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Wheat yellow rust disease poses a significant threat to global wheat yield and grain quality. Early detection of this disease will help to minimize the loss caused by its effects. Existing models work well on images taken in a controlled environment, whereas a uniform background is placed behind the leaf, but these models fail to produce good results in natural settings. Previous research also involves manual interventions in the pipeline to achieve good classification results such as cropping the images, using uniform backgrounds, etc. These systems are not practical to use in natural environments where there will be a lot of background noise to the image and manual cropping becomes an extra step for the farmer. Moreover, the unavailability of the dataset in which images of leaves are taken in a natural setting became another challenge. In this research, a dataset is curated and leaves are annotated for object detection, object segmentation further the leaves are classified into 3 classes ie healthy, resistant, and susceptible. A novel unsupervised image rotation algorithm is proposed that takes input from YOLOv8 to align the leave in such a way that maximum background can be removed by a rectangular bounding box. Then the comparison between multiple state-of-the-art segmentation models ie. UNET, Segment-Anything (SAM), Segnet, LinkNet, PSPNet, FPN, Deep-Labv3+ (Xception), and DeepLabv3+ (Mo-bileNet) has shown that UNET has outperformed all the other segmentation models with an IOU score of 0.9563. Lastly for classification, the performance of multiple convolution neural networks ie. VGG16, Resnet 101(v2), Xception, Mo-bileNetV2, and Transformer-based models ie. Swin trans-former and MobileVit have been compared. Swin transformer has outperformed the state-of-the-art CNN models with an accuracy of 95.8%. This paper proposes a complete robust pipeline that can be deployed in natural environment and does not need any manual intervention to produce good results. This research shows that good localization of leaves and removal of unwanted background noise at the earliest stage of the pipeline will assist the segmentation model to effectively segment the leaf from the background which will enable classification models to achieve high classification accuracy, even when dealing with very small datasets. [ABSTRACT FROM AUTHOR]

Introduction: Fungal foliar diseases can severely affect the productivity of the peanut crop worldwide. Late leaf spot is the most frequent disease and a major problem of the crop in Brazil and many other tropical countries. Only partial resistance to fungal diseases has been found in cultivated peanut, but high resistances have been described on the secondary gene pool. Methods: To overcome the known compatibility barriers for the use of wild species in peanut breeding programs, we used an induced allotetraploid (Arachis stenosperma × A. magna)4x, as a donor parent, in a successive backcrossing scheme with the high-yielding Brazilian cultivar IAC OL 4. We used microsatellite markers associated with late leaf spot and rust resistance for foreground selection and high-throughput SNP genotyping for background selection. Results: With these tools, we developed agronomically adapted lines with high cultivated genome recovery, high-yield potential, and wild chromosome segments from both A. stenosperma and A. magna conferring high resistance to late leaf spot and rust. These segments include the four previously identified as having QTLs (quantitative trait loci) for resistance to both diseases, which could be confirmed here, and at least four additional QTLs identified by using mapping populations on four generations. Discussion: The introgression germplasm developed here will extend the useful genetic diversity of the primary gene pool by providing novel wild resistance genes against these two destructive peanut diseases. [ABSTRACT FROM AUTHOR]

The common rust disease of maize is caused by the obligate biotrophic fungus Puccinia sorghi. The maize Rp1-D allele imparts resistance against the P. sorghi IN2 isolate by initiating a defense response that includes a rapid localized programmed cell death process, the hypersensitive response (HR). In this study, to identify AvrRp1-D from P. sorghi IN2, we employed the isolation of haustoria, facilitated by a biotin-streptavidin interaction, as a powerful approach. This method proves particularly advantageous in cases where the genome information for the fungal pathogen is unavailable, enhancing our ability to explore and understand the molecular interactions between maize and P. sorghi. The haustorial transcriptome generated through this technique, in combination with bioinformatic analyses such as SignalP and TMHMM, enabled the identification of 251 candidate effectors. We ultimately identified two closely related genes, AvrRp1-D.1 and AvrRp1-D.2, which triggered an Rp1-D-dependent defense response in Nicotiana benthamiana. AvrRp1-D-induced Rp1-D-dependent HR was further confirmed in maize protoplasts. We demonstrated that AvrRp1-D.1 interacts directly and specifically with the leucine-rich repeat (LRR) domain of Rp1-D through yeast two-hybrid assay. We also provide evidence that, in the absence of Rp1-D, AvrRp1-D.1 plays a role in suppressing the plant immune response. Our research provides valuable insights into the molecular interactions driving resistance against common rust in maize. Author summary: The common rust disease of maize is caused by the obligate biotrophic fungus Puccinia sorghi. Resistance to common rust is controlled by race-specific dominant NLR (nucleotide-binding domain and leucine-rich repeats) genes and by a variety of non-race-specific quantitative trait loci. The maize Rp1-D is a coiled-coil-NLR protein conferring race-specific resistance that includes a rapid localized programmed cell death, hypersensitive response (HR). In this study, to identify AvrRp1-D from an avirulent P. sorghi IN2, we employed the isolation of haustoria, facilitated by a biotin-streptavidin interaction, as a powerful approach. This method proves particularly advantageous in cases where the genome information for the fungal pathogen is unavailable, enhancing our ability to explore and understand the molecular interactions between maize and P. sorghi. The haustorial transcriptome is generated through this technique in combination with bioinformatic analyses. We identified two closely related genes, AvrRp1-D.1 and AvrRp1-D.2, which triggered an Rp1-D-dependent defense response in Nicotiana benthamiana. AvrRp1-D-induced Rp1-D-dependent HR was further confirmed in maize protoplasts. We demonstrated that AvrRp1-D.1 interacts directly and specifically with the leucine-rich repeat domain of Rp1-D through yeast two-hybrid assay. Our research provides valuable insights into the molecular interactions driving resistance against common rust in maize. [ABSTRACT FROM AUTHOR]

Wheat yellow (stripe) rust, caused by the fungus Puccinia striiformis f.sp. tritici (Pst), is a devastating disease of wheat worldwide. The success of Pst is largely due to the pathogens ability to rapidly overcome host resistance, generating new races that are easily dispersed between territories through wind-borne transmission of Pst urediniospores. Thus, first signs of entry of new Pst races into a region is usually captured by changes in disease severity. To examine any alterations of winter wheat variety response to Pst infection in Serbia, we analyzed yield and Pst disease severity in field trials conducted in 2014, 2021, and 2023. We specifically focused on analyzing Pst disease severity at growth stages related to yield. Associations between qualitative variables (variety, year) and quantitative variables (yield in untreated plots, yield loss, and disease index (DI) of Pst infection) were analyzed using Principal Component Analysis with mixed data. A General Linear Model was used to investigate the most influential factors on yield, yield loss, and Pst infection. The results indicated that yellow rust disease severity increased over the past decade, suggesting a potential recent change in the Pst population in Serbia. Comparative population genetic analysis of Pst samples from the 2023 wheat season and those collected in Serbia in 2014 confirmed a potential change in the Pst population. In addition, we found that yield losses across wheat varieties varied independently of Pst infection levels, indicating that wheat varieties differ in their ability to overcome damage caused by high levels of Pst infection. Given that the level of pathogen pressure triggering susceptibility reactions is cultivar-specific, our study highlights the need for a deeper focus on the mechanisms underlying these differences. Expanding our understanding of the interactions between pathogens, plant defense responses, and the ability of cultivars to mitigate yield losses will better equip us to predict and prevent potential yield losses in commercial wheat varieties due to yellow rust in the future. [ABSTRACT FROM AUTHOR]

Wheat is one of the most important food crop cultivated across the globe which ensures sustainability and food security to massive world's population, but its production is threatened by both biotic factors like rust (caused by Puccinia species) and abiotic stresses such as salinity. In this study, 41 salt-tolerant wheat lines were screened for rust resistance at both seedling and adult plant stages. Rust resistance genes were characterized through gene matching technique and molecular markers analysis. Yr2 was confirmed in 23 lines, while Yr9 along with Lr26 / Sr31 were postulated in six lines with the help of SRT and molecular markers. Except for KRL2013, none showed complete resistance to all Puccinia striiformis f. sp. tritici (Pst). Lr24/Sr24 genes were confirmed in HD2851 and KRL2029, and Lr13 was detected in a maximum of 24 wheat lines, with varying reaction responses to different leaf rust pathotypes. Several lines carried additional resistance genes such as Sr11 , Sr28 , and Lr68. Lr68 an effective race non-specific APR gene identified in 15 wheat lines with the help of CsGs-STS marker. Although many salt-tolerant wheat lines were susceptible to yellow rust during the seedling stage, a few lines showed APR in the years during 2020 and 2021. Three lines (KRL213, KRL219 and KRL238) showed complete resistance at adult plant stage to leaf rust. These findings offer insights into the genetic basis of rust resistance in salt-tolerant wheat, aiding breeding strategies. [ABSTRACT FROM AUTHOR]

Invasive pathogens threaten the sustainability of forest ecosystems globally. Trees possess intrinsic pathogen defence mechanisms, including major gene resistance (MGR) and quantitative disease resistance (QDR). Plant‐symbiotic fungi can enhance tree defences, generating far‐reaching ecosystem impacts. However, the specific contributions of various fungal guilds to this symbiont‐mediated resistance remain unclear. In this study, we inoculated six Pinus monticola seedling families exhibiting resistance (MGR or QDR) or high susceptibility to the introduced invasive pathogen Cronartium ribicola, the causative agent of white pine blister rust (WPBR), with endophytic and ectomycorrhizal fungi, either alone or in combination (symbiont treatments), in an open‐air greenhouse study. Over a period of 25 months, we monitored the growth, foliar terpene defences, and disease progression in trees before and after C. ribicola infection and in trees inoculated with the symbionts but never inoculated with C. ribicola. We observed enhanced inducible host defences and evidence of defensive priming in response to symbiont treatments. In WPBR‐free control treatments, differences in pine defences coincided with an increased seedling growth rate. For WPBR‐infected seedlings, symbiont treatments reduced disease symptoms in seedlings with QDR and to a lesser extent in susceptible families, but not in those with MGR. Furthermore, disease symptoms correlated with variations in terpene composition. Synthesis and applications: Interactions with fungal symbionts should be considered when breeding native trees for resistance against invasive pathogens. Our study underscores the capacity of endophytic and ectomycorrhizal fungi to enhance tree growth and defence while also reducing disease symptoms. We also show that fungi can induce long‐lasting changes in conifer foliar terpenes, suggesting potential applications in tree protection from invasive pathogens. [ABSTRACT FROM AUTHOR]

Wheat stem rust (Puccinia graminis f. sp. tritici) is the major threat to wheat production in Ethiopia due to the menace of high losses in grain yield and quality. A wheat stem rust survey was undertaken during the main cropping seasons (late October to early November) of 2015 and 2016 in the Horro Guduru Wollega highlands, western Ethiopia. The purposes of the survey were to assess the wheat stem rust distribution and disease intensity and determine its association with biophysical factors and cultivation practices. A total of 221 wheat fields in eight districts were assessed. Wheat stem rust was prevalent in both cropping seasons. The mean disease incidence ranged from 56.3 to 63.7%, while the disease severity mean ranged from 15.7 to 21.6%, respectively. Logistic regression was used to analyze the association of wheat stem rust with independent variables. Increased incidence (>50%) and severity (>5%) were strongly (P < 0.0001) associated with lower altitude (≤2400 m), susceptible varieties, broadcast sowing method, fungicide-unsprayed wheat fields, and wheat growth at flowering and milking stages. The survey indicates a highly prevalent wheat stem rust epidemic associated with biophysical factors and cultivation practices in the major wheat-growing districts. A combination of cultivation practices such as sowing wheat in rows, optimum fertilization, deployment of rust-resistant varieties, and effective fungicide application would be the most effective methods for managing wheat stem rust in the Horro Guduru Wollega highlands. [ABSTRACT FROM AUTHOR]

Brown rust (caused by Puccinia melanocephala H. & P. Sydow) is one of the most devastating diseases in commercial sugarcane production. It could reduce sugarcane yield by up to 50% depending on the susceptibility levels of cultivars. Breeding disease‐resistant cultivars is the most effective, economical, and environmentally friendly option to control brown rust. A genome‐wide association study was conducted on a field trial using 432 sugarcane clones following an augmented design with two replications. Brown rust was screened using the whorl inoculation method over two crop cycles. The genotype data were obtained through target enrichment sequencing technologies. The gene actions considering six different models and marker dosage effects were included during the marker‐trait analysis. A total of seven, nine, and seven nonredundant marker‐trait associations were identified for plant cane, first ratoon, and across two crop cycles, respectively. The most significant (p‐value 6.17E−20) marker (chr01p59833543) has the additive effect of −0.63 for the diplo‐additive model and reduced disease severity the most (41.35%) due to heterozygote (AG) over homozygote allele (AA) combination in the tested clones. Gene annotation of the monoploid sugarcane genome R570 suggested that six putative candidate genes were co‐located with significant markers associated with brown rust resistance in sugarcane. The putative candidate genes regulated the formation of a cell wall barrier that plays a crucial role in controlling brown rust pathogen infection. The results of this study will open the path to exploiting new resistance sources for brown rust resistance in commercial sugarcane. [ABSTRACT FROM AUTHOR]

The virulence analysis of Puccinia stiiformis f. sp. tritici (Pst), the cause of wheat stripe rust, is essential for predicting and managing the disease epidemic in Southwest China, where the wheat cultivation has significantly reduced in the past few decades due to the impact of this disease. From 2020 to 2021, 196 Pst isolates were collected from Guizhou, Yunnan, and Sichuan. The virulence and race assessments were conducted using Chinese differential genotypes. Additionally, the resistance expression of 102 wheat lines was evaluated in 2021 in two disease nurseries located in Ningnan and Jiangyou. All the 45 Pst isolates from Guizhou and Yunnan belonged to pathogroup Hybrid 46, with 36 identified as race CYR32. Among the 69 isolates from the Liangshan Prefecture, 67 belonged to the Hybrid 46 group, while the remaining two were identified as race CYR34 in the G-22 group. Furthermore, all 79 isolates from the western Sichuan Basin belonged to the G-22 group, with 54 identified as race CYR34. The diversity indices of the Pst populations from Guizhou, Sichuan, and Yunnan exhibited a sequential decline. Virulence variation among the Pst populations from Yunnan, Guizhou, and the Ganzi-Liangshan region was minimal; however, significant virulence differences were observed when these populations were compared to those from the western Sichuan Basin. Results from disease nurseries indicated that Pst virulence was notably stronger in Ningnan compared to that in Jiangyou. The Sichuan Basin exhibits a notable diversity in Pst virulence, coupled with a more frequent genetic exchange occurring between the Liangshan Prefecture and the Yunnan-Guizhou Plateau. This information is essential for developing effective management strategies to mitigate the impact of wheat stripe rust in this region. [ABSTRACT FROM AUTHOR]

Wheat leaf rust caused by Puccinia triticina (Pt) is an important disease of bread wheat in Zimbabwe. This study was carried out to determine the distribution, avirulence/virulence profile(s) and genotypic variation among isolates of the pathogen. In total, 104 single-pustule isolates were established from infected wheat samples that were collected from the main wheat production regions in Zimbabwe in surveys conducted from 2019 to 2021. Phenotyping of the isolates on a set of 46 differential and additional wheat lines revealed a single Pt race, MCDS. For genotypic assessment, 48 Pt isolates, including eight South African races, were genotyped with 19 microsatellite markers. Using the Bayesian model, isolates were subdivided into three clusters in both a DARwin neighbour-joining tree and STRUCTURE analysis. The results confirmed a high genetic similarity between the Zimbabwean Pt isolates and the South African races MCDS, MCPS and MFPS. Furthermore, Pt isolates from Zimbabwe were clonal, which was in accordance with all 104 isolates that typed to race MCDS. [ABSTRACT FROM AUTHOR]

The continuous emergence of new Puccinia striiformis Westend f. sp. tritici Erikss (Pst) races requires a sustained search for useful sources of resistance. A CIMMYT bread wheat line (pedigree: Milan/S87230//Babax; renamed NSRPan4) was identified as highly resistant to South African Pst races. A recombinant inbred line (RIL) mapping population was developed by crossing NSRPan4 with Avocet S. Stripe rust data collected for RILs, using Pst race 6E22A + , include seedling infection types determined under controlled conditions as well as adult plant responses determined in field trials over three consecutive seasons. Quantitative trait loci (QTL) mapping identified stripe rust resistance genes/QTL on chromosomes 2A and 2B, temporarily designated as QYr.ufs-2A.2(YR17) and QYr.ufs-2B.1, respectively. The QTL interval on chromosome 2A, which includes the LR37/YR17/SR38 gene complex (also referred to as the 2NS/2AS or 2NVS segment), conferred a significant seedling (R2 23.5%) and adult plant resistance effect (R2 up to 54.5%). The QTL on 2B contributed up to 46.4% of phenotypic variance observed. Three minor QTL, temporarily designated as QYr.ufs-1B.1 (possibly LR46/YR29), QYr.ufs-3D.1 and QYr.ufs-7A.1 were also detected. Our results support findings that notwithstanding the reported virulence for YR17, the LR37/YR17/SR38 segment remains useful in combination with other sources of resistance in certain genetic backgrounds and environments. Together with QYr.ufs-2B.1 and in the presence of the detected minor QTL and yet unidentified resistances, it was a consistent major contributor to the high level of stripe rust resistance in NSRPan4 to South African races of Pst. [ABSTRACT FROM AUTHOR]

Genomic selection (GS) is becoming increasingly widespread and applied due to the promising results obtained, cost savings in generating single nucleotide polymorphism (SNP) markers, and the development of statistical models that allow to improve the analysis robustness and accuracy. The composition and size of the training population have a major influence on GS, which poses challenges for interspecific biparental populations. Another factor is the use of different reference genomes from other species to perform SNP calling, which could make it possible to explore variability in interspecific crosses comprehensively. Late leaf rust is a disease caused by the pathogen Acculeastrum americanum, and there are reports on genetic resistance in Rubus occidentalis, which leads to the need for interspecific hybridizations, aiming to combine the fruit quality of R. idaeus with the resistance of R. occidentalis. The present study was carried out with a population of 94 interspecific raspberry hybrids. We evaluated the effect of different reference genomes on the SNP markers discovery, as well as training population optimization strategies on the accuracy of genomic predictions, namely the CV-α, leaving-one-family-out (LOFO), pairwise families, and stratified k-fold. The average predictive accuracies ranged from − 0.33 to 0.44 and We demonstrated higher prediction accuracy and more precise estimates when we combined stratified sampling to compose the training set (CV-α and k-fold stratified CV) and the panel of Unique markers. These results corroborate that genomic prediction aligned with SNP calling and training population optimization strategies can significantly increase genetic gains in interspecific biparental crosses. [ABSTRACT FROM AUTHOR]

SUMMARY: Hypersensitive response‐programmed cell death (HR‐PCD) regulated by Ca2+ signal is considered the major regulator of resistance against Puccinia triticina (Pt.) infection in wheat. In this study, the bread wheat variety Thatcher and its near‐isogenic line with the leaf rust resistance locus Lr26 were infected with the Pt. race 260 to obtain the compatible and incompatible combinations, respectively. The expression of translationally controlled tumor protein (TaTCTP) was upregulated upon infection with Pt., through a Ca2+‐dependent mechanism in the incompatible combination. The knockdown of TaTCTP markedly increased the area of dying cell and the number of Pt. haustorial mother cells (HMCs) at the infection sites, whereas plants overexpressing the gene exhibited enhanced resistance. The interaction between TaTCTP and calcineurin B‐like protein‐interacting protein kinase 23 (TaCIPK23) was also investigated, and the interaction was found occurred in the endoplasmic reticulum. TaCIPK23 phosphorylated TaTCTP in vitro. The expression of a phospho‐mimic TaTCTP mutant in Nicotiana benthamiana promoted HR‐like cell death. Silencing TaCIPK23 or TaCIPK23/TaTCTP co‐silencing resulted in the same results as silencing TaTCTP. This suggested that TaTCTP is a novel phosphorylation target of TaCIPK23, and both participate in the resistance of wheat to Pt. in the same pathway. Significance Statement: Wheat leaf rust caused by Puccinia triticina infection causes losses to agriculture worldwide. Calcium signaling and its mediated hypersensitive response are critical for leaf rust resistance in wheat. By demonstrating the phosphorylation of TaTCTP by TaCIPK23 and their contribution to the leaf rust resistance phenotype in wheat, this study reveals the mechanism by which calcium mediates biotic stress resistance and provides valuable insights for future crop improvement strategies. [ABSTRACT FROM AUTHOR]

Wheat leaf rust, caused by Puccinia triticina, poses a growing threat to global wheat production, necessitating alternative strategies for effective disease management. This study investigated the potential of gamma-aminobutyric acid (GABA) to enhance resistance to leaf rust in two wheat cultivars: the susceptible Morocco and moderately resistant Sakha 94 cultivar. Our findings revealed that GABA significantly improved resistance in both cultivars to P. triticina, particularly in Morocco, by mitigating disease severity and reducing pustule density and size while extending both incubation and latent periods. This study assessed the effectiveness of two GABA application methods: plants received 1 mM GABA treatment, as a foliar spray, twenty-four hours prior to infection (pre-GABA), and plants received 1 mM GABA treatment both 24 h before and after infection (pre-/post-GABA), with the latter yielding significantly better results in reducing infection severity and improving plant resilience. Additionally, GABA application influenced stomatal behavior, promoting closure that may enhance resilience against leaf rust. GABA application on plants also modulated the production of reactive oxygen species (ROS). This led to a stronger oxidative burst in both susceptible and moderately resistant cultivars. GABA increased O2●− levels in guard cells and surrounding stomata, enhancing stomatal closure and the hypersensitive response. GABA enhanced the accumulation of soluble phenols and increased the activity of key antioxidant enzymes, catalase (CAT) and peroxidase (POX), which are vital for managing oxidative stress. To the best of our knowledge, this investigation represents the first report into the impact of GABA on wheat leaf rust disease. [ABSTRACT FROM AUTHOR]

The microbial community plays a vital role in root–environment interactions, which affect plant performance under biotic stress. Rust disease significantly affects plant growth, which may also affect rhizosphere microbial community. However, there is a scarcity of studies investigating the microbial community of rhizosphere under rust disease stress. Iris lactea is a widely utilized plant in gardening and landscaping due to its versatility and ornamental value, but it is often susceptible to rust disease in landscape settings. In this study, we compared the bacterial communities between bulk soil (non-cultivated control), rhizosphere soil of healthy Iris lactea plants, and rhizosphere soil of Iris lactea plants infected with rust disease (rhizosphere-R). Results revealed significant alterations in the abundance and composition of bacterial communities associated with rust disease infection. Specifically, the rhizosphere-R samples exhibited a decreased Shannon index at 1.9% compared to bulk soil and the relative abundance of Proteobacteria was increased at 31.65%. Moreover, distinct changes in β-diversity were shown between bulk soil and rhizosphere samples. Notably, potentially pathogenic bacteria increased in abundance under rust disease stress, while beneficial bacterial taxa decreased. Overall, our results show that rust disease affects the rhizosphere microbial community, which emphasizes the ecological implications of plant–microbe interactions under biotic stress and implications for developing targeted rhizobacterial-based biocontrol strategies. [ABSTRACT FROM AUTHOR]

Leaf rust caused by Puccinia triticina (Pt) is one of the most impactful diseases causing substantial losses in common wheat (Triticum aestivum L.) crops. In adult plants resistant to Pt, a horizontal adult plant resistance (APR) is observed: APR protects the plant against multiple pathogen races and is distinguished by durable persistence under production conditions. The Lr46/Yr29 locus was mapped to chromosome 1B of common wheat genome, but the identity of the underlying gene has not been demonstrated although several candidate genes have been proposed. This study aimed to analyze the expression of nine candidate genes located at the Lr46/Yr29 locus and their four complementary miRNAs (tae-miR5384-3p, tae-miR9780, tae-miR9775, and tae-miR164), in response to Pt infection. The plant materials tested included five reference cultivars in which the molecular marker csLV46G22 associated with the Lr46/Yr29-based Pt resistance was identified, as well as one susceptible control cultivar. Biotic stress was induced in adult plants by inoculation with fungal spores under controlled conditions. Plant material was sampled before and at 6, 12, 24, 48 hours post inoculation (hpi). Differences in expression of candidate genes at the Lr46/Yr29 locus were analyzed by qRT-PCR and showed that the expression of the genes varied at the analyzed time points. The highest expression of Lr46/Yr29 candidate genes (Lr46-Glu1, Lr46-Glu2, Lr46-Glu3, Lr46-RLK1, Lr46-RLK2, Lr46-RLK3, Lr46-RLK4, Lr46-Snex, and Lr46-WRKY) occurred at 12 and 24 hpi and such expression profiles were obtained only for one candidate gene among the nine genes analyzed (Lr46-Glu2), indicating that it may be a contributing factor in the resistance response to Pt infection. [ABSTRACT FROM AUTHOR]

Stripe rust and powdery mildew are serious diseases that severely decrease the yield of wheat. Planting wheat cultivars with powdery mildew and stripe rust resistance genes is the most effective way to control these two diseases. Introducing disease resistance genes from related species into the wheat genome via chromosome translocation is an important way to improve wheat disease resistance. In this study, nine novel T1RS.1AL translocation lines were developed from the cross of wheat cultivar Chuannong25 (CN25) and a Chinese rye Qinling. The results of non-denaturing fluorescence in situ hybridization and PCR showed that all new lines were homozygous for the T1RS.1AL translocation. These new T1RS.1AL translocation lines exhibited strong resistance to stripe rust and powdery mildew. The cytogenetics results indicated that the resistance of the new lines was conferred by the 1RS chromosome arms, which came from Qinling rye. The genetic analysis indicated that there were new dominant resistance genes on the 1RS chromosome arm resistant to stripe rust and powdery mildew, and their resistance patterns were different from those of Yr9, Pm8, and Pm17 genes. In addition, the T1RS.1AL translocation lines generally exhibited better agronomic traits in the field relative to CN25. These T1RS.1AL translocations have great potential in wheat-breeding programs in the future. [ABSTRACT FROM AUTHOR]

Leaf rust is a widespread foliar wheat disease causing substantial yield losses worldwide. Slow rusting is "adult plant" resistance that significantly slows epidemic development and thereby reduces yield loss. Wheat accession CI 13227 was previously characterized as having slow-rusting resistance. To validate the quantitative trait loci (QTLs) and develop diagnostic markers for slow rusting resistance in CI 13227, a new population of recombinant inbred lines of CI 13227 × Everest was evaluated for latent period, final severity, area under the disease progress curve, and infection type in greenhouses and genotyped using genotyping-by-sequencing. Four QTLs were identified on chromosome arms 2BL, 2DS, 3BS, and 7BL, explaining 6.82 to 28.45% of the phenotypic variance for these traits. Seven kompetitive allele-specific polymorphism markers previously reported to be linked to the QTLs in two other CI 13227 populations were validated. In addition, the previously reported QLr.hwwg-7AL was remapped to 2BL (renamed QLr.hwwg-2BL) after adding new markers in this study. Phenotypic data showed that the recombinant inbred lines harboring two or three of the QTLs had a significantly longer latent period. QLr.hwwg-2DS on 2DS showed a major effect on all rust resistance traits and was finely mapped to a 2.7-Mb interval by two newly developed flanking markers from exome capture. Three disease-resistance genes and two transporter genes were identified as the putative candidates for QLr.hwwg-2DS. The validated QTLs can be used as slow-rusting resistance resources, and the markers developed in this study will be useful for marker-assisted selection. [ABSTRACT FROM AUTHOR]

The leaf rust (Puccinia triticina f. sp. tritici), stripe rust (Puccinia striiformis f. sp. tritici), and stem rust (Puccinia graminis f. sp. tritici) are major fungal constraints affecting wheat production worldwide. Identifying and deploying wheat varieties with diverse resistance are the best ways to manage all the rusts. Therefore, a continuous search goes on to identify diverse germplasm with effective rust resistance that expresses at different stages of plant growth (seedling and adult plant). A set of 22 rust resistant wheat genotypes and 4 checks (controls), viz., Avocet‐Yr10, Avocet ‐Yr15, Agra Local, and respective positive checks were studied for characterising rust resistance genes using host–pathogen interactions complemented by molecular markers. Among 22 elite genotypes, 05 genotypes amplified 191 bp fragment with marker PSY1E1, confirmed the presence of gene Lr19/Sr25. These genotypes also expressed resistance to most virulent leaf rust pathotypes, 77‐5 and 77‐9 in host–pathogen interaction test (HPI). Seven genotypes showed the presence of Lr34/Yr18/Sr57/Pm38/Ltn1 in homozygous state, whereas G4 showed its presence in heterozygous condition. Among 22 genotypes, 16 genotypes possessed Yr10. Five genotypes (22.7%) exhibited two gene combinations, Lr19/Sr25, and Yr10 as revealed through the detection of 191 bp fragment with marker PSY1E1 and 260 bp fragment with co‐dominantly inherited microsatellite marker Xpsp3000, respectively. All five genotypes (G2, G3, G8, G9, and G18) also expressed brown glumes controlled by the gene Rg1 tightly linked to Yr10 on the 1BS chromosome. Broad spectrum rust resistance present in these lines in good agronomic backgrounds could be used as potent genetic donors for diverse and durable rust resistance breeding programmes in wheat. [ABSTRACT FROM AUTHOR]

Wheat leaf rust, caused by the fungus Puccinia triticina (Pt), severely affects the grain quality and quantity of bread wheat (Triticum aestivum L.). Hairpin small(s)RNAs, like micro(mi)RNAs and their variants [including isomiRNAs (isomiRs) and microRNA‐like RNAs (milRNAs)], along with their corresponding target genes, bestow leaf rust disease resistance, development and progression from both interacting species. However, the regulatory networks remain inadequately understood. Thirteen differentially expressed novel miRNAs, including two isomiRs and three milRNAs were discerned from induced reads of wheat sRNA libraries, and a further 5,393 and 1,275 candidate target genes were predicted in wheat and Pt, respectively. Functional annotation divulged that wheat‐originated miRNAs/isomiRs were involved in resistance, while Pt‐derived milRNAs imparted pathogenesis. The identified milRNAs‐ Tae‐Pt‐milR5, Tae‐Pt‐milR12, and Tae‐Pt‐milR14b and their cleavage sites on Pt target gene MEP5 were confirmed through degradome library screening, suggesting cross‐kingdom translocation of Pt virulent genes in wheat host. Co‐expression analysis of miRNAs/isomiRs‐target genes provided insights into combating leaf rust disease, while co‐expression analysis of milRNAs‐target gene pairs reflected the extent of pathogenicity exerted by Pt with varied expression levels at the analyzed time points. The analysis pinpointed leaf rust‐responsive candidate hairpin sRNAs‐ Tae‐miR8, Tae‐Pt‐miR12, Tae‐Pt‐miR14a, and Tae‐Pt‐miR14b in wheat and Tae‐Pt‐milR12 in Pt. This study provides new insights into the hairpin sRNAs involved in the resistance and pathogenesis of wheat and Pt, respectively. Furthermore, crucial hairpin sRNAs and their promising targets for future biotechnological interventions to augment stress resilience have been identified. [ABSTRACT FROM AUTHOR]

Developing a new coffee cultivar can take up to 25 years using traditional approaches. The implementation of molecular tools into the coffee breeding pipeline can speed up the development of high‐yielding varieties with multiple resistance to pests and diseases. This study aimed to verify the presence of gene pyramiding for resistance to coffee berry disease (CBD) and coffee leaf rust and access the breeding potential of a breeding population of coffee (Coffea arabica L.) that presents partial phenotypic resistance to coffee leaf miner. A progeny of 128 individuals was evaluated in 2019 during the coffee maturation stage for 11 agronomic traits. The individuals were genotyped for four loci related to rust and CBD resistance. Gene pyramiding was verified based on the presence of markers linked with the resistance alleles. Genetic parameters were estimated, and a selection index was used to rank the individuals based on the phenotypic evaluation. Gene pyramiding for rust and CBD was detected in ∼82% of the individuals. Moreover, the phenotypic evaluation of rust indicated high levels of resistance, confirmed by the presence of the resistance alleles. Ninety‐five percent of the 38 top‐ranked individuals presented resistance alleles and could be used in an interpopulation recurrent selection scheme with marker‐assisted selection. The studied coffee population has the potential to be used in coffee breeding programs since it presents vigorous individuals with low levels of coffee leaf miner incidence (CLMI) and gene pyramiding for CBD and rust resistance, the main pest and diseases of this crop. Core Ideas: The Ck‐1 gene that confers resistance to coffee berry disease is present in 68% of the individuals of the F2 population.Most of the F2 individuals have rust‐resistance genes.The 38 top‐ranked individuals presented multiple resistance loci. [ABSTRACT FROM AUTHOR]

Wheat stripe rust, caused by Puccinia striiformis, is one of the most serious diseases on wheat yield. It is of great significance to timely and accurately detect the disease, in order to monitor and prevent the wheat stripe rust. The stripe rust can infect the internal physical and chemical characteristics and external morphological structure of wheat. Solar-induced chlorophyll fluorescence (SIF) can be expected for the remote sensing detection of crop stress. The red-band sunlight-induced chlorophyll fluorescence (RSIF) has more information about photosystem II (PSII), thus sensitively representing the photosynthetic physiological state of plants. The SIF escape rate is closely related to the canopy geometry, leaf optical properties, and light energy utilization efficiency of vegetation. In this study, field-measured data was used to invert and calculate the SIF and its escape rate (εCP) at different scales (canopy scale SIFCanopy and photosystem scale SIFPS) in the red and far-red band. The contents of four wheat pigments were obtained to combine the leaf area index (LAI) closely related to vegetation growth. The physiological basis of RSIF escape rate (RεCP) was determined to monitor the wheat stripe rust. Subsequently, the response characteristics of RεCP under stripe rust stress were explored to compare with the SIF and its derived parameters (fluorescence yield ФF, apparent SIF yield SIFy) in the red and far-red light bands, the normalized difference vegetation index (NDVI), the MERIS terrestrial chlorophyll index (MTCI) and the simple ratio vegetation index (SR). In addition, a systematic analysis was performed on the response characteristics to SL under different disease severity (SL) and different chlorophyll contents (Chl). The results indicate that the correlations between nitrogen balance index (NBI), Chl, flavonoids (Flav), anthocyanins (Anth), and LAI and SL all reached the P<0.01 level, among which the correlation between Chl and SL was the highest. The correlations of RεCP with NBI, Chl, Flav, and Anth increased by 29.06% and 31.52% on average, respectively, compared with photosystem-scale RSIF and photosystem-scale far-red band SIF (far-red solarinduced chlorophyll fluorescence, FRSIF). The correlation with LAI increased by 15.63%, compared with the canopy-scale FRSIF. RεCP better reflected the variation in the crop physiology and canopy structure caused by disease stress. RεCP shared the highest correlation with SL, which was 60.87%, 42.31%, 17.46%, 39.62%, 34.55%, 5.71%, 13.85%, and 21.31% higher than those of canopy-scale FRSIF (FRSIFCanopy), photosystem-scale FRSIF (FRSIFPS), photosystem-scale RSIF (RSIFPS), apparent SIF yield in the red light band (RSIFy), fluorescence yield in the red light band (RФF), NDVI, MTCI and SR, respectively. In the mild to moderate (0%45%) disease conditions, the correlation between RεCP and SL increased by an average of 56.34% and 53.97%, respectively, compared with SIF and their derived parameters and vegetation index at the P<0.01 level. RεCP was sensitively responded to the variation in SL, which was better than the rest parameters. RεCP was most sensitive to the wheat stripe rust stress under the low (Chl≤30) and medium to high chlorophyll content (Chl>30). The correlation with SL increased by an average of 42.77% and 43.25%, respectively, compared with SIF and their derived parameters and vegetation index at the P<0.01 level. RεCP can serve as a suitable factor for remote sensing monitoring of wheat stripe rust. RεCP can greatly contribute to disease prevention for better yields. The finding can also provide a strong reference and powerful tool for remote sensing monitoring of crops in agricultural production. RSIF and escape rate can be incorporated into the remote sensing monitoring, in order to greatly improve the detection and monitoring of plant health status. [ABSTRACT FROM AUTHOR]

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]

Spring bread wheat (Triticum aestivum) is a major crop in Russia and in Kazakhstan. The rust pathogens, leaf rust caused by the fungus Puccinia triticina, stem rust incited by P. graminis and yellow rust caused by P. striiformis, are the significant biotic factors affecting wheat production. In this study, 40 new promising spring wheat genotypes from the Kazakhstan-Siberia Network for Spring Wheat Improvement (KASIB) were tested for resistance to leaf, stem and yellow rust at the seedling stage, and for identification of rust resistance genes using molecular markers. In addition, the collection was tested for leaf rust resistance and grain yields in the South Urals agroclimatic zone of Russia in 2023. As a result, 16 accessions with seedling resistance to leaf rust, 21 to stem rust and 4 to yellow rust were identified. Three breeding accessions were resistant to all rust species, and nine to P. triticina and P. graminis. Wheat accessions resistant to leaf rust at the seedling stage were also resistant in the field. Molecular analysis showed the presence of cataloged resistance genes, Lr1, Lr3a, Lr9, Lr10, Lr19, Lr20, Lr24, Lr26, Sr15, Sr24, Sr25, Sr31, Sr38, Yr9 and Yr18; uncatalogued genes Lr6Agi1 and Lr6Agi2 from Thinopyrum intermedium and LrAsp from Aegilops speltoides; and 1AL.1RS translocation. The current analysis showed an increase in leaf and stem rust resistance of new KASIB genotypes and their genetic diversity due to the inclusion of alien genetic material in breeding. [ABSTRACT FROM AUTHOR]

Wheat leaf rust, caused by Puccinia triticina, is one of the most common fungal diseases of wheat in China and occurs widely in various wheat-growing regions. To clarify the epidemic, spread rules, and population structure of P. triticina among different regions, 217 isolates of P. triticina collected from Hebei, Shandong, Sichuan, and Xinjiang in China were tested by 34 Thatcher near-isogenic lines and 21 pairs of EST-SSR primers. A total of 83 races were identified, and THTT, PHTT, THTS, and PHJT were the most predominant races in the four provinces in 2009. We found enriched virulence and genetic diversity in the four P. triticina populations and a significant correlation between genetic polymorphism and geographic regions. However, no significant correlation was found between virulence phenotypes and molecular genotypes. Moreover, a notable high level of gene flow (Nm = 2.82 > 1) among four P. triticina populations was detected. The genetic relationship among Hebei, Shandong, and Sichuan populations was close, possibly due to the spread of P. triticina from Sichuan to Shandong and then to Hebei. In contrast, the Xinjiang population was relatively independent. Genetic differentiation analysis showed some level of differentiation among or within populations of P. triticina in the four provinces, and the genetic variation within populations (74.97%) was higher than across populations (25.03%). Our study provides a basis for a better understanding of the regional migration, epidemic, and population structure of P. triticina in China. [ABSTRACT FROM AUTHOR]

Stripe rust is a serious wheat disease occurring worldwide. At present, the most effective way to control it is to grow resistant cultivars. In this study, a population of 221 recombinant inbred lines (RILs) derived via single-seed descent from a hybrid of a susceptible wheat line, SY95-71, and a resistant line, XK502, was tested in three crop seasons from 2022 to 2024 in five environments. A genetic linkage map was constructed using 12,577 single-nucleotide polymorphisms (SNPs). Based on the phenotypic data of infection severity and the linkage map, five quantitative trait loci (QTL) for adult plant resistance (APR) were detected using the inclusive composite interval mapping (ICIM) method. These five loci are QYrxk502.swust-1BL, QYrxk502.swust-2BL, QYrxk502.swust-3AS, QYrxk502.swust-3BS, and QYrxk502.swust-7BS, explaining 5.67–19.64%, 9.63–36.74%, 9.58–11.30%, 9.76–23.98%, and 8.02–12.41% of the phenotypic variation, respectively. All these QTL originated from the resistant parent XK502. By comparison with the locations of known stripe rust resistance genes, three of the detected QTL, QYrxk502.swust-3AS, QYrxk502.swust-3BS, and QYrxk502.swust-7BS, may harbor new, unidentified genes. From among the tested RILs, 16 lines were selected with good field stripe rust resistance and acceptable agronomic traits for inclusion in breeding programs. [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]

'Kikatiti' pinto bean (Phaseolus vulgaris L.) (Reg. no. CV‐361, PI 705149) was developed by the dry bean breeding program at the University of Nebraska, Agricultural Research Division, and submitted for release in 2021 by the Sokoine University of Agriculture in Morogoro as an upright indeterminate pinto bean with high yield potential and multiple disease resistance across bean production environments in Tanzania. Kikatiti was officially released in 2024 by the National Seed Committee. Kikatiti is an F7:8 derived line developed using the pedigree breeding method in Nebraska. The exceptional performance of Kikatiti in Tanzania was first identified by evaluation of the Durango Diversity Panel (DDP), which consisted of 200 accessions in on‐station trials conducted in Arusha and Mbeya. Kikatiti was identified as accession DDP‐094 (advanced breeding line NE2‐09‐3). Kikatiti yielded 1584 kg ha−1 across 5 years of trials in Tanzania and matured in 89 days. Kikatiti is resistant to bean rust conferred by the Ur‐3 and Ur‐11 genes, resistant to all strains of Bean common mosaic virus and Bean common mosaic necrosis virus conferred by the I and bc‐3 genes, moderately resistant to common bacterial blight conferred by the SAP6 quantitative trait locus, avoids white mold disease due to its upright architecture, and is moderately susceptible to angular leaf spot disease. Kikatiti has large seed size (35.9 g 100 seeds−1), and in on‐farm trials, farmers ranked Kikatiti above local pinto cultivars for its performance and market potential. Kikatiti has the potential to expand pinto bean production across East Africa. Core Ideas: Kikatiti pinto bean has superior productivity in Tanzania.Kikatiti pinto possesses an effective combination of resistance genes to combat bean rust disease in East Africa.Kikatiti pinto possesses an effective combination of resistance genes to combat Bean common mosaic necrosis virus.Farmers ranked Kikatiti above local pinto cultivars for performance and market potential in on‐farm trials. [ABSTRACT FROM AUTHOR]

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BACKGROUND: Microstegium vimineum (Trin.) A. Camus, commonly called stiltgrass, is a dominant weed in the United States and China. Although a lot of control approaches have been attempted, an economic, effective and practical measure has not been available to control the weed so far. RESULTS: A serious rust disease of Microstegium vimineum was observed in three regions of Wenzhou city in China, from 2019 to 2021, with a disease incidence ranging from 82% to 97%. Typical rust disease symptoms on Microstegium vimineum were prominently visible during the early monsoon season (June–July), with chlorotic spots on the leaf surfaces. The morphological characterization of the strain WZ‐1 which was isolated from the diseased leaves was consistent with Puccinia polliniicola. The virulence tests showed that the average disease index of Microstegium vimineum plants could reach 35% at 10 days post‐inoculation. The host specificity of Puccinia polliniicola was tested on 64 plant species from 12 families and it did not cause any diseased symptoms on 24 major crops and 36 weeds, but slightly infected four gramineous weeds, Arthraxon hispidus, Polypogon fugax, Cynodon dactylon, and Microstegium ciliatum. However, newly‐produced urediniospores were not observed on the slightly infected plants. The urediniospores of strain WZ‐1 infected the Microstegium vimineum leaves by two main approaches: mycelium or appressorium invaded the stoma; and mycelium or appressorium directly invaded intercellular spaces. Field experiments showed that the rust disease naturally prevailed among Microstegium vimineum populations, causing severe rust disease symptoms on the leaf surface. The rust epidemic effectively controlled all of the target plants in the closed plot where the rust was released. CONCLUSION: Puccinia polliniicola strain WZ‐1 has great potential to be used as a classical biological control agent against Microstegium vimineum. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Leaf rust, caused by the pathogenic biotrophic rust fungus Puccinia triticina (Pt), is one of the most destructive wheat diseases worldwide; its negative impact on crop yields is exacerbated by increasing temperatures due to climate change. Ascarosides are nematode pheromones that induce resistance to microbial pathogens and pests in a wide range of crops, making them valuable components in biocontrol scenarios. We investigated the effect on infection of various wheat (Triticum aestivum) genotypes with the virulent Pt race 77W × R by ascr#18, the major ascaroside secreted into the rhizosphere by plant-parasitic nematodes. Spraying the leaves with ascr#18 24 h before inoculation with fungal uredospores slowed disease development and resulted in a reduction of the number of rust pustules on treated compared to untreated leaves. Dose–response analysis over the nano- and micromolar range revealed a broad optimum concentration down to 0.01nM ascr#18. Microscopic analysis showed very early arrest of the fungus at the appressorial stage, with associated enhanced local accumulation of H2O2 and abortive stoma penetration. Similarly, ascr#18 also induced strong resistance to Pt race PKTTS, confirming its race-unspecific biocontrol activity. The results of this study are consistent with and extend previous research that has shown that ascr#18 activates plant immunity and thus protects plants from pathogens even at very low doses. [ABSTRACT FROM AUTHOR]

Worldwide food security is severely threatened by the devastating wheat stripe rust disease. The utilization of resistant wheat cultivars represents the most cost‐effective and efficient strategy for combating this disease. However, the lack of resistant resources has been a major bottleneck in breeding for wheat disease resistance. Therefore, revealing novel gene resources for combating stripe rust and elucidating the underlying resistance mechanism is of utmost urgency. In this study, we identified that the soybean NF‐YB transcription factor GmNF‐YB20 in wheat provides resistance to the stripe rust fungus (Puccinia striiformis f. sp. tritici, Pst). Wheat lines with stable overexpression of the GmNF‐YB20 enhanced resistance against multiple Pst races. Transcriptome profiling of GmNF‐YB20 transgenic wheat under Pst infection unveiled its involvement in the lipid signaling pathway. RT‐qPCR assays suggested that GmNF‐YB20 increased transcript levels of multiple nonspecific lipid transfer protein (LTP) genes during wheat‐Pst interaction, luciferase reporter analysis illustrates that it activates the transcription of TaLTP1.50 in wheat protoplast, and GmNF‐YB20 overexpressed wheat plants had higher total LTP content in vivo during Pst infection. Overexpression of TaLTP1.50 in wheat significantly increased resistance to Pst, whereas knockdown of TaLTP1.50 exhibited the opposite trends, indicating that TaLTP1.50 plays a positive role in wheat resistance. Taken together, our findings provide perspective regarding the molecular mechanism of GmNF‐YB20 in wheat and highlight the potential use for wheat breeding. Summary statement: The soybean transcription factor GmNF‐YB20 confers resistance to stripe rust in transgenic wheat by regulating nonspecific lipid transfer protein genes. Our findings provide perspective regarding the molecular mechanism of GmNF‐YB20 in wheat and highlight the potential use for wheat breeding. [ABSTRACT FROM AUTHOR]

Terminal heat stress and foliar diseases like rusts and spot blotch are the major concerns for sustainable wheat production in South Asia. Eastern Indo-Gangetic plains witness the crucial role of heat stress during grain-filling duration (GFD) and occurrence of rust diseases and spot blotch in wheat. One hundred promising wheat genotypes were selected from five international wheat yield trials and evaluated at three sites in India for yield components and disease resistance. To identify potential donors, these lines were further screened under timely sown (normal sown) and late sown (heat stress) conditions. Analysis of variation in the studied traits revealed significant differences among all the genotypes in both environments. Grain yield showed a positive and significant correlation with NDVI, chlorophyll index, flag leaf length, flag leaf area, tiller per plant, number of grains per spike, peduncle length and 1000 grain weight (TGW) in both environments. Grain zinc and iron content was substantially increased under late sown condition. As per heat susceptibility index of GFD, TGW, NDVI and grain yield per plot, 10 tested entries were found heat tolerant. Ten promising entries with low disease score were listed as spot blotch donors. Markers linked with seven rust resistance genes, three spot blotch genes and two markers linked with quality-related traits, namely yellow pigment (Psy-A1) and polyphenol oxidase activity (Ppo-1A) and rust pathotypes, were also used to identify the presence of individual genes. Promising entries 46 (CWYT-613; GID 7631433) and 58 (41ESWYT-137; GID 8240588), common for both tested conditions, were identified and promoted under the breeding programme. [ABSTRACT FROM AUTHOR]

AbstractWestern white pine (Pinus monticola) with genetic tolerance to white pine blister rust disease caused by Cronartium ribicola constitutes an invaluable resource for the mitigation of this disease as well as the restoration of the species and its utilization in managed forests. In the last several years, typical root-rot symptoms and sudden tree death have been observed in some western white pine plantations located in British Columbia (BC) in Canada, and a few Phytophthora species were found to be associated with symptomatic trees. Our objectives were to survey one of the plantations located in south-west BC on Vancouver Island to confirm the presence of these Phytophthora species and other oomycetes and test their pathogenicity on western white pine by completing Koch’s postulates. We used direct plating of root samples on PARP(H)-CMA media and by baiting for oomycetes in soil and root samples. Ten oomycetes, including four Phytophthora species (Phytophthora cinnamomi, P. cactorum-like, P. cryptogea and P. pseudocryptogea) were isolated from roots and soil samples of diseased Pi. monticola trees. The Phytophthora species were identified using ITS, β-tubulin and TEF1 gene regions. Koch’s postulates were validated with controlled inoculations of 1-year old seedlings; mortality occurred as early as 15 days after inoculation with P. cinnamomi when the seedlings were maintained in warm temperature conditions (25°C). Molecular typing of two P. cinnamomi cultures using Oxford Nanopore MinIONTM sequencing indicated that they belong to one of the two main clonal clusters of mating type A2 that have been recognized as the main drivers of the global P. cinnamomi epidemic. [ABSTRACT FROM AUTHOR]

Soybean is one of the most economically important crops worldwide. However, soybean yield can be substantially decreased by many diseases. Soybean genotypes could have different reactions to pathogen infection. As a first step toward investigating the biochemical basis of soybean resistance and susceptibility to disease, phytochemicals in the seeds of 52 soybean genotypes previously reported to have different reactions to diseases of soybean rust (SBR), Phomopsis seed decay (PSD), and purple seed stain (PSS) were analyzed. Using GC-MS, a total of 46 compounds were tentatively identified which included 11 chemical groups. Among those, the major group was esters, followed by carboxylic acid, ketone, and sugar moieties. Compounds having reported antioxidant, anti-microbial, and anti-inflammatory activities were also identified. UHPLC-DAD/MS analysis indicated that there were five major isoflavone components presented in the samples, including daidzin, glycitin, genistin, malonyldaidzin, and malonylglycitin. Isoflavones have been reported to play an important role in defense from plant pathogens. Although there was variance in the isoflavone content among soybean genotypes, those with the SBR resistance Rpp6 gene (PI 567102B, PI 567104B, PI 567129) consistently exhibited the highest concentrations of daidzin, glycitin, genistin, and malonyldaidzin. The SBR resistant genotype, PI 230970 (Rpp2) had the greatest amount of genistin. The SBR resistant genotype, PI 200456 (Rpp5) resistant genotype uniquely contained glycitein, a compound that was absent in the other 51 genotypes examined. A PSD-resistant genotype PI 424324B had nearly four times the amount of stigmasterol as PI 556625, which was susceptible to SBR, PSD, and PSS in our previous tests. Results of this study provide useful information for further investigation of the biochemical basis of soybean resistance to diseases. The results may also aid in selection of soybean lines for breeding for resistance to soybean rust and other diseases. [ABSTRACT FROM AUTHOR]

White rust disease caused by a biotrophic oomycete Albugo candida is one of the most serious impediments in realizing the production potential of Brassica juncea. Due to the obligate nature of the pathogen, R-gene-based resistance is unstable as the newer virulent races emerge quickly. For this, a deep understanding of the molecular basis of resistance is essential for developing durable resistant varieties. In this study, we selected one susceptible cultivar, 'Pusa Jaikisan' and its single R gene based resistant NIL, 'Pusa Jaikisan WRR as the source of understanding the defense mechanism in B. juncea against A. candida. Comparative histochemical analysis at 12 dpi showed higher callose deposition in the resistant cultivar than in the susceptible which hints towards its possible role in defense mechanism. Based on the biochemical markers observation, total protein was found to have a negative correlation with the resistance. The antioxidant enzymes (POX, CAT, and SOD) and non-enzymatic ROS scavenging compounds such as polyphenols and proline showed a positive correlation with the white rust resistance. Polyphenol Oxidase (PPO) total chlorophyll and total carotenoids were also found to be more abundant in the 'Pusa Jaikisan WRR'. Based on the heat map analysis, PAL was identified to be the comparatively most induced enzyme involved in the defense mechanism. The polyphenol oxidase, total chlorophyll and total carotenoids were also found to show higher activity in the 'Pusa Jaikisan WRR'. Furthermore, to study the defense response of 'Pusa Jaikisan WRR' compared to 'Pusa Jaikisan' against A. candida infection, the gene expression analyses of salicylic acid (SA)-marker PR protein genes (PR1 and PR2) and jasmonic acid (JA)-marker PR protein genes (PR3 and PR12) were done by qRT-PCR. Based on the results, PR2 emerged as the best possible gene for defense against A. candida followed by PR1. PR3 and PR12 also showed positive correlation with the disease resistance which may be due to the JA pathway acting complementary to the SA pathway in case of B. juncea-A. candida interaction. This provides evidence for the JA-SA hormonal crosstalk to be synergistic in case of the white rust resistance. [ABSTRACT FROM AUTHOR]

Leaf rust (caused by Puccinia triticina Erikss., Pt) is a severe foliar disease of cultivated wheat worldwide. Severe development of the disease results in significant losses in seed yield and quality. Growing immune varieties is the most rational method for Pt control in terms of effectiveness and ecological safety. However, the gene pool of cultivated wheat is very narrow for seedling Pt effective resistance genes, which hampers breeding for this trait. One of the well-known methods to broaden genetic diversity for resistance is the introgression of highly effective genes from wild relatives into the genomes of cultivated wheat. The Aegilops L. species have been proven to be perfectly suited for this purpose. No gene for Pt resistance has been transferred to wheat from Aegilops biuncialis Vis. (Lorent's goatgrass) up to now. Previously, we selected eight accessions of the species from the VIR (N.I. Vavilov All-Russian Institute of Plant Genetic Resources) genebank that showed a perfect level of resistance to leaf rust. In this research, we studied the genetic control of resistance using hybridological, phytopathological, and molecular analyses. According to the F1–F3 hybrid evaluation results, each accession possesses one dominant gene for Pt resistance, and genes in different accessions are allelic or very tightly linked. Phytopathological test clone analysis showed that this gene is not identical to Lr9, Lr19, Lr24, Lr39, and Lr47, which are effective against Pt populations in some areas of Russia. This conclusion was partially supported by the results of the identification of DNA markers specific to these genes in bread wheat. Thus, we identified one dominant gene (temporarily symbolized as LrBi1) for effective seedling Pt resistance; it is recommended for introgression to cultivated wheat via interspecific hybridization. [ABSTRACT FROM AUTHOR]

Chrysomyxa rusts cause significant damage to spruce in both natural forests and plantations. Particularly, Three Chrysomyxa species, Chrysomyxa deformans, Chrysomyxa qilianensis, and Chrysomyxa rhododendri, listed as National Forest Dangerous Pests in China, have severely affected many economically and ecologically important spruce native species in China. Also, Chrysomyxa arctostaphyli, an important plant quarantine fungus, causes a damaging broom rust disease on spruce. Therefore, rapid, and efficient detection tools are urgently needed for proper rust disease detection and management. In this study, a sensitive, genus-specific loop-mediated isothermal amplification (LAMP) assay targeting the ITS-28S rRNA region was developed to detect the presence of Chrysomyxa in spruce needle and bud samples. After optimization and validation, the LAMP assay was found to be sensitive to detect as low as 5.2 fg/µL DNA, making it suitable for rapid on-site testing for rust infection. The assay was also specific to Chrysomyxa species, with no positive signals from other rust genus/species. The application of LAMP in the early detection of rust infections in spruce needles and buds was investigated, and spatial colonization profiles as well as the means of overwintering of Chrysomyxa woroninii in infected buds and branches were verified using the LAMP assay. This LAMP detection method will facilitate further studies on the characteristics of the life cycle and inoculation of other systemic rusts. [ABSTRACT FROM AUTHOR]

The maize leaf diseases create severe yield reductions and critical problems. The maize leaf disease should be discovered early, perfectly identified, and precisely diagnosed to make greater yield. This work studies three main leaf diseases: common rust, blight, and grey leaf spot. This approach involves pre-processing, including sampling and labelling, while ensuring class balance and preventing overfitting via the SMOTE algorithm. The maize leaf dataset with augmentation was used to classify these diseases using several deep-learning pre-trained networks, including VGG16, Resnet34, Resnet50, and SqueezeNet. The model was evaluated using a maize leaf dataset that included various leaf classes, mini-batch sizes, and input sizes. Performance measures, recall, precision, accuracy, F1-score, and confusion matrix were computed for each network. The SqueezeNet learning model produces an accuracy of 97% in classifying four different classes of plant leaf datasets. Comparatively, the SqueezeNet learning model has improved accuracy by 2–5% and reduced the mean square error by 4–11% over VGG16, Resnet34, and Resnet50 deep learning models. [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]

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]

Barley crops are at risk of being attacked by several leaf diseases. Net blotch, brown rust, Rhynchosporium and Ramularia leaf spot are among the most widespread and can cause severe attack and yield losses. Two trial protocols targeting Ramularia and net blotch, respectively, have been tested in several countries in 2021 and 2022. Ramularia trials were situated in Germany, Ireland, Scotland, and Denmark. The net blotch trials were placed in Denmark, Belgium, the UK, Germany, Finland, and France. In the two protocols, 12–13 different fungicide solutions including co-formulations of DMIs, SDHIs, QoIs, and multi-site inhibitors have been tested to compare efficacy and yield responses. Against Ramularia leaf spot, the fungicides were applied at GS 47–51 and against net blotch at GS 37–45. In six trials, the efficacy against Ramularia leaf spot was scored. The results showed a superior control from the co-formulation fluxapyroxad + metyltetraprole (78–100% control), but also solo mefentrifluconazole and the mixtures fluxapyroxad + mefentrifluconazole performed well (average 74–76% control). The mixture fluxapyroxad + metyltetraprole provided the best yield increase followed by Ascra Xpro. Folpet as a solo solution was inferior. Following the net blotch protocol, only three trials developed enough disease to rank the different fungicides; however, in five trials ranking against brown rust was also possible. Most treatments gave very good control of net blotch, and brown rust (> 80% control). The mixture fluxapyroxad + metyltetraprole delivered the best control against all diseases overall. Average yield responses from eight trials showed very similar increases from the tested fungicides. [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]

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]

The article examines brown rust development in sugarcane in relation to weather parameters in Western Maharashtra, India. The study observes the effect of maximum and minimum temperature, morning relative humidity, afternoon relative humidity and rainfall on the incidence and build-up of common rust on sugarcane. It measures the standard residuals of percent disease index of common rust of sugarcane.

Rust fungi (Pucciniales) are plant pathogens that can cause devastating yield losses to economically important crops and threaten native plants with extinction. Rusts are usually controlled with fungicides when rust-resistant plant varieties are unavailable. However, natural enemies may offer an alternative to chemicals by acting as biological controls. The larvae of Mycodiplosis Rübsaamen (49 spp.) feed on the spores of rusts and powdery mildew fungi and have been suggested as a potential biocontrol candidate for disease-causing rusts. However, little is known about the phylogenetic relationships, biogeography, and host range of this genus. We screened 5,665 rust specimens from fungarium specimens and field collections and recovered a total of 363 larvae on 315 rust specimens from 17 countries. Three mitochondrial and 2 nuclear loci were amplified and sequenced for the phylogenetic reconstruction of 129 individuals. We recovered 12 clades, of which 12 and 10 were supported with maximum likelihood and Bayesian inference, respectively. Of the 12 clades, 7 comprised species from multiple continents and climatic regions, and 5 comprised species from a single region. Individuals forming clades were collected from 2 to 18 rust species, suggesting that Mycodiplosis species have a broad host range. In total, Mycodiplosis larvae were identified on 44 different rust species collected from 18 plant families. Future studies should focus on expanding field sampling efforts, including data from additional gene regions, and incorporating morphological data to further elucidate species diversity and distribution patterns. [ABSTRACT FROM AUTHOR]

Employing race‐specific resistance genes remains an effective strategy to protect wheat from leaf rust caused by Puccinia triticina (Pt) worldwide, while the newly emerged Pt races, owing to rapid genetic evolution, frequently overcome the immune response delivered by race‐specific resistance genes. The molecular mechanisms underlying the newly evolved virulence Pt pathogen remain unknown. Here, we identified an avirulence protein AvrLr15 from Pt that induced Lr15‐dependent immune responses. Heterologously produced AvrLr15 triggered pronounced cell death in Lr15‐isogenic wheat leaves. AvrLr15 contains a functional signal peptide, localized to the plant nucleus and cytosol and can suppress BAX‐induced cell death. Evasion of Lr15‐mediated resistance in wheat was associated with a deletion and point mutations of amino acids in AvrLr15 rather than AvrLr15 gene loss in the Lr15‐breaking Pt races, implying that AvrLr15 is required for the virulence function of Pt. Our findings identified the first molecular determinant of wheat race‐specific immunity and facilitated the identification of the first AVR/R gene pair in the Pt–wheat pathosystem, which will provide a molecular marker to monitor natural Pt populations and guide the deployment of Lr15‐resistant wheat cultivars in the field. [ABSTRACT FROM AUTHOR]