Ustilaginoidea virens is a flower-infecting fungus that forms false smut balls in rice panicle. Rice false smut has long been considered a minor disease, but recently it occurred frequently and emerged as a major dise...Ustilaginoidea virens is a flower-infecting fungus that forms false smut balls in rice panicle. Rice false smut has long been considered a minor disease, but recently it occurred frequently and emerged as a major disease in rice production. In vitro co-cultivation of U. virens strain with young rice panicles showed that U. virens enters inside of spikelets from the apex and then grows downward to infect floral organs. In response to U. virens infection, rice host exhibits elevated ROS accumulation and enhanced callose deposition. The secreted compounds of U. virens can suppress rice pollen germination. Examination of sectioning slides of freshly collected smut balls demonstrated that both pistil and stamens of rice flower are infected by U. virens, hyphae degraded the contents of the pollen cells, and also invaded the filaments. In addition, U. virens entered rice ovary through the thin-walled papillary cells of the stigma, then decomposed the integuments and infected the ovary. The invaded pathogen could not penetrate the epidermis and other layers of the ovary. Transverse section of the pedicel just below the smut balls showed that there were no fungal hyphae observed in the vascular bundles of the pedicel, implicating that U. virens is not a systemic flower-infecting fungus.展开更多
Peanuts can be affected by the presence of pathogenic microorganisms. The fungus <i>Thecaphora frezii</i> (<i>T. frezii</i>), which belongs to the taxonomic class Ustilaginomycetes, is the caus...Peanuts can be affected by the presence of pathogenic microorganisms. The fungus <i>Thecaphora frezii</i> (<i>T. frezii</i>), which belongs to the taxonomic class Ustilaginomycetes, is the causal agent of the disease known as “peanut smut”. The life cycle of this fungus includes three stages, namely teliospores, basidiospores and hyphae. In the hyphae stage, infection occurs in the peanut plant, which requires the involvement of some enzymes secreted by the fungus. These include the Plant Cell Wall-Degrading Enzymes (PCWDEs), which degrade various polysaccharides. This study aimed to identify the presence of transcript for enzymes belonging to the PCWDEs from three stages of <i>T. frezii</i>. For this, total RNA was extracted from the three ontogenetic stages of <i>T. frezii</i>. These samples were analyzed using an RNA-Seq approach and some transcripts were quantified using Real Time PCR. The analysis of the data provided by the RNA-Seq of the three <i>T. frezii</i> stages, it was possible to identify some transcripts that could encode enzymes compatible with polysaccharides degradation that are part of the plant cell wall. In <i>T. frezii</i> transcriptome, 40 deduced proteins would be enzymes with functions of PCWDEs were identified. They were divided into 27 glycoside hydrolases;two polysaccharide lyases;three carbohydrate esterases and eight enzymes with auxiliary activities. In addition, the fungal SNF1 gene was identified whose activity could be affected by high glucose level, and indirectly influence the levels of some PCWDEs. The analysis of the PCWDEs could help to understand part of the fungal infection process and possibly find substances that can control its development.展开更多
A plant expression vector harboring four antifungal genes was delivered into the embryogenic calli of ‘9311’, an indica restorer line of Super Hybrid Rice, via modified biolistic particle bombardment. Southern blot ...A plant expression vector harboring four antifungal genes was delivered into the embryogenic calli of ‘9311’, an indica restorer line of Super Hybrid Rice, via modified biolistic particle bombardment. Southern blot analysis indicated that in the regenerated hygromycin-resistant plants, all the four anti-fungal genes, including RCH10, RAC22, β-Glu and B-RIP, were integrated into the genome of ‘9311’, co-transmitted altogether with the marker gene hpt in a Mendelian pattern. Some transgenic R1 and R2 progenies, with all transgenes displaying a normal expression level in the Northern blot analysis, showed high resistance to Magnaporthe grisea when tested in the typical blast nurseries located in Yanxi and Sanya respectively. Furthermore, transgenic F1 plants, resulting from a cross of R2 homo-zygous lines with high resistance to rice blast with the non-transgenic male sterile line Peiai 64S, showed not only high resistance to M. grisea but also enhanced resistance to rice false smut (a disease caused by Ustilaginoidea virens) and rice kernel smut (another disease caused by Tilletia barclayana).展开更多
文摘Ustilaginoidea virens is a flower-infecting fungus that forms false smut balls in rice panicle. Rice false smut has long been considered a minor disease, but recently it occurred frequently and emerged as a major disease in rice production. In vitro co-cultivation of U. virens strain with young rice panicles showed that U. virens enters inside of spikelets from the apex and then grows downward to infect floral organs. In response to U. virens infection, rice host exhibits elevated ROS accumulation and enhanced callose deposition. The secreted compounds of U. virens can suppress rice pollen germination. Examination of sectioning slides of freshly collected smut balls demonstrated that both pistil and stamens of rice flower are infected by U. virens, hyphae degraded the contents of the pollen cells, and also invaded the filaments. In addition, U. virens entered rice ovary through the thin-walled papillary cells of the stigma, then decomposed the integuments and infected the ovary. The invaded pathogen could not penetrate the epidermis and other layers of the ovary. Transverse section of the pedicel just below the smut balls showed that there were no fungal hyphae observed in the vascular bundles of the pedicel, implicating that U. virens is not a systemic flower-infecting fungus.
文摘Peanuts can be affected by the presence of pathogenic microorganisms. The fungus <i>Thecaphora frezii</i> (<i>T. frezii</i>), which belongs to the taxonomic class Ustilaginomycetes, is the causal agent of the disease known as “peanut smut”. The life cycle of this fungus includes three stages, namely teliospores, basidiospores and hyphae. In the hyphae stage, infection occurs in the peanut plant, which requires the involvement of some enzymes secreted by the fungus. These include the Plant Cell Wall-Degrading Enzymes (PCWDEs), which degrade various polysaccharides. This study aimed to identify the presence of transcript for enzymes belonging to the PCWDEs from three stages of <i>T. frezii</i>. For this, total RNA was extracted from the three ontogenetic stages of <i>T. frezii</i>. These samples were analyzed using an RNA-Seq approach and some transcripts were quantified using Real Time PCR. The analysis of the data provided by the RNA-Seq of the three <i>T. frezii</i> stages, it was possible to identify some transcripts that could encode enzymes compatible with polysaccharides degradation that are part of the plant cell wall. In <i>T. frezii</i> transcriptome, 40 deduced proteins would be enzymes with functions of PCWDEs were identified. They were divided into 27 glycoside hydrolases;two polysaccharide lyases;three carbohydrate esterases and eight enzymes with auxiliary activities. In addition, the fungal SNF1 gene was identified whose activity could be affected by high glucose level, and indirectly influence the levels of some PCWDEs. The analysis of the PCWDEs could help to understand part of the fungal infection process and possibly find substances that can control its development.
基金the National High-Tech Research and Development Project (863) (Grant No. 101-01-02-02)National Specific Program for Research+1 种基金Industrialization of Transgenic Plant (Grant Nos. J00-A-009 and J99-B-012),Science & Technology Project of Guangdong Province (Grant No. B201)
文摘A plant expression vector harboring four antifungal genes was delivered into the embryogenic calli of ‘9311’, an indica restorer line of Super Hybrid Rice, via modified biolistic particle bombardment. Southern blot analysis indicated that in the regenerated hygromycin-resistant plants, all the four anti-fungal genes, including RCH10, RAC22, β-Glu and B-RIP, were integrated into the genome of ‘9311’, co-transmitted altogether with the marker gene hpt in a Mendelian pattern. Some transgenic R1 and R2 progenies, with all transgenes displaying a normal expression level in the Northern blot analysis, showed high resistance to Magnaporthe grisea when tested in the typical blast nurseries located in Yanxi and Sanya respectively. Furthermore, transgenic F1 plants, resulting from a cross of R2 homo-zygous lines with high resistance to rice blast with the non-transgenic male sterile line Peiai 64S, showed not only high resistance to M. grisea but also enhanced resistance to rice false smut (a disease caused by Ustilaginoidea virens) and rice kernel smut (another disease caused by Tilletia barclayana).
