a foliar disease of wheat (Triticum aestivum) that adversely affects both grain yield and quality. Growing resistant cultivars offers an effective and environmentally sustainable solution to managing PM. However, relying on the same genetic source of resistance can lead to resistance breakdown as Bgt isolates rapidly evolve. To mitigate this, identifying novel resistance sources is crucial. In this study, 225 diverse wheat genotypes were evaluated at adult plant stage in disease nurseries over the three crop seasons (2018/2019, 2019/2020 and 2020/2021). Using disease and genotyping data from 12,160 single‐nucleotide polymorphism (SNP) markers, a genome‐wide association study (GWAS) was conducted to identify novel resistance loci. We identified 22 marker loci significantly (at p < 0.005) associated with PM resistance, distributed across 14 wheat chromosomes (1A, 1B, 1D, 2A, 2B, 2D, 3A, 3B, 4A, 4B, 5D, 6A, 7A and 7B). Of these, seven loci overlap with previously identified regions, while the remaining 15 loci represent novel regions reported for the first time in this study. The identified SNP markers have significant potential for wheat breeding programmes, as they can accelerate the development of PM‐resistant cultivars through marker‐assisted selection.

Genome‐Wide Association Mapping and Genomic Prediction of Septoria nodorum Blotch Resistance in Central European Winter Wheat (Triticum aestivum L.)

ABSTRACTSeptoria nodorum blotch (SNB) is a fungal disease of wheat caused by the necrotrophic fungus Parastagonospora nodorum (Berk.), considered as one of the most devastating fungal diseases affecting winter wheat (Triticum aestivum L.). The complex inheritance of resistance to SNB poses significant challenges to breeding programmes. Improving selection precision and identifying novel resistance QTLs are crucial for enhancing SNB resistance. This study investigated strategies for crop genetic improvement, including genome‐wide association mapping (GWAS) and genomic prediction (GP), within a practical breeding programme. A population of 1500 winter wheat breeding lines was phenotyped for SNB resistance over 5 years across 19 geographical locations under natural infection conditions. Despite highly unbalanced breeder's data, medium to high heritabilities for SNB resistance were achieved. GWAS identified 11 significant marker‐trait associations for SNB resistance across Chromosomes 2A, 2B, 4B, 4D, 5D and 7B. GP fivefold cross‐validation analysis revealed a predictive ability of 0.52 for SNB resistance. The resistant wheat genotypes and SNP markers identified in this study will be valuable assets for future breeding efforts to enhance SNB resistance in wheat.

Quantitative Trait Loci Mapping for Powdery Mildew Resistance in Wheat Genetic Population

Background/Objectives: Powdery mildew is a prevalent wheat disease that affects yield and quality. The characterization and fine mapping of genes associated with powdery mildew resistance can benefit marker-assisted breeding. Methods: In this study, quantitative trait loci (QTL) associated with powdery mildew were mapped using a high-density 35K DArT genetic linkage map developed from a population of double haploid lines (DHs) created by crossing “Jinmai 33 (a highly resistance line) with Yannong 19 (a highly susceptible line)”. Results: Three stable QTLs for powdery mildew were identified on chromosomes 1B, 2B, and 6A combined with the composite interval graphing method and multiple interval mapping, explaining phenotypic variations (PVE) that range from 4.98% to 13.25%. Notably, Qpm.sxn-1B and Qpm.sxn-2B were identified across three environments, with the PVE ranging from 9.37% to 13.25% and from 4.98% to 5.23%, respectively. The synergistic effects of these QTLs were contributed by the parental line “Jinmai 33”. Qpm.sxn-1B was the major stable QTL, and Qpm.sxn-2B was close to Pm51. Furthermore, Qpm.sxn-6A was identified in two environments, accounting for PVE values of 7.13% and 7.65%, respectively, with the resistance effects originating from the male parent. Remarkably, this locus has not been reported previously, indicating that Qpm.sxn-6A represents a newly dis-covered QTL governing powdery mildew genes. Conclusions: Five molecular markers available for mark-er-assisted selection were selected for tracking Qpm.sxn-1B and Qpm.sxn-2B in the program. The identification of this novel newly discovered QTL and markers reported in this study will be useful for marker-assisted selection of powdery mildew resistance.

Survey, isolation and characterisation of Bipolaris sorokiniana (Shoem.) causing spot blotch disease in wheat under the climatic conditions of the Indo–Gangetic plains of India

Survey, isolation and characterisation of Bipolaris sorokiniana (Shoem.) causing spot blotch disease in wheat under the climatic conditions of the Indo–Gangetic plains of India

Do Different Wheat Ploidy Levels Respond Differently Against Stripe Rust Infection: Interplay between Reactive Oxygen Species (ROS) and the Antioxidant Defense System?

Wheat stripe rust (Puccinia striiformis f. sp. tritici, Pst) is the most damaging wheat disease, causing substantial losses in global wheat production and productivity. Our study aimed to unravel the complex reciprocity between reactive oxygen species and the antioxidant defense system as a source of resistance against stripe rust in diploid, tetraploid and hexaploid wheat genotypes. The significant genetic variability for stripe rust in the materials under study was evident as the genotypes showed contrasting responses during both the adult and seedling stages. Our thorough perspective on the biochemical responses of wheat genotypes to stripe rust infection revealed distinct patterns in oxidative damage, antioxidant enzymes and photosynthetic pigments. Principal component analysis revealed inverse correlations between antioxidants and ROS, underscoring their key function in maintaining the cellular redox balance and protecting plants against oxidative damage. Diploid (Ae. tauschii) wild wheat exhibited a better biochemical defense system and greater resistance to stripe rust than the tetraploid (T. durum) and hexaploid (Triticum aestivum) wheat genotypes. The antioxidant enzyme activity of durum wheat was moderate compared to diploid and hexaploid wheat genotypes. The hexaploid wheat genotypes exhibited increased ROS production, reduced antioxidant enzyme activity and decreased photosynthetic pigment levels. This study enhances understanding of the antioxidant defense system across different wheat ploidies facing stripe rust, serving as a valuable strategy for improving crop disease resistance. This study validated the biochemical response of stripe rust-resistant and susceptible candidate genotypes, which will be used to develop genetic resources for discovering stripe rust resistance genes in wheat.

Abscisic acid-, stress-, ripening-induced 2 like protein, TaASR2L, promotes wheat resistance to stripe rust.

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most destructive wheat diseases. The plant hormone abscisic acid (ABA) plays a key regulatory role in plant response to stress. ABA-, stress-, ripening-induced proteins (ASR) have been shown to be abundantly induced in response to biotic and abiotic stresses to protect plants from damage. However, the function of wheat ASR2-like protein (TaASR2L) in plants under biotic stress remains unclear. In this study, transient silencing of TaASR2L using a virus-induced gene silencing system substantially reduced wheat resistance to Pst. TaASR2L interaction with serine/arginine-rich splicing factor SR30-like (TaSR30) was validated mainly in the nucleus. Knockdown of TaSR30 expression substantially reduced wheat resistance to Pst. Overexpression of TaASR2L and TaSR30 demonstrated that they can promote the expression of ABA- and resistance-related genes to enhance wheat resistance to Pst. In addition, the expression levels of TaSR30 and TaASR2L were substantially increased by exogenous ABA, and the resistance of wheat to Pst was increased, and the expression of PR genes was induced. Therefore, these results suggest that TaASR2L interacts with TaSR30 by promoting PR genes expression and enhancing wheat resistance to Pst.

Evaluation of durum and hard red spring wheat panels for sensitivity to necrotrophic effectors produced by Parastagonospora nodorum.

Septoria nodorum blotch is an important disease of both durum and hard red spring wheat (HRSW) worldwide. The disease is caused by the necrotrophic fungal pathogen Parastagonospora nodorum when compatible gene-for-gene interactions occur between pathogen-produced necrotrophic effectors (NEs) and corresponding host sensitivity genes. To date, nine sensitivity gene-NE interactions have been identified, but there is little information available regarding their overall frequency in durum and HRSW. Here, we infiltrated a global HRSW panel (HRSWP) and the Global Durum Panel (GDP) with P. nodorum NEs SnToxA, SnTox1, SnTox267, SnTox3, and SnTox5. Frequencies of sensitivity to SnTox1 and SnTox5 were higher in durum compared to HRSW and vice versa for SnTox267 and SnTox3. Strong associations for the known sensitivity loci Tsn1, Snn1, Snn2, Snn3, Snn5, and Snn7 along with potentially novel sensitivity loci on chromosome arms 7DS and 3BL associated with SnToxA and SnTox267, respectively, were identified in the HRSWP. In the GDP, Snn1, Snn3, and Snn5 were identified along with novel loci associated with sensitivity to SnTox267 on chromosome arms 2AS, 2AL, and 6AS and with SnTox5 sensitivity on 2BS and 7BL. These results reveal additional NE sensitivity loci beyond those previously described demonstrating a higher level of genetic complexity of the wheat-P. nodorum system than previously thought. Knowledge regarding the prevalence and genomic locations of SNB susceptibility genes in HRSW and durum will prove useful for developing efficient breeding strategies and improving varieties for SNB resistance.

Development and Characterization of Two Wheat-Rye Introgression Lines with Resistance to Stripe Rust and Powdery Mildew.

Rye (Secale cereale L.) genes, which contribute to the tertiary gene pool of wheat, include multiple disease resistance genes useful for the genetic improvement of wheat. Introgression lines are the most valuable materials for wheat breeding because of their small alien segments and limited or lack of linkage drag. In the present study, wheat-rye derivative lines SN21627-2 and SN21627-6 were produced via distant hybridization. A genomic in situ hybridization analysis revealed that SN21627-2 and SN21627-6 lack alien segments, while a multi-color fluorescence in situ hybridization analysis detected structural changes in both introgression lines. At the seedling and adult plant stages, SN21627-2 and SN21627-6 were highly resistant to stripe rust and powdery mildew. Primers for 86 PCR-based landmark unique gene markers and 345 rye-specific SLAF markers were used to amplify SN21627-2 and SN21627-6 genomic DNA. Eight markers specific to rye chromosome 2R were detected in both introgression lines, implying these lines carry chromosome 2R segments with genes conferring stripe rust and powdery mildew resistance. Therefore, SN21627-2 and SN21627-6 are resistant to more than one major wheat disease, making them promising bridging parents for breeding disease-resistant wheat lines.

Proteomic identification of apoplastic proteins from rice, wheat, and barley after Magnaporthe oryzae infection

The fungal pathogen Magnaporthe oryzae causes devastating blast disease in various cereals, including rice (Oryza sativa), wheat (Triticum aestivum), maize (Zea mays), and barley (Hordeum vulgare). Despite previous reports on fungal host specificity, the mechanisms underlying differential host infection strategies remain unclear. This study aimed to identify differentially abundant proteins (DAPs) in the apoplast of rice, barley, and wheat following infection with two M. oryzae pathovars using liquid chromatography-tandem mass spectrometry (LC–MS/MS). LC–MS/MS analysis revealed an enrichment of both M. oryzae and host proteins in the apoplast during the compatible reaction compared to the incompatible reaction. DAPs from M. oryzae involved in the host interaction included secreted extracellular enzymes (e.g., hydrolases), which were significantly increased in the M. oryzae Oryzae (MoO)-infected rice apoplast. Among host proteins, the proportion of protein-modifying enzymes increased in the M. oryzae Triticum (MoT)-infected rice and MoO-infected wheat apoplastic fluids, particularly rice glycosidases, peroxidases, and serine proteases, as well as wheat serine proteases. Furthermore, DAPs from MoL-infected rice were enriched in carbohydrate metabolism, suggesting that carbohydrate metabolism-related proteins may play a vital role in rice resistance to MoL. Additionally, protein-modifying and cytoskeletal proteins, as well as stress-responsive proteins, were enriched in the MoO-infected wheat apoplastic fluid. Finally, DAPs from both MoO- and MoL-infected barley were enriched in hydrogen peroxide catabolism, suggesting that peroxidases may be vital for barley resistance to M. oryzae. The identification of DAPs from both M. oryzae strains and the three host plants offers valuable insights into the host specificity mechanisms of M. oryzae in cereal crops.

Diversity of Northwestern and North Caucasian Populations of <i>Puccinia striiformis</i> f. sp. <i>tritici</i> by Virulence and Microsatellite Loci in 2022

Yellow rust (Puccinia striiformis f. sp. tritici, Pst) is a potentially dangerous disease of wheat. Genetic protection of wheat is an environmentally safe method of control. For its successful application, information on the structure of regional populations of the pathogen is needed. The purpose of these studies is to characterize the virulence and molecular polymorphism of Russian Pst populations in 2022. Wheat leaves with Pst urediniopustules were obtained from the North Caucasus (Krasnodar Territory, Dagestan, Kalmykia) and Northwestern (Leningrad region) regions. Virulence analysis was performed on 14 isogenic lines (AvocetNIL) and 15 differentiator varieties. The polymorphism of 20 microsatellite loci was evaluated in molecular analysis. We used SSR markers recommended by the Global Rust Reference Center. Virulence was studied in 74 monopustular isolates: 29 Dagestan, 10 Krasnodar, 5 Kalmyk, 30 northwestern. Resistance to all isolates was shown for lines with genes Yr5, Yr10, Yr15, Yr24, Yr26 and varieties Moro (Yr10, YrMor) and Nord Desprez (Yr3, YrND, Yr+). Isolates virulent to the AvYr17 line were detected for the first time in Dagestan and Krasnodar populations. They were moderately represented in the northwestern population (13%). Significant variation was observed in lines and varieties with the Yr1 and Yr3 genes. There was a decrease in virulence to Yr7 and YrSp compared to 2019–2021. 28 phenotypes (races) were determined in the virulence analysis (15 in Dagestan, 11 in North West, 3 in Krasnodar and 2 in Kalmyk). A common phenotype was noted for three North Caucasian Pst samples. The genetic distances between the identified phenotypes were estimated. In the multidimensional diagram, most of them combined together in a common group, with the exception of three Dagestan phenotypes with the fewest virulence alleles. According to the Fst index, Dagestan and Kalmyk Pst collections were characterized by high similarity; others differed moderately from them. The long-term virulence dynamics (2019–2022) of Pst populations in the Northwestern and North Caucasian regions was assessed. High similarity was determined between all regional population samples in 2019 and 2020. The northwestern and Dagestan populations differed slightly from them in 2021 and 2022. In 2022, the Krasnodar and Kalmyk populations were divided into separate groups, which differed from each other and from the main group. Long-term results of virulence analysis indicate a high dynamic of the structure of Pst populations in Russia. All North Caucasian isolates and 23 Northwestern isolates were used in the SSR analysis. Six loci (RYN3, RYN9, RYN12, WU6, RJO21, RJO24) were monomorphic. Three polymorphic alleles were identified in the RYN13 and RJO27 loci and two in the remaining studied ones. Significant deviations from the Hardy-Weinberg equilibrium are noted for most loci. The observed heterozygosity exceeded the expected one, which indicates an excess of heterozygotes and the clonal origin of the population. The studied collection of isolates was represented by 20 multilocus genotypes (MGs) (Dagestan and Northwestern – 11 each, Krasnodar – 3, Kalmyk – 1). Common genotypes were detected in Dagestan, Krasnodar and Northwestern populations (MG_1); Dagestan, Kalmyk and Northwestern (MG_2); Dagestan and Krasnodar (MG_3, MG_4). The genetic distances between MGs were estimated. In the multidimensional diagram, they are divided into 4 groups. The main group included 80% of MGs. One Dagestan MG, two Northwestern MG and MG_3 common for Dagestan and Krasnodar collections, significantly differentiated from the main group and among themselves. According to the Fst index, most regional Pst collections were moderately differentiated among themselves, with the exception of Dagestan and Kalmyk, which is consistent with the virulence analysis. According to the Mantel test, a moderate correlation was found between the results of virulence analysis and SSR (r = 0.6). This indicates that both analyses can be used in assessing the genetic polymorphism of Pst. The high variability of Russian populations based on virulence and microsatellite loci determines the need for annual monitoring of regional Pst populations in Russia.

Analyses of Wheat Resistance to Fusarium Head Blight Using Different Inoculation Methods

Fusarium head blight is a devastating wheat disease that causes yield reduction and mycotoxins contamination, leading to multiple negative consequences for the economy, health, and food safety. Despite the tremendous efforts that have been undertaken over the last several decades to harness the disease, the problem remains a challenging issue. Due to global warming, its impact has become increasingly severe in Baltic and Nordic countries. The improvement of wheat resistance is hampered by complicated genetic inheritance, the scarcity of adapted resistant breeding materials, and difficulties in obtaining accurate and reproducible data due to the high interaction and dependency of the disease development on the environment. In this study, the resistance of 335 genotypes, 9 of which were of exotic origin and the remainder of which were adapted to the environments of Lithuania, Latvia, Estonia, or Norway, was studied in 8 trials using spray and point inoculation with spore suspensions and grain spawn inoculation under field and/or greenhouse conditions. The best linear unbiased estimates (BLUEs) of each genotype within the individual trials and the adjusted means across the trials were determined to reduce the environmental effects. Genotypes that exhibited excellent Type I or Type II resistance and overall resistance were identified.

Diversity of Northwestern and North Caucasian Populations of Puccinia striiformis f. sp. tritici by Virulence and Microsatellite Loci in 2022.

Yellow rust (Puccinia striiformis f. sp. tritici (Pst)) is a potentially dangerous disease of wheat. Genetic protection of wheat is an environmentally safe method to control the disease, but its successful application requires information on the structure of regional populations of the pathogen. Virulence and molecular polymorphism were characterized in two Russian Pst populations in 2022. Wheat leaves with Pst urediniopustules were collected from the North Caucasus (Krasnodar Krai, Dagestan, and Kalmykia) and Northwestern Russia (Leningrad Oblast). Virulence was tested on 14 isogenic lines (AvocetNIL) and 15 differentiator cultivars. Polymorphism at 20 microsatellite loci was evaluated in molecular analyses. The SSR markers were as recommended by the Global Rust Reference Center. Virulence was assessed in 74 monopustular isolates, including 29 Dagestan, 10 Krasnodar, 5 Kalmyk, and 30 Northwestern ones. Resistance to all isolates was observed in lines with the genes Yr5, Yr10, Yr15, Yr24, and Yr26 and the cultivars Moro (Yr10, YrMor) and Nord Desprez (Yr3, YrND, Yr+). Isolates virulent to the AvYr17 line were detected for the first time in the Dagestan and Krasnodar populations. Their occurrence was moderate (13%) in the Northwestern population. A significant variation was observed in lines and cultivars with the Yr1 and Yr3 genes. Virulence to Yr7 and YrSp was found to be lower than in 2019 to 2021. In total, 28 phenotypes (races) were determined in the virulence analysis (15 in Dagestan, 11 in the Northwestern region, 3 in Krasnodar, and 2 in Kalmykia). A common phenotype was detected in three North Caucasian Pst samples. Genetic distances between the phenotypes were estimated. Most phenotypes grouped together in a multidimensional diagram, with the exception of three Dagestan phenotypes with the fewest virulence alleles. Based on the Fst index, the Dagestan and Kalmyk Pst collections were high similar to each other and differed moderately from the other collections. Long-term trends in virulence (from 2019 to 2022) were assessed in the Pst populations. A high similarity was observed between all regional population samples in 2019 and 2020. The Northwestern and Dagestan populations slightly differed from the other populations in 2021 and 2022. In 2022, the Krasnodar and Kalmyk populations formed separate groups, which differed from each other and from the main group. The long-term virulence analysis indicated that the structure of Pst populations is highly dynamic in Russia. All North Caucasian isolates and 23 Northwestern isolates were used in the SSR analysis. Six loci (RYN3, RYN9, RYN12, WU6, RJO21, and RJO24) were monomorphic. Three polymorphic alleles were identified in each of the RYN13 and RJO27 loci; two alleles, in each of the remaining loci examined. Significant deviations from Hardy-Weinberg equilibrium were observed for most loci. The observed heterozygosity exceeded the expected one, suggesting a clonal origin of the Pst population. Twenty multilocus genotypes (MGs) were found in the total isolate collection (11 in Dagestan, 11 in the Northwestern region, 3 in Krasnodar, and 1 in Kalmykia). Common MGs were detected in the Dagestan, Krasnodar, and Northwestern populations (MG_1); Dagestan, Kalmyk, and Northwestern populations (MG_2); and Dagestan and Krasnodar populations (MG_3 and MG_4). Genetic distances between MGs were estimated. MGs formed four groups in a multidimensional diagram. A major group included 80% of MGs. One Dagestan MG, two Northwestern MGs, and MG_3 common for the Dagestan and Krasnodar collections were significantly differentiated from the major group and differed from each other. Based on Fst, most regional Pst collections were moderately differentiated from each other, with the exception of the Dagestan and Kalmyk collections. The finding was consistent with the virulence analysis results. The Mantel test detected a moderate correlation between the virulence and SSR data (r = 0.6). This indicates that both analyses can be used to assess genetic polymorphism in Pst. The high variability of the virulence and microsatellite loci warrants annual monitoring of regional Pst populations in Russia.

Phenotypic Selection of Bread Wheat (Triticum aestivum L.) Elite Lines for Diseases Resistance and Yield Potential

Wheat diseases and pests globally threaten wheat production. Wheat rust diseases are the most distractive biotic constraint of wheat in Ethiopia. Therefore, this experiment aimed to select and develop wheat rust resistance bread wheat varieties for the farmers. The result of the study revealed highly significant variation existed among tested genotypes for Plant Height (PHT), Days to Heading (DTH), Days to Maturity (DTM), Thousand Kernel Weight (TKW), Hectoliter Weight (HLW), and Yield (YLD) at (P< 0.001). Out the forty-nine introduced genotypes, five genotypes: EBW222153, EBW222159, EBW222160, EBW222162, and EBW222164, showed resistance to moderately resistance for both yellow rust and stem rust diseases across the two test locations. Also, they delivered high average yield: 5.9 tha-1, 4.46 tha-1, 5.17tha-1,4.15 tha-1, and 4.79tha-1 respectively. Furthermore, all the above-mentioned genotypes, except EBW222162, showed significantly higher yield at (P<0.05) than the check variety, Shaki. Furthermore, EBW222153, EBW222159, EBW222160, EBW222162, EBW222164, and EBW222178 would resistance to moderately resistance for stem rust at Melkasa. Thus, the selection of these genotypes and advancing to the next stage of breeding pipelines enables to release noble bread wheat varieties for the farmers.

Coexistence of Celiac Disease and Allergic Wheat Sensitivity: An Observational Study of Daily Clinical Practice

Introduction: Although separate immunogenic mechanisms are involved, IgE-type sensitization to wheat and celiac disease (CD) may coexist. We observationally assessed the importance of this relationship in daily practice using CD and wheat sensitization screenings. Methods: Celiac antibody (CA) screening and food prick tests (FPTs) were requested simultaneously from patients who presented to the Allergy Clinic between January 2022 and December 2023 and had any complaint accompanied by CD symptoms/findings (non-celiac group). Patients with positive CA (CA+) underwent endoscopy. As another group, FPT results were recorded for patients previously diagnosed with CD following a gluten-free diet (celiac group). Results: In total, 169 patients (124 non-celiac and 45 celiac) were included in the study. Wheat prick positivity (WP+) was observed in 1 patient with CD. Among 65 WP+ patients without a CD diagnosis, 14 (20.3%) tested positive for CA+, and histopathology detected CD in 4 of these cases. Among the 59 WP– patients, 4 (8.8%) had CA+. The CA+ status of those with WP+ was significantly higher than those with WP– (p = 0.023). Conclusion: The 4 patients unaware of their CD exhibited WP+, with a higher rate of CA+ observed in the WP+ group. The association between WP+ and CA+ suggests that an impaired intestinal barrier may lead to simultaneous T helper 1 and 2 type inflammatory responses. Although different types of sensitization to the same food would not typically be expected, growing evidence indicates that this phenomenon does occur. Further studies are necessary to confirm these findings and to explore the underlying causes.

First Report of Fusarium compactum Causing Fusarium Head Blight of Wheat in China.

Fusarium head blight (FHB), a devastating wheat disease caused by several species of Fusarium, threatens global wheat yield and quality (Erenstein et al. 2022). In August 2023, wheat spikes exhibiting clear FHB symptoms were observed in fields in Yunnan, China (24°16'46″ N, 102°29'46″ E), with an incidence rate of approximately 10%. Diseased wheat spikes exhibited a bleached, wilted appearance, with abundant orange sporodochia on the glumes, similar to previous reports (Osborne et al. 2007). Twenty-four symptomatic spikes were collected from a single field, and sporodochia were washed with sterile water to prepare a spore suspension of 1 × 10³ spores/ml, which was inoculated onto potato dextrose agar (PDA) to obtain monosporic cultures. Four reference strains (KUNCC 3418 to KUNCC 3420, and KUNCC 3431) were deposited at the Kunming Institute of Botany Culture Collection, Chinese Academy of Sciences (KUNCC). For species identification, four strains were cultured on PDA and carnation leaf agar (CLA) at 25°C, with incubation under a 12-hour near-UV light/dark cycle on CLA and in complete darkness for 24 hours on PDA. Colonies on PDA grew rapidly, appearing white and loosely flocculent. Abundant pale orange, translucent sporodochia formed on CLA. Sporodochial conidiogenous cells were monophialidic or polyphialidic, subulate to subcylindrical, 9.5-12 μm × 3-3.5 μm. Sporodochial macroconidia were naviculate to fusiform, with an elongate, tapering apical cell and a foot-shaped basal cell, 3-6-septate, 33-67.5 μm × 3.5-5.5 μm. The ITS, tef1-α, rpb1, rpb2, and cam regions were amplified and sequenced using primers ITS1/ITS4, EF-1/EF-2, rpb1-F7/G2R, rpb2-5F2/11aR, and CL1/CL2A, respectively (White et al. 1990; O'Donnell et al. 2000; O'Donnell et al. 2010; Reeb et al. 2004; O'Donnell et al. 1998). These sequences were deposited in GenBank for cam (PP951603 to PP951606), ITS (PP946846 to PP946849), tef-1α (PP719217, PP731572 to PP731574), rpb1 (PP719219, PP737839 to PP737841), and rpb2 (PP719218, PP951607 to PP951609). BLASTn analyses of these sequences showed an identity range of 99.7% to 100% with the epitype strain NRRL 36323 of F. compactum (GenBank: cam = GQ505560, ITS = MH855177, tef-1α = GQ505648, and rpb2 = GQ505826), with base pair matches of 663/665 bp for cam, 488/488 bp for ITS, 641/641 bp for tef-1α, and 892/892 bp for rpb2. Both morphological and BLASTn analyses confirmed these isolates as F. compactum (Leslie & Summerell 2006; Han et al. 2023). Pathogenicity tests were performed by spraying 1 ml of spore suspension (1 × 108 spores/ml) of F. compactum strains onto spikes of the wheat cultivar Yunmai 126 at the flowering stage (n = 9). Controls (n = 9) were treated only with sterile water. Following treatment, the wheat spikes were covered with plastic bags and incubated at 25°C for 10 days. After 14 days, the inoculated spikes turned bleached and dry, showing FHB symptoms, while the wheat spikes in the control treatment remained asymptomatic. The pathogenic fungus re-isolated from all diseased samples was confirmed as F. compactum. It has been frequently reported in association with crown and root rot of wheat, particularly in regions such as Turkey and Iran (Tunali et al. 2008; Besharati et al. 2017). To our knowledge, this is the first report of F. compactum on diseased wheat spikes in China. This finding provides valuable insights into the spread of F. compactum.

Development of wheat-tetraploid Thinopyrum elongatum 4EL small fragment translocation lines with stripe rust resistance gene Yr4EL.

Two small fragment translocation lines (T4DS·4DL-4EL and T5AS·5AL-4EL) showed high resistance to stripe rust and resistance gene Yr4EL was localized to an about 35 Mb region at the end of chr arm 4EL. Stripe rust, caused by the fungus Puccinia striiformis f. sp. tritici, is a devastating wheat disease worldwide. Deployment of disease resistance (R) genes in wheat cultivars is the most effective way to control the disease. Previously, the all-stage stripe rust R gene Yr4EL from tetraploid Thinopyrum elongatum was introduced into common wheat as 4E(4D) substitution and T4DS·4EL translocation lines. To further map and utilize Yr4EL, Chinese Spring (CS) mutant pairing homoeologous gene ph1b was used in crossing to induce recombination between chromosome (chr) 4EL and wheat chromosomes. Two small fragment translocation lines T4DS·4DL-4EL and T5AS·5AL-4EL with Yr4EL resistance were selected using molecular markers and confirmed by genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH), and Wheat660K SNP array analyses. We mapped Yr4EL to an about 35Mb region at the end of chr 4EL, corresponding to 577.76-612.97Mb based on the diploid Th. elongatum reference genome. In addition, two competitive allele-specific PCR (KASP) markers co-segregating with Yr4EL were developed to facilitate molecular marker-assisted selection in breeding. The T4DS·4DL-4EL lines were crossed and backcrossed with wheat cultivars SM482 and CM42, and the resulting pre-breeding lines showed high stripe rust resistance and potential for wheat breeding with good agronomic traits. These lines represent new germplasm for wheat stripe rust resistance breeding, as well as providing a solid foundation for Yr4EL fine mapping and cloning.

Modeling spatiotemporal distribution of yellow rust wheat pathogen using machine learning algorithms: Insights from environmental assessment

The yellow rust pathogen (Puccinia striiformis Westend) poses a significant threat to wheat production in the world, necessitating a comprehensive understanding of its spatiotemporal distribution and the influence of climatic factors. In this study, we employed an ensemble of four prominent machine learning algorithms to assess the impact of various environmental and remote sensing variables on the spread of yellow rust at a national scale. Our analysis incorporated 55 climatic parameters, including monthly temperature, precipitation, solar radiation, and wind speed. The results demonstrated that the RF algorithm yielded robust predictions, with a Receiver Operator Characteristic (ROC) of 0.916 and True Skill Statistic (TSS) of 0.748. Furthermore, the study identified key influencing variables for wheat disease modeling, such as annual precipitation, temperature seasonality, and isothermality. Projections based on the model indicate a potential decrease in disease spread by 2050 in specific regions. The findings underscore the efficacy of ensemble modeling in predicting the spatiotemporal distribution of yellow rust on a large scale, offering valuable insights for the development of robust agricultural management strategies in the face of evolving climate conditions.

Survey of Fungal Diseases on Barley, Wheat, and Oats at Tillering to Stem Extension Stages in Southern Regions of Korea during 2020-2021

Cereal, including barley, wheat, and oats, is a major winter food crop in Korea. Despite recent changes in agricultural environments in response to climate change, fungal diseases that could affect cereal productivity remain poorly understood. In this study, we investigated the incidence of diseases in barley, wheat, and oats in the southern part of Korea. We collected fungal pathogens from seven locations where cereals were grown. In March-April of 2020 and 2021, a total of 92 fungal isolates were collected, mainly from the stem base or leaves of cereal crops during the tillering and stem extension stages of cereals in Korea. The collected isolates were identified based on morphological and molecular biological characteristics. The dominant species was <i>Ceratobasidium cereale</i> (42.4%), followed by <i>Pyrenophora teres</i> (21.7%), <i>P. avenae</i> (10.9%), <i>Alternaria alternata</i> (6.5%), and <i>Epicoccum tobaicum</i> (6.5%). In addition, <i>P. tritici-repentis</i> (3.3%), <i>Cladosporium</i> sp. (3.3%), <i>Fusarium</i> sp. (3.3%), and <i>Nigrospora</i> sp. (2.2%) were also collected as minority groups. Our results will provide information on fungal pathogens that occur during the growing season of cereals in Korea, particularly during the tillering and stem extension stages. In addition, the isolates collected from this study can serve as a valuable resource for conducting simulations on climate change, focusing on temperature and humidity.

Research Progress of Bacillus subtilis in Wheat Growth Promotion and Disease Control

Wheat is one of the main food crops in the world, and its output is related to the world food security. In recent years, with the change of climate conditions and the overuse of chemical pesticides, the growing environment of wheat is facing severe challenges, and wheat diseases occur frequently, which seriously affects the growth and yield of wheat. As a new type of green growth promotion and control measures, biological control provides a more sustainable and environmentally friendly way for crops to cope with the challenges of the growing environment. Bacillus subtilis is a kind of PGPR widely found in plant rhizosphere soil. It has strong broad-spectrum antibacterial activity and resistance to stress. In this paper, the mechanism of Bacillus subtilis in promoting wheat growth and the control principle and effect of pathogenic bacteria in wheat were reviewed, and the existing problems were analyzed and prospected in order to provide reference for the application of Bacillus subtilis in agricultural field.