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Key message: A new stripe rust resistance gene YrBDT in Chinese landrace wheat Baidatou was mapped to a 943.6-kb interval on chromosome arm 6DS and co-segregated with a marker CAPS3 developed from candidate gene TraesCS6D03G0027300. Stripe rust caused by Puccinia striiformis f. sp. tritici (Pst) is a devastating foliar disease of wheat. Chinese landrace wheat Baidatou has shown high resistance to a broad spectrum of Pst races at both the seedling and adult-plant stages for decades in the Longnan region of Gansu province, a hot spot for stripe rust epidemics. Here, we report fine mapping and candidate gene analysis of stripe rust resistance gene YrBDT in Baidatou. Analysis of F1, F2 plants and F2:3 lines indicated that resistance in Baidatou to Pst race CYR31 was conferred by a single dominant gene, temporarily designated YrBDT. Bulked segregant exome capture sequencing (BSE-seq) analysis revealed 61 high-confidence polymorphic SNPs concentrated in a 5.4-Mb interval at the distal of chromosome arm 6DS. Several SNPs and InDels were also identified by genome mining of DNA sampled from the parents and contrasting bulks. The YrBDT locus was mapped to a 943.6-kb (4,658,322–5,601,880 bp) genomic region spanned by markers STS2 and STS3 based on IWGSC RefSeq v2.1, including five putative disease resistance genes. There was high collinearity of the target interval among Chinese Spring RefSeq v2.1, Ae. tauschii AL8/78 and Fielder genomes. The expression level of TraesCS6D03G0027300 showed significant association with Pst infection, and a gene-specific marker CAPS3 developed from TraesCS6D03G0027300 co-segregated with YrBDT suggesting this gene as a candidate of YrBDT. The resistance gene and flanking markers can be used in marker-assisted selection for improvement of stripe rust resistance. [ABSTRACT FROM AUTHOR]

The importance of monitoring and management of yellow rust, caused by Puccinia striiformis f. sp. tritici (Pst), has markedly increased in Russia over recent years because of intensifying negative effects of this destructive disease on wheat production. The Pst virulence survey was conducted in 2019–2021 in the European (North‐West, Volga, North Caucasus) and Asian (Siberia) parts of Russia, and the same 109 isolates have been genotyped here with 20 SSR markers. Fifty‐three multilocus genotypes (MLGs) were detected, seven of which occurred in two or more regions. The most frequent MLG was found in three European Pst collections (except Dagestan) and Siberia. SSR‐based variation within the regional collections was low because many MLGs were closely related. Nevertheless, each collection contained relatively different small genotype groups. No clear geographic structure of the Russian Pst population was observed because the five studied regional collections shared groups of similar genotypes. The most singular SSR genotype was identified in the North‐West collection, but genotypes of four invasive isolates belonging to the PstS2 temperature‐adapted aggressive strain did not considerably differ from others. The observed heterozygosity at all SSR loci exceeded the expected one in all regional Pst collections, which could imply asexual reproduction of the pathogen. Both the SSR and virulence analyses demonstrated similar patterns of relationships between the regional Pst collections, although the magnitude of differences between the collections was larger for virulence pathotypes. However, no significant association was established between the virulence pathotypes and SSR genotypes because multiple pathotypes had the same genotype and vice versa. [ABSTRACT FROM AUTHOR]

The emerging malting industry in California needs adapted cultivars for a sustainable local barley production. 'UC‐Alameda' (Reg. no. CV‐381, PVP 202300263, PI 701932) is a two‐row, spring malting barley (Hordeum vulgare L.) released by the University of California, Davis, Agricultural Experiment Station, in 2022. UC‐Alameda is a highly productive cultivar with satisfactory malting quality for local craft maltsters. UC‐Alameda is adapted to the California Central Valley (Sacramento and San Joaquin Valleys) and is resistant to the most common diseases present in this region (e.g., Barley yellow dwarf virus, Cereal yellow dwarf virus, stripe rust, and powdery mildew) and moderately resistant to scald and net blotch. It was evaluated in preliminary trials, as B9K62, from 2017 to 2023 at Davis, CA, and by the University of California Regional Small Grains Testing program, as UC1911, from 2018 to 2023 for late fall planting in the Central Valley. UC‐Alameda is a non‐glycosidic nitrile producer, which is an important trait for craft‐maltsters and distillers. UC‐Alameda satisfies the quality criteria of the local craft malting and brewing industry interested in sourcing locally grown malting barley. Core Ideas: UC‐Alameda is a new two‐row spring malting barley for California.UC‐Alameda is a non‐glycoside nitrile producer.UC‐Alameda meets the requirements of California local maltsters and brewers.UC‐Alameda is resistant to the common barley pathogens present in the Central Valley of California.UC‐Alameda is resistant to stripe and stem rust. [ABSTRACT FROM AUTHOR]

The composition of seed storage proteins determines the suitability of bread wheat cultivar for different end-use products. high-molecular-weight glutenin subunits are the major determinants of the processing quality of bread wheat flour. The spontaneous translocation of the 1RS arm of Secale cereale L. in bread wheat is associated with higher grain yield and abiotic stress tolerance, but it leads to deterioration in the end-use quality due to the presence of rye storage secalin protein encoded by Sec-1 locus. The 1RSWR.1BL recombinant line W1635 without Sec-1, over-expressed Glu1-Bx7 (Bx7OE) and two stripe rust resistance genes Yr5 and Yr17 were used as the donor for marker-assisted breeding in the bread wheat cultivars UP2338 and HS240 with 1RS.1BL translocation. A strong positive correlation was found between the micro-SDS sedimentation test (MST) values and Bx7OE in the derivatives along with Glu-D1 (5 + 10) indicating the efficacy of Bx7OE in improving the end-use quality. In addition to this, the introgression of Yr5 and Yr17 genes led to stripe rust resistance in the derivatives for their stable and environment friendly production. [ABSTRACT FROM AUTHOR]

Stripe rust, induced by Puccinia striiformis f. sp. tritici, is the most harmful and prevalent disease in temperate regions worldwide, affecting wheat production areas globally. An effective strategy for controlling the disease involves enhancing genetic resistance against stripe rust, achieved through Egyptian breeding efforts not previously conducted on wheat genotypes. The resistance level to stripe rust in thirty-eight wheat genotypes was assessed using marker-assisted selection methods. The investigation suggests that wheat breeding programs can utilize slow-rusting Yr genes, which are effective resistance genes, to develop novel genotypes with stripe rust resistance through marker-assisted breeding. Based on the four disease responses of the wheat genotypes under investigation, the results categorized the genotypes into three groups. The first group included resistant genotypes, the second group exhibited a slow-rusting character with the lowest disease symptom rates, and the last group displayed the highest disease characteristics rates throughout the three seasons, comprising fast-rusting genotypes. The rust-resistant genes identified were Yr5, Yr9, Yr10, Yr15, Yr17, Yr18, Yr26, Yr29, Yr30, and Yr36. Genes Yr26, Yr30, and Yr36 were present in all genotypes. Genotypes Misr3, Misr4, Giza168, Giza167, Giza170, Giza171, Gemmeiza9, and Gemmeiza10 carried the Yr9 gene. Only one genotype, Sids13, was found to have the Yr17 gene. Genes Yr18 and Yr29 were identified in Sids14, Giza168, Giza170, Gemmeiza9, and Gemmeiza10. However, none of the wheat genotypes showed the presence of Yr5, Yr10, or Yr15. Several backcrossing generations were conducted to introduce the Yr5 and Yr10 genes into susceptible genotypes (Misr1, Misr2, and Gemmeiza11). These genotypes are cultivated globally and are known for producing high-quality flour, making them of great importance to farmers. The study demonstrates significant potential for enhancing wheat genotypes for stripe rust resistance and increased production. [ABSTRACT FROM AUTHOR]

The wild species Thinopyrum intermedium (genome JJJSJSStSt) serves as a valuable germplasm resource providing novel diseases resistance and agronomically important genes for wheat improvement. Two wheat-Th. intermedium partial amphiploids, TAI7045 (2n = 56) and 78784 (2n = 56), exhibit high resistance to stripe rust and powdery mildew, and their chromosome constitutions have been characterized. With the aim to transfer novel resistance genes from Th. intermedium, the crosses of common wheat line MY11 with TAI7045 and 78784 were produced, and their individual F2-F5 progenies were characterized using sequential non-denaturing fluorescence in situ hybridization (ND-FISH) and molecular markers. We identified a set of wheat-Th. intermedium addition lines, involving the chromosomes 1St-JS, 2St, 2St-JS, 3St, 4J, 4St, 5St, 5J.St, 6JS.J, and 7JS. Above all, the stable wheat-Th. intermedium small segmental translocation lines with chromosomes 4DS.4DL-4StL-4DL-4JL and 4DS.4DL-4StL-4DL were selected. Combining data from specific marker amplification and resistance evaluation, we mapped the gene(s) for resistance to powdery mildew and stripe rust in the 233.56–329.88 Mb region of the long arm of the 4St chromosome from the reference Th. intermedium genome. The new wheat-Th. intermedium introgressions will be used as novel germplasm for breeding purposes. [ABSTRACT FROM AUTHOR]

Chloroplasts are key players in photosynthesis and immunity against microbial pathogens. However, the precise and timely regulatory mechanisms governing the control of photosynthesis-associated nuclear genes (PhANGs) expression in plant immunity remain largely unknown. Here we report that TaPIR1, a Pst-induced RING-finger E3 ubiquitin ligase, negatively regulates Pst resistance by specifically interacting with TaHRP1, an atypical transcription factor histidine-rich protein. TaPIR1 ubiquitinates the lysine residues K131 and K136 in TaHRP1 to regulate its stability. TaHRP1 directly binds to the TaHRP1-binding site elements within the PhANGs promoter to activate their transcription via the histidine-rich domain of TaHRP1. PhANGs expression induces the production of chloroplast-derived ROS. Although knocking out TaHRP1 reduces Pst resistance, TaHRP1 overexpression contributes to photosynthesis, and chloroplast-derived ROS production, and improves disease resistance. TaPIR1 expression inhibits the downstream activation of TaHRP1 and TaHRP1-induced ROS accumulation in chloroplasts. Overall, we show that the TaPIR1-mediated ubiquitination and degradation of TaHRP1 alters PhANGs expression to disrupt chloroplast function, thereby increasing plant susceptibility to Pst. Wheat E3 ubiquitin ligase TaPIR1-mediated ubiquitination and degradation of an atypical transcription factor TaHRP1 alters PhANGs expression to disrupt chloroplast function and ROS accumulation, increasing plant susceptibility to wheat stripe rust. [ABSTRACT FROM AUTHOR]

Barley stripe or yellowrust (BYR) caused by Puccinia striiformis f. sp. hordei (Psh) is a significant constraint to barley production. The disease is best controlled by genetic resistance, which is considered the most economical and sustainable component of integrated disease management. In this study, we assessed the diversity of resistance to Psh in a panel of international barley genotypes (n = 266) under multiple disease environments (Ecuador, India, and Mexico) using genome-wide association studies (GWASs). Four quantitative trait loci (QTLs) (three on chromosome 1H and one on 7H) associated with resistance to Psh were identified. The QTLs were validated by mapping resistance to Psh in five biparental populations, which detected key genomic regions on chromosomes 1H (populations Pompadour/Zhoungdamei, Pompadour/Zug161, and CI9214/Baudin), 3H (Ricardo/Gus), and 7H (Fumai8/Baronesse). The QTL RpshQ.GWA.1H.1 detected by GWAS and RpshQ.Bau.1H detected using biparental mapping populations co-located were the most consistent and stable across environments and are likely the same resistance region. RpshQ.Bau.1H was saturated using population CI9214/Baudin by enriching the target region, which placed the resistance locus between 7.9 and 8.1 Mbp (flanked by markers sun_B1H_03, 0.7 cM proximal to Rpsh_1H and sun_B1H_KASP_02, 3.2 cM distal on 1HS) in the Morex reference genome v.2. A Kompetitive Allele Specific PCR (KASP) marker sun_B1H_KASP_01 that cosegregated for RpshQ.Bau.1H was developed. The marker was validated on 50 Australian barley cultivars, showingwell-defined allelic discrimination and presence in six genotypes (Baudin, Fathom, Flagship, Grout, Sakurastar, and Shepherd). This marker can be used for reliable marker-assisted selection and pyramiding of resistance to Psh and in diversifying the genetic base of resistance to stripe rust. [ABSTRACT FROM AUTHOR]

Preventing the widespread occurrence of stripe rust in wheat largely depends on the identification of new stripe rust resistance genes and the breeding of cultivars with durable resistance. In previous study, we reported 6E of wheat–tetraploid Thinopyrum elongatum 6E (6D) substitution line contains adult-stage stripe rust resistance genes. In this study, three novel wheat–tetraploid Th. elongatum translocation lines were generated from the offspring of a cross between common wheat and the 6E (6D) substitution line. Genomic in situ hybridization (GISH), fluorescence in situ hybridization chromosome painting (FISH painting), repetitive sequential FISH, and 55 K SNP analyses indicated that K227-48, K242-82, and K246-6 contained 42 chromosomes and were 6DL·6ES, 2DL·6EL, and 6DS·6EL translocation lines, respectively. The assessment of stripe rust resistance revealed that K227-48 was susceptible to a mixture of Pst races, whereas the 6EL lines K242-82 and K246-6 were highly resistance to stripe rust at the adult stage. Thus, this resistance was due to the chromosome arm 6EL of tetraploid Th. elongatum. The improved agronomic performance of 6DS·6EL translocation line may be a useful novel germplasm resource for wheat breeding programs. For the application of marker-assisted selection (MAS), 47 simple sequence repeat (SSR) markers were developed, showing specific amplification on the chromosome 6E using the whole-genome sequence of diploid Th. elongatum. The 6DS·6EL translocation line and SSR markers have the potential to be deploy for future stripe rust resistance wheat breeding program. [ABSTRACT FROM AUTHOR]

Wheat cultivar Zhongmai 895 was earlier found to carry YR86 in an 11.6 Mb recombination-suppressed region on chromosome 2AL when crossed with Yangmai 16. To fine-map the YR86 locus, we developed two large F2 populations from crosses Emai 580/Zhongmai 895 and Avocet S/Zhongmai 895. Remarkably, both populations exhibited suppressed recombination in the same 2AL region. Collinearity analysis across Chinese Spring, Aikang 58, and 10+ wheat genomes revealed a 4.1 Mb chromosomal inversion spanning 708.5-712.6 Mb in the Chinese Spring reference genome. Molecular markers were developed in the breakpoint and were used to assess a wheat cultivar panel, revealing that Chinese Spring, Zhongmai 895, and Jimai 22 shared a common sequence named InvCS, whereas Aikang 58, Yangmai 16, Emai 580, and Avocet S shared the sequence named InvAK58. The inverted configuration explained the suppressed recombination observed in all three bi-parental populations. Normal recombination was observed in a Jimai 22/Zhongmai 895 F2 population, facilitating mapping of YR86 to a genetic interval of 0.15 cM corresponding to 710.27-712.56 Mb falling within the inverted region. Thirty-three high-confidence genes were annotated in the interval using the Chinese Spring reference genome, with six identified as potential candidates for YR86 based on genome and transcriptome analyses. These results will accelerate map-based cloning of YR86 and its deployment in wheat breeding. [ABSTRACT FROM AUTHOR]

Stripe rust poses a severe menace to wheat cultivation worldwide, occurring as the most devastating disease threatening global wheat industry. The use of resistance genes has been considered as an effective method for management of rust diseases. However, for most of yellow rust (Yr) genes, the molecular mechanisms and pathways responsible for resistance response against Puccinia striiformis (Pst) infection are not well understood. In this study, transcriptome analysis was conducted in two cultivars viz. PBW343 (susceptible) and FLW30 (resistant) to the pathotype 46S119 of Pst in India. The inoculation with Pst pathotype 46S119 was followed by leaf sample collection at different hours per inoculation (hpi) viz. 12, 48, and 72. The transcriptome analysis revealed a total of 18,482 differentially expressed genes (DEGs) across different time points. However, a set of 159 genes were identified to exhibit a genome-wide association with P ≤ 0.05 level of significance, which can be represented as Nominally Significant GWAS Geneset (NSGG). By utilizing Weighted Gene Co-expression Network Analysis (WGCNA), we identified 924 and 79 genes from the DEGs and NSGG dataset belonging to different modules. Functional validation of genes was done to confirm the transcriptional expression of four potential genes, including two hub genes associated with the defence mechanism against rust infection. [ABSTRACT FROM AUTHOR]

• Rye wheat derivatives were meticulously bred through strategic hybridisation of secale cereal and bread wheat. • The derivatives were successfully validated via miotic abnormalities, FISH signals, and molecular markers. • The Anther size, pollen viability, tiller numbers, and thousand kernel weight are key contributors to grain yield. • The rye wheat derivative lines showed significant improvement in stripe rust resistance and floral traits. Interspecific plant hybridisation is a pivotal evolutionary process shaping speciation dynamics. In the context of bread wheat cultivation in India, stripe rust stands out as the predominant factor contributing to yield reduction. With the objective of improving stripe rust resistance and floral traits, diverse back-crossed population was meticulously developed through triticale-wheat crosses. The BC 2 F 7 generation of rye-wheat derivatives underwent a comprehensive analysis encompassing genetic variability, trait associations, multiple regressions, and principal component, with a focus on floral and yield attributes. The meticulously chosen stripe rust-resistant derivative lines underwent comprehensive evaluation, including an assessment of chromosomal abnormalities, fluorescence in situ hybridisation, and rye genome-specific molecular markers analysis. The statistical analysis substantiates that the derived population exhibits significant variations for all the examined traits. Positive correlations were observed with anther size, pollen viability, tiller number, thousand kernel weight, and grain yield. Multiple regression analysis reveals that anther size, pollen viability, tiller number, and thousand kernel weights emerge as pivotal contributors influencing grain yield. Moreover, the three principal components exhibit more than one eigen-value, thereby signifying their capacity to encapsulate the maximum variability within the dataset. In addition, chromosomal abnormalities, encompassing univalent, multivalent, laggards, bridge chromosomes, and micronuclei, were observed within the PMCs of rye wheat derivative lines. Fluorescence in-situ hybridisation unequivocally demonstrated rye introgression by green signals. Furthermore, the affirmation of rye introgression was corroborated by rye genome-specific molecular markers. Hence, Comprehensive methods unveil promising traits in rye-wheat lines, advancing wheat breeding in India. [ABSTRACT FROM AUTHOR]

Red solar-induced chlorophyll fluorescence (SIFB) is closely related to the photosynthetically active radiation absorbed by chlorophyll. The scattering and reabsorption of SIFB by the vegetation canopy significantly change the spectral intensity and shape of SIF, which affects the relationship between SIF and crop stress. To address this, we propose a method of modifying SIFB using SIF spectral shape characteristic parameters to reduce this influence. A red pseudokurtosis (PKB) parameter that can characterize spectral shape features was calculated using full-spectrum SIF data. On this basis, we analyzed the photosynthetic physiological mechanism of PKB and found that it significantly correlates with both the fraction of photosynthetically active radiation absorbed by chlorophyll(fPARchl) and the red SIF escape rate (fesc680); thus, it is closely related to the scattering and reabsorption of SIFB by the vegetation canopy. Consequently, we constructed an expression of PKB to modify SIFB. To evaluate the modified SIFB (MSIFB) in monitoring the severity of wheat stripe rust, we analyzed the correlations between SIFB, MSIFB, SIFB-VIs (a fusion of the vegetation index and SIFB), and MSIFB-VIs (a fusion of the vegetation index and MSIFB) with the severity level (SL), respectively. The results show that the correlation between MSIFB and the severity of wheat stripe rust increased by an average of 25.6% and at least 16.95% compared with that for SIFB. In addition, we constructed remote sensing monitoring models for wheat stripe rust using linear regression methods, with SIFB, MSIFB, SIFB-VIs, and MSIFB-VIs as independent variables. PKB significantly improves the accuracy and robustness of models based on SIFB and its fusion index SIFB-VIs in the constructed testing set. The R-value between the predicted SL and the measured SL of the remote sensing monitoring model for wheat stripe rust was established using MSIFB-VIs as the independent variable, and it was improved by an average of 39.49% compared with the model using SIFB-VIs. The RMSE was reduced by an average of 18.22%. Therefore, the SIFB modified by PKB can weaken the effects of chlorophyll reabsorption and canopy architecture on SIFB and improve the ability of SIFB to detect stress information. [ABSTRACT FROM AUTHOR]

The complex III of the mitochondrial respiration chain is an effective fungicidal target in plant pathogenic fungi. Especially the QoIs (FRAC Group 11 and 11A) fungicides cover a broad pathogen spectrum, that includes ascomycetes, basidiomycetes and oomycetes, by inhibiting the complex III at the outer binding site. Many of the target pathogens have developed resistance mediated by the target site mutation G143A. All fungicides that belong to Group 11 are affected by this mutation. Metyltetraprole has been recently developed, and it also binds at the Qo-site but is not affected by the G143A mutation and has therefore been classified differently (FRAC Group 11A). In experiments on solid medium with sequential exposure to complex III inhibitors, laboratory mutants of Zymoseptoria tritici with a resistance to metyltetraprole could be selected. Resistance to metyltetraprole was mediated by the target site mutation in the cytochrome B gene leading to the aa change Y132C. Metyltetraprole resistant isolates could only be generated from wildtype parents, but not from G143A parents. Further experiments used serial batch cultivations in liquid media with increasing fungicide concentrations. These were aimed to select double mutants that harboured both G143A and Y132C. Several different parental strains were treated with increasing concentrations of metyltetraprole, but no Y132C mutants were found when G143A parents were used. When Y132C mutants were used as the initial inoculum, and these were exposed to increasing concentrations of pyraclostrobin, the parental mutation was replaced by G143A within a few cycles; this could suggest that both mutations are incompatible. [ABSTRACT FROM AUTHOR]

Wheat production in cooler regions like the north-western Himalayas, is significantly impeded by devastating diseases, namely stripe rust (SR) and powdery mildew (PM). Genetic resistance against SR and PM loses effectiveness over time which underscores the importance of periodic disease screening. This study aims to assess resistance to SR and PM in 81 wheat genotypes across multiple locations over three years (2019–20, 2021–22 and 2022–23); and detect candidate genes (Yr5, Yr10 and Pm24) for resistance using respective molecular markers viz., SSR/STS primers (STS7/8, Xp3000 and Xgwm337). The resistance towards SR and PM under natural epiphytotic conditions was displayed by eight and twelve genotypes respectively, across all locations. Notably, four genotypes (DH 202, HPW 368, HPW 373 and DH 114) were found resistant to both diseases. The phenotypic disease reaction for SR and PM was further validated through molecular markers. Genotypes DH 202, DH208, DH 217, CIMMYT Entry no. 23 and VL 829 emerged as high yielding disease resistant genotypes. Agrometeorological parameters specifically, precipitation and relative humidity exhibited significant positive correlations with disease incidence, leading to reduced grain yields. Genotype and genotype by environment interaction (GGE) biplot identified stable genotypes with less disease incidence over locations. Additionally, Kukumseri may serve as the optimal test site for screening wheat germplasm against SR, while Palampur and Kukumseri could be ideal for PM screening. Genotypes exhibiting combined disease resistance to both SR and PM, alongwith superior agronomic traits, hold promise for immediate deployment as wheat varieties or as potential donors for breeding resistant cultivars. [ABSTRACT FROM AUTHOR]

Cultivar resistance is a major asset for the management of crop diseases and can play an important role in agroecological transition. However, the wide deployment of a reduced number of resistance genes can lead to a rapid adaptation of pathogen populations and to a loss of resistance efficiency. The objective of this study was to characterize and discuss different trajectories of adult plant ratings for resistance to yellow rust in French wheat cultivars between 1963 and 2018. Among 719 cultivars assessed for at least 2 years, 590 cultivars showed no variation in their resistance scores, despite a mean of 4.3 years and up to 33 years of assessment. A set of descriptive variables was computed in order to compare the evolution of resistance score of 129 cultivars that experienced resistance variation. We applied a principal component analysis and a hierarchical clustering on principal components to this subdataset to constitute clusters corresponding to different cultivar profiles. Clusters C1 and C2 had small resistance variations (1–2 points on a 1–9 scale); Cluster C3 had long assessment durations and several small drops in resistance score and could be associated with quantitative resistance erosion; Cluster C4 included major drops in resistance score (4–5 points), often associated with known breakdowns of major resistance genes. Cases of limited drops in resistance score as a known resistance gene was broken down suggest the presence of efficient adult plant resistance. We discuss the use of information extracted from this dataset and methods to further explore sources of resistance to yellow rust present in French cultivars. [ABSTRACT FROM AUTHOR]

Many factors are known to influence infection by cereal rusts, including environmental variables such at light, humidity and temperature, the topography of the leaf surface, as well as plant volatiles. However, few studies have aimed to link these factors. Previously, the quantity of light received by wheat seedlings prior to inoculation with Puccinia striiformis f. sp. tritici (Pst) urediniospores was shown to influence yellow rust infection efficiency. In this study we show that germination and the ability of germlings (germinated urediniospores) to enter stomata is enhanced on wheat seedlings subjected to high quantities of light pre‐inoculation with Pst urediniospores, while on seedlings exposed to a long dark period germination and infection were compromised. Using headspace collections and gas chromatography–mass spectrometry (GC–MS) analysis thereof, we link this effect of high light quantity to quantitative changes in the profile of volatile organic compounds (VOCs). We show that the VOCs within headspace collections from wheat seedlings exposed to high quantities of light were able to support greater levels of Pst urediniospore germination than the headspace collections from wheat seedlings exposed to a period of dark. In vitro analysis of individual VOCs identified compounds that enhanced Pst urediniospore germination. These VOCs included the sesquiterpene caryophyllene, the monoterpene α‐pinene, the fatty acid α‐linolenic acid, the organic alcohols 1‐hexanol, 3‐hexen‐1‐ol and 5‐hexen‐1‐ol, the aldehyde cis‐3‐hexenal and the ester hexyl acetate. [ABSTRACT FROM AUTHOR]

In this study, the compound 1-(4-(tert-butyl) phenyl)-3-hydroxy-2-methylpyridine-4 (1H) - one (hereinafter referred to as HAINU-19) was used as the active ingredient to prepare the microemulsion and determine its antifungal activity. First, through the screening solvents, co-solvents, and transparent, the formulation of 2.5% HAINU-19 microemulsion (mass fraction) was determined as follows: 2.5% HAINU-19, 15% ethanol, 10% cyclohexanone, 20% transparent (1601# : 500# : AC1810 = 3 : 3 : 1), with distilled water making up to 100%. All indicators meet national standards. The bioassay result of pot experiments showed that the protective and curative effects of 2.5% HAINU-19 microemulsion on wheat stripe rust were 100% at 1000, 500, and 250-fold dilutions, and curative effects were 76.67%, 81.00%, and 82.33%, respectively. The field trial results showed that the 2.5% HAINU19 microemulsion had a control efficacy of 86.13% on rice sheath blight at a 100-fold dilution and 71.24% at a 200-fold dilution. This study can provide an experimental basis and technical support for the development and application of the antifungal compound HAINU-19. [ABSTRACT FROM AUTHOR]

Puccinia striiformis f. sp. tritici (Pst) is a devastating obligate fungal biotroph that causes stripe rust disease in wheat in temperate and cooler regions, especially in Kazakhstan and Turkey. Chemical control of Pst is not a sustainable or economic strategy in these countries. Therefore, a suitable alternative to these pesticides, such as the development of resistant wheat cultivars, is needed. During the present investigation, a large set of wheat germplasms was characterized to determine the presence of the broad-spectrum resistance Yr15 gene using Y15K1_F2/uhw30_1R primers. This collection contained 360 accessions including 233 durum and bread wheat collected from KASIB cultivars and advanced lines that were developed by eight breeding programs within the Kazakhstan-Siberia Wheat Improvement Network and Turkey, and 127 wild emmer collected from Turkey only. The positive control was wild emmer IDs WEW 83-1, WEW 84-1, and WEW-85, which previously showed positive amplification of the Yr15 gene with these primers. Yr15, a broad-spectrum R-gene derived from wild emmer wheat encoding a putative kinase-pseudokinase protein designated as wheat tandem kinase 1, comprises a unique R-gene structure in wheat against the yellow (stripe) rust. None of the tested cultivated wheat germplasms from 174 durum wheat of the KASIB Network or 59 of bread wheat from Turkey showed positive amplification, but 89 of 127 (70.07%) wild Triticum dicoccoides showed positive amplification. The collection from the Karacadağ regions showed the maximum number of genotypes (46) with positive amplification for Yr15, followed by Eruh (10), Şırnak (5), Malazgir-Tunceli (4), Tunceli (4), Şırnak-Uludere yol (3), Tunceli-Pülümür (3), and Karacadağ/Kerteş Köyü –Siverek (3). We conclude that wild wheat cultivars are a good source of the Yr15 gene and that introgression of this gene into the cultivated wheat germplasm of both countries should be performed to manage the Pst pathogen in the future. [ABSTRACT FROM AUTHOR]

Wheat contributes one‐fifth of the global food supply with an estimated 29% of global production in low and lower‐middle income countries. As production expands across southern Asia, yields are often negatively impacted by outbreaks of fungal rust diseases. A wheat rust early warning and advisory system comprising surveillance, near real‐time disease risk forecasts and advisory dissemination has been established in two target countries in South Asia, including Nepal and Bangladesh. However, as wheat rust spores can be aerially transmitted over long distances, near real‐time estimates of disease incidence are required from sources of infection in neighbouring regions. To address this challenge, we developed and tested a novel algorithm to generate proxy observations of infection sources using online media reports in two neighbouring countries, India and Pakistan. Media sampling could provide an effective alternative where data from ground surveys are not readily available in near real‐time. Our results show that west Nepal was exposed to a substantial inoculum pressure from aerially dispersed stripe rust spores originating from India and Pakistan. There were no outbreaks of stripe rust disease in Bangladesh with only very low levels of cross‐border dispersion and generally unfavourable environmental conditions for infection. We further describe how proxy observations informed farmer decision‐making in near real‐time in Nepal and filled a knowledge gap in identifying early sources of infection for a major outbreak of stripe rust during 2020 in Nepal. Our results highlight the importance of international cooperation in mitigating transboundary plant pathogens. [ABSTRACT FROM AUTHOR]

Sphaerellopsis species are putative hyperparasites of rust fungi and may be promising biological control agents (BCA) of rust diseases. However, few detailed studies limit potential BCA development in Sphaerellopsis. Here, we explored the biogeography, host-specificity, and species diversity of Sphaerellopsis and examined the early infection stage of one species, S. macroconidialis, to infer its trophic status. We randomly screened 5,621 rust specimens spanning 99 genera at the Arthur Fungarium for the presence of Sphaerellopsis. We identified 199 rust specimens infected with Sphaerellopsis species on which we conducted morphological and multi-locus phylogenetic analyses. Five Sphaerellopsis species were recovered, infecting a total of 122 rust species in 18 genera from 34 countries. Sphaerellopsis melampsorinearum sp. nov. is described as a new species based on molecular phylogenetic data and morphological features of the sexual and asexual morphs. Sphaerellopsis paraphysata was the most commonly encountered species, found on 77 rust specimens, followed by Sphaerellopsis macroconidialis on 56 and S. melampsorinearum on 55 examined specimens. The type species, Sphaerellopsis filum, was found on 12 rust specimens and Sphaerellopsis hakeae on a single specimen. We also recovered and documented for the first time, the sexual morph of S. macroconidialis, from a specimen collected in Brazil. Our data indicate that Sphaerellopsis species are not host specific and furthermore that most species are cosmopolitan in distribution. However, S. paraphysata is more abundant in the tropics, and S. hakeae may be restricted to Australia. Finally, we confirm the mycoparasitic strategy of S. macroconidialis through in-vitro interaction tests with the urediniospores of Puccinia polysora. Shortly after germination, hyphae of S. macroconidialis began growing along the germ tubes of P. polysora and coiling around them. After 12 days of co-cultivation, turgor loss was evident in the germ tubes of P. polysora, and appressorium-like structures had formed on urediniospores. The interaction studies indicate that Sphaerellopsis species may be more effective as a BCA during the initial stages of rust establishment. [ABSTRACT FROM AUTHOR]

Wheat is one of the most significant food security crops in Ethiopia. However, the production and productivity of wheat is far below its potential due to many challenges. Wheat disease epidemics, typified by wheat rusts, are among the most important challenges, causing large‐scale production losses that put farmers' income and food security at risk. We analysed and presented the long‐term and comprehensive wheat rust surveillance results to better understand the past rust disease occurrences, ultimately contributing to future wheat production and rust control strategies. A total of 1140 wheat fields have been surveyed from 2009 to 2021 throughout four administrative zones of the North Western Amhara region. We identified spatial and temporal trends in the distribution and status of wheat stem rust (Sr), yellow rust (Yr) and leaf rust (Lr) using a combination of different statistical tools and data‐analysis methods. The results of the study indicated that 52.5%, 11.3% and 3.4% of the wheat fields were infected with yellow, stem and leaf rust, respectively. Even so, the distribution and intensity of wheat rust disease vary across locations, elevations and cultivated varieties. The associations between altitude and disease prevalence show a linear correlation. We also identified hotspots of yellow and stem rust, which will be used by the country's wheat rust disease early warning system. In order to reverse low varietal diversification in the farmer's field, it is necessary to work with all stakeholders involved in the wheat production sector in a better synergy. [ABSTRACT FROM AUTHOR]

An attempt was undertaken to comprehend how phenotypic markers, leaf tip necrosis (LTN), and pseudo black chaff (PBC), are associated with pleiotropic resistance genes in wheat (Triticum spp.). Pleiotropic resistance to stripe rust (Puccinia striiformis f. sp. tritici), leaf rust (P. triticina), stem rust (P. graminis f. sp. tritici) and powdery mildew (Blumeria graminis f. sp. tritici) was evaluated in 57 Egyptian spring wheat cultivars at seedling stage in greenhouse and at adult plant stage in field during 2021/22 and 2022/23. At seedling stage, pleiotropic resistance rated moderately resistance (MR) was observed in five cultivars, Misr-3 (all three rusts), Misr-4 (stripe rust, leaf rust, powdery mildew), Giza-168 (leaf rust, stem rust, powdery mildew), Sakha-94 and Sids-13 (leaf rust, stem rust). At adult plant stage, Misr-4 outperformed all other evaluated cultivars, exhibiting a high level of pleiotropic adult plant resistance (PAPR) against all diseases investigated. High levels of PAPR were also noticed against the three rusts in nine cultivars, Misr-3, Sakha-93, Sakha-94, Sakha-95, Giza-156, Giza-168, Giza-171, Gemmeiza-10 and Sids-13, and moderate levels against powdery mildew in Misr-3, Sakha-95, Giza-156. Four PAPR genes were characterized in cultivars based on phenotypic and molecular markers. Phenotypic markers (LTN and PBC) were observed in 23 cultivars. Molecular marker csLV34 indicated the presence of Lr34/Yr18/Sr57/Pm38/Ltn1 in six cultivars, whilst marker Xwmc44 indicated that Lr46/Yr29/Sr58/Pm39/Ltn2 was present in five cultivars. Marker Xcfd71 indicated the presence of Lr67/Yr46/Sr55/Pm46/Ltn3 in 19 cultivars. Gene Sr2/Yr30/Lr27/Pbc was identified with marker csSr2 in three cultivars. A complete association between LTN and molecular markers was recorded, while a strong association (r = 0.73) was recorded between PBC and molecular markers. Findings demonstrated the reliability of phenotypic markers in predicting pleiotropic resistance in wheat, which would facilitate marker-assisted selection in breeding programs. [ABSTRACT FROM AUTHOR]

Yellow rust caused by Puccinia striiformis f. sp. tritici (Pst) is one of the most important wheat diseases. Adult plant resistance (APR) genes have gained the attention of breeders and scientists because they show higher durability compared to major race-specific genes. Here, we determined the effect of the APR genes Yr18, Yr29 and Yr46 in North-West European field conditions against three currently important Pst races. We used three pairs of sibling wheat lines developed at CIMMYT, which consisted of a line with the functional resistance gene and a sibling with its non-functional allele. All APR genes showed significant effects against the Pst races Warrior and Warrior (–), and a race of the highly aggressive strain PstS2. The effects of Yr18 and Yr46 were especially substantial in slowing down disease progress. This effect was apparent in both Denmark, where susceptible controls reached 100 percent disease severity, and in United Kingdom where disease pressure was lower. We further validated field results by quantifying fungal biomass in leaf samples and by micro-phenotyping of samples collected during early disease development. Microscopic image analyses using deep learning allowed us to quantify separately the APR effects on leaf colonization and pustule formation. Our results show that the three APR genes can be used in breeding yellow rust resistant varieties of spring wheat to be grown in North-West European conditions, and that deep learning image analysis can be an effective method to quantify effects of APR on colonisation and pustule formation. [ABSTRACT FROM AUTHOR]

SUMMARY Plant fungal parasites manipulate host metabolism to support their own survival. Among the many central metabolic pathways altered during infection, the glyoxylate cycle is frequently upregulated in both fungi and their host plants. Here, we examined the response of the glyoxylate cycle in bread wheat (Triticum aestivum) to infection by the obligate biotrophic fungal pathogen Puccinia striiformis f. sp. tritici (Pst). Gene expression analysis revealed that wheat genes encoding the two unique enzymes of the glyoxylate cycle, isocitrate lyase (TaICL) and malate synthase, diverged in their expression between susceptible and resistant Pst interactions. Focusing on TaICL, we determined that the TaICL B homoeolog is specifically upregulated during early stages of a successful Pst infection. Furthermore, disruption of the B homoeolog alone was sufficient to significantly perturb Pst disease progression. Indeed, Pst infection of the TaICL‐B disruption mutant (TaICL‐BY400*) was inhibited early during initial penetration, with the TaICL‐BY400* line also accumulating high levels of malic acid, citric acid, and aconitic acid. Exogenous application of malic acid or aconitic acid also suppressed Pst infection, with trans‐aconitic acid treatment having the most pronounced effect by decreasing fungal biomass 15‐fold. Thus, enhanced TaICL‐B expression during Pst infection may lower accumulation of malic acid and aconitic acid to promote Pst proliferation. As exogenous application of aconitic acid and malic acid has previously been shown to inhibit other critical pests and pathogens, we propose TaICL as a potential target for disruption in resistance breeding that could have wide‐reaching protective benefits for wheat and beyond. [ABSTRACT FROM AUTHOR]

Actin filaments and their associated actin-binding proteins play key roles in plant innate immune signaling. CAP1, or cyclase-associated protein 1, is an important regulatory factor of the actin cytoskeleton-associated signaling network and was hypothesized here to be involved in resistance against wheat stripe rust because TaCAPl expression was upregulated in response to Puccinia striiformis f. sp. tritici (Pst). Downregulation of TaCAPl expression led to decreased resistance against P.vt, in contrast to increased resistance upon TaCAPl overexpressing, as demonstrated by the changes of phenotypes and hyphal growth. We found increased expression of pathogenesis-responsive or relative related genes and disease grade changed in 'TaCAPl overexpressing plants. Our results also showed TaCAP 1 -regulated host resistance to Pst by inducing the production and accumulation of reactive oxygen species and mediating the salicylic acid signaling pathway. Additionally, TaCAPl interacted with chlorophyll a/b- bindtng proteins TaLHCBU and TaLHCBI.4, also known as the lightharvesting chlorophyll-protein complex II subunit B. which belong to the light-harvesting complex II protein family. Silencing of two TaLHCBl genes showed higher susceptibility to Pst, which reduced wheat resistance against Pst. Therefore, the data presented herein further illuminate our understanding that TaCAPl interacts with TaLHCBls and functions as a positive regulator of wheat resistance against stripe rust. [ABSTRACT FROM AUTHOR]

Protein phosphorylation plays an important role in immune signaling transduction in plant resistance to pathogens. Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), severely devastates wheat production. Nonetheless, the molecular mechanism of wheat resistance to stripe rust remains limited. In this study, quantitative phosphoproteomics was employed to investigate the protein phosphorylation changes in wheat challenged by Pst. A total of 1537 and 2470 differentially accumulated phosphoproteins (DAPs) were identified from four early infection stage (6, 12, 18 and 24 h post-inoculation) in incompatible and compatible wheat-Pst interactions respectively. KEGG analysis revealed that Oxidative Phosphorylation, Phosphatidylinositol Signaling, and MAPK signaling processes are distinctively enriched in incompatible interaction, while Biosynthesis of secondary metabolites and RNA degradation process were significantly enriched in compatible interactions. In particular, abundant changes in phosphorylation levels of chloroplast proteins were identified, suggesting the regulatory role of photosynthesis in wheat-Pst interaction, which is further emphasized by protein-protein interaction (PPI) network analysis. Motif-x analysis identified [xxxxSPxxxx] motif, likely phosphorylation sites for defensive response-related kinases, and a new [xxxxSSxxxx] motif significantly enriched in incompatible interaction. The results shed light on the early phosphorylation events contributing to wheat resistance against Pst. Moreover, our study demonstrated that the phosphorylation levels of Nucleoside diphosphate kinase TaNAPK1 are upregulated at 12 hpi with CYR23 and at 24 hpi with CYR31. Transient silencing of TaNAPK1 was able to attenuate wheat resistance to CYR23 and CYR31. Our study provides new insights into the mechanisms underlying Pst-wheat interactions and may provide database to find potential targets for the development of new resistant varieties. [ABSTRACT FROM AUTHOR]

Stripe rust (Puccinia striiformis West. f.sp. tritici, Pst) is a destructive disease that seriously threatens wheat production globally. Exploring novel resistance genes for use in wheat breeding is an urgent need, as continuous Pst evolution frequently leads to a breakdown of host resistance. Here, we identified a set of wheat–Dasypyrum villosum 01I139 (V#6) disomic introgression lines for the purpose of determining their responses to a mixture of Pst isolates CYR32, CYR33 and CYR34 at both seedling and adult-plant stages. The results showed that all introgression lines exhibited high susceptibility at the seedling stage, with infection-type (IT) scores in the range of 6–8, whereas, for chromosomes 5V#6 and 7V#6, disomic addition lines NAU5V#6-1 and NAU7V#6-1 displayed high resistance at the adult-plant stage, indicating that adult-plant resistance (APR) genes were located on them. Further, in order to transfer the stripe-rust resistance on chromosome 7V#6, four new wheat–D. villosum introgression lines were identified, by the use of molecular cytogenetic approaches, from the self-pollinated seeds of 7D and 7V#6, in double monosomic line NAU7V#6-2. Among them, NAU7V#6-3 and NAU7V#6-4 were t7V#6L and t7V#6S monosomic addition lines, and NAU7V#6-5 and NAU7V#6-6 were homozygous T7DS·7V#6L and T7DL·7V#6S whole-arm translocation lines. Stripe-rust tests and genetic analyses of chromosome 7V#6 introgression lines revealed a dominant APR gene designated as Yr7VS on the chromosome arm 7V#6S. Comparison with the homozygous T7DL·7V#6S translocation line and the recurrent parent NAU0686 showed no significant differences in yield-related traits. Thus, T7DL·7V#6S whole-arm translocation with the APR gene Yr7VS provided a valuable germplasm for breeding for resistance. [ABSTRACT FROM AUTHOR]

The development and deployment of diverse resistance sources in novel wheat cultivars underpin the durable control of stripe rust. The objectives of this study were to identify quantitative trait loci (QTL) associated with stripe rust resistance in the Chinese wheat breeding line YN1813 and to provide wheat breeders with original genes with potentially durable resistance. A total of 306 F7:8 recombinant inbred lines (RIL), derived from a cross between YN1813 (infection type 0–3 and disease severity 1–36%) and the moderately susceptible landrace Chinese Spring (IT 7–9 and DS 41–65%), were assessed for stripe rust disease severity in the field at Qingshui in Gansu and Pixian in Sichuan in 2020 and 2021 following inoculation with a mixture of the currently predominant Pst races. The parents and RIL were genotyped using the Wheat 55K single-nucleotide polymorphism (SNP) array. The total length of the constructed genetic linkage map was 3896.30 cm, with an average interval of 1.30 cm between adjacent markers. Two major QTL were identified on chromosome 7B and 7D across all tested environments. QYr.hau-7B was mapped to a 2.26 cm interval between the SNP markers AX-110908486–AX-89658728–AX-109489314 on chromosome 7B, explaining 0.9% to 16.9% of the phenotypic variation. QYr.hau-7D was positioned in a 0.67 cm interval flanked by the SNP markers AX-111654594 and AX-89378255, explaining 0.4% to 21.4% of the phenotypic variation. The QTL on 7D likely correspond to the previously known gene Yr18, whereas QYr.hau-7B was presumed to be a novel gene adjacent to YrZH84 or the core part of YrZH84. SNP markers closely linked with QYr.hau-7B were converted to allele-specific quantitative PCR-based genotyping assay (AQP) markers and validated in a panel of 712 wheat accessions. The group possessing a positive allele (TT) of AQP_AX-89658728 significantly (p < 0.05) decreased the IT by 45.8% and the DS by 63.2%. QYr.hau-7B and its markers could be useful in breeding programs to improve the level and durability of stripe rust resistance. [ABSTRACT FROM AUTHOR]

Abstract Stripe rust, induced by Puccinia striiformis f. sp. tritici, is the most harmful and prevalent disease in temperate regions worldwide, affecting wheat production areas globally. An effective strategy for controlling the disease involves enhancing genetic resistance against stripe rust, achieved through Egyptian breeding efforts not previously conducted on wheat genotypes. The resistance level to stripe rust in thirty-eight wheat genotypes was assessed using marker-assisted selection methods. The investigation suggests that wheat breeding programs can utilize slow-rusting Yr genes, which are effective resistance genes, to develop novel genotypes with stripe rust resistance through marker-assisted breeding. Based on the four disease responses of the wheat genotypes under investigation, the results categorized the genotypes into three groups. The first group included resistant genotypes, the second group exhibited a slow-rusting character with the lowest disease symptom rates, and the last group displayed the highest disease characteristics rates throughout the three seasons, comprising fast-rusting genotypes. The rust-resistant genes identified were Yr5, Yr9, Yr10, Yr15, Yr17, Yr18, Yr26, Yr29, Yr30, and Yr36. Genes Yr26, Yr30, and Yr36 were present in all genotypes. Genotypes Misr3, Misr4, Giza168, Giza167, Giza170, Giza171, Gemmeiza9, and Gemmeiza10 carried the Yr9 gene. Only one genotype, Sids13, was found to have the Yr17 gene. Genes Yr18 and Yr29 were identified in Sids14, Giza168, Giza170, Gemmeiza9, and Gemmeiza10. However, none of the wheat genotypes showed the presence of Yr5, Yr10, or Yr15. Several backcrossing generations were conducted to introduce the Yr5 and Yr10 genes into susceptible genotypes (Misr1, Misr2, and Gemmeiza11). These genotypes are cultivated globally and are known for producing high-quality flour, making them of great importance to farmers. The study demonstrates significant potential for enhancing wheat genotypes for stripe rust resistance and increased production.

Abstract Wheat is an essential food commodity cultivated throughout the world. However, this crop faces continuous threats from fungal pathogens, leaf rust (LR) and stripe rust (YR). To continue feeding the growing population, these major destructors of wheat must be effectively countered by enhancing the genetic diversity of cultivated germplasm. In this study, an introgression line with hexaploid background (IL sp3603 ) carrying resistance against Pt pathotypes 77−5 (121R63-1), 77−9 (121R60-1) and Pst pathotypes 46S119 (46E159), 110S119 (110E159), 238S119 (238E159) was developed from donor wheat wild progenitor, Aegilops speltoides acc pau 3603. To understand the genetic basis of resistance and map these genes (named Lr sp3603 and Yr sp3603 ), inheritance studies were carried out in F6 and F7 mapping population, developed by crossing IL sp3603 with LR and YR susceptible cultivar WL711, which revealed a monogenic (single gene) inheritance pattern for each of these traits. Bulk segregant analysis combined with 35 K Axiom SNP array genotyping mapped both genes as separate entities on the short arm of chromosome 6B. A genetic linkage map, comprising five markers, 1 SNP, 1 PLUG and three gene based SSRs, covered a genetic distance of 12.65 cM. Lr sp3603 was flanked by markers Tag-SSR14 (located proximally at 2.42 cM) and SNP AX-94542331 (at 3.28 cM) while Yr sp3603 was mapped at one end closest to AX-94542331 at 6.62 cM distance. Functional annotation of Lr sp3603 target region (∼ 1 Mbp) revealed 10 gene IDs associated with disease resistance mechanisms including three encoding typical R gene domains.

Stripe Rust, caused by Puccinia striiformis Westend f. sp. tritici , is an important fungal disease of wheat worldwide. In this study, 41 wheat genotypes from various institutes across India were screened for adult plant resistance (APR) in field trials, and the presence of effective stripe rust resistance genes was evaluated in the laboratory using ten molecular markers.The bread wheat variety Agra local was used as a susceptible control. Molecular characterization studies revealed that the gene Yr 2 was found in 29 entries, Yr5 in 15 entries, Yr9 in 7 entries, Yr10 in 18 entries, Yr15 in 18 entries, Yr17 in 12 entries, Yr18 in 29 entries, Yr36 in 21 entries, Yr40 in 31 entries while Yr65 was absent in all the entries. The genotypes PBW780 and High Rainfall Wheat Screening Nursery (HRWSN) line 2105 had seven Yr genes conferring resistant phenotypes, suggesting that these were excellent sources of effectual stripe rust resistance. The coefficient of infection showed adequate genotypic variations for rust severity, 41 genotypes showed year-specific responses, suggesting strong G × E interactions.

Abstract Wheat is one of the major food crops worldwide. Stripe rust can cause a great loss of wheat yield, especially when the disease is prevalent. Chemical control not only causes the loss of resistance to stripe rust but also has a serious impact on the human body and environment. Therefore, the most economical measure to control wheat stripe rust is to cultivate resistant varieties. Rapid variation of stripe rust races often leads to rapid "loss" of resistance to stripe rust disease; therefore, breeders and researchers have to continuously explore new stripe rust resistance genes to provide new resistance sources for the rapid variation of stripe rust races. Previous studies have confirmed that PI660076, a spring wheat line, showed stripe rust resistance under natural conditions at the adult stage, which has great value in breeding programs. In this study, a recombinant inbred lines (RIL) population was constructed by crossing the wheat line PI660076 with the stripe rust-susceptible line AvS. Genotyping of the population was performed using a wheat 15 K SNP array. Three QTLs were identified using phenotypic data over four years across three environments. The resistance type of each QTL was determined by inoculating the RIL lines with single and homozygous QTL during the seedling and adult stages under controlled conditions. The all-stage resistance (ASR) QTL, QYr076.jaas-2A (flanked by SNP marker AX-11048464 and Kompetitive Allele-Specific PCR (KASP) marker KASP_4940) explained 7.13–16.58% and 6.95–7.25% of infection type (IT) and disease severity (DS), respectively. The adult-plant resistance (APR) resistance QTL, QYr076.jaas-4D.1 (flanked by KASP marker KASP_0795 and SNP marker AX-111567243,) explained 6.85–12.70% and 7.94–17.26% of IT and DS, respectively. The APR resistance QTL, QYr076.jaas-4D.2 flanked by KASP markers KASP_9130 and KASP_6535, explained 7.97–39.19% and 8.77–20.55% of the phenotypic variation in IT and DS, respectively. All the three QTLs are likely to be new. The obtained results lay a foundation for further utilization of the stripe rust-resistant line PI660076, as well as for fine mapping and molecular marker-assisted selection breeding. Graphical Abstract

Abstract Background Wheat rusts are important biotic stresses, development of rust resistant cultivars through molecular approaches is both economical and sustainable. Extensive phenotyping of large mapping populations under diverse production conditions and high-density genotyping would be the ideal strategy to identify major genomic regions for rust resistance in wheat. The genome-wide association study (GWAS) population of 280 genotypes was genotyped using a 35 K Axiom single nucleotide polymorphism (SNP) array and phenotyped at eight, 10, and, 10 environments, respectively for stem/black rust (SR), stripe/yellow rust (YR), and leaf/brown rust (LR). Results Forty-one Bonferroni corrected marker-trait associations (MTAs) were identified, including 17 for SR and 24 for YR. Ten stable MTAs and their best combinations were also identified. For YR, AX-94990952 on 1A + AX-95203560 on 4A + AX-94723806 on 3D + AX-95172478 on 1A showed the best combination with an average co-efficient of infection (ACI) score of 1.36. Similarly, for SR, AX-94883961 on 7B + AX-94843704 on 1B and AX-94883961 on 7B + AX-94580041 on 3D + AX-94843704 on 1B showed the best combination with an ACI score of around 9.0. The genotype PBW827 have the best MTA combinations for both YR and SR resistance. In silico study identifies key prospective candidate genes that are located within MTA regions. Further, the expression analysis revealed that 18 transcripts were upregulated to the tune of more than 1.5 folds including 19.36 folds (TraesCS3D02G519600) and 7.23 folds (TraesCS2D02G038900) under stress conditions compared to the control conditions. Furthermore, highly expressed genes in silico under stress conditions were analyzed to find out the potential links to the rust phenotype, and all four genes were found to be associated with the rust phenotype. Conclusion The identified novel MTAs, particularly stable and highly expressed MTAs are valuable for further validation and subsequent application in wheat rust resistance breeding. The genotypes with favorable MTA combinations can be used as prospective donors to develop elite cultivars with YR and SR resistance.

Abstract Stripe rust of wheat, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most important diseases of wheat worldwide. Identification of new and elite Pst-resistance loci or genes has the potential to enhance overall resistance to this pathogen. Here, we conducted an integrated genome-wide association study (GWAS) and transcriptomic analysis to screen for loci associated with resistance to stripe rust in 335 accessions from Yunnan, including 311 landraces and 24 cultivars. Based on the environmental phenotype, we identified 113 protein kinases significantly associated with Pst resistance using mixed linear model (MLM) and generalized linear model (GLM) models. Transcriptomic analysis revealed that 52 of 113 protein kinases identified by GWAS were up and down regulated in response to Pst infection. Among these genes, a total of 15 receptor kinase genes were identified associated with Pst resistance. 11 candidate genes were newly discovered in Yunnan wheat germplasm. Our results revealed that resistance alleles to stripe rust were accumulated in Yunnan wheat germplasm, implying direct or indirect selection for improving stripe rust resistance in elite wheat breeding programs.

Abstract Triticum militinae (2n = 4X = 28, AtAtGG), belonging to the secondary gene pool of wheat, is known to carry resistance to many diseases. Though some disease resistance genes were reported from T. timopheevii, the closest wild relative of T. militinae, there are no reports from T. militinae. Twenty-one T. militinae Derivatives (TMD lines) developed at the Division of Genetics, IARI, New Delhi, were evaluated for leaf and stripe rusts at seedling and adult plant stages. Eight TMD lines (6–4, 6–5, 11–6, 12–4, 12–8, 12–12, 13–7 and 13–9) showed seedling resistance to both leaf and stripe rusts while six TMD lines (7–5, 7–6, 11–5, 13–1, 13–3 and 13–4) showed seedling resistance to leaf rust but adult plant resistance to stripe rust and three TMD lines (9–1, 9–2 and 15) showed seedling resistance to leaf rust but susceptibility to stripe rust. Three TMD lines (2–7, 2–8 and 6–1) with adult plant resistance to leaf and stripe rusts were found to carry the known gene Lr34/Yr18. Ten TMD lines (7–5, 7–6, 9–1, 9–2, 11–5, 11–6, 12–12, 12–4, 12–8, and 15) with seedling resistance to leaf rust, showing absence of known genes Lr18 and Lr50 with linked markers requires further confirmation by the test of allelism studies. As not a single stripe rust resistance gene has been reported from T. militinae or its close relative T. timpopheevii, all the 8 TMD lines (6–4, 6–5, 11–6,12–4, 12–8, 12–12, 13–7 and 13–9) identified of carrying seedling resistance to stripe rust and 3 TMD lines (13–1, 13–3 and 13–4) identified of carrying adult plant resistance to stripe rust are expected to carry unknown genes. Also, all the TMD lines were found to be cytologically stable and thus can be used in inheritance and mapping studies.

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a serious disease that affects wheat worldwide. There is a great need to develop cultivars with combinations of all-stage resistance (ASR) and adult-plant resistance (APR) genes for sustainable control of the disease. QYrsv.swust-1BL in the Italian durum wheat (Triticum turgidum ssp. durum) cultivar Svevo is effective against Pst races in China and Israel, and the gene has been previously mapped to the long arm of chromosome 1B. The gene is flanked by SNP (single nucleotide polymorphism) markers IWB5732 and IWB4839 (0.75 cM). In the present study, we used high-density 660K SNP array genotyping and the phenotypes of 137 recombinant inbred lines (RILs) to fine map the QYrsv.swust-1BL locus within a 1.066 Mb region in durum wheat Svevo (RefSeq Rel. 1.0) on chromosome arm 1BL. The identified 1.066 Mb region overlaps with a previously described map of Yr29/QYr.ucw-1BL, a stripe rust APR gene. Twenty-five candidate genes for QYrsv.swut-1BL were identified through comparing polymorphic genes within the 1.066 Mb region in the resistant cultivar. SNP markers were selected and converted to Kompetitive allele-specific polymerase chain reaction (KASP) markers. Five KASP markers based on SNP were validated in a F2 and F2:3 breeding population, providing further compelling evidence for the significant effects of QYrsv.swut-1BL. These markers should be useful in marker-assisted selection for incorporating Yr29/QYrsv.swust-1BL into new durum and common wheat cultivars for resistance to stripe rust. [ABSTRACT FROM AUTHOR]

AbstractWheat stripe rust disease caused by Puccinia striiformis f. sp. tritici (Pst) seriously affects wheat yield. We studied the fungal infection process and host response between wheat ‘AvS’ and its near-isogenic line ‘AvS+Yr10’, which formed compatible and incompatible interactions, respectively, when challenged with Pst race CYR32. The difference in reactive oxygen species (ROS) accumulation between the compatible and incompatible interactions was analyzed by measuring the hydrogen peroxide (H2O2) concentration and observing H2O2 production. Hydrogen peroxide concentrations, H2O2 accumulation areas, necrotic areas and expression of several resistance-related genes in the AvS+Yr10/CYR32 interaction were higher than those in the AvS/CYR32 interaction during the entire infection process. Pst growth was effectively inhibited in the AvS+Yr10 all-stage resistant wheat line. Thus, ROS accumulation is crucial in wheat defence against pathogens. [ABSTRACT FROM AUTHOR]

Wheat is one of the major food crops worldwide. Stripe rust can cause a great loss of wheat yield, especially when the disease is prevalent. Chemical control not only causes the loss of resistance to stripe rust but also has a serious impact on the human body and environment. Therefore, the most economical measure to control wheat stripe rust is to cultivate resistant varieties. Rapid variation of stripe rust races often leads to rapid "loss" of resistance to stripe rust disease; therefore, breeders and researchers have to continuously explore new stripe rust resistance genes to provide new resistance sources for the rapid variation of stripe rust races. Previous studies have confirmed that PI660076, a spring wheat line, showed stripe rust resistance under natural conditions at the adult stage, which has great value in breeding programs. In this study, a recombinant inbred lines (RIL) population was constructed by crossing the wheat line PI660076 with the stripe rust-susceptible line AvS. Genotyping of the population was performed using a wheat 15 K SNP array. Three QTLs were identified using phenotypic data over four years across three environments. The resistance type of each QTL was determined by inoculating the RIL lines with single and homozygous QTL during the seedling and adult stages under controlled conditions. The all-stage resistance (ASR) QTL, QYr076.jaas-2A (flanked by SNP marker AX-11048464 and Kompetitive Allele-Specific PCR (KASP) marker KASP_4940) explained 7.13–16.58% and 6.95–7.25% of infection type (IT) and disease severity (DS), respectively. The adult-plant resistance (APR) resistance QTL, QYr076.jaas-4D.1 (flanked by KASP marker KASP_0795 and SNP marker AX-111567243,) explained 6.85–12.70% and 7.94–17.26% of IT and DS, respectively. The APR resistance QTL, QYr076.jaas-4D.2 flanked by KASP markers KASP_9130 and KASP_6535, explained 7.97–39.19% and 8.77–20.55% of the phenotypic variation in IT and DS, respectively. All the three QTLs are likely to be new. The obtained results lay a foundation for further utilization of the stripe rust-resistant line PI660076, as well as for fine mapping and molecular marker-assisted selection breeding. [ABSTRACT FROM AUTHOR]

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a devastating fungal disease, leading to huge yield losses in wheat production. Identification of resistance genes and closely linked molecular markers can greatly facilitate breeding resistant wheat cultivars. Shaannong69 conferred high resistance to stripe rust both at the seedling and adult-plant stages. The Pst race CYR31 was used to infect Shaannong69, Huixianhong, F1 and F2 plants and F2:3 lines at the seedling stage in the greenhouse. Genetic analysis identified a single dominant gene, designated as YrSN69, conferring resistance to Pst race CYR31 in Shaannong69. Seventy-four of 176 SNPs with the absolute value of ∆SNP-index more than 0.85 were identified in 753.33–766.18 Mb on chromosome 2BL based on bulked segregant RNA sequencing. Fifteen kompetitive allele-specific PCR markers were developed to genotype susceptible F2 plants derived from the Shaannong69/Huixianhong cross. YrSN69 was mapped on chromosome arm 2BL in a 2.0 cM genetic interval, with genetic distances of 0.2 cM and 1.8 cM to markers 2BC17 and 2BA20, respectively, corresponding to a 3.16 Mb physical region based on the IWGSC RefSeq v1.1 with 44 high-confidence annotated genes. The YrSN69 is likely to be a new allele of Yr72 in comparison with known Yr genes on chromosome 2BL. These results provide a solid foundation for map-based cloning of YrSN69 and marker-assisted selection for pyramiding stripe rust resistance genes. [ABSTRACT FROM AUTHOR]

The ATP-binding cassette (ABC) transporter family is one of the largest protein families in plants and plays an essential role in addressing biotic and abiotic stresses. Wheat, a vital global grain crop, faces multifaceted safety challenges, primarily from fungal diseases like stripe rust and powdery mildew. In the present study, we identified the whole genome of the wheat ABC family, and 463 nonredundant ABC genes were identified. The ABC family can be divided into nine evolutionary branches and eight subfamilies based on phylogenetic tree analysis. This paper delved deeper into characterizing the gene structure, promoter region, and gene expression within the TaABC family. Segmental duplication was the main reason for the expansion of the TaABC genes. Ka/Ks analysis suggested that most TaABC genes were intensely purified and selected. The collinear analysis of TaABC and other species showed that the ABC genes were conserved in evolution. RNA-seq data and qPCR data from wheat infected with powdery mildew or stripe rust showed that most TaABC genes were induced to change expression. The candidate genes TaABCB15-3B and TaABCG38 exhibited responsiveness to powdery mildew in resistant/susceptible wheat, while remaining unresponsive to stripe rust. Our findings serve as a valuable reference for gaining a deeper understanding of the function and evolution of TaABCs, aiding in the identification of enduring disease resistance genes within the TaABCs of wheat. [ABSTRACT FROM AUTHOR]

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the main diseases of wheat worldwide. Mianyang of Sichuan province in Southwest China is one of main regions for winter Pst inoculum production and spring epidemic and provides urediniospores for infecting wheat in the surrounding regions. Understanding the urediniospore dynamics is important to predict and manage stripe rust. In this study, spore trapping coupled with a TaqMan real-time quantitative PCR method was used to monitor airborne Pst urediniospores from December 2019 to December 2022 in Mianyang. Weather conditions (temperature, relative humidity, daily sunshine duration, and precipitation) were collected for the same period. These data were used to study the relationship of airborne urediniospore density with climatic conditions. The results showed that Pst urediniospores were captured all year round, and the annual peak of urediniospore densities occurred in the period from March to April in which the urediniospores accounted for the largest proportion of the annual total urediniospores. The density of urediniospores in the period of March to April was linearly related to the average sunshine duration of 20 days and average temperature of 15 days prior to the final day of a 7-day trapping period. This relationship needs to be tested in other regions where Pst can sporulate during the winter before it can be integrated with Pst infection conditions to predict rust development. [ABSTRACT FROM AUTHOR]

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a devastating disease in wheat worldwide. Discovering and characterizing new resistance genes/QTL is crucial for wheat breeding programs. In this study, we fine-mapped and characterized a stripe rust resistance gene, YRAYH, on chromosome arm 5BL in the Chinese wheat landrace Anyuehong (AYH). Evaluations of stripe rust response to prevalent Chinese Pst races in near-isogenic lines derived from a cross of Anyuehong and Taichung 29 showed that YrAYH conferred a high level of resistance at all growth stages. Fine mapping using a large segregating population of 9748 plants, narrowed the YRAYH locus to a 3.7 Mb interval on chromosome arm 5BL that included 61 annotated genes. Transcriptome analysis of two NIL pairs identified 64 upregulated differentially expressed genes (DEGs) in the resistant NILs (NILs-R). Annotations indicated that many of these genes have roles in plant disease resistance pathways. Through a combined approach of fine-mapping and transcriptome sequencing, we identified a serine/threonine-protein kinase SRPK as a candidate gene underlying YrAYH. A unique 25 bp insertion was identified in the NILs-R compared to the NILs-S and previously published wheat genomes. An InDel marker was developed and co-segregated with YrAYH. Agronomic trait evaluation of the NILs suggested that YrAYH not only reduces the impact of stripe rust but was also associated with a gene that increases plant height and spike length. [ABSTRACT FROM AUTHOR]

Two new species of Polyporales, Cerrena caulinicystidiata and Polyporus minutissimus, are illustrated and described on the basis of morphological studies and phylogenetic analyses from southern China and Vietnam. C. caulinicystidiata is characterized by annual, resupinate, sometimes effused-reflexed basidiocarps, greyish orange to brownish orange pore surface, irregular pores (3–8 per mm), a trimitic hyphal system, pyriform to ventricose cystidia, and subglobose basidiospores 3.2–4.5 × 2.8–3.5 µm in size. P. minutissimus is characterized by annual, solitary, fan-shaped with a depressed center or infundibuliform basidiocarps, obvious black stipe, cream to buff yellow pileal surface with glabrous, occasionally zonate and radially aligned stripes, angular pores (6–9 per mm), a dimitic hyphal system, and cylindrical basidiospores, 5–9.2 × 2.2–4 μm. Detailed descriptions and illustrations of the two new species are provided. The differences between the two new species and their morphologically similar and phylogenetically related species are discussed. [ABSTRACT FROM AUTHOR]

In this study, we evaluated the stripe rust resistance type and estimated the published resistance genes in 13 Roegneria species including 29 materials. Afterward, we conducted artificial crosses and investigated the morphology characters, genome constitution, and stripe rust resistance of the intergeneric hybrid F1 between stripe rust resistance Roegneria material and common wheat. The results showed as follows: 82.76% of the 29 tested materials exhibited stripe rust resistance at adult stage, and they contained more than 5 alleles of stripe rust resistance genes, which might still carry new resistance genes to wheat stripe rust. An intergeneric hybrids R. ciliaris-CSph2a F1 was generated using the screened high stripe rust resistance Roegneria ciliaris [Trin.] Nevski (ZY11004-R) and common wheat mutant CSph2a, and raised based on the embryo rescue technology. F1 hybrid contained 35 chromosomes with StYABD genome constitution and an average of 26.84 monovalents during pollen mother cell metaphase I. Besides, F1 exhibited morphological intermediacy, except the perennial living was inherited form from maternal R. ciliaris with high resistance to wheat stripe rust. [ABSTRACT FROM AUTHOR]

Overall, there is a major wish that European farmers implement integrated pest management (IPM), particularly to reduce dependence on pesticides. In the European Rustwatch project, partners conducted nineteen trials across nine different countries during 2020 and 2021 to investigate different IPM strategies, focusing on controlling rust diseases in winter wheat. The trials included the use of varieties with contrasting levels of resistance, variety mixtures, reduced fungicide rates, thresholds, and Decision Support Systems (DSSs), and testing alternative products to fungicides. Sixteen trials developed yellow rust (Puccinia striiformis f. sp. tritici) infections, and six trials developed brown rust (Puccinia triticina) infections. Resistant varieties proved highly effective in keeping down yellow rust infection, and variety mixtures also effectively reduced infection levels and stabilized yields. Rust was fully controlled using 25% of standard fungicide rates, even under high disease pressure. Using DSSs provided sufficient control of rust diseases and resulted in competitive net economic returns due to fewer fungicide applications. The alternative products tested included two biological control agents and four alternative chemistries, which all gave inferior and insufficient control against rust compared with chemical fungicides. The trial work demonstrated that there are good and reliable options for including IPM into disease control in wheat. [ABSTRACT FROM AUTHOR]

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Rust diseases continue to cause economic losses to wheat production worldwide. Host-plant resistance significantly non-race-specific or combining race-specific and non-race-specific resistance is the most efficient, economic and ecofriendly way to control wheat rusts, besides eliminating the use of fungicides. Evidence on the effects of race-specific and non-race-specific resistance categories on stripe rust caused by Puccinia striiformis Westend. f. sp. tritici Eriks. and Henn and leaf rust (Puccinia triticina) development and in defending yield component losses in Indian wheat cultivars is still limited. Experiment was conducted to study the impacts of stripe rust and leaf rust on grain yield and yield components of some Indian wheat cultivars under artificial epiphytotic conditions. Cultivars with highly effective adult plant resistance to stripe rust viz. HD 2733, HD 2967, HD 3263, HS 562, NIAW 34, HI 1621, DBW 187, HD 3226, VL 829, VL 829, C 306, HD 3086, and NI 5439, and HD 3086, HD 3226, HI 1620, DBW 187, WH 1124, HI 1628, HS 562, RAJ 4496, MACS 6222, and VL 907 for resistance to leaf rust exhibited low values of epidemiological parameters as well as low yield components' losses despite moderate disease levels might possessing APR gene(s). In this study, cultivars having slow rusting resistance with low values of epidemiological parameters were identified. These cultivars can be best utilized in varietal development programs to get improved varieties with high levels of durable resistance against novel virulent races of leaf rust. [ABSTRACT FROM AUTHOR]

A total of 139 triticale × wheat progenies (including recombinant inbred lines and doubled haploids) were developed indigenously. Screening at cytogenetic level using genomic in situ hybridization and fluorescence in situ hybridization revealed maximum progenies (48%) carrying 1RS.1BL translocation. D-R genome substitution ranging from 1 to 7 chromosomes of rye showed significantly more biological yield (9.29 g), 1000 grain weight (48.26 g), number of tillers per plant (6.67) and plant height (106.06 cm) than other progenies depicting the contribution of rye chromatin towards plant yield. Thirteen per cent of lines were found without rye chromatin. Screening of all progenies against yellow rust pathogen revealed about 85% lines to be resistant with varying levels of resistance. In vitro testing for drought tolerance showed non-significant difference among progenies carrying variable rye introgressions. The progenies developed in the present study may present novel germplasm and utilized in the future wheat improvement programmes. [ABSTRACT FROM AUTHOR]