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Wheat stripe rust, triggered by Puccinia striiformis f. sp. tritici, is among the most widespread and damaging wheat (Triticum L.) diseases. The development of cultivars harboring adult plant resistance (APR) to stripe rust is a better approach to control the disease. The current study aimed to map APR to stripe rust via the QTL mapping of 165 F2–6 recombinant inbred lines (RILs), derivatives of Weimai 8/Zhengzhou 5389. The collection of phenotypic data for the stripe-rust resistance of both parents and all 165 RILs were conducted at Baoding, Hebei Province, during the 2016–2017 cropping seasons, and at Mianyang, Sichuan Province, during the 2017–2018 and 2018–2019 sowing seasons. The RIL populations and parents were also genotyped with 860 pairs of simple-sequence-repeat (SSR) primers to map APR QTLs to stripe-rust resistant. Moreover, a 55K SNP chip was used for small group bulk segregant analysis conducted to locate the genetic map location and concentration of the SNP markers on the wheat genome. Inclusive composite interval mapping (IciMapping 3.2) software identified four QTLs of stripe-rust resistance on chromosomes 1B, 2AS, 2BS, and 7DS, named QYr.wmy-1B, QYr.wmy-2AS, QYr.wmy-2BS, and QYr.wmy-7DS, which significantly explained 11.56–16.64%, 9.35–12.70%, 7.27–9.95%, and 11.49–15.07% of the phenotypic variation, respectively. All these QTLs were found from the resistant parent, Weimai 8. Meanwhile, the QTLs located on chromosomes 1B and 2AS were found close to Yr18 and Yr9, respectively. Furthermore, the results indicated that QYr.wmy-1B is possibly Yr9 and QYr.wmy-2AS is similar to Yr18 or might be a new QTL, whilst QYr.wmy-2BS and QYr.wmy-7DS were found to be different from previously reported stripe-rust-resistance QTLs and are possibly new QTLs. Overall, the QTLs and their closely associated molecular markers detected in this study could be a great source of input for marker-assisted selection to adult plant stripe-rust resistance in wheat-breeding programs.

Ca2+ plays a crucial role as a secondary messenger in plant development and response to abiotic/biotic stressors. Calcium-dependent protein kinases (CDPKs/CPKs) are essential Ca2+ sensors that can convert Ca2+ signals into downstream phosphorylation signals. However, there is limited research on the function of CDPKs in the context of wheat–Puccinia striiformis f. sp. tritici (Pst) interaction. In this study, we aimed to address this gap by identifying putative CDPK genes from the wheat reference genome and organizing them into four phylogenetic clusters (I-IV). To investigate the expression patterns of the TaCDPK family during the wheat–Pst interaction, we analyzed time series RNA-seq data and further validated the results through qRT-PCR assays. Among the TaCDPK genes, TaCDPK7 exhibited a significant induction during the wheat–Pst interaction, suggesting that it has a potential role in wheat resistance to Pst. To gain further insights into the function of TaCDPK7, we employed virus-induced gene silencing (VIGS) to knock down its expression which resulted in impaired wheat resistance to Pst, accompanied by decreased accumulation of hydrogen peroxide (H2O2), increased fungal biomass ratio, reduced expression of defense-related genes, and enhanced pathogen hyphal growth. These findings collectively suggest that TaCDPK7 plays an important role in wheat resistance to Pst. In summary, this study expands our understanding of wheat CDPKs and provides novel insights into their involvement in the wheat–Pst interaction.

Wheat stripe rust (yellow rust) caused by Puccinia striiformis f. sp. tritici (Pst) is a serious biotic stress factor limiting wheat production worldwide. Emerging evidence demonstrates that long non-coding RNAs (lncRNAs) participate in various developmental processes in plants via post-transcription regulation. In this study, RNA sequencing (RNA-seq) was performed on a pair of near-isogenic lines—rust resistance line FLW29 and rust susceptible line PBW343—which differed only in the rust susceptibility trait. A total of 6,807 lncRNA transcripts were identified using bioinformatics analyses, among which 10 lncRNAs were found to be differentially expressed between resistance and susceptible lines. In order to find the target genes of the identified lncRNAs, their interactions with wheat microRNA (miRNAs) were predicted. A total of 199 lncRNAs showed interactions with 65 miRNAs, which further target 757 distinct mRNA transcripts. Moreover, detailed functional annotations of the target genes were used to identify the candidate genes, pathways, domains, families, and transcription factors that may be related to stripe rust resistance response in wheat plants. The NAC domain protein, disease resistance proteins RPP13 and RPM1, At1g58400, monodehydroascorbate reductase, NBS-LRR-like protein, rust resistance kinase Lr10-like, LRR receptor, serine/threonine-protein kinase, and cysteine proteinase are among the identified targets that are crucial for wheat stripe rust resistance. Semiquantitative PCR analysis of some of the differentially expressed lncRNAs revealed variations in expression profiles of two lncRNAs between the Pst-resistant and Pst-susceptible genotypes at least under one condition. Additionally, simple sequence repeats (SSRs) were also identified from wheat lncRNA sequences, which may be very useful for conducting targeted gene mapping studies of stripe rust resistance in wheat. These findings improved our understanding of the molecular mechanism responsible for the stripe rust disease that can be further utilized to develop wheat varieties with durable resistance to this disease.

Wheat yield has been constrained by stripe rust disease globally. A wheat landrace (Qishanmai, QSM) consistently showed lower stripe rust severities in multiple year studies than susceptible check varieties including Suwon11 (SW) at the adult plant stage. To detect QTL for reducing the severity in QSM, 1218 recombinant inbred lines (RILs) were developed from SW x QSM. QTL detection was conducted firstly using 112 RILs selected for similarity in pheno- morphological characters. The 112 RILs were assessed for stripe rust severity at the 2nd leaf, 6th leaf and flag leaf stages under field and greenhouse conditions, and genotyping was done primarily with a single nucleotide polymorphism (SNP) array. On the basis of these phenotypic and genotypic data, a major QTL (QYr.cau-1DL) was detected on chromosome 1D at the 6th leaf and flag leaf stages. Further mapping was conducted by genotyping 1218 RILs using new simple sequence repeat (SSR) markers, which were developed by referring to the sequences of the wheat line Chinese Spring (IWGSC RefSeq v1.0). QYr.cau-lDL was mapped within a 0.5 cM (5.2 Mb) interval delimited by the SSR markers 1D- 320.58 and 1D-325.79. These markers were applied to select for QYr.cau-lDL by screening F2 or BC4F2 plants of the wheat crosses RL6058 x QSM, Lantian10 x QSM and Yannong21 x QSM. F2:3 or BC4F2:3 families derived from the selected plants were assessed for stripe rust resistance in the fields of two locations and in a greenhouse. Wheat plants carrying the resistant marker haplotype in homozygous state for QYr.cau-lDL showed lower stripe rust severities (by 44% to 48%) than plants lacking this QTL. The trial of RL6058 (a carrier of Yr18) x QSM also indicated that QYr.cau-lDL had larger effect than Yr18 on reducing severity; they acted synergistically, yielding an elevated level of stripe rust resistance. [ABSTRACT FROM AUTHOR]

Brassinazole-resistant (BZR) transcription factors (TFs) are key players in brassinolides (BRs) signaling pathway, which is widely involved in regulating plant growth and development, as well as in plant responding to a variety stresses. Despite their critical roles, little is known about BZR TFs in wheat. In this study, we performed genome-wide analysis of BZR gene family from wheat genome, and 20 TaBZRs were identified. Based on the phylogenetic relationships of TaBZR and BZRs from rice and Arabidopsis, all BZR genes were clustered into four groups. The intron-exon structural patterns and conserved protein motifs of TaBZRs showed high group specificity. TaBZR5, 7, and 9 were significantly induced after salt, drought treatment, and stripe rust infection. However, TaBZR16, which was significantly upregulated under NaCl application, was not expressed during wheat-stripe rust fungus interaction. These results indicated that BZR genes in wheat play different roles in response to various stresses. The results of this study will lay a foundation for further in-depth functional studies of TaBZRs and will provide information for the breeding and genetic improvement of wheat against drought and salt stresses. [ABSTRACT FROM AUTHOR]

Thirteen known Yr gene-associated markers pertaining to genes (Yr5,Yr10,Yr15,Yr24/Yr26) were used to identify the genes in selected wheat germplasm which were found resistant under field conditions at two locations in Punjab, India against stripe rust. In field evaluation, 38 genotypes exhibited highly resistant response, with a final rust severity (FRS) ranging from 0 to TR. Seven genotypes expressed a resistant to moderately resistant response with FRS ranging from 5MR–10S. In race-specific phenotying against most prevalent pathotypes of Pucciniastriiformistritici (46S119,110S119 &238S119) by seedling reaction test (SRT) 14 genotypes (29.2%) were found to be immune (IT = 0), 28 genotypes (58.3%) were resistant (IT = 1), and 3 genotypes (6.3%) were moderately resistant (IT = 2). Yr5 was detected in sixteen lines with the help of two markers Xwmc175 and Xgwm120 linked with Yr5. Yr10 was detected in ten lines with the marker Xpsp3000 and Yr15 was detected in fourteen lines with two linked markers; Xgwm413 and Xgwm273. Likewise, Yr24/26 was detected in 15 lines with two linked markers, namely Xbarc181 and Xbarc187. Based on the race specific phenotyping data and marker data, fourteen lines were found to carry a single gene, 16 showed the presence of two gene combinations, and seven genotypes were found to have a combination of three genes. Frequencies of Yr5, Yr15 and Yr26/Yr24 was high among test wheat germplasm in comparison to Yr10. [ABSTRACT FROM AUTHOR]

Wheat is one of the major food crops in the world. However, stripe rust fungus significantly decreases wheat yield and quality. In the present study, transcriptomic and metabolite analyses were conducted in R88 (resistant line) and CY12 (susceptible cultivar) during Pst-CYR34 infection due to the limited availability of information regarding the underlying mechanisms governing wheat–pathogen interactions. The results revealed that Pst infection promoted the genes and metabolites involved in phenylpropanoid biosynthesis. The key enzyme gene TaPAL to regulate lignin and phenolic synthesis has a positive resistance contribution to Pst in wheat, which was verified by the virus-induced gene silencing (VIGS) technique. The distinctive resistance of R88 is regulated by the selective expression of genes involved in the fine-tuning of wheat–Pst interactions. Furthermore, metabolome analysis suggested that lignin biosynthesis-related metabolite accumulation was significantly affected by Pst. These results help to elucidate the regulatory networks of wheat–Pst interactions and pave the way for durable resistance breeding in wheat, which may ease environmental and food crises around the world. [ABSTRACT FROM AUTHOR]

Blumeria graminis forma specialis tritici (B.g. tritici) is the airborne fungal pathogen that causes powdery mildew disease on hexaploid bread wheat. Calmodulin-binding transcription activators (CAMTAs) regulate plant responses to environments, but their potential functions in the regulation of wheat–B.g. tritici interaction remain unknown. In this study, the wheat CAMTA transcription factors TaCAMTA2 and TaCAMTA3 were identified as suppressors of wheat post-penetration resistance against powdery mildew. Transient overexpression of TaCAMTA2 and TaCAMTA3 enhanced the post-penetration susceptibility of wheat to B.g. tritici, while knockdown of TaCAMTA2 and TaCAMTA3 expression using transient- or virus-induced gene silencing compromised wheat post-penetration susceptibility to B.g. tritici. In addition, TaSARD1 and TaEDS1 were characterized as positive regulators of wheat post-penetration resistance against powdery mildew. Overexpressing TaSARD1 and TaEDS1 confers wheat post-penetration resistance against B.g. tritici, while silencing TaSARD1 and TaEDS1 enhances wheat post-penetration susceptibility to B.g. tritici. Importantly, we showed that expressions of TaSARD1 and TaEDS1 were potentiated by silencing of TaCAMTA2 and TaCAMTA3. Collectively, these results implicated that the Susceptibility genes TaCAMTA2 and TaCAMTA3 contribute to the wheat–B.g. tritici compatibility might via negative regulation of TaSARD1 and TaEDS1 expression. [ABSTRACT FROM AUTHOR]

SUMMARY: Protein–protein interactions (PPIs) are a fundamental process in cellular biogenesis. Here we have developed a split GAL4 RUBY assay that enables macroscopically visual PPI detection in plant leaves in real time. Candidate interacting protein partners are fused to specific domains of the yeast GAL4 and herpes simplex virus VP16 transcription factors and transiently expressed in Nicotiana benthamina leaves by Agrobacterium infiltration. PPI, that may be either direct or indirect, results in transcriptional activation of a RUBY reporter gene leading to the production of the highly visual metabolite, betalain, in leaf tissue of living plants. Samples require no processing for in planta visual qualitative assessment, but with very simple processing steps the assay is quantitative. Its accuracy is demonstrated using a series of known interacting protein partners and mutant derivatives including transcription factors, signalling molecules and plant resistance proteins with cognate pathogen effectors. Using this assay, association between the wheat Sr27 stem rust disease resistance protein and corresponding AvrSr27 avirulence effector family produced by the rust pathogen is detected. Interaction is also observed between this resistance protein and the effector encoded by the corresponding avrSr27‐3 virulence allele. However, this association appears weaker in the split GAL4 RUBY assay, which coupled with lower avrSr27‐3 expression during stem rust infection, likely enables virulent races of the rust pathogen to avoid Sr27‐mediated detection. Significance Statement: Most proteins do not function in isolation, and understanding what proteins they interact with can provide key insights into their structure and function. Here we have developed a visual protein–protein interaction assay that detects protein interaction in plant leaves in real time. [ABSTRACT FROM AUTHOR]

Stripe rust, which is caused by Puccinia striiformis f. sp. tritici, is one of the most devastating foliar diseases of common wheat worldwide. Breeding new wheat varieties with durable resistance is the most effective way of controlling the disease. Tetraploid Thinopyrum elongatum (2n = 4x = 28, EEEE) carries a variety of genes conferring resistance to multiple diseases, including stripe rust, Fusarium head blight, and powdery mildew, which makes it a valuable tertiary genetic resource for enhancing wheat cultivar improvement. Here, a novel wheat–tetraploid Th. elongatum 6E (6D) disomic substitution line (K17-1065-4) was characterized using genomic in situ hybridization and fluorescence in situ hybridization chromosome painting analyses. The evaluation of disease responses revealed that K17-1065-4 is highly resistant to stripe rust at the adult stage. By analyzing the whole-genome sequence of diploid Th. elongatum, we detected 3382 specific SSR sequences on chromosome 6E. Sixty SSR markers were developed, and thirty-three of them can accurately trace chromosome 6E of tetraploid Th. elongatum, which were linked to the disease resistance gene(s) in the wheat genetic background. The molecular marker analysis indicated that 10 markers may be used to distinguish Th. elongatum from other wheat-related species. Thus, K17-1065-4 carrying the stripe rust resistance gene(s) is a novel germplasm useful for breeding disease-resistant wheat cultivars. The molecular markers developed in this study may facilitate the mapping of the stripe rust resistance gene on chromosome 6E of tetraploid Th. elongatum. [ABSTRACT FROM AUTHOR]

Thirteen known Yr gene-associated markers pertaining to genes (Yr5,Yr10,Yr15,Yr24/Yr26) were used to identify the genes in selected wheat germplasm which were found resistant under field conditions at two locations in Punjab, India against stripe rust. In field evaluation, 38 genotypes exhibited highly resistant response, with a final rust severity (FRS) ranging from 0 to TR. Seven genotypes expressed a resistant to moderately resistant response with FRS ranging from 5MR–10S. In race-specific phenotying against most prevalent pathotypes of Pucciniastriiformistritici (46S119,110S119 &238S119) by seedling reaction test (SRT) 14 genotypes (29.2%) were found to be immune (IT = 0), 28 genotypes (58.3%) were resistant (IT = 1), and 3 genotypes (6.3%) were moderately resistant (IT = 2). Yr5 was detected in sixteen lines with the help of two markers Xwmc175 and Xgwm120 linked with Yr5. Yr10 was detected in ten lines with the marker Xpsp3000 and Yr15 was detected in fourteen lines with two linked markers; Xgwm413 and Xgwm273. Likewise, Yr24/26 was detected in 15 lines with two linked markers, namely Xbarc181 and Xbarc187. Based on the race specific phenotyping data and marker data, fourteen lines were found to carry a single gene, 16 showed the presence of two gene combinations, and seven genotypes were found to have a combination of three genes. Frequencies of Yr5, Yr15 and Yr26/Yr24 was high among test wheat germplasm in comparison to Yr10. [ABSTRACT FROM AUTHOR]

Puccinia striiformis f. sp. tritici (Pst) is the causative agent of wheat stripe rust, which can lead to a significant loss in annual wheat yields. Therefore, there is an urgent need for a deeper comprehension of the basic mechanisms underlying Pst infection. Effectors are known as the agents that plant pathogens deliver into host tissues to promote infection, typically by interfering with plant physiology and biochemistry. Insights into effector activity can significantly aid the development of future strategies to generate disease-resistant crops. However, the functional analysis of Pst effectors is still in its infancy, which hinders our understanding of the molecular mechanisms of the interaction between Pst and wheat. In this review, we summarize the potential roles of validated and proposed Pst effectors during wheat infection, including proteinaceous effectors, non-coding RNAs (sRNA effectors), and secondary metabolites (SMs effectors). Further, we suggest specific countermeasures against Pst pathogenesis and future research directions, which may promote our understanding of Pst effector functions during wheat immunity attempts. [ABSTRACT FROM AUTHOR]

Wheat stripe rust, caused by the obligate biotrophic fungus Puccinia striiformis f. sp. tritici (Pst), seriously affects wheat production. Here, we report the complete genome sequence and biological characterization of a new mitovirus from P. striiformis strain GS-1, which was designated as "Puccinia striiformis mitovirus 2" (PsMV2). Genome sequence analysis showed that PsMV2 is 2658 nt in length with an AU-rich of 52.3% and comprises a single ORF of 2348 nt encoding an RNA-dependent RNA polymerase (RdRp). Phylogenetic analysis indicated that PsMV2 is a new member of the genus Unuamitovirus within the family Mitoviridae. In addition, PsMV2 multiplied highly during Pst infection and it suppresses programmed cell death (PCD) triggered by Bax. Silencing of PsMV2 in Pst by barley stripe mosaic virus (BSMV)-mediated Host Induced Gene Silencing (HIGS) reduced fungal growth and decreased pathogenicity of Pst. These results indicate PsMV2 promotes host pathogenicity in Pst. Interestingly, PsMV2 was detected among a wide range of field isolates of Pst and may have coevolved with Pst in earlier times. Taken together, our results characterized a novel mitovirus PsMV2 in wheat stripe rust fungus, which promotes the virulence of its fungal host and wide distribution in Pst which may offer new strategies for disease control. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effect of the rust fungus Puccinia lagenophorae on total phenols, phenolic acids, and defense-related enzymes in the leaf tissues of the host, Senecio aegyptius. The infection increased the total phenol and defense-related enzymes in the host leaf tissues when compared to healthy tissues. The analysis using HPLC revealed the existence of 10 phenolic acids in healthy and infected host leaves. The infection increased the amounts of caffeic, chlorogenic, ferulic, p-coumaric, and salicylic acids. The examination by TEM revealed the presence of peroxidase activity on the host microbodies, Golgi bodies, endoplasmic reticulum, and the thickening of xylem vessels. After the infection, the activity was localized at the penetration sites of fungal haustoria and in amorphous materials found between the intercellular hyphae and the host cell wall. The heaviest peroxidase activity was detected in heavily infected vascular tissue, due to the monokaryotic infection. [ABSTRACT FROM AUTHOR]

Wheat stripe rust (Puccinia striiformis Westend f. sp. tritici; Pst) is a severe disease that affects wheat-growing areas worldwide. In the last few years, Pst head infection (PstHI) was recorded to cause severe yield damage in Egypt. Little information is known about PstHI. In the current study, a set of 34 Egyptian cultivars were evaluated for their Pst foliar infection (PstFI) and PstHI in two growing seasons (2021 and 2022) in Egypt. High genotypic variations in PstFI and PstHI were found. A very weak correlation was found between the resistance to PstFI and PstHI in both growing seasons. Therefore, the resistance to each symptom might be controlled by different genetic systems. The effect of PstFI and PstHI on kernel traits was investigated. PstHI was found to significantly reduce kernel width and weight in heavily diseased years. Therefore, a significant reduction in wheat yield and quality is expected in case of severe PstHI. Three Egyptian genotypes were resistant to PstFI and PstHI in both growing seasons. These genotypes could help in improving the resistance to both symptoms. However, due to the low genetic distance among them, looking for additional sources of resistance is recommended. In 2021, higher head infection was found compared with 2022. Highly significant differences in maximum temperature, minimum temperature, maximum dew point, and average dew point were found between the two growing seasons. Out of these four factors, dew point and ambient temperature were found to be possible reasons for increasing PstHI. Furthermore, 51 isolines carrying different resistance genes were included in the evaluation. At least ten stripe rust resistance genes were found to be effective against PstFI and PstHI. These ten genes should be included in future breeding programs to improve Pst resistance and understand the effect of climate change on Pst. [ABSTRACT FROM AUTHOR]

Puccinia, which comprises 4000 species, is the largest genus of rust fungi and one of the destructive plant pathogenic rust genera that are reported to infect both agricultural and nonagricultural plants with severe illnesses. The presence of bi-celled teliospores is one of the major features of these rust fungi that differentiated them from Uromyces, which is another largest genus of rust fungi. In the present study, an overview of the current knowledge on the general taxonomy and ecology of the rust genus Puccinia is presented. The status of the molecular identification of this genus along with updated species numbers and their current statuses in the 21st century are also presented, in addition to their threats to both agricultural and nonagricultural plants. Furthermore, a phylogenetic analysis based on ITS and LSU DNA sequence data available in GenBank and the published literature was performed to examine the intergeneric relationships of Puccinia. The obtained results revealed the worldwide distribution of Puccinia. Compared with other nations, a reasonable increase in research publications over the current century was demonstrated in Asian countries. The plant families Asteraceae and Poaceae were observed as the most infected in the 21st century. The phylogenetic studies of the LSU and ITS sequence data revealed the polyphyletic nature of Puccinia. In addition, the presences of too short, too lengthy, and incomplete sequences in the NCBI database demonstrate the need for extensive DNA-based analyses for a better understanding of the taxonomic placement of Puccinia. [ABSTRACT FROM AUTHOR]

Stripe rust (Puccinia striiformis f. sp. tritici (Pst)) and powdery mildew (Blumeria graminis f. sp. tritici (Bgt)) are important diseases of wheat in Canada and worldwide. Molecular detection methods permit spore detection of few spores; therefore, there is a need to determine initial inoculum thresholds for pathogens to cause disease under both controlled environments and in the field. Susceptible wheat cultivars 'Avocet' and 'AC Barrie' were inoculated with different quantities of spores (0, 103, 104, 105, 106, and 107) of Pst and Bgt. Disease incidence, severity and infection type were evaluated. Results of controlled environment studies showed that the minimum number of spores necessary to cause appreciable incidence and severity for Pst was at higher spore concentrations of 105–106 spores. Conversely, low incidence and severity levels were observed at 103–104 spores for Bgt. Despite occurrence of natural Pst infection, results of field studies in 2016 and 2017 in Southern Alberta demonstrated that significant increases in severity levels were observed following application of 1.2 × 107 spores. Collectively, these results demonstrated that stripe rust severities increased with increasing spore concentration only at high spore levels. In contrast, Bgt severity increased with spore concentration from 103 to 107 spores mL−1. In vitro and in vivo spore germination tests demonstrated germination rates of Pst spores were reduced at lower spore concentrations compared to germination rates at the higher concentrations. Understanding of minimum spore numbers required for disease development will be a prerequisite for predicting epidemics and devising fungicide control measures for future sustainable agricultural systems. [ABSTRACT FROM AUTHOR]

Wheat yellow rust (YR) is a most devastating disease in wheat worldwide. In recent years, the epidemic in China has expanded from traditional areas to the middle and lower reaches of the Yangtze River due to the changes in climate and cropping systems. To facilitate YR resistance breeding, it is meaningful to explore resistance loci from local germplasm resources. In this study, a linkage mapping was performed in a recombinant inbred line (RIL) population derived from Ningmai 9 × Yangmai 158 using a high‐density genetic map and phenotypic identification for adult plant resistance (APR) to YR in four environments. Phenotypic analysis showed that Yangmai 158 had better APR than Ningmai 9. Disease severity in different environments was significantly correlated with each other, and it was found that disease severity was significantly influenced by genotype, environment and their interaction. A total of 19 quantitative trait loci (QTLs) were identified, of which four could be detected in multiple environments and four corresponding KASP markers were then developed. Lines with different QTLs from the population including 476 chromosome segment substitution lines (CSSLs) were evaluated for APR. The results revealed that Qyr‐4B.4 and Qyr‐5B.2 could significantly reduce the disease severity, with their combination showing a better effect. The findings of the study can be beneficial for wheat YR resistance breeding in the middle and lower reaches of the Yangtze River. [ABSTRACT FROM AUTHOR]

Wheat stripe rust is one of the diseases that seriously affect wheat production worldwide. Breeding resistant cultivars is an effective way to control this disease. The wheat stripe rust resistance gene Yr62 has high-temperature adult-plant resistance (HTAP). In this study, PI 660,060, a single Yr62 gene line, was crossed with four Chinese wheat cultivars, LunXuan987 (LX987), Bainongaikang58 (AK58), ZhengMai9023 (ZM9023), and HanMai6172 (H6172). F1 seeds of four cross combinations were planted and self-crossed to develop the advance generations in the field. The seeds of each cross were mixed harvested and about 2400 to 3000 seeds were sown in each generation for F1 to F4 to maintain the maximum possible genotypes. Forty-five lines were selected and evaluated for resistance to stripe rust and agronomic traits, including plant height, number of grains per spike, and tiller number, in F5 and F6. Then, 33 lines with good agronomic traits and high disease resistance were developed to F9 generation. SSR markers Xgwm251 and Xgwm192 flank linked with the Yr62 were used to detect the presence of Yr62 in these 33 F9 lines. Of these, 22 lines were confirmed with the resistance gene Yr62. Finally, nine lines with good agronomic traits and disease resistance were successfully selected. The selected wheat lines in this study provide material support for the future breeding of wheat for stripe rust resistance. [ABSTRACT FROM AUTHOR]

Stripe rust (Sr), caused by Puccinia striiformis f. sp. tritici (Pst), is the most devastating disease that poses serious threat to the wheat-growing nations across the globe. Developing resistant cultivars is the most challenging aspect in wheat breeding. The function of resistance genes (R genes) and the mechanisms by which they influence plant-host interactions are poorly understood. In the present investigation, comparative transcriptome analysis was carried out by involving two near-isogenic lines (NILs) PBW343 and FLW29. The seedlings of both the genotypes were inoculated with Pst pathotype 46S119. In total, 1106 differentially expressed genes (DEGs) were identified at early stage of infection (12 hpi), whereas expressions of 877 and 1737 DEGs were observed at later stages (48 and 72 hpi) in FLW29. The identified DEGs were comprised of defense-related genes including putative R genes, 7 WRKY transcriptional factors, calcium, and hormonal signaling associated genes. Moreover, pathways involved in signaling of receptor kinases, G protein, and light showed higher expression in resistant cultivar and were common across different time points. Quantitative real-time PCR was used to further confirm the transcriptional expression of eight critical genes involved in plant defense mechanism against stripe rust. The information about genes are likely to improve our knowledge of the genetic mechanism that controls the stripe rust resistance in wheat, and data on resistance response–linked genes and pathways will be a significant resource for future research. [ABSTRACT FROM AUTHOR]

Summary: Blumeria graminis f. sp. tritici (Bgt) is a globally important fungal pathogen of wheat that can rapidly evolve to defeat wheat powdery mildew (Pm) resistance genes. Despite periodic regional deployment of the Pm1a resistance gene in US wheat production, Bgt strains that overcome Pm1a have been notably nonpersistent in the United States, while on other continents, they are more widely established.A genome‐wide association study (GWAS) was conducted to map sequence variants associated with Pm1a virulence in 216 Bgt isolates from six countries, including the United States. A virulence variant apparently unique to Bgt isolates from the United States was detected in the previously mapped gene AvrPm1a (BgtE‐5612) on Bgt chromosome 6; an in vitro growth assay suggested no fitness reduction associated with this variant.A gene on Bgt chromosome 8, Bgt‐51526, was shown to function as a second determinant of Pm1a virulence, and despite < 30% amino acid identity, BGT‐51526 and BGTE‐5612 were predicted to share > 85% of their secondary structure. A co‐expression study in Nicotiana benthamiana showed that BGTE‐5612 and BGT‐51526 each produce a PM1A‐dependent hypersensitive response.More than one member of a B. graminis effector family can be recognized by a single wheat immune receptor, and a two‐gene model is necessary to explain virulence to Pm1a. [ABSTRACT FROM AUTHOR]

"Mutagenomics" is the combination of random mutagenesis, phenotypic screening, and whole-genome re-sequencing to uncover all tagged and untagged mutations linked with phenotypic changes in an organism. In this study, we performed a mutagenomics screen on the wheat pathogenic fungus Zymoseptoria tritici for altered morphogenetic switching and stress sensitivity phenotypes using Agrobacterium-mediated "random" T-DNA mutagenesis (ATMT). Biological screening identified four mutants which were strongly reduced in virulence on wheat. Whole genome re-sequencing defined the positions of the T-DNA insertion events and revealed several unlinked mutations potentially affecting gene functions. Remarkably, two independent reduced virulence mutant strains, with similarly altered stress sensitivities and aberrant hyphal growth phenotypes, were found to have a distinct loss of function mutations in the ZtSSK2 MAPKKK gene. One mutant strain had a direct T-DNA insertion affecting the predicted protein's N-terminus, while the other possessed an unlinked frameshift mutation towards the C-terminus. We used genetic complementation to restore both strains' wild-type (WT) function (virulence, morphogenesis, and stress response). We demonstrated that ZtSSK2 has a non-redundant function with ZtSTE11 in virulence through the biochemical activation of the stress-activated HOG1 MAPK pathway. Moreover, we present data suggesting that SSK2 has a unique role in activating this pathway in response to specific stresses. Finally, dual RNAseq-based transcriptome profiling of WT and SSK2 mutant strains revealed many HOG1-dependent transcriptional changes in the fungus during early infection and suggested that the host response does not discriminate between WT and mutant strains during this early phase. Together these data define new genes implicated in the virulence of the pathogen and emphasise the importance of a whole genome sequencing step in mutagenomic discovery pipelines. [ABSTRACT FROM AUTHOR]

Background: Yellow or stripe rust, caused by the fungus Puccinia striiformis f. sp. tritici (Pst) is an important disease of wheat that threatens wheat production. Since developing resistant cultivars offers a viable solution for disease management, it is essential to understand the genetic basis of stripe rust resistance. In recent years, meta-QTL analysis of identified QTLs has gained popularity as a way to dissect the genetic architecture underpinning quantitative traits, including disease resistance. Results: Systematic meta-QTL analysis involving 505 QTLs from 101 linkage-based interval mapping studies was conducted for stripe rust resistance in wheat. For this purpose, publicly available high-quality genetic maps were used to create a consensus linkage map involving 138,574 markers. This map was used to project the QTLs and conduct meta-QTL analysis. A total of 67 important meta-QTLs (MQTLs) were identified which were refined to 29 high-confidence MQTLs. The confidence interval (CI) of MQTLs ranged from 0 to 11.68 cM with a mean of 1.97 cM. The mean physical CI of MQTLs was 24.01 Mb, ranging from 0.0749 to 216.23 Mb per MQTL. As many as 44 MQTLs colocalized with marker–trait associations or SNP peaks associated with stripe rust resistance in wheat. Some MQTLs also included the following major genes- Yr5, Yr7, Yr16, Yr26, Yr30, Yr43, Yr44, Yr64, YrCH52, and YrH52. Candidate gene mining in high-confidence MQTLs identified 1,562 gene models. Examining these gene models for differential expressions yielded 123 differentially expressed genes, including the 59 most promising CGs. We also studied how these genes were expressed in wheat tissues at different phases of development. Conclusion: The most promising MQTLs identified in this study may facilitate marker-assisted breeding for stripe rust resistance in wheat. Information on markers flanking the MQTLs can be utilized in genomic selection models to increase the prediction accuracy for stripe rust resistance. The candidate genes identified can also be utilized for enhancing the wheat resistance against stripe rust after in vivo confirmation/validation using one or more of the following methods: gene cloning, reverse genetic methods, and omics approaches. [ABSTRACT FROM AUTHOR]

Chitin is the main component of fungal cell walls, which can be recognized by pattern recognition receptors (PRRs) as pathogen-associated molecular patterns (PAMP). Chitinase in filamentous fungi has been reported to degrade immunogenic chitin oligomers, thereby preventing chitin-induced immune activation. In this study, we identified the chitinase families in 10 fungal genomes. A total of 131 chitinase genes were identified. Among the chitinase families, 16 chitinase genes from Puccinia striiformis f. sp. tritici (Pst) were identified, and the expression of PstChia1 was the highest during Pst infection. Further studies indicated that PstChia1 is highly induced during the early stages of the interaction of wheat and Pst and has chitinase enzyme activity. The silencing of PstChia1 revealed that PstChia1 limited the growth and reduced the virulence of Pst. The expression level of TaPR1 and TaPR2 was induced in PstChia1 knockdown plants, suggesting that PstChia1 is involved in regulating wheat resistance to Pst. Our data suggest that PstChia1 contributes to pathogenicity by interfering with plant immunity and regulating the growth of Pst. [ABSTRACT FROM AUTHOR]

Rye (Secale cereale L.) is an important genetic resource for improving the disease resistance of wheat. An increasing number of rye chromosome segments have been transferred into modern wheat cultivars via chromatin insertions. In this study, 185 recombinant inbred lines (RILs) derived from a cross between a wheat accession containing rye chromosomes 1RS and 3R and a wheat-breeding founder parent Chuanmai 42 from southwestern China were used to decipher the cytological and genetic effects of 1RS and 3R via fluorescence/genomic in situ hybridization and quantitative trait locus (QTL) analyses. Chromosome centromere breakage and fusion were detected in the RIL population. Additionally, the recombination of chromosomes 1BS and 3D from Chuanmai 42 was completely suppressed by 1RS and 3R in the RIL population. In contrast to chromosome 3D of Chuanmai 42, rye chromosome 3R was significantly associated with white seed coats and decreased yield-related traits, as revealed by QTL and single marker analyses, whereas it had no effect on stripe rust resistance. Rye chromosome 1RS did not affect yield-related traits and it increased the susceptibility of plants to stripe rust. Most of the detected QTLs that positively affected yield-related traits were from Chuanmai 42. The findings of this study suggest that the negative effects of rye-wheat substitutions or translocations, including the suppression of the pyramiding of favorable QTLs on paired wheat chromosomes from different parents and the transfer of disadvantageous alleles to filial generations, should be considered when selecting alien germplasm to enhance wheat-breeding founder parents or to breed new varieties. [ABSTRACT FROM AUTHOR]

Plant cell walls are composed of polysaccharides such as cellulose, hemicelluloses, and pectins, whose location and function differ depending on plant type. UDP‐Ara mutases (UAMs) have been reported to play important roles in plant development and response to various plant stresses (abiotic and biotic). However, little work has been reported on UAM in wheat. In this study, we dissected the role of the UAM family member, UAM3, during the interaction between wheat and the stripe rust fungus, Puccinia striiformis f. sp. tritici (Pst), and in response to treatment with salicylic acid (SA). RNA interference (RNAi)‐based stable silencing of TaUAM3 resulted in decreased resistance to Pst fungus. In addition, CRISPR‐mediated genome editing (GE) of TaUAM3 enhanced the susceptibility of wheat to Pst or compromised disease resistance accompanied by increased fungal growth and decreased H2O2 production in plant tissues. Moreover, the transcript levels of pathogenesis‐related (PR) genes and reactive oxygen species (ROS)‐generating genes were down‐regulated in both the RNAi‐silenced and CRISPR‐edited plants, while the ROS‐scavenging gene, TaCAT3, was up‐regulated. Therefore, TaUAM3 positively regulates the resistance of wheat to Pst. [ABSTRACT FROM AUTHOR]

Stripe rust is one of the most destructive wheat diseases in China, negatively affecting the production safety and causing yield losses of wheat. Thus, it is important to analyze the environmental suitability and dynamic changes of wheat stripe rust in China. The occurrence of stripe rust is affected by multiple factors. Therefore, this study combined data from various disciplinary fields such as remote sensing, meteorology, biology, and plant protection to evaluate the environmental suitability of stripe rust in China using species distribution models. The study also discusses the importance and effect of various variables. Results revealed that meteorological factors had the greatest impact on the occurrence of stripe rust, especially temperature and precipitation. Wheat growth factors have a greater impact from April to August. Elevation has a greater impact in summer. The ensemble model results were better than the single model, with TSS and AUC greater than 0.851 and 0.971, respectively. Overlapping analysis showed that the winter stripe rust suitable areas were mainly in the Sichuan Basin, Northwestern Hubei, Southern Shaanxi, and Southern Henan wheat areas. In spring, the suitable areas of stripe rust increased in Huang-Huai-Hai and the middle and lower reaches of the Yangtze River and Guanzhong Plain, and the development of northwestern wheat areas such as Xinjiang and Gansu slightly lagged behind. In summer, wheat threatened by stripe rust is mainly in late-ripening spring wheat areas in Gansu, Ningxia, Qinghai, and Xinjiang. This study can provide a scientific basis for optimizing and improving the comprehensive management strategy of stripe rust. [ABSTRACT FROM AUTHOR]

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a devastating disease threatening global wheat production. Biocontrol by beneficial microorganisms is considered an alternative to synthetic fungicide applications. This study aimed to investigate the mechanisms involved in the biocontrol of wheat stripe rust by streptomycetes. A streptomycete strain XF, isolated from the rhizospheric soil of peony, was identified as Streptomyces tauricus based on morphological characteristics and phylogenetic analysis. We determined the inhibitory effect of XF on Pst and biocontrol effect on the disease using XF fermentation filtrate (FL) and actinomycete cell suspension (AC). Results revealed that FL inhibited urediniospore germination by up to 99% and rendered a lethality rate of 61.47% against urediniospores. Additionally, crude extract of ethyl acetate phase of FL caused cytoplasm releases from urediniospores and the deformation of germ tubes. Furthermore, histochemical analyses revealed that treatments of plants with AC and FL increased reactive oxygen species, inhibited haustorium formation, and reduced the biomass of Pst in leaves. Electron microscopy showed that XF mycelium was able to colonize the leaf surface. Moreover, gene expression assays revealed that AC and FL treatments induced the expression of a number of pathogenesis-related genes in wheat leaves. Besides, in the greenhouse experiments, the control effects of AC and FL reached 65.48% and 68.25%, respectively. In the field, application of XF fermentation broth significantly reduced the disease indices of stripe rust by 53.83%. These findings suggest that XF is a potential biocontrol agent for managing wheat stripe rust disease. [ABSTRACT FROM AUTHOR]

Plant-microbe interactions are a phenomenal display of symbiotic/parasitic relationships between living organisms. Plant growth-promoting rhizobacteria (PGPR) are some of the most widely investigated plant-beneficial microbes due to their capabilities in stimulating plant growth and development and conferring protection to plants against biotic and abiotic stresses. As such, PGPR-mediated plant priming/induced systemic resistance (ISR) has become a hot topic among researchers, particularly with prospects of applications in sustainable agriculture. The current study applies untargeted ultra-high performance liquid chromatography-high-definition mass spectrometry (UHPLC-HDMS) to investigate PGPR-based metabolic reconfigurations in the metabolome of primed wheat plants against Puccinia striiformis f. sp. tricti (Pst). A seed biopriming approach was adopted, where seeds were coated with two PGPR strains namely Bacillus subtilis and Paenibacillus alvei (T22) and grown under controlled conditions in a glasshouse. The plants were infected with Pst one-week postgermination, followed by weekly harvesting of leaf material. Subsequent metabolite extraction was carried out for analysis on a UHPLC-HDMS system for data acquisition. The data was chemometrically processed to reveal the underlying trends and data structures as well as potential signatory biomarkers for priming against Pst. Results showed notable metabolic reprogramming in primary and secondary metabolism, where the amino acid and organic acid content of primed-control, primed-challenged and non-primed-challenged plants were differentially reprogrammed. Similar trends were observed from the secondary metabolism, in which primed plants (particularly primedchallenged) showed an up-regulation of phenolic compounds (flavonoids, hydroxycinnamic acids-HCAs- and HCA amides) compared to the non-primed plants. The metabolomics-based semi-quantitative and qualitative assessment of the plant metabolomes revealed a time-dependent metabolic reprogramming in primed-challenged and primed-unchallenged plants, indicating the metabolic adaptations of the plants to stripe rust infection over time. [ABSTRACT FROM AUTHOR]

The fungus Puccinia striiformis f. sp. tritici (Pst) is an important threat to wheat production because it can cause wheat stripe rust. The present study aimed to identify new stripe rust resistance genes and to provide a theoretical and practical basis for breeding wheat varieties with broad spectrum, stable, and durable resistance. Wheat leaves inoculated with wheat stripe rust fungus Chinese yellow rust 34 were collected at different time points for transcriptomic analysis based on the wheat stripe rust susceptible varieties AVOCET S (AVS) and AVSYr15NIL [near-isogenic line (NIL) derived from AVS]. The results showed that the number of upregulated genes in the two varieties was 294, 364, 398, and 604, and the number of downregulated genes was 520, 178, 570, and 345 on the 1st, 3rd, 5th, and 7th days post inoculation, respectively. Gene Ontology and Kyoto Encyclopedia of Gene and Genomes enrichment analyses found enrichment of differentially expressed genes in the peroxisome proliferators-activated receptor signaling pathways, plant-pathogen interaction, and styrene acrylic acid biosynthesis that encoded protein kinases, signal transduction, transcription factors, and functional protein components. Differentially expressed genes were randomly selected for quantitative reverse transcription PCR analysis, and the change trend was the same as in the transcriptome data. The results of this study suggest that genes in AVSYr15NIL related to the stripe rust response could be valuable for understanding the mechanisms involved in stripe rust resistance. [ABSTRACT FROM AUTHOR]

Application of physical modification techniques such as the radiation of gamma rays could induce rust resistance and improve the performance of wheat plants through the development of new products. During the growing seasons of 2020-2021 and 2021-2022, two field experiments were done to see how well five types of bread wheat (NING MAI 50-0CHN, SAKHA 93, GIZA 168, SIDS 12, and SKAUZ) did when they were exposed to 5, 10, 15, 20, and 25 Kr of gamma rays. The experiments looked at how well the rust was controlled, how much yield was produced, and how the seedlings grew. Results showed that wheat genotypes significantly differed in rust infection and other parameters in both seasons at different gamma-ray ratios. Sakha 93 gave high resistance to yellow rust with high seedling dry weight and seedling vigor index 2, but Giza 168 gave the highest leaf rust resistance with increased doses of gamma rays. On the other hand, the SKAUZ genotype surpassed other genotypes in germination percentage and grain yield in both seasons. A dose of 25 kr was the most beneficial for rust resistance and yield attributes in comparison to the control, while a dose of 5 kr caused improvement in seedling parameters. Results exhibited that the interaction effect between wheat genotypes and gamma rays was significant on all studied traits in both seasons. Finally, it is concluded that gamma rays play an important role in inducing rust resistance and improving grain yield. [ABSTRACT FROM AUTHOR]

Wheat stripe rust caused by Puccinia striiformis f. sp. tritici is a destructive disease. Its pathogen frequently adapts to newly invaded regions and overcomes resistance in wheat cultivars. This disease is especially important in China due to its favorable conditions for the stripe rust epidemic and the recombination population structure of pathogens. Xinjiang is a vast epidemic region in China, but very limited research on this disease has been performed in this region. In this study, we identified 25 races from 129 isolates collected from winter wheat fields from five different regions (Nileke, Xinyuan, Gongliu, Huocheng, and Qapqal) of Yili, Xinjiang, using the Chinese set of 19 differential wheat lines. All isolates were virulent on the differentials Fulhad and Early Premium, but no isolates were virulent on Yr5. Among the 25 races, Suwon11-1 was the most prevalent, followed by CYR34. Both races were found in four out of the five locations. It is important to continue monitoring stripe rust and its pathogen races in this region, as it forms a pathway between China and Central Asia. Collaborative research is essential for controlling stripe rust in this region, other regions in China, and neighboring countries. [ABSTRACT FROM AUTHOR]

Wheat Research Institute (WRI), Faisalabad, Pakistan, a premier foundational birthplace of the Green revolution in Pakistan, has played a vital role in attaining food self-sufficiency. Latest grown varieties have succumbed to ever-changing pathogens, unable to stand in the fields. Hence, the initiative to develop an indigenous type to withstand high disease pressure producing better grain yield transpired during 2008-2009, with the hybridization of Dilkash-20 (WBLL*2/4/SNI/TRAP#1/3/KAUZ*2/TRAP//KAUZ/5/PB.96//LU26/HD2179). It proceeded with segregating generations from F2 to F7 from 2009 to 2016. During 2016-2017 and 2017-2018, its testing followed at station yield trials, including Preliminary (A) and Regular (B), under code V-16005. It produced a significantly higher yield (10.86% and 10.40%) than the check varieties (Faisalabad-08 [FSD-08] and Punjab-11 [PB-11]). In provincial trials, it out-yielded a check variety by 4.06%. Testing in national yield trials, line V-16005 produced 17.40% and 12.03% higher grain yield than check cultivars during 2018-2019 and 2019-2020, respectively. It yielded better when planted on the first 10 days of November with a 100 kg ha-1 seed rate and 120:90:60 NPK (kg ha-1) fertilizer rate. The Dilkash-20 variety is a medium-height (105-115 cm), semi-erect producing 425 tillers per m2, with 119 days to heading and 145-150 days to maturity. It is of excellent quality, with protein (15.1%), starch (52.7%), gluten (28.7%), and test weight (72.1 kg hl-1), highly suitable for chapatti making. It has an effectual, durable resistance against brown and yellow rusts based on adult plant resistance genes. Therefore, the Punjab Seed Council approved Dilkash-20 for general cultivation throughout the irrigated areas of Punjab. [ABSTRACT FROM AUTHOR]

Plant cell surface-localized receptor-like kinases (RLKs) recognize invading pathogens and transduce the immune signals inside host cells, subsequently triggering immune responses to fight off pathogen invasion. Nonetheless, our understanding of the role of RLKs in wheat resistance to the biotrophic fungus Puccinia striiformis f. sp. tritici (Pst) remains limited. During the differentially expressed genes in Pst infected wheat leaves, a Leucine-repeat receptor-like kinase (LRR-RLK) gene TaBIR1 was significantly upregulated in the incompatible wheat-Pst interaction. qRT-PCR verified that TaBIR1 is induced at the early infection stage of Pst. The transient expression of TaBIR1-GFP protein in N. bentamiana cells and wheat mesophyll protoplasts revealed its plasma membrane location. The knockdown of TaBIR1 expression by VIGS (virus induced gene silencing) declined wheat resistance to stripe rust, resulting in reduced reactive oxygen species (ROS) production, callose deposition, and transcripts of pathogenesis-related genes TaPR1 and TaPR2, along with increased Pst infection area. Ectopic overexpression of TaBIR1 in N. benthamiana triggered constitutive immune responses with significant cell death, callose accumulation, and ROS production. Moreover, TaBIR1 triggered immunity is dependent on NbBAK1, the silencing of which significantly attenuated the defense response triggered by TaBIR1. TaBIR1 interacted with the NbBAK1 homologues in wheat, co-receptor TaSERK2 and TaSERK5, the transient expression of which could restore the impaired defense due to NbBAK1 silencing. Taken together, TaBIR1 is a cell surface RLK that contributes to wheat stripe rust resistance, probably as a positive regulator of plant immunity in a BAK1-dependent manner. [ABSTRACT FROM AUTHOR]

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

Crop diseases can cause major yield losses, so the ability to detect and identify them in their early stages is important for disease control. Deep learning methods have shown promise in classifying multiple diseases; however, many studies do not use datasets that represent real field conditions, necessitating either further image processing or reducing their applicability. In this paper, we present a dataset of wheat images taken in real growth situations, including both field and glasshouse conditions, with five categories: healthy plants and four foliar diseases, yellow rust, brown rust, powdery mildew and Septoria leaf blotch. This dataset was used to train a deep learning model. The resulting model, named CerealConv, reached a 97.05% classification accuracy. When tested against trained pathologists on a subset of images from the larger dataset, the model delivered an accuracy score 2% higher than the best‐performing pathologist. Image masks were used to show that the model was using the correct information to drive its classifications. These results show that deep learning networks are a viable tool for disease detection and classification in the field, and disease quantification is a logical next step. [ABSTRACT FROM AUTHOR]

Rust diseases are among the major constraints for wheat production woridwide due to the emergence and spread of highly destructive races of Pice·cinia. The most common approach to minimize yield losses due to rust is to use cultivars that are genetically resistant. Modern wheat cultivars. landraces. and wild relatives can contain undiscovered resistance genes. which typically encode kinase or nucleotide-binding site leucine rich repeat (NLR) domain containing receptor proteins. Recent research has shown that these genes can provide either resistance in all growth stages (allstage resistance: ASR) or specially in later growth stages (adult-plant resistance: APR). ASR genes are pathogen and race-specific, meaning can function against selected races of the P{{ccinia fungus due to the necessity to recognize specific avirulence molecules in the pathogen. APR genes are either pathogen-specific or multipathogen resistant but often race-nonspecific. Prediction of resistance genes through rust infection screening alone remains complex when more than one resistance gene is present. However, breakthroughs during the past half century such as the single-nucleotide polymorphism-based genotyping techniques and resistance gene isolation strategies like mutagenesis. resistance gene enrichment. and sequencing (MutRenteq). mutagenesis and chi-omosome sequencing (MutChroinSeq), and association genetics combined with RenSeq (AgRenSeq) enables rapid tran.sfer of resistance from source to modern cultivars. There is a strong need for combining multiple genes for better efficacy and longer-lasting resistance. Hence. techniques like gene cassette creation speeds up the gene combination process. but their widespread adoption and commercial use is limited due to their transgenic nature. [ABSTRACT FROM AUTHOR]

Although Blufensins (Bln) have important functions in the response of plants to biotic stress the precise functioning of Bln in wheat remains largely unknown. Here we isolated a Bln gene (TaBln4) from Suwon 11 infected by Puccinia striiformis f. sp. tritici (Pst). Expression of TaBln4 increased in host plants at the early stage of infection with a virulent Pst race (CYR31) but was unchanged in response to infection by an avirulent race (CYR23). Transcription levels of TaBln4 were also regulated by hormone and abiotic stresses. Expression of TaBln4 in tobacco leaves suppressed Bax-induced programmed cell death. Knockdown of TaBln4 by virus-induced gene silencing inhibited colonization of race CYR31 by increasing the accumulation of H2O2 and formation of hypersensitive responses (HR). Transient overexpression of TaBln4 by a transient overexpression system (BSMV-VOX) increased the susceptibility of wheat to CYR31. Results from bimolecular fluorescence complementation and pull-down assays demonstrated that TaBLN4 interacted with calmodulin. Taken together, our results suggest that TaBln4 negatively regulates resistance in wheat to Pst in a reactive oxygen species (ROS)- and HR-dependent manner. [ABSTRACT FROM AUTHOR]

With >7000 species the order of rust fungi has a disproportionately large impact on agriculture, horticulture, forestry and foreign ecosystems. The infectious spores are typically dikaryotic, a feature unique to fungi in which two haploid nuclei reside in the same cell. A key example is Phakopsora pachyrhizi, the causal agent of Asian soybean rust disease, one of the world's most economically damaging agricultural diseases. Despite P. pachyrhizi's impact, the exceptional size and complexity of its genome prevented generation of an accurate genome assembly. Here, we sequence three independent P. pachyrhizi genomes and uncover a genome up to 1.25 Gb comprising two haplotypes with a transposable element (TE) content of ~93%. We study the incursion and dominant impact of these TEs on the genome and show how they have a key impact on various processes such as host range adaptation, stress responses and genetic plasticity. Asian soybean rust caused by Phakopsora pachyrhizi is an important plant pathogen, but an accurate genome assembly for this fungus has been lacking. This study sequenced three independent P. pachyrhizi isolates and generated reference quality assemblies and genome annotations, representing a critical step for further in-depth studies of this pathogen and the development of new methods of control. [ABSTRACT FROM AUTHOR]

A change in agricultural policy in the European Union aims, among other things, to halve the use of pesticides and increase the share of organic farming to 25% by 2030. One of the challenges associated with this target will be the control of plant fungal diseases. The key methods in organic farming include the selection of less susceptible crop varieties. In order to test this method, a long-term trial of organic farming in Eastern Poland was established. In total, 41 different winter wheat varieties were grown from 2018 to 2022 and their resistance to fungal leaf diseases was monitored. Brown rust was found to be the disease causing the highest infestation towards the end of vegetation, often exceeding 80% of the flag leaf area. However, yield reductions were mainly related to the severe occurrence of leaf Septoria. Other leaf diseases such as tan spot, yellow rust, powdery mildew, and fusariosis were of little importance and only occurred at low infestations of Septoria and brown rust. The course of the weather was found to have a significant effect on disease incidence. Drought occurring in May and June significantly increased the incidence of brown rust and Septoria, while prolonged rains increased tan spot and Fusarium infestation. Greater overall infestation occurred in years with high average temperatures. Ten varieties with high resistance to foliar fungal diseases were selected and can be recommended for organic farming. [ABSTRACT FROM AUTHOR]

Wheat stripe rust, due to infection by Puccinia striiformis f. sp. tritici (Pst), is a devastating disease that causes significant global grain yield losses. Yr36, which encodes Wheat Kinase START1 (WKS1), is an effective high-temperature adult-plant resistance gene and confers resistance to a broad spectrum of Pst races. We previously showed that WKS1 phosphorylates the thylakoid ascorbate peroxidase protein and reduces its ability to detoxify peroxides, which may contribute to the accumulation of reactive oxygen species (ROS). WKS1-mediated Pst resistance is accompanied by leaf chlorosis in Pst-infected regions, but the underlying mechanisms remain elusive. Here, we show that WKS1 interacts with and phosphorylates PsbO, an extrinsic member of photosystem II (PSII), to reduce photosynthesis, regulate leaf chlorosis, and confer Pst resistance. A point mutation in PsbO-A1 or reduction in its transcript levels by RNA interference resulted in chlorosis and reduced Pst sporulation. Biochemical analyses revealed that WKS1 phosphorylates PsbO at two conserved amino acids involved in physical interactions with PSII and reduces the binding affinity of PsbO with PSII. Presumably, phosphorylated PsbO proteins dissociate from the PSII complex and then undergo rapid degradation by cysteine and aspartic proteases. Taken together, these results demonstrate that perturbations of wheat PsbO by point mutation or phosphorylation by WKS1 reduce the rate of photosynthesis and delay the growth of Pst pathogen before the induction of ROS.

The important roles of plant microRNAs (miRNAs) in adaptation to nitrogen (N) deficiency in different crop species especially cereals (rice, wheat, maize) have been under discussion since last decade with little focus on potential wild relatives and landraces. Indian dwarf wheat (Triticum sphaerococcum Percival) is an important landrace native to the Indian subcontinent. Several unique features, especially high protein content and resistance to drought and yellow rust, make it a very potent landrace for breeding. Our aim in this study is to identify the contrasting Indian dwarf wheat genotypes based on nitrogen use efficiency (NUE) and nitrogen deficiency tolerance (NDT) traits and the associated miRNAs differentially expressed under N deficiency in selected genotypes. Eleven Indian dwarf wheat genotypes and a high NUE bread wheat genotype (for comparison) were evaluated for NUE under control and N deficit field conditions. Based on NUE, selected genotypes were further evaluated under hydroponics and miRNome was compared by miRNAseq under control and N deficit conditions. Among the identified, differentially expressed miRNAs in control and N starved seedlings, the target gene functions were associated with N metabolism, root development, secondary metabolism and cell-cycle associated pathways. The key findings on miRNA expression, changes in root architecture, root auxin abundance and changes in N metabolism reveal new information on the N deficiency response of Indian dwarf wheat and targets for genetic improvement of NUE. [ABSTRACT FROM AUTHOR]

Introduction: The accurate severity assessment of wheat stripe rust is the basis for the pathogen-host interaction phenotyping, disease prediction, and disease control measure making. Methods: To realize the rapid and accurate severity assessment of the disease, the severity assessment methods of the disease were investigated based on machine learning in this study. Based on the actual percentages of the lesion areas in the areas of the corresponding whole single diseased wheat leaves of each severity class of the disease, obtained after the image segmentation operations on the acquired single diseased wheat leaf images and the pixel statistics operations on the segmented images by using image processing software, under two conditions of considering healthy single wheat leaves or not, the training and testing sets were constructed by using two modeling ratios of 4:1 and 3:2, respectively. Then, based on the training sets, two unsupervised learning methods including K-means clustering algorithm and spectral clustering and three supervised learning methods including support vector machine, random forest, and K-nearest neighbor were used to build severity assessment models of the disease, respectively. Results: Regardless of whether the healthy wheat leaves were considered or not, when the modeling ratios were 4:1 and 3:2, satisfactory assessment performances on the training and testing sets can be achieved by using the optimal models based on unsupervised learning and those based on supervised learning. In particular, the assessment performances obtained by using the optimal random forest models were the best, with the accuracies, precisions, recalls, and F1 scores for all the severity classes of the training and testing sets equal to 100.00% and the overall accuracies of the training and testing sets equal to 100.00%. Discussion: The simple, rapid, and easy-to-operate severity assessment methods based on machine learning were provided for wheat stripe rust in this study. This study provides a basis for the automatic severity assessment of wheat stripe rust based on image processing technology, and provides a reference for the severity assessments of other plant diseases. [ABSTRACT FROM AUTHOR]

In the present era of climate instability, Canadian wheat production has been frequently affected by abiotic stresses and by dynamic populations of pathogens and pests that are more virulent and aggressive over time. Genetic diversity is fundamental to guarantee sustainable and improved wheat production. In the past, the genetics of Brazilian cultivars, such as Frontana, have been studied by Canadian researchers and consequently, Brazilian germplasm has been used to breed Canadian wheat cultivars. The objective of this study was to characterize a collection of Brazilian germplasm under Canadian growing conditions, including the reaction of the Brazilian germplasm to Canadian isolates/pathogens and to predict the presence of certain genes in an effort to increase genetic diversity, improve genetic gain and resilience of Canadian wheat. Over 100 Brazilian hard red spring wheat cultivars released from 1986 to 2016 were evaluated for their agronomic performance in eastern Canada. Some cultivars showed good adaptability, with several cultivars being superior or statistically equal to the highest yielding Canadian checks. Several Brazilian cultivars had excellent resistance to leaf rust, even though only a few of these tested positive for the presence of either Lr34 or Lr16, two of the most common resistance genes in Canadian wheat. Resistance for stem rust, stripe rust and powdery mildew was variable among the Brazilian cultivars. However, many Brazilian cultivars had high levels of resistance to Canadian and African - Ug99 strains of stem rust. Many Brazilian cultivars had good Fusarium head blight (FHB) resistance, which appears to be derived from Frontana. In contrast FHB resistance in Canadian wheat is largely based on the Chinese variety, Sumai-3. The Brazilian germplasm is a valuable source of semi-dwarf (Rht) genes, and 75% of the Brazilian collection possessed Rht-B1b. Many cultivars in the Brazilian collection were found to be genetically distinct from Canadian wheat, making them a valuable resource to increase the disease resistance and genetic variability in Canada and elsewhere. [ABSTRACT FROM AUTHOR]

In order to create a successful and efficient breeding programme, it is highly helpful to analyse the gene action governing the expression of different traits. The objective of the present study was to use generation mean analysis to ascertain the kind and extent of gene action in bread wheat utilizing six generations (P1, P2, F1, F2, BC1 and BC2) of the four crosses, cross I (HD 2967 x PBW 752), cross II (RSP 561 x PBW 779), cross III (RSP 561 x PBW 780), and cross IV (JAUW 584 x WH 1184). These crosses included elite stripe rust resistant wheat genotypes in addition to locally adapted cultivars. The results showed that all the traits in all crosses had highly significant estimated mean effects (m), showing the quantitative inheritance of the selected traits. For grain yield and most of the selected characters, it was found that additive gene effects was shown to be less significance than dominance type gene effects. Among the different characters studied in the four crosses, the degree of dominance x dominance was large and negatively significant, whereas additive x additive gene actions were high and positively significance. In wheat breeding, it was found that selection for the improvement of grain yield and its contributing traits must be postponed until later generations because additive x dominant gene effects was of lesser significance. [ABSTRACT FROM AUTHOR]

Summary: Wheat is a globally vital crop, but its limited genetic variation creates a challenge for breeders aiming to maintain or accelerate agricultural improvements over time. Introducing novel genes and alleles from wheat's wild relatives into the wheat breeding pool via introgression lines is an important component of overcoming this low variation but is constrained by poor genomic resolution and limited understanding of the genomic impact of introgression breeding programmes. By sequencing 17 hexaploid wheat/Ambylopyrum muticum introgression lines and the parent lines, we have precisely pinpointed the borders of introgressed segments, most of which occur within genes. We report a genome assembly and annotation of Am. muticum that has facilitated the identification of Am. muticum resistance genes commonly introgressed in lines resistant to stripe rust. Our analysis has identified an abundance of structural disruption and homoeologous pairing across the introgression lines, likely caused by the suppressed Ph1 locus. mRNAseq analysis of six of these introgression lines revealed that novel introgressed genes are rarely expressed and those that directly replace a wheat orthologue have a tendency towards downregulation, with no discernible compensation in the expression of homoeologous copies. This study explores the genomic impact of introgression breeding and provides a schematic that can be followed to characterize introgression lines and identify segments and candidate genes underlying the phenotype. This will facilitate more effective utilization of introgression pre‐breeding material in wheat breeding programmes. [ABSTRACT FROM AUTHOR]

In order to understand the disease resistance level of wheat varieties in Hebei province, the resistance to powdery mildew, stripe rust, and leaf rust of 212 winter wheat varieties registered in Hebei province from 2013 to 2021 were analyzed. The results showed that the overall level of resistance to stripe rust was good, and the proportion of resistant varieties was 53.78%, while the level of resistance to leaf rust and powdery mildew was poor, but fluctuated greatly between years, in 2014, 100% of wheat varieties were resistant to leaf rust, while in 2016, 2018 and 2011, 3.44%, 6.67%, and 11.11% of wheat varieties were of resistance, respectively, the changing range of the percentage of wheat varieties with resistance to powdery mildew accounting for the registered varieties was from 22.23% to 36.36% in other years, and the percentage of wheat varieties with resistance to powdery mildew in 2014, 2016, and 2020 was relatively good, the percentage of resistant varieties was 33.33%, 24.14%, and 29.72%, respectively. The percentage of resistant varieties was less than 20% in other years. There were 37 varieties resistant to leaf rust and 35 varieties resistant to powdery mildew, the resistant varieties accounted for 17.45% and 16.50% of the registered varieties, but there were few varieties with resistance to two or more diseases, and the varieties with resistance to both stripe rust and leaf rust accounted for 7.08%, and no varieties with resistance to both leaf rust and powdery mildew, the cultivars with resistance to both stripe rust and powdery mildew accounted for 4.72%, and the cultivars (4.72%) with resistance to all of the three diseases accounted for 4.72%. The pedigree analysis of the parents of the varieties with high resistance to leaf rust and powdery mildew showed that the resistant sources of wheat breeding for disease resistance in Hebei province mainly came from Shandong province, while the local resistant germplasm resources in Hebei province were relatively scarce. The results further indicated that it was urgent to introduce and create wheat germplasm resources with disease resistance in Hebei province, and the monitoring and control of main diseases should be done well in wheat production to ensure stable and high yield of wheat in Hebei province. [ABSTRACT FROM AUTHOR]