The aquatic grass Zizania latifolia grows symbiotically with the fungus Ustilago esculenta producing swollen structures called Jiaobai, widely cultivated in China. A new disease of Z. latifolia was found in Zhejiang Province, China. Initial lesions appeared on the leaf sheaths or sometimes on the leaves near the leaf sheaths. The lesions extended along the axis of the leaf shoots and formed long brown to dark brown streaks from the leaf sheath to the leaf, causing sheath rot and death of entire leaves on young plants. The pathogen was isolated and identified as the bacterium Pantoea ananatis, based on 16S ribosomal RNA (rRNA) gene sequencing, multilocus sequence analysis (atpD (β-subunit of ATP synthase F1), gyrB (DNA gyrase subunit B), infB (translation initiation factor 2), and rpoB (β‍-subunit of RNA polymerase) genes), and pathogenicity tests. Ultrastructural observations using scanning electron microscopy revealed that the bacterial cells colonized the vascular tissues in leaf sheaths, forming biofilms on the inner surface of vessel walls, and extended between vessel elements via the perforated plates. To achieve efficient detection and diagnosis of P. ananatis, species-specific primer pairs were designed and validated by testing closely related and unrelated species and diseased tissues of Z. latifolia. This is the first report of bacterial sheath rot disease of Z. latifolia caused by P. ananatis in China.
Pantoea/genetics* ; Plant Diseases/microbiology* ; Poaceae/microbiology* ; Virulence

Rice stripe virus (RSV) transmitted by the small brown planthopper causes severe rice yield losses in Asian countries. Although viral nuclear entry promotes viral replication in host cells, whether this phenomenon occurs in vector cells remains unknown. Therefore, in this study, we systematically evaluated the presence and roles of RSV in the nuclei of vector insect cells. We observed that the nucleocapsid protein (NP) and viral genomic RNAs were partially transported into vector cell nuclei by utilizing the importin α nuclear transport system. When blocking NP nuclear localization, cytoplasmic RSV accumulation significantly increased. In the vector cell nuclei, NP bound the transcription factor YY1 and affected its positive regulation to FAIM. Subsequently, decreased FAIM expression triggered an antiviral caspase-dependent apoptotic reaction. Our results reveal that viral nuclear entry induces completely different immune effects in vector and host cells, providing new insights into the balance between viral load and the immunity pressure in vector insects.
Animals ; Cell Nucleus ; Hemiptera/metabolism* ; Insect Vectors/genetics* ; Insecta ; Nucleocapsid Proteins/metabolism* ; Oryza ; Plant Diseases ; Tenuivirus/metabolism* ; Virus Replication

The cultivation and production of cucumber are seriously affected by downy mildew caused by Pseudoperonospora cubensis. Downy mildew damages leaves, stems and inflorescences, and then reduces the yield and quality of cucumber. This review summarized the research advances in cucumber downy mildew, including pathogen detection and defense pathways, regulatory factors, mining of pathogens-resistant candidate genes, proteomic and genomic analysis, and development of QTL remarks. This review may facilitate clarifying the resistance mechanisms of cucumber to downy mildew.
Cucumis sativus/genetics* ; Oomycetes/genetics* ; Peronospora ; Plant Diseases/genetics* ; Proteomics

Medicinal plants are beneficial to human health. However,most of the major producing regions of medicinal plants suffer from rust disease,which threatens the yield and quality of Chinese medicinal materials,thus causes huge economic loss,and hinders the sustainable development of the Chinese medicine industry. By the end of 2020,rust disease had been reported in medicinal plants of 76 species and 33 families. In the 76 species,79 rust pathogens were detected. The majority of these pathogens belonged to Puccinia( 33,39. 24%),Coleosporium( 14,15. 19%),and Aecidium( 11,13. 92%). Of these 79 rust pathogens,10 were autoecious and 13 were heteroecious. Through literature research,this study reviewed the symptoms,pathogen species,severity and distribution,prevalence and occurrence conditions,and control measures of rust disease in medicinal plants,and thereby summarized the research status of rust disease in medicinal plants and the gap with other plants,which is expected to serve as a reference for further research on rust disease in medicinal plants.
Basidiomycota/genetics* ; Humans ; Plant Diseases ; Plants, Medicinal

The general secretory (Sec) pathway represents a common mechanism by which bacteria secrete proteins, including virulence factors, into the extracytoplasmic milieu. However, there is little information about this system, as well as its associated secretory proteins, in relation to the fire blight pathogen Erwinia amylovora. In this study, data mining revealed that E. amylovora harbors all of the essential components of the Sec system. Based on this information, we identified putative Sec-dependent secretory proteases in E. amylovora on a genome-wide scale. Using the programs SignalP, LipoP, and Phobius, a total of 15 putative proteases were predicted to contain the N-terminal signal peptides (SPs) that might link them to the Sec-dependent pathway. The activities of the predicted SPs were further validated using an Escherichia coli-based alkaline phosphatase (PhoA) gene fusion system that confirmed their extracytoplasmic property. Transcriptional analyses showed that the expression of 11 of the 15 extracytoplasmic protease genes increased significantly when E. amylovora was used to inoculate immature pears, suggesting their potential roles in plant infection. The results of this study support the suggestion that E. amylovora might employ the Sec system to secrete a suite of proteases to enable successful infection of plants, and shed new light on the interaction of E. amylovora with host plants.
Erwinia amylovora/metabolism* ; Escherichia coli/genetics* ; Peptide Hydrolases/genetics* ; Plant Diseases/microbiology* ; Pyrus/microbiology*

Leymus racemosus had a high resistant capacity to wheat scab (Fusarum head blight). The transfer of scab resistant gene from L. racemosus to Triticum aestivum is of great significance for broadening the germplasm of wheat resistance. To obtain Triticum aestivum-Leymus racemosus translocation line with scab resistance, we irradiated the pollen of T. aestivum-L. racemosus disomic addition line DA7Lr by ⁶⁰Co-γ-rays 1 200 R (100 R/min) prior to pollinating to emasculation T. aestivum cv. Chinese Spring. One plant with one translocation chromosome was detected in the M1 by GISH. The plant with one translocation chromosome was self-pollinated, and at meiotic metaphase I its progenies with two translocation chromosomes were analyzed for chromosome pairing behavior in their pollen mother cells (PMCs). One rod bivalent was observed at meiotic metaphase I, indicating that the plant with two translocation chromosomes was one translocation homozygote. Sequential GISH-FISH analysis, using Oligo-pAs1-2 and Oligo-pSc119.2-2 as probe, translocation line was confirmed as T6DL·7LrS. The translocation line had higher resistance to wheat scab and feasibility to be used as a new source in wheat breeding resistant to scab disease.
Chromosomes, Plant ; Disease Resistance ; genetics ; In Situ Hybridization, Fluorescence ; Plant Breeding ; Plant Diseases ; genetics ; Poaceae ; genetics ; Pollen ; Translocation, Genetic ; Triticum ; genetics

In this study, we analyzed the physical interactions of the dominant negative isoform of MoYpt7. Our results show that MoYpt7 interacts with MoGdi1. The dominant negative isoform of MoYpt7 (dominant negative isoform, N125I) is essential for colony morphology, conidiation, and pathogenicity in the rice blast fungus. These results further demonstrate the biological functions of MoYpt7 in Magnaporthe oryzae.
DNA Mutational Analysis ; Fungal Proteins/metabolism* ; Gene Expression Regulation, Fungal ; Genes, Fungal ; Green Fluorescent Proteins/metabolism* ; Magnaporthe/genetics* ; Microscopy, Fluorescence ; Mutation ; Oryza/microbiology* ; Phenotype ; Plant Diseases/microbiology* ; Protein Isoforms

We report the recovery of a 7068-nt viral sequence from the "viral fossils" embedded in the genome of Alhagi sparsifolia, a typical desert plant. Although the full viral genome remains to be completed, the putative genome structure, the deduced amino acids and phylogenetic analysis unambiguously demonstrate that this viral sequence represents a novel species of the genus Badnavirus. The putative virus is tentatively termed Alhagi bacilliform virus (ABV). Southern blotting and inverse polymerase chain reaction (PCR) data indicate that the ABV-related sequence is integrated into the A. sparsifolia genome, and probably does not give rise to functional episomal virus. Molecular evidence that the ABV sequence exists widely in A. sparsifolia is also presented. To our knowledge, this is the first endogenous badnavirus identified from plants in the Gobi desert, and may provide new clues on the evolution, geographical distribution as well as the host range of the badnaviruses.
Badnavirus/genetics* ; Biological Evolution ; Desert Climate ; Fabaceae/virology* ; Genes, Plant ; Genetic Variation ; Genome, Viral ; Geography ; Open Reading Frames ; Phylogeny ; Plant Diseases/virology* ; Plasmids ; Sequence Analysis, RNA

A transgenic maize event ZD12-6 expressing a Bacillus thuringiensis (Bt) fusion protein Cry1Ab/Cry2Aj and a modified 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) protein G10 was characterized and evaluated. Southern blot analysis indicated that ZD12-6 is a single copy integration event. The insert site was determined to be at chromosome 1 by border sequence analysis. Expression analyses of Bt fusion protein Cry1Ab/Cry2Aj and the EPSPS protein G10 suggested that they are both expressed stably in different generations. Insect bioassays demonstrated that the transgenic plants are highly resistant to Asian corn borer (Ostrinia furnacalis), cotton boll worm (Helicoverpa armigera), and armyworm (Mythimna separata). This study suggested that ZD12-6 has the potential to be developed into a commercial transgenic line.
3-Phosphoshikimate 1-Carboxyvinyltransferase/metabolism* ; Animals ; Bacillus thuringiensis Toxins ; Bacterial Proteins/metabolism* ; China ; Disease Resistance/genetics* ; Drug Resistance/genetics* ; Endotoxins/metabolism* ; Gene Expression Profiling ; Glycine/chemistry* ; Hemolysin Proteins/metabolism* ; Insecta ; Plant Diseases/prevention & control* ; Plants, Genetically Modified/genetics* ; Zea mays/genetics* ; Glyphosate

Maize is one of the most important food crops. Rice black-streaked dwarf virus is a maize rough dwarf disease pathogen. The occurrence and transmission of maize rough dwarf disease brings great damage to maize production. The technology of using artificial miRNA to build antiviral plant has been proven effective in a variety of plants. However, such trials in maize have not been reported. We designed primers based on the sequence of maize zea-miR159a precursor and sequence of function protein genes and silencing RBSDV coding genes in RBSDV genome. We constructed amiRNA (artificial miRNA) gene for silencing RBSDV coding gene and gene silencing suppressor. We constructed pCAMBIA3301-121-amiRNA plant expression vector for transforming maize inbred lines Z31 by using agrobacterium mediated method. After molecular analysis of transgenic maize, homozygous lines with high miRNA expression were selected by molecular detection for a subsequent natural infection experiment. We studied the severity of maize rough dwarf disease according to a grading standard (grade 0 to 4). The experiment results showed that the disease resistance of transgenic homozygous maize with the anti-rough dwarf virus amiRNA vector was better than that of wild type. Among the transgenic maize, S6-miR159 transgenic maize had high disease resistance. It is feasible to create new maize variety by the use of artificial miRNA.
Disease Resistance ; genetics ; Gene Silencing ; Genetic Vectors ; MicroRNAs ; genetics ; Plant Diseases ; genetics ; virology ; Plants, Genetically Modified ; genetics ; Reoviridae ; pathogenicity ; Zea mays ; genetics