Channel: CELL BIOLOGY, PHYSIOLOGY, BIOCHEMISTRY, AND MOLECULAR BIOLOGY http://zwblxb.magtech.com.cn EN-US http://zwblxb.magtech.com.cn/EN/current.shtml http://zwblxb.magtech.com.cn 5 Fusarium spp. causing lotus rhizome rot disease around the world. From the microscopic and ultra-microscopic levels, this study revealed the changes to the rhizome and its vascular tissues during Fusarium infection. The observation of paraffin-embedded tissue sections showed that with the development of the disease, necrotic cells stained by toluidine blue appeared around the vascular bundles, and the closer to the bundles, the more numerous necrotic cells and the more densely distributed. In order to further reveal the influence of pathogen infection on vascular bundles, brightfield optical and scanning electron microscopy were used to observe the lotus fibers in the diseased lotus rhizomes. The results showed that the smooth and compact lotus fibers became rough and dispersed with the disease tending to be more severe, and a large number of galls-like protrusions and other possible metabolic attachments were attached to the surface. These changes to the vascular bundles are likely to reduce the water and nutrient transportation, and finally the aboveground parts of the plant exhibited the symptoms of water loss and wilting. The results of this study revealed the cellular biological mechanism of the disease symptom development, and provided a basis of histology for the breeding of resistant varieties in the future.]]> Tobamovirus, showed stronger pathogenicity than tobacco mosaic virus (TMV) and tomato mosaic virus (ToMV) in most solanaceae crops. To figure out the cytopathological changes of tobacco plants that were infected by ToMMV, we constructed a full-length infectious cDNA clone of ToMMV, and carried out transmission electron microscopy observation. The results showed that the rod-shaped virions of ToMMV were 220-310 nm in length and 16-18 nm in diameter. ToMMV virions were also observed in the seeds of ToMMV-infected Nicotiana tabacum var. Xanthi nc. ToMMV virions were dispersed or angularly-layered in cytoplasm or vacuoles. Multivesicular bodies, small vesicles, myeloid bodies, mitochondrial cristae were observed to be reduced or disappeared in both N. tabacum var. Xanthi nc and N. rustica infected with ToMMV. In addition, broken chloroplast membranes and large amount of small peripheral vesicles protruding into the disintegrated chloroplasts were observed in the infected N. tabacum var. Xanthi nc showing mosaic and distortion symptoms, while large amount of small vesicles were observed in the cells of infected N. tabacum var. Xanthi nc showing leaf narrowing. However, chloroplasts changes were less frequent in N. rustica with systemic necrosis symptoms. In this study, the construction of ToMMV infectious clone and the observation of cytopathological changes in tobacco plants infected with ToMMV, provided important bases for the further study of the pathogenesis of ToMMV and its interaction with the host.]]> Lasiodiplodia theobromae is an important plant pathogenic fungus, infecting more than 500 species of woody plants and causing serious damages worldwide. The secreted proteins of pathogenic fungi play important roles in pathogen invasion, expansion, and colonization in plants. Although there are more reports on the involvement of classical secreted proteins in fungal pathogenicity, the roles of non-classical secreted proteins in the pathogenesis of plant pathogenic fungi have rarely been investigated. In this study, 238 candidate non-classical secreted protein-coding genes were obtained by bioinformatic prediction based on the whole genome sequence of L. theobromae. Gene functional prediction and GO enrichment analysis showed that these genes are enriched in the carbon-sulfur lyase activity pathway. The annotation results based on PHI-base showed that 15 non-classical protein-coding genes might be related to the pathogenicity of L. theobromae. Predication of subcellular location using ApoplastP showed that 4 of them were located in plant apoplast and 11 were located in plant proplastids. Reverse transcription quantitative PCR (RT-qPCR) analysis results further verified that the transcriptional expression levels of the above candidate non-classical secreted protein-coding genes were significantly changed after treatment with grapevine branch tissues, indicating that these non-classical secreted proteins may play important roles in grapevine-L. theobromae interaction. The results lay a foundation for further understanding of the pathogenic mechanism of non-classical secreted proteins of L. theobromae.]]> Alternaria solani is an important disease in potato production, which seriously affects the yield and quality of potatoes. To reveal the interaction mechanism between A. solani and its host plant potato, we screened the effector candidates produced by A. solani during its interaction with potato plant using RNA transcriptome sequencing technology and biological software (signalp-4.1, tmhmm-2.0c, phobius101 and ProtComp v3) combined with characteristics analysis of effector proteins. As a result, 137 differentially expressed candidate proteins were obtained, and four (Gene03396, Gene06670, Gene02858 and Gene06508)of them were selected for further analysis. Based on the result of RNA-seq analysis, Gene03396, Gene06670 and Gene02858 had an up-regulated expression pattern at three time points (3, 4 and 5 dpi) compared with that at 0 dpi, whereas Gene06508 had a downregulated expression pattern. The four proteins do not have a common motif according to the MEME analysis result. Transient overexpression of the target effector candidate genes in tobacco showed that Gene03396 and Gene02858 directly induced tobacco cell necrosis, and Gene06670 inhibited programmed cell death (PCD) induced by BCL2-associated X, indicating that effector candidates function by stimulating plant immunity or inhibiting host defense response. The subcellular localization results revealed that Gene03396 was located on the cell membrane, while Gene06670 and Gene02858 may be located in the intercellular space. These results provide a basis for further identifying the effector proteins of A. solani and revealing the underlying pathogenic mechanism of the pathogen.]]>