Distinct experiences and care needs of advanced cancer patients with good ECOG performance status: a qualitative phenomenological study.

BACKGROUND: Advanced cancer patients with good Eastern Cooperative Oncology Group (ECOG) performance status (score 0-1) are underrepresented in current qualitative reports compared with their dying counterparts. AIM: To explore the experiences and care needs of advanced cancer patients with good ECOG. DESIGN: A qualitative phenomenological approach using semi-structured interview was employed. Data was analyzed using the Colaizzi's method. SETTING/PARTICIPANTS: Purposive sample of terminal solid cancer patients on palliative care aged 18-70 years with a 0-1 ECOG score were recruited from a tertiary general hospital. RESULTS: Sixteen participants were interviewed. Seven themes were generated from the transcripts, including experiencing no or mild symptoms; independence in self-care, decision-making, and financial capacity; prioritization of cancer growth suppression over symptom management; financial concerns; hope for prognosis and life; reluctance to discuss death and after-death arrangements; and use of complementary and alternative medicine (CAM) and religious coping. CONCLUSIONS: Advanced cancer patients with good ECOG have distinct experiences and care needs from their dying counterparts. They tend to experience no or mild symptoms, demonstrate a strong sense of independence, and prioritize cancer suppression over symptom management. Financial concerns were common and impact their care-related decision-making. Though being hopeful for their prognosis and life, many are reluctant to discuss death and after-death arrangements. Many Chinese patients use herbal medicine as a CAM modality but need improved awareness of and accessibility to treatment options. Healthcare professionals and policy-makers should recognize their unique experiences and needs when tailoring care strategies and policies.

Race and Virulence Dynamics of Puccinia triticina in China During 2007 to 2021.

The challenge of wheat leaf rust on wheat production is a recurring issue. Race identification of Puccinia triticina (Pt) serves as the foundation for preventing and controlling this disease. In a 15-year study, we identified 2,900 isolates of Pt from 20 provinces, cities, or autonomous regions in China during 2007 to 2021 and found 332 virulence phenotypes with 11 predominant phenotypes: PHT (8.3%), THT (5.4%), PHK (4.5%), PHJ (3.7%), THJ (3.6%), SHJ (3.5%), THS (3.3%), FGD (2.9%), THK (2.6%), PHS (2.4%), and PHD (2.0%). The virulence frequency for 40 Lr genes was identified across different years and areas; one major reason for the race dynamics was the attenuation to Lr1 and Lr26, which was more evident in southwest China. Lr9, Lr24, Lr28, Lr38, and Lr42 maintained effectiveness in China, while Lr2c, Lr10, Lr12, Lr14a, Lr14b, Lr22a, Lr33, and Lr36 nearly lost their effectiveness against wheat leaf rust disease. No significant difference was found among predominant phenotypes in different areas (P > 0.1). However, 12 Lr sites were found to have differences in virulence frequencies with values greater than 20% across various locations; furthermore, the lowest and highest virulence values were observed in north China (Area 1) and northwest China (Area 5), respectively. According to phenotype dynamics, PHT, THT, FGD, THK, and PHS are more likely to persist over time. In addition, much attention should be given toward discovering rising combinations of virulent phenotypes.

Intelligent reprogramming of wheat for enhancement of fungal and nematode disease resistance using advanced molecular techniques.

Wheat (Triticum aestivum L.) diseases are major factors responsible for substantial yield losses worldwide, which affect global food security. For a long time, plant breeders have been struggling to improve wheat resistance against major diseases by selection and conventional breeding techniques. Therefore, this review was conducted to shed light on various gaps in the available literature and to reveal the most promising criteria for disease resistance in wheat. However, novel techniques for molecular breeding in the past few decades have been very fruitful for developing broad-spectrum disease resistance and other important traits in wheat. Many types of molecular markers such as SCAR, RAPD, SSR, SSLP, RFLP, SNP, and DArT, etc., have been reported for resistance against wheat pathogens. This article summarizes various insightful molecular markers involved in wheat improvement for resistance to major diseases through diverse breeding programs. Moreover, this review highlights the applications of marker assisted selection (MAS), quantitative trait loci (QTL), genome wide association studies (GWAS) and the CRISPR/Cas-9 system for developing disease resistance against most important wheat diseases. We also reviewed all reported mapped QTLs for bunts, rusts, smuts, and nematode diseases of wheat. Furthermore, we have also proposed how the CRISPR/Cas-9 system and GWAS can assist breeders in the future for the genetic improvement of wheat. If these molecular approaches are used successfully in the future, they can be a significant step toward expanding food production in wheat crops.

Microbiome Signature of Endophytes in Wheat Seed Response to Wheat Dwarf Bunt Caused by Tilletia controversa Kühn.

Wheat dwarf bunt leads to the replacement of seeds with fungal galls containing millions of teliospores of the pathogen Tilletia controversa Kühn. As one of the most devastating internationally quarantined wheat diseases, wheat dwarf bunt spreads to cause distant outbreaks by seeds containing teliospores. In this study, based on a combination of amplicon sequencing and isolation approaches, we analyzed the seed microbiome signatures of endophytes between resistant and susceptible cultivars after infection with T. controversa. Among 310 bacterial species obtained only by amplicon sequencing and 51 species obtained only by isolation, we found 14 overlapping species by both methods; we detected 128 fungal species only by amplicon sequencing, 56 only by isolation, and 5 species by both methods. The results indicated that resistant uninfected cultivars hosted endophytic communities that were much more stable and beneficial to plant health than those in susceptible infected cultivars. The susceptible group showed higher diversity than the resistant group, the infected group showed more diversity than the uninfected group, and the microbial communities in seeds were related to infection or resistance to the pathogen. Some antagonistic microbes significantly suppressed the germination rate of the pathogen's teliospores, providing clues for future studies aimed at developing strategies against wheat dwarf bunt. Collectively, this research advances the understanding of the microbial assembly of wheat seeds upon exposure to fungal pathogen (T. controversa) infection. IMPORTANCE This is the first study on the microbiome signature of endophytes in wheat seed response to wheat dwarf bunt caused by Tilletia controversa Kühn. Some antagonistic microbes suppressed the germination of teliospores of the pathogen significantly, which will provide clues for future studies against wheat dwarf bunt. Collectively, this research first advances the understanding of the microbial assembly of wheat seed upon exposure to the fungal pathogen (T. controversa) infection.

Physiological and metabolic analyses provide insight into soybean seed resistance to fusarium fujikuroi causing seed decay.

Seed-borne pathogens cause diverse diseases at the growth, pre- and post-harvest stage of soybean resulting in a large reduction in yield and quality. The physiological and metabolic aspects of seeds are closely related to their defense against pathogens. Recently, Fusarium fujikuroi has been identified as the dominant seed-borne fungi of soybean seed decay, but little information on the responses of soybean seeds induced by F. fujikuroi is available. In this study, a time-course symptom development of seed decay was observed after F. fujikuroi inoculation through spore suspension soaking. The germination rate and the contents of soluble sugar and soluble protein were significantly altered over time. Both chitinase and ß-1,3-glucanase as important fungal cell wall-degrading enzymes of soybean seeds were also rapidly and transiently activated upon the early infection of F. fujikuroi. Metabolic profile analysis showed that the metabolites in glycine, serine, and threonine metabolism and tryptophan metabolism were clearly induced by F. fujikuroi, but different metabolites were mostly enriched in isoflavone biosynthesis, flavone biosynthesis, and galactose pathways. Interestingly, glycitein and glycitin were dramatically upregulated while daidzein, genistein, genistin, and daidzin were largely downregulated. These results indicate a combination of physiological responses, cell wall-related defense, and the complicated metabolites of soybean seeds contributes to soybean seed resistance against F. fujikuroi, which are useful for soybean resistance breeding.

Maize-soybean relay strip intercropping reshapes the rhizosphere bacterial community and recruits beneficial bacteria to suppress Fusarium root rot of soybean.

Rhizosphere microbes play a vital role in plant health and defense against soil-borne diseases. Previous studies showed that maize-soybean relay strip intercropping altered the diversity and composition of pathogenic Fusarium species and biocontrol fungal communities in the soybean rhizosphere, and significantly suppressed soybean root rot. However, whether the rhizosphere bacterial community participates in the regulation of this intercropping on soybean root rot is not clear. In this study, the rhizosphere soil of soybean healthy plants was collected in the continuous cropping of maize-soybean relay strip intercropping and soybean monoculture in the fields, and the integrated methods of microbial profiling, dual culture assays in vitro, and pot experiments were employed to systematically investigate the diversity, composition, and function of rhizosphere bacteria related to soybean root rot in two cropping patterns. We found that intercropping reshaped the rhizosphere bacterial community and increased microbial community diversity, and meanwhile, it also recruited much richer and more diverse species of Pseudomonas sp., Bacillus sp., Streptomyces sp., and Microbacterium sp. in soybean rhizosphere when compared with monoculture. From the intercropping, nine species of rhizosphere bacteria displayed good antagonism against the pathogen Fusarium oxysporum B3S1 of soybean root rot, and among them, IRHB3 (Pseudomonas chlororaphis), IRHB6 (Streptomyces), and IRHB9 (Bacillus) were the dominant bacteria and extraordinarily rich. In contrast, MRHB108 (Streptomyces virginiae) and MRHB205 (Bacillus subtilis) were the only antagonistic bacteria from monoculture, which were relatively poor in abundance. Interestingly, introducing IRHB3 into the cultured substrates not only significantly promoted the growth and development of soybean roots but also improved the survival rate of seedlings that suffered from F. oxysporum infection. Thus, this study proves that maize-soybean relay strip intercropping could help the host resist soil-borne Fusarium root rot by reshaping the rhizosphere bacterial community and driving more beneficial microorganisms to accumulate in the soybean rhizosphere.

Folding Features and Dynamics of 3D Genome Architecture in Plant Fungal Pathogens.

The folding and dynamics of three-dimensional (3D) genome organization are fundamental for eukaryotes executing genome functions but have been largely unexplored in nonmodel fungi. Using high-throughput sequencing coupled with chromosome conformation capture (Hi-C) data, we generated two chromosome-level assemblies for Puccinia striiformis f. sp. tritici, a fungus causing stripe rust disease on wheat, for studying 3D genome architectures of plant pathogenic fungi. The chromatin organization of the fungus followed a combination of the fractal globule model and the equilibrium globule model. Surprisingly, chromosome compartmentalization was not detected. Dynamics of 3D genome organization during two developmental stages of P. striiformis f. sp. tritici indicated that regulation of gene activities might be independent of the changes of genome organization. In addition, chromatin conformation conservation was found to be independent of genome sequence synteny conservation among different fungi. These results highlighted the distinct folding principles of fungal 3D genomes. Our findings should be an important step toward a holistic understanding of the principles and functions of genome architecture across different eukaryotic kingdoms. IMPORTANCE Previously, our understanding of 3D genome architecture has mainly come from model mammals, insects, and plants. However, the organization and regulatory functions of 3D genomes in fungi are largely unknown. In this study, we comprehensively investigated P. striiformis f. sp. tritici, a plant fungal pathogen, and revealed distinct features of the 3D genome, comparing it with the universal folding feature of 3D genomes in higher eukaryotic organisms. We further suggested that there might be distinct regulatory mechanisms of gene expression that are independent of chromatin organization changes during the developmental stages of this rust fungus. Moreover, we showed that the evolutionary pattern of 3D genomes in this fungus is also different from the cases in mammalian genomes. In addition, the genome assembly pipeline and the generated two chromosome-level genomes will be valuable resources. These results highlighted the unexplored distinct features of 3D genome organization in fungi. Therefore, our study provided complementary knowledge to holistically understand the organization and functions of 3D genomes across different eukaryotes.

Current Status and Future Perspectives of Genomics Research in the Rust Fungi.

Rust fungi in Pucciniales have caused destructive plant epidemics, have become more aggressive with new virulence, rapidly adapt to new environments, and continually threaten global agriculture. With the rapid advancement of genome sequencing technologies and data analysis tools, genomics research on many of the devastating rust fungi has generated unprecedented insights into various aspects of rust biology. In this review, we first present a summary of the main findings in the genomics of rust fungi related to variations in genome size and gene composition between and within species. Then we show how the genomics of rust fungi has promoted our understanding of the pathogen virulence and population dynamics. Even with great progress, many questions still need to be answered. Therefore, we introduce important perspectives with emphasis on the genome evolution and host adaptation of rust fungi. We believe that the comparative genomics and population genomics of rust fungi will provide a further understanding of the rapid evolution of virulence and will contribute to monitoring the population dynamics for disease management.

Metabolomic Analysis of Wheat Grains after Tilletia laevis Kühn Infection by Using Ultrahigh-Performance Liquid Chromatography-Q-Exactive Mass Spectrometry.

Tilletia laevis causes common bunt disease in wheat, with severe losses of production yield and seed quality. Metabolomics studies provide detailed information about the biochemical changes at the cell and tissue level of the plants. Ultrahigh-performance liquid chromatography-Q-exactive mass spectrometry (UPLC-QE-MS) was used to examine the changes in wheat grains after T. laevis infection. PCA analysis suggested that T. laevis-infected and non-infected samples were scattered separately during the interaction. In total, 224 organic acids and their derivatives, 170 organoheterocyclic compounds, 128 lipids and lipid-like molecules, 85 organic nitrogen compounds, 64 benzenoids, 31 phenylpropanoids and polyketides, 21 nucleosides, nucleotides, their analogues, and 10 alkaloids and derivatives were altered in hyphal-infected grains. According to The Kyoto Encyclopedia of Genes and genomes analysis, the protein digestion and absorption, biosynthesis of amino acids, arginine and proline metabolism, vitamin digestion and absorption, and glycine, serine, and threonine metabolism pathways were activated in wheat crops after T. laevis infection.

Comparative Transcriptome Analysis Reveals the Gene Expression and Regulatory Characteristics of Broad-Spectrum Immunity to Leaf Rust in a Wheat-Agropyron cristatum 2P Addition Line.

Wheat leaf rust (caused by Puccinia triticina Erikss.) is among the major diseases of common wheat. The lack of resistance genes to leaf rust has limited the development of wheat cultivars. Wheat-Agropyron cristatum (A. cristatum) 2P addition line II-9-3 has been shown to provide broad-spectrum immunity to leaf rust. To identify the specific A. cristatum resistance genes and related regulatory pathways in II-9-3, we conducted a comparative transcriptome analysis of inoculated and uninoculated leaves of the resistant addition line II-9-3 and the susceptible cultivar Fukuhokomugi (Fukuho). The results showed that there were 66 A. cristatum differentially expressed genes (DEGs) and 1389 wheat DEGs in II-9-3 during P. triticina infection. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment and gene set enrichment analysis (GSEA) revealed that the DEGs of II-9-3 were associated with plant-pathogen interaction, MAPK signaling pathway-plant, plant hormone signal transduction, glutathione metabolism, and phenylpropanoid biosynthesis. Furthermore, many defense-related A. cristatum genes, such as two NLR genes, seven receptor kinase-encoding genes, and four transcription factor-encoding genes, were identified. Our results indicated that the key step of resistance to leaf rust involves, firstly, the gene expression of chromosome 2P upstream of the immune pathway and, secondly, the effect of chromosome 2P on the co-expression of wheat genes in II-9-3. The disease resistance regulatory pathways and related genes in the addition line II-9-3 thus could play a critical role in the effective utilization of innovative resources for leaf rust resistance in wheat breeding.

ITRAQ-Based Proteomic Analysis of Wheat (Triticum aestivum) Spikes in Response to Tilletia controversa Kühn and Tilletia foetida Kühn Infection, Causal Organisms of Dwarf Bunt and Common Bunt of Wheat.

Dwarf bunt and common bunt diseases of wheat are caused by Tilletia controversa Kühn and Tilletia foetida Kühn, respectively, and losses caused by these diseases can reach 70-80% in favourable conditions. T. controversa and T. foetida are fungal pathogens belonging to the Exobasidiomycetes within the basidiomycetous smut fungi (Ustilaginomycotina). In order to illuminate the proteomics differences of wheat spikes after the infection of T. controversa and T. foetida, the isobaric tags for relative and absolute quantification (iTRAQ) technique was used for better clarification. A total of 4553 proteins were differentially detected after T. controversa infection; 4100 were upregulated, and 453 were downregulated. After T. foetida infection, 804 differentially expressed proteins were detected; 447 were upregulated and 357 were downregulated. In-depth data analysis revealed that 44, 50 and 82 proteins after T. controversa and 9, 6 and 16 proteins after T. foetida were differentially expressed, which are antioxidant, plant-pathogen interaction and glutathione proteins, respectively, and 9 proteins showed results consistent with PRM. The top 20 KEGG enrichment pathways were identified after pathogen infection. On the basis of gene ontology, the upregulated proteins were linked with metabolic process, catalytic activity, transferase activity, photosynthetic membrane, extracellular region and oxidoreductase activity. The results expanded our understanding of the proteome in wheat spikes in response to T. controversa and T. foetida infection and provide a basis for further investigation for improving the defense mechanism of the wheat crops.

Evaluation of Fusarium Head Blight Resistance in 410 Chinese Wheat Cultivars Selected for Their Climate Conditions and Ecological Niche Using Natural Infection Across Three Distinct Experimental Sites.

Exploiting wheat cultivars with stable resistance to Fusarium Head blight (FHB) and toxin accumulation is a cost-effective and environmentally friendly strategy to reduce the risk of yield losses and contamination with mycotoxins. To facilitate the deployment of stable cultivar resistance, we evaluated FHB resistance and resistance to mycotoxin accumulation in 410 wheat lines bred by local breeders from four major wheat growing regions in China after natural infection at three distinct locations (Hefei, Yangzhou and Nanping). Significant differences in disease index were observed among the three locations. The disease indexes (DI's) in Nanping were the highest, followed by Yangzhou and Hefei. The distribution of DI's in Yangzhou showed the best discrimination of FHB resistance in cultivars. Growing region and cultivar had significant effect on DI and mycotoxins. Among the climate factors, relative humidity and rainfall were the key factors resulting in the severe disease. Even though most cultivars were still susceptible to FHB under the strongly conducive conditions applied, the ratio of resistant lines increased in the Upper region of the Yangtze River (UYR) and the Middle and Lower Region of the Yangtze River (MLYR) between 2015 and 2019. Deoxynivalenol (DON) was the dominant mycotoxin found in Hefei and Yangzhou, while NIV was predominant in Nanping. Disease indexes were significantly correlated with DON content in wheat grain.

Changes in the Density and Composition of Rhizosphere Pathogenic Fusarium and Beneficial Trichoderma Contributing to Reduced Root Rot of Intercropped Soybean.

The dynamic of soil-borne disease is closely related to the rhizosphere microbial communities. Maize-soybean relay strip intercropping has been shown to significantly control the type of soybean root rot that tends to occur in monoculture. However, it is still unknown whether the rhizosphere microbial community participates in the regulation of intercropped soybean root rot. In this study, rhizosphere Fusarium and Trichoderma communities were compared in either healthy or root-rotted rhizosphere soil from monocultured and intercropped soybean, and our results showed the abundance of rhizosphere Fusarium in intercropping was remarkably different from monoculture. Of four species identified, F. oxysporum was the most aggressive and more frequently isolated in diseased soil of monoculture. In contrast, Trichoderma was largely accumulated in healthy rhizosphere soil of intercropping rather than monoculture. T. harzianum dramatically increased in the rhizosphere of intercropping, while T. virens and T. afroharzianum also exhibited distinct isolation frequency. For the antagonism test in vitro, Trichoderma strains had antagonistic effects on F. oxysporum with the percentage of mycelial inhibition ranging from 50.59-92.94%, and they displayed good mycoparasitic abilities against F. oxysporum through coiling around and entering into the hyphae, expanding along the cell-cell lumen and even dissolving cell walls of the target fungus. These results indicate maize-soybean relay strip intercropping significantly increases the density and composition proportion of beneficial Trichoderma to antagonize the pathogenic Fusarium species in rhizosphere, thus potentially contributing to the suppression of soybean root rot under the intercropping.

Long-Distance Transport of Puccinia striiformis f. sp. tritici by Upper Airflow on the Yunnan-Guizhou Plateau Disrupts the Balance of Agricultural Ecology in Central China.

Long-distance dispersal of plant pathogens in the air can establish diseases in other areas and lead to an increased risk of large-scale epidemics. Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most destructive diseases of wheat in China. Hubei is an important overwintering region for Pst in China, and this overwintering region is a determinant of stripe rust severity in eastern China. In 2017, stripe rust disease caused a pandemic in the Hubei region and resulted in great yield losses of wheat. To explain the disease pandemic, a total of 595 single-lesion samples of stripe rust were collected in spring, including 204 in five provinces in 2017 and 391 in four provinces in 2018, and genotyped with 13 simple sequence repeat makers. The samples were classified into 12 subpopulations based on the locations and year of collection. Genetic diversity was determined for the collection and each subpopulation. Differentiation and gene flow were determined between subpopulations. STRUCTURE analyses and discriminant analysis of principal components were conducted, and the results were used to infer the relationships between subpopulations. Our study revealed a new route of Pst transmission from the Yunnan-Guizhou Plateau to the Hubei region. The Pst inoculum of northwestern Hubei came from Gansu in the northwest, whereas the inoculum in southern Hubei came from the Yunnan-Guizhou Plateau via upper airflow. After the initial inocula infected wheat plants and multiplied in northern and southern Hubei, urediniospores produced in these regions further spread together along the middle reach of Hanshui Valley and made exchanges there. The finding of the new transmission route of Pst is important for improving integrated stripe rust disease management, which should have a profound impact on the balance of agricultural ecology in China.

Transcriptomics Analysis of Wheat Tassel Response to Tilletia laevis Kühn, Which Causes Common Bunt of Wheat.

Tilletia laevis Kühn [synonym T. foetida (Wallr.) Liro] can lead to a wheat common bunt, which is one of the most serious diseases affecting kernels, a serious reduction in grain yield, and losses can reach up to 80% in favorable environments. To understand how wheat tassels respond to T. laevis, based on an RNA-Seq technology, we analyzed a host transcript accumulation on healthy wheat tassels and on tassels infected by the pathogen. Our results showed that 7,767 out of 15,658 genes were upregulated and 7,891 out of 15,658 genes were downregulated in wheat tassels. Subsequent gene ontology (GO) showed that differentially expressed genes (DEGs) are predominantly involved in biological processes, cellular components, and molecular functions. Additionally, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that 20 pathways were expressed significantly during the infection of wheat with T. laevis, while biosynthesis of amino acids, carbon metabolism, and starch and sucrose metabolism pathways were more highly expressed. Our findings also demonstrated that genes involved in defense mechanisms and myeloblastosis (MYB) transcription factor families were mostly upregulated, and the RNA-seq results were validated by quantitative real-time polymerase chain reaction (qRT-PCR). This is the first report on transcriptomics analysis of wheat tassels in response to T. laevis, which will contribute to understanding the interaction of T. laevis and wheat, and may provide higher efficiency control strategies, including developing new methods to increase the resistance of wheat crops to T. laevis-caused wheat common bunt.

Analyses of Wheat Yellow Rust Populations Reveal Sexual Recombination and Seasonal Migration Pattern of Puccinia striiformis f. sp. tritici in Gangu, Northwestern China.

Puccinia striiformis f. sp. tritici is the causal agent of wheat yellow rust with records of regular and severe epidemics in China. This study explored the population dynamics of the yellow rust pathogen in Gangu, northwestern China. In Gangu, the Weihe River runs from west to east and divides Gangu into three regions: North and South mountain, with the valley in between. To study the genetic structure of the pathogen in local populations, samples were collected over 3 years from the three regions at different altitudes both within and between the wheat cropping seasons. A total of 811 P. striiformis f. sp. tritici isolates were successfully genotyped using 16 simple sequence repeat markers. The results suggest that P. striiformis f. sp. tritici can survive year-round in Gangu. The P. striiformis f. sp. tritici populations migrated among the regions, and the migration pattern was not related to altitude. The oversummering populations in the North and South mountain regions were genetically different from each other; and the P. striiformis f. sp. tritici populations collected from the lower altitude in the valley had no relationship with any of the populations collected in the spring or fall, indicating that they too have a different origin. Signatures of random mating were found in the populations collected in both North and South mountain regions, but not in the valley populations.

Characteristics of the Infection of Tilletia laevis Kühn (syn. Tilletia foetida (Wallr.) Liro.) in Compatible Wheat.

Tilletia laevis Kühn (syn. Tilletia foetida (Wallr.) Liro.) causes wheat common bunt, which is one of the most devastating plant diseases in the world. Common bunt can result in a reduction of 80% or even a total loss of wheat production. In this study, the characteristics of T. laevis infection in compatible wheat plants were defined based on the combination of scanning electron microscopy, transmission electron microscopy and laser scanning confocal microscopy. We found T. laevis could lead to the abnormal growth of wheat tissues and cells, such as leakage of chloroplasts, deformities, disordered arrangements of mesophyll cells and also thickening of the cell wall of mesophyll cells in leaf tissue. What's more, T. laevis teliospores were found in the roots, stems, flag leaves, and glumes of infected wheat plants instead of just in the ovaries, as previously reported. The abnormal characteristics caused by T. laevis may be used for early detection of this pathogen instead of molecular markers in addition to providing theoretical insights into T. laevis and wheat interactions for breeding of common bunt resistance.

Metabolomics analysis of grains of wheat infected and noninfected with Tilletia controversa Kühn.

Dwarf bunt caused by the pathogen Tilletia controversa Kühn is one of the most serious quarantine diseases of winter wheat. Metabolomics studies provide detailed information about the biochemical changes at the cell and tissue levels of plants. In the present study, a liquid chromatography/mass spectrometry (LC/MS) metabolomics approach was used to investigate the changes in the grain metabolomics of infected and noninfected with T. controversa samples. PCA suggested that T. controversa-infected and noninfected samples were separated during the interaction. LC/MS analysis showed that 62 different metabolites were recorded in the grains, among which a total of 34 metabolites were upregulated and 28 metabolites were downregulated. Prostaglandins (PGs) and 9-hydroxyoctadecadienoic acids (9-HODEs) are fungal toxin-related substances, and their expression significantly increased in T. controversa-infected grains. Additionally, the concentrations of cucurbic acid and octadecatrienoic acid changed significantly after pathogen infection, which play a large role in plant defense. The eight different metabolic pathways activated during T. controversa and wheat plant interactions included phenylalanine metabolism, isoquinoline alkaloid biosynthesis, starch and sucrose metabolism, tyrosine metabolism, sphingolipid metabolism, arginine and proline metabolism, alanine, aspartate, and glutamate metabolism, and tryptophan metabolism. In conclusion, we found differences in the metabolic profiles of wheat grains after T. controversa infection. To our knowledge, this is the first study to evaluate the metabolites in wheat grains after T. controversa infection.

Development of an Agrobacterium tumefaciens-mediated transformation system for Tilletia controversa Kühn.

Dwarf bunt of wheat caused by Tilletia controversa Kühn has been identified an international quarantine disease, which replace the grain material into millions of teliospores. Agrobacterium tumefaciens-mediated transformation (ATMT) system is a powerful tool for fungi transformation with significant advantages of simple operation, high efficiency, and genetic stability of transformants. In this study, we constructed ATMT system for T. controversa. All the transformants were tested using Acetosyringone (AS) concentration at 150 µmol/l, hygromycin B at 25 µg/ml, 1 × 106 T. controversa hypha cells/ml, A. tumefaciens with OD600 of 0.5 co-cultivation at 16 °C for 48 h and culture was incubated at 16 °C for 20 days. Using the ATMT method, we cultivated 8 generations of transformants on complete medium (CM) containing hygromycin B antibiotic and validated by PCR, which indicate that T-DNA had been successfully inserted into each of T. controversa transformants. In addition, thermal asymmetric interlaced PCR (TAIL-PCR) evaluated the Ti element inserts were at random sites in the fungal genome. Thus, ATMT approach is an efficient tool for insertional mutagenesis of T. controversa.

Wheat Varietal Response to Tilletia controversa J. G. Kühn Using qRT-PCR and Laser Confocal Microscopy.

Tilletia controversa J. G. Kühn is a causal organism of dwarf bunt in wheat. Understanding the interaction of wheat and T. controversa is of practical and scientific importance for disease control. In this study, the relative expression of TaLHY and TaPR-4 and TaPR-5 genes was higher in a resistant (Yinong 18) and moderately resistant (Pin 9928) cultivars rather than susceptible (Dongxuan 3) cultivar at 72 h post inoculation (hpi) with T. controversa. Similarly, the expression of defensin, TaPR-2 and TaPR-10 genes was observed higher in resistant and moderately resistant cultivars after exogenous application of phytohormones, including methyl jasmonate, salicylic acid, and abscisic acid. Laser confocal microscopy was used to track the fungal hyphae in the roots, leaves, and tapetum cells, which of susceptible cultivar were infected harshly by T. controversa than moderately resistant and resistant cultivars. There were no fungal hyphae in tapetum cells in susceptible cultivar after methyl jasmonate, salicylic acid and abscisic acid treatments. Moreover, after T. controversa infection, the pollen germination was of 80.06, 58.73, and 0.67% in resistant, moderately resistant and susceptible cultivars, respectively. The above results suggested that the use using of resistant cultivar is a good option against the dwarf bunt disease.