Disease Of Wheat Research Articles

Varietal resistance of Algerian bread wheat against Fusarium culmorum, the main agent of crown rot on wheat

Fusarium crown rot (FCR) is one of the serious wheat diseases. FC11 is one strain among 34 isolates obtained in a previous study, and identified as Fusarium culmorum strain highly pathogenic. FC11 was assigned the accession number MW151664 by NCBI GenBank. Two resistance/sensitivity tests were conducted on 9 cultivars (cv) of bread wheat. The In vitro test in the oven with the parameters; percentage of germination inhibition (%GI), to determine the tolerance of seedlings germination, and the Area Under the Disease Progress Curve (AUDPC) to test the tolerance to the initial infection of germinated coleoptiles. In in-vivo test in the growth chamber, the disease severity (DS) parameter used to test the cultivars ability to tolerate FCR induced by F. culmorum. The results showed that all cultivars were susceptible to FC11 with a significant decrease in germination and coleoptile emergence rate with GI% and AUDPC values reached up to 68.35, and 68.98% for cv. Boumerzoug and Hidhab, respectively. The cv. Bordj Mehis and Ain Abid showed significant susceptibility to F. culmorum, where length of the vegetative system and fresh weight (RCL% and RCW%) were negatively affected up to 28.66 and 56.66%, respectively. In this work, the cv. Akhamokh showed an interesting level of FCR tolerance among other cultivars tested.

Exploiting Rye in Wheat Quality Breeding: The Case of Arabinoxylan Content.

Rye (Secale cereale subsp. cereale L.) has long been exploited as a valuable alternative genetic resource in wheat (Triticum aestivum L.) breeding. Indeed, the introgression of rye genetic material led to significant breakthroughs in the improvement of disease and pest resistance of wheat, as well as a few agronomic traits. While such traits remain a high priority in cereal breeding, nutritional aspects of grain crops are coming under the spotlight as consumers become more conscious about their dietary choices and the food industry strives to offer food options that meet their demands. To address this new challenge, wheat breeding can once again turn to rye to look for additional genetic variation. A nutritional aspect that can potentially greatly benefit from the introgression of rye genetic material is the dietary fibre content of flour. In fact, rye is richer in dietary fibre than wheat, especially in terms of arabinoxylan content. Arabinoxylan is a major dietary fibre component in wheat and rye endosperm flours, and it is associated with a variety of health benefits, including normalisation of glycaemic levels and promotion of the gut microbiota. Thus, it is a valuable addition to the human diet, and it can represent a novel target for wheat-rye introgression breeding.

Virulence characterization of the wheat stripe rust pathogen, Puccinia striiformis f. sp. tritici, in Turkey from 2018 to 2020

Stripe (yellow) rust caused by Puccinia striiformis f. sp. tritici (Pst) is the most devastating disease of wheat in Turkey. Virulence characterization of the Pst population is critical to prevent large-scale epidemics, by developing wheat cultivars with durable resistance against the disease. In this study, 38 Pst races, including 25 races that were not previously reported, were identified from 140 isolates obtained from most regions of Turkey from 2018 to 2020 using a differential set containing 18 single Yr gene wheat lines (NILs) of ‘Avocet’. Virulence to Yr15 was not observed among any of the isolates. Virulence to the remaining 17-Yr genes was detected at various frequencies. The frequencies of virulence to Yr6, Yr9, Yr7, Yr8, Yr43, YrExp2, Yr44, YrTr1, and Yr27 were high (57.1 to 100.0%), to Yr1, Yr17, Yr32, and YrTye were moderate (24.3 to 42.9%), and to YrSP, Yr24, and Yr10 were low (9.3 to 17.1%). Only one race was virulent to Yr5 (0.7%). Many of the races identified were common among regions, indicating that Pst races migrate throughout Turkey. However, the Black Sea (BS) and the Mediterranean (ME) regions were differentiated from other regions by unique races absent in other regions, and the Yr5-virulent race, respectively. To sum up, the virulences of the races identified and their distributions among regions provided an understanding of pathogen migration and may contribute to the development of resistant wheat cultivars against stripe rust.

Haplotype Analysis Sheds Light on the Genetic Evolution of the Powdery Mildew Resistance Locus Pm60 in Triticum Species.

Wheat powdery mildew (Blumeria graminis f. sp. tritici, Bgt, recently clarified as B. graminis s. str.), is one of the most destructive diseases of wheat. Pm60 is a nucleotide-binding leucine-rich repeat (NLR) gene that confers race-specific resistance to Bgt. Allelic variants (Pm60, Pm60a, and Pm60b) were found in Triticum urartu and T. dicoccoides, the wild progenitors of wheat. In the present study, we studied the diversity of the Pm60 locus in a large set of wheat germplasm and found 20 tetraploid wheats harboring the Pm60 alleles, which correspond to three novel haplotypes (HapI-HapIII). HapI (Pm60 allele) and HapII (Pm60a allele) were present in domesticated tetraploid wheats, whereas HapIII (Pm60a allele) was identified in wild tetraploid T. araraticum. A sequence comparison of HapII and HapIII revealed that they differed by three SNPs and a GCC deletion. Results of the phylogenetic analysis revealed that HapII was more closely related to the functional haplotype MlIW172. Infection tests showed that HapII-carrying lines display a partial resistance response to Bgt#GH, while HapI was susceptible. Our results provide insights into the genetic evolution of the Pm60 locus and potential valuable alleles for powdery mildew resistance breeding.

Triazoles and Strobilurin Mixture Affects Soil Microbial Community and Incidences of Wheat Diseases.

Pesticides are widely used in agriculture as a pest control strategy. Despite the benefits of pesticides on crop yields, the persistence of chemical residues in soil has an unintended impact on non-targeted microorganisms. In the present study, we evaluated the potential adverse effects of a mixture of fungicides (difenoconazole, epoxiconazole, and kresoxim-methyl) on soil fungal and bacterial communities, as well as the manifestation of wheat diseases. In the fungicide-treated soil, the Shannon indices of both fungal and bacterial communities decreased, whereas the Chao1 indices did not differ compared to the control soil. Among bacterial taxa, the relative abundances of Arthrobacter and Sphingomonas increased in fungicide-treated soil due to their ability to utilize fungicides and other toxic compounds. Rhizopus and plant-beneficial Chaetomium were the dominant fungal genera, with their prevalence increasing by 2-4 times in the fungicide-treated soil. The genus Fusarium, which includes phytopathogenic species, which are notably responsible for root rot, was the most abundant taxon in each of the two conditions but its relative abundance was two times lower in fungicide-treated soils, consistent with a lower level of disease incidence in plants. The prediction of metabolic pathways revealed that the soil bacterial community had a high potential for degrading various pollutants, and the soil fungal community was in a state of recovery after the application of quinone outside inhibitor (QoI) fungicides. Fungicide-treated soil was characterized by an increase in soil microbial carbon, compared with the control soil. Collectively, the obtained results suggest that the application of difenoconazole, epoxiconazole, and kresoxim-methyl is an effective approach for pest control that does not pose a hazard for the soil ecosystem in the short term. However, it is necessary to carry out additional sampling to take into account the spatio-temporal impact of this fungicide mixture on the functional properties of the soil.

Management of take-all disease caused by Gaeumannomyces graminis var. tritici in wheat through Bacillus subtilis strains.

Wheat (Triticum aestivum) is the second largest grain crop worldwide, and one of the three major grain crops produced in China. Take-all disease, caused by Gaeumannomyces graminis var. tritici (Ggt) infection, is a widespread and devastating soil-borne disease that harms wheat production. At present, the prevention and control of wheat take-all depend largely on the application of chemical pesticides. Chemical pesticides, however, not only lead to increased drug resistance of pathogens but also leave significant residues in the soil, causing serious environmental pollution. In this study, we investigated the application of Bacillus subtilis to achieve take-all disease control in wheat while reducing pesticide application. Antagonistic bacteria were screened by plate test, species identification of strains was performed by Gram staining and sequencing of 16s rDNA, secondary metabolite activity of strains was detected by clear circle method, strain compatibility and effect of compounding on Ggt were detected by plate, and the application prospects of specific strains were analyzed by greenhouse and field experiments. We found that five B. subtilis strains, JY122, JY214, ZY133, NW03, Z-14, had significant antagonistic effects against Ggt, and could secrete antimicrobial proteins including amylase, protease, and cellulase. Furthermore, Z-14 and JY214 cultures have also been shown to change the morphology of Ggt mycelium. These results also showed that Z-14, JY214, and their combination can control take-all disease in wheat at a reduced level of pesticide use. In summary, we screened two Bacillus spp. strains, Z-14 and JY214, that could act as antagonists that contribute to the biological control of wheat take-all disease. These findings provide resources and ideas for controlling crop diseases in an environmentally friendly manner.

Nematode Genome Announcement: A Draft Genome of Seed Gall Nematode, Anguina tritici.

Anguina tritici is the first plant-parasitic nematode described in literature, dating back to the year 1743. It is responsible for causing earcockle (seed gall) and tundu diseases in wheat and rye. Notably, this nematode has been observed to survive in an anhydrobiotic state for up to 32 years within wheat seed galls. These exceptional characteristics have inspired the sequencing of the A. tritici genome. In this study, we present the initial draft genome of A. tritici, obtained using the Illumina MiSeq platform with coverage of 60-fold. The genome is estimated to have a size of 164 Mb and comprises 39,965 protein-coding genes, exhibiting a GC content of 39.1%. The availability of this genome data will serve as a foundation for future functional biological investigations, particularly for genes whose functions remain unknown to this day.

Measuring resistance in durum wheat-Zymoseptoria tritici interaction using aggressiveness quantitative traits

Phenotyping for quantitative resistance to Septoria tritici blotch (STB), one of the most economically devastating diseases of durum wheat (Triticum durum Desf.) in North African region, is a limiting factor for breeding progress. Here we tested main phenotypic markers of aggressiveness affecting host damage and pathogen reproduction reported in earlier studies for measuring differences in quantitative host resistance. A collection of 11 Tunisian durum wheat genotypes varying in resistance to the pathogen was inoculated by a highly aggressive and virulent isolate of Zymoseptoria tritici in a replicated field and controlled experiments, conducted in 2017-2018 at the experimental station of the Regional Field Crops Research Center of Beja in Tunisia. The severity of infection caused by Z. tritici isolate, including percentage of leaf area covered by chlorotic lesions (PLACCL), percentage of leaf area covered by necrosis (PLACN), and percentage of leaf area covered by pycnidia (PLACP) as well as latent period (LP) and pycnidia density (PYCdens) were assessed visually and quantified. The results showed that there were significant differences in all assessed traits on the tested genotypes and significant positive correlations were obtained between PLACN, PLACP and PYCdens. Similarly, there was a significant negative correlation between LP and these last traits. The PLACP was found as the more reliable trait to discriminate genotypes to different classes of resistance, consistent with the results obtained for the remaining traits. These data suggest that using both necrotic leaf area (PLACN) bearing pycnidia and PYCdens can improve selection for quantitative STB resistance.

SSR variability of stem rust pathogen on spring bread wheat in Russia.

Wheat stem rust caused by Puccinia graminis f. sp. tritici Erikss. & E. Henning (Pgt), which used to be a harmful disease of winter wheats in the southern part of Russia, has been largely affecting the yield of spring bread wheat in the territories of temperate climate zone since 2009. A total of 222 Pgt isolates were obtained from samples of susceptible cultivars of spring bread wheat in Central and Volga regions, and Omsk and Novosibirsk provinces in 2019. Genotyping of the isolates was carried out at 16 SSR loci. Number of alleles, proportion of heterozygotes and deviation from Hardy-Weinberg equilibrium were determined at each SSR locus. Based on genetic variability of SSR genotypes, it was shown that the Pgt population is subdivided into two large clusters in the territory of Russian temperate climate zone: "European" population (the Central region) and "Asian" one (the Volga region and two main wheat provinces of Western Siberia). Both the Pgt populations are characterized by a mixed mode of reproduction (sexual and clonal), but different sources of inoculum seem to shape a genotype structure within them. A group of Pgt genotypes with high variability, the inbreeding coefficient closed to zero and low observed heterozygosity was revealed among samples from Omsk. Moreover, two singular SSR genotypes identified among the Asian samples of Pgt isolates should attract a special attention in monitoring of stem rust in order to disclose unexpected rapid changes of the pathogen in the corresponding regions and to prevent the disease outbreak.

Mapping Quantitative Trait Loci for Type II Fusarium Head Blight Resistance in Two Wheat Recombinant Inbred Line Populations Derived from Yangmai 4 and Yangmai 5.

Fusarium head blight (FHB) is a destructive wheat disease worldwide and significantly affects grain yield and quality in wheat. To understand the genetic basis underlying type II FHB resistance in two elite wheat cultivars Yangmai 4 (YM4) and Yangmai 5 (YM5), quantitative trait loci (QTL) mapping was conducted in two recombinant inbred lines (RIL) populations derived from the crosses of YM4 and YM5 with susceptible cultivar Yanzhan 1 (YZ1), respectively. Survey with markers linked to Fhb1, Fhb2, Fhb4, and Fhb5 in landrace Wangshuibai indicated the non-existence of these known FHB resistance genes/QTL in YM4, YM5, and YZ1. One overlapped resistance QTL was identified in both RIL populations, namely QFhb.Y4.2D/QFhb.Y5.2D, with a large effect on FHB resistance. One novel resistance QTL QFhb.Y4.5A mapped on chromosome 5A was detected only in YM4/YZ1 population. The resistance alleles of both QFhb.Y4.2D/QFhb.Y5.2D and QFhb.Y4.5A did not increase the plant height and did not significantly affect the heading date and flowering date. Kompetitive Allele-Specific PCR markers for QFhb.Y4.2D/QFhb.Y5.2D and QFhb.Y4.5A had been developed to verify in an additional set of 244 geographically diverse cultivars/lines. Pyramiding of the two resistance alleles decreased the percentage of symptomatic spikelets by 51.77% relative to the cultivars/lines without these two resistance alleles. QFhb.Y4.2D/QFhb.Y5.2D and QFhb.Y4.5A were shown to be useful alternatives in FHB resistance breeding programs. The results will facilitate the marker-assisted selection for introgression of the favorable alleles for improving FHB resistance in breeding programs.

PASTE: The Way Forward for Large DNA Insertions.

PASTE: The Way Forward for Large DNA Insertions.

Development of Diagnostic Markers and Applied for Genetic Diversity Study and Population Structure of Bipolaris sorokiniana Associated with Leaf Blight Complex of Wheat

Bipolaris sorokiniana, a key pathogenic fungus in the wheat leaf blight complex, was the subject of research that resulted in the development of fifty-five polymorphic microsatellite markers. These markers were then used to examine genetic diversity and population structure in Indian geographical regions. The simple sequence repeat (SSR) like trinucleotides, dinucleotides, and tetranucleotides accounted for 43.37% (1256), 23.86% (691), and 16.54% (479) of the 2896 microsatellite repeats, respectively. There were 109 alleles produced by these loci overall, averaging 2.36 alleles per microsatellite marker. The average polymorphism information content value was 0.3451, with values ranging from 0.1319 to 0.5932. The loci's Shannon diversity varied from 0.2712 to 1.2415. These 36 isolates were divided into two main groups using population structure analysis and unweighted neighbour joining. The groupings were not based on where the isolates came from geographically. Only 7% of the overall variation was found to be between populations, according to an analysis of molecular variance. The high amount of gene flow estimate (NM = 3.261 per generation) among populations demonstrated low genetic differentiation in the entire populations (FST = 0.071). The findings indicate that genetic diversity is often minimal. In order to examine the genetic diversity and population structure of the B. sorokiniana populations, the recently produced microsatellite markers will be helpful. This study's findings may serve as a foundation for developing improved management plans for the leaf blight complex and spot blotch of wheat diseases in India.

Long-Term Studies of Wheat Leaf Rust in the North-Western Region of Russia

Leaf rust, caused by Puccinia triticina (Pt), is a widely occurring disease of wheat in the North-Western Region of Russia. Annual Pt surveys of wheat in this region have been conducted between 2001 and 2021. In total, 740 single urediniospore isolates were analyzed over 20 years. Virulence to Lr9, Lr19 and Lr24 were rare in 2001–2010 and was not detected after 2010. Temporal variation in virulence was determined on Thatcher lines with Lr1, Lr2a, Lr2b and Lr2c genes and was found to be relatively high. Virulence to Lr1 increased to 100% from 2001 to 2014. Until 2010, most northwestern Pt isolates were avirulent to Lr2a and virulent to Lr2b and Lr2c. In the middle of 2010, avirulence to Lr2a, Lr2b, Lr2c and Lr15 began to increase. Strong variability between years was revealed for virulence to Lr20 and Lr26. Based on a set of 20 differential lines, 122 virulence pathotypes were detected. More than half of those were observed only once across all years. Pathotypes were divided into groups of B-, C-, D- and F-, virulent to Lr1 and Lr2a, dominating until 2009. From 2010 pathotype groups M- and P-, virulent to Lr1 and avirulent to Lr2a, began to dominate. Temporal differentiation of northwestern Pt population for virulence was determined. High similarity was observed for Pt accessions in 2001–2009 and 2010–2015 and these two groups differed moderately from each other. Pt accessions from 2016–2019 and 2020–2021 differed from each other and from accessions from the previous collection period. Field response of Lr differential lines was studied in the North-Western Region during 1998–2022. Wheat genotypes with genes Lr9, Lr19, Lr23, Lr24, Lr25, Lr28, Lr29, Lr35, Lr39, Lr42, Lr43, Lr45, Lr47, Lr48, Lr49, Lr50, Lr51, Lr53 and Lr57 remained resistant throughout the period of the study. Leaf rust severity in lines TcLr12, TcLr21, TcLr22a, Gatcher (Lr27+31), TcLr44 and Pavon (Lr46) varied from 1% to 30% before 2014 and significantly decreased after 2014. A general trend of decreasing virulence of the Pt pathogen has been observed in the North-Western Region over the recent years.

Synergistic effect of Pseudomonas azotoformans and Trichoderma gamsii in management of Fusarium crown rot of wheat

Fusarium crown rot is the major soil-borne disease of wheat and occurs throughout cereal producing areas of the world including Algeria. This study evaluated 10 bacterial and fungal strains, originating from Algeria as potential biological control agents against three soil-borne phytopathogens responsible for Fusarium crown rot of wheat (Fusarium pseudograminearum ON687723, F. graminearum ON685926 and F. equisti MK361175). All benificial microbial strains tested inhibited the pathogens mycelial growth in vitro. Isolate P58 (Pseudomonas azotoformans NR_113600) was the most effective antagonist against all the test pathogens in direct confrontation assay, and exhibited average of 70% growth inhibition of Fusarium spp. Isolate T2 (Trichoderma gamsii MK361138) proved suppression efficacy in the range of 61.87 to 71.64% toward plant pathogens. Under greenhouse conditions, wheat seeds treated with isolate P58 and T2 separately reduced the severity of crown rot disease significantly and improved the growth parameters of wheat seedlings as compared to control. The combined use of Pseudomonas azotoformans and Trichoderma gamsii increased the effectiveness of the antagonists and promoted wheat growth. Thus, it can be concluded that these strains can be utilized as a biocontrol agent for management of soilborne cereal pathogens.

Fungal Pathogens Associated with Crown and Root Rot in Wheat-Growing Areas of Northern Kyrgyzstan.

Fungal species associated with crown and root rot diseases in wheat have been extensively studied in many parts of the world. However, no reports on the relative importance and distribution of pathogens associated with wheat crown and root rot in Kyrgyzstan have been published. Hence, fungal species associated with wheat crown/root rot were surveyed in three main wheat production regions in northern Kyrgyzstan. Fungal species were isolated on 1/5 strength potato-dextrose agar amended with streptomycin (0.1 g/L) and chloramphenicol (0.05 g/L). A total of 598 fungal isolates from symptomatic tissues were identified using morphological features of the cultures and conidia, as well as sequence analysis of the nuclear ribosomal internal transcribed spacer (ITS) region, the translation elongation factor 1α (TEF1), and the RNA polymerase II beta subunit (RPB2) genes. The percentage of fields from which each fungus was isolated and their relative percentage isolation levels were determined. Bipolaris sorokiniana, the causal agent of common root rot, was the most prevalent pathogenic species isolated, being isolated from 86.67% of the fields surveyed at a frequency of isolation of 40.64%. Fusarium spp. accounted for 53.01% of all isolates and consisted of 12 different species. The most common Fusarium species identified was Fusarium acuminatum, which was isolated from 70% of the sites surveyed with an isolation frequency of 21.57%, followed by Fusarium culmorum, Fusarium nygamai, Fusarium oxysporum, and Fusarium equiseti, all of which had a field incidence of more than 23%. Inoculation tests with 44 isolates representing 17 species on the susceptible Triticum aestivum cv. Seri 82 revealed that Fusarium pseudograminearum and F. culmorum isolates were equally the most virulent pathogens. The widespread distribution of moderately virulent B. sorokiniana appears to be a serious threat to wheat culture, limiting yield and quality. With the exception of F. culmorum, the remaining Fusarium species did not pose a significant threat to wheat production in the surveyed areas because common species, such as F. acuminatum, F. nygamai, F. oxysporum, and F. equiseti, were non-pathogenic but infrequent species, such as Fusarium redolens, Fusarium algeriense, and F. pseudograminearum, were highly or moderately virulent. Curvularia inaequalis, which was found in three different fields, was mildly virulent. The remaining Fusarium species, Fusarium solani, Fusarium proliferatum, Fusarium burgessii, and Fusarium tricinctum, as well as Microdochium bolleyi, Microdochium nivale, and Macrophomina phaseolina, were non-pathogenic and considered to be secondary colonizers. The implications of these findings are discussed.

Wheat leaf rust fungus effector Pt13024 is avirulent to TcLr30.

Wheat leaf rust, caused by Puccinia triticina Eriks. (Pt), is a global wheat disease threatening wheat production. Dissecting how Pt effector proteins interact with wheat has great significance in understanding the pathogenicity mechanisms of Pt. In the study, the cDNA of Pt 13-5-72 interacting with susceptible cultivar Thatcher was used as template to amplify Pt13024 gene. The expression pattern and structure of Pt13024 were analyzed by qRT-PCR and online softwares. The secretion function of Pt13024 signal peptide was verified by the yeast system. Subcellular localization of Pt13024 was analyzed using transient expression on Nicotiana benthamiana. The verification that Pt13024 inhibited programmed cell death (PCD) was conducted on N. benthamiana and wheat. The deletion mutation of Pt13024 was used to identify the virulence function motif. The transient transformation of wheat mediated by the type III secretion system (TTSS) was used to analyze the activity of regulating the host defense response of Pt13024. Pt13024 gene silencing was performed by host-induced gene silencing (HIGS). The results showed that Pt13024 was identified as an effector and localized in the cytoplasm and nucleus on the N. benthamiana. It can inhibit PCD induced by the Bcl-2-associated X protein (BAX) from mice and infestans 1 (INF1) from Phytophthora infestans on N. benthamiana, and it can also inhibit PCD induced by DC3000 on wheat. The amino acids 22 to 41 at N-terminal of the Pt13024 are essential for the inhibition of programmed cell death (PCD) induced by BAX. The accumulation of reactive oxygen species and deposition of callose in near-isogenic line TcLr30, which is in Thatcher background with Lr30, induced by Pt13024 was higher than that in 41 wheat leaf rust-resistant near-isogenic lines (monogenic lines) with different resistance genes and Thatcher. Silencing of Pt13024 reduced the leaf rust resistance of Lr30 during the interaction between Pt and TcLr30. We can conclude that Pt13024 is avirulent to TcLr30 when Pt interacts with TcLr30. These findings lay the foundation for further investigations into the role of Pt effector proteins in pathogenesis and their regulatory mechanisms.

Spore-Trapping Device: An Efficient Tool to Manage Fungal Diseases in Winter Wheat Crops.

Leaf airborne diseases cause major shortfalls in agricultural crops. The introduction of technical means can significantly improve early-warning systems for plant diseases as well as provide timely and accurate forecasts. In this paper, we aim to evaluate the possibilities of detecting a phytopathogenic infection using a spore-catching device developed at the Federal Research Center of Biological Plant Protection (FRCBPP) on winter wheat varieties of different levels of susceptibility to major economically important leaf diseases, taking into account climatic conditions. The device captures spores in the surface layer of air among crop plants. We conducted research in the experimental fields of FRCBPP in 2019-2021. The objects of the study were four cultivars of winter wheat. They were selected according to the degree of resistance to various leaf diseases. We studied the progress of wheat diseases according to generally accepted international scales the onset of the first manifestations to their maximum development. We studied the aerogenic infection in wheat crops using the FRCBPP developed portable device for determining the infestation of plants. Sampling was carried out in the same period as the visual assessment. The samples were taken in the crops of each variety at five points. The sampling time was one minute. As a result of research on experimental crops of four varieties of winter wheat, we observed the development of such diseases as powdery mildew (Erysiphe graminis), yellow spot (Pyrenophora tritici-repentis), septoria leaf spot (Septoria tritici), yellow (Puccinia striiformis) and brown rust (Puccinia triticina). In a laboratory study of samples under a light microscope, all of the listed pathogens were found except for septoria leaf spot. Two-way analysis of variance confirmed the statistically significant separate and cumulative influence of the cultivar and year factor on winter wheat diseases. A generalized correlation analysis for three growing seasons (2019-2021) showed that an average statistically significant correlation coefficient (0.5-0.6) remains for the total groups for powdery mildew, yellow and brown rust. This indicator for the causative agent of yellow spot was equal to 0.4 with a high level of statistical significance. Thus, we conclude that by using a spore-catching device, it is possible to identify spores of economically significant pathogens in winter wheat crops and predict the further development of pathogens, taking into account the cultivar and annual climate factors.

The Use of Genetic Material of Tall Wheatgrass to Protect Common Wheat from Septoria Blotch in Western Siberia

The Septoria blotch is one of the most economically harmful diseases of common wheat in Russia and the world. The disease is mainly caused by two pathogen species: Zymoseptoria tritici that damages the leaves, and Parastagonospora nodorum that strikes the leaves and ears. Resistance genes of the alien relatives are traditionally used for genetic defense of cultivars. The aims of the research were to study the resistance of the tall wheatgrass Thinopyrum ponticum (Podp.) Z.-W. Liu and R.-C. Wang and perspective introgressive lines of spring common wheat with its genetic material to Septoria blotch, and to characterize their agronomical properties to be used in breeding programs in Western Siberia. The studies were carried out in 2015–2019 in the field conditions of the southern forest-steppe (Omsk, Russia) on a natural infection background and according to standard methods. The Septoria diseases developed on the wheat in the period of milk-wax ripeness, independently of humid or dry weather conditions. In 2016, a sharp increase in leaf lesion was noted, probably associated with changes in the Z. tritici population. In 2017, the ratio of Z. tritici and P. nodorum was similar, and in 2019 Z. tritici prevailed. During the research, the lines that combined leaf and ear resistance to damage with high yield and grain quality were selected.

GSEYOLOX-s: An Improved Lightweight Network for Identifying the Severity of Wheat Fusarium Head Blight

Fusarium head blight (FHB) is one of the most detrimental wheat diseases. The accurate identification of FHB severity is significant to the sustainable management of FHB and the guarantee of food production and security. A total of 2752 images with five infection levels were collected to establish an FHB severity grading dataset (FHBSGD), and a novel lightweight GSEYOLOX-s was proposed to automatically recognize the severity of FHB. The simple, parameter-free attention module (SimAM) was fused into the CSPDarknet feature extraction network to obtain more representative disease features while avoiding additional parameters. Meanwhile, the ghost convolution of the model head (G-head) was designed to achieve lightweight and speed improvements. Furthermore, the efficient intersection over union (EIoU) loss was employed to accelerate the convergence speed and improve positioning precision. The results indicate that the GSEYOLOX-s model with only 8.06 MB parameters achieved a mean average precision (mAP) of 99.23% and a detection speed of 47 frames per second (FPS), which is the best performance compared with other lightweight models, such as EfficientDet, Mobilenet-YOLOV4, YOLOV7, YOLOX series. The proposed GSEYOLOX-s was deployed on mobile terminals to assist farmers in the real-time identification of the severity of FHB and facilitate the precise management of crop diseases.

Important wheat diseases in the US and their management in the 21st century.

Wheat is a crop of historical significance, as it marks the turning point of human civilization 10,000 years ago with its domestication. Due to the rapid increase in population, wheat production needs to be increased by 50% by 2050 and this growth will be mainly based on yield increases, as there is strong competition for scarce productive arable land from other sectors. This increasing demand can be further achieved using sustainable approaches including integrated disease pest management, adaption to warmer climates, less use of water resources and increased frequency of abiotic stress tolerances. Out of 200 diseases of wheat, 50 cause economic losses and are widely distributed. Each year, about 20% of wheat is lost due to diseases. Some major wheat diseases are rusts, smut, tan spot, spot blotch, fusarium head blight, common root rot, septoria blotch, powdery mildew, blast, and several viral, nematode, and bacterial diseases. These diseases badly impact the yield and cause mortality of the plants. This review focuses on important diseases of the wheat present in the United States, with comprehensive information of causal organism, economic damage, symptoms and host range, favorable conditions, and disease management strategies. Furthermore, major genetic and breeding efforts to control and manage these diseases are discussed. A detailed description of all the QTLs, genes reported and cloned for these diseases are provided in this review. This study will be of utmost importance to wheat breeding programs throughout the world to breed for resistance under changing environmental conditions.