Landscape pathology is a research approach that can provide validation of the effectiveness of regional controls of forest disease at a landscape scale. In this paper, we analyzed the effects of stand features, manage...Landscape pathology is a research approach that can provide validation of the effectiveness of regional controls of forest disease at a landscape scale. In this paper, we analyzed the effects of stand features, management approaches, and geographical locations on poplar canker disease incidence （DI） and disease severity index （DSI） of individual trees at a 10 km x 10 km mesoscale landscape in Qingfeng County, China. DI varied significantly with stand age, tree densities, and the degree of canopy closure. DI in stands younger than 4 years old was significantly lower than that in the stands over 6 years old and reached the highest value at a stand age of 8-10 years. Overall, DI was positively correlated with stand age, stand density, andthe degree of canopy closure. DI was significantly lower in agro-forest stand patches than in other three patch types, i.e. isolated patch, pure stand patch, and mixed stand patch. Poplar plantations distributed around and near to villages exhibited significantly higher DI mainly due to human activities and herbivores. Fragmentation or connectivity in this mesoscale landscape seemed not impact disease occurrence. DSI was not significantly correlated with stand density, but varied significantly with tree varieties and trees ages. DSI was highest in stands of 10-12 year trees for all poplar varieties we studied here. Plantation density and plantation age were thus critical factors in determining DI and DSI. A logistic predictive model of disease occurrence was developed for the study area, considering varieties, age, height, density, canopy cover, stand types, patch types, management status, and stand geographical locations. Our study here shows that adjustment of stand density by thinning at different plantation ages is an effective approach controlling the occurrence canker disease in short-rotation poplar plantations at the landscape scale.展开更多
Poplar canker,caused by the fungus Cytospora chrysosperma,results in tremendous losses in poplar plantations in China.Although NADPH oxidases(NOXs)play important roles in the development and pathogenicity of several p...Poplar canker,caused by the fungus Cytospora chrysosperma,results in tremendous losses in poplar plantations in China.Although NADPH oxidases(NOXs)play important roles in the development and pathogenicity of several pathogenic fungi,their roles in C.chrysosperma remain unclear.In this study,we characterized three NOX genes(CcNox1,CcNox2,and CcNoxR)in C.chrysosperma.All three genes were highly upregulated during poplar branch infection,and deletion of any of them severely reduced virulence on poplar branches.Furthermore,deletion of either CcNox1 or CcNoxR resulted in a significant increase in endogenous reactive oxygen species production in hyphae,enhanced influx of Ca^(2+),the disruption of redox homeostasis and compromised mitochondrial integrity.Moreover,biosynthesis and secretion of a known virulence factor oxalic acid was obviously defective and exogenous oxalic acid supplementation rescued the virulence of the mutants.Taken together,our findings reveal that NOXs play important roles in redox homeostasis,mitochondrial integrity and pathogenicity in C.chrysosperma.展开更多
The poplar bacterial canker caused by Erwinia sp. is a serious disease spreading in most parts of Northeast China, where poplars are cultivated. The disease seriously infects those poplars belonging to section Aigeiro...The poplar bacterial canker caused by Erwinia sp. is a serious disease spreading in most parts of Northeast China, where poplars are cultivated. The disease seriously infects those poplars belonging to section Aigeiros or the intersection hybrids of section Tacamahaca and section Aigeiros and their clones. Five fine poplar cultivars resistant to the bacterial canker have been obtained by screening tests. They are Lz2(Populus simonii × nigra var. italica), A15(P. × sp.), 613(P. × sp.), A102and A98(P. × simonii × sp.). The following chemicals are obviously effective, such as: 50% DT germicide, 40% XF-136 and 10% C.C.M.A. or 12.5% ramphencol and 50,000 ppm/ml validamycin, with which the stems or the roots can be watered.展开更多
This is the first time that biological induced resistance has been used in the research of the bacterial canker on poplar. After inoculated with less-aggressive strains, middle-aggressive strains and non-aggressive st...This is the first time that biological induced resistance has been used in the research of the bacterial canker on poplar. After inoculated with less-aggressive strains, middle-aggressive strains and non-aggressive strains (high-aggressive strains have been treated with 400W ultraviolet lamp for 30 min on super-clean working table) poplar seedlings have been inoculated with high-aggressive strams. the results of those experiments shown that strain 3 (from Suihua, Heilongjiang)and strain 9 (from Liaoning) can significantly enhance the activities of the peroxidase of host. and the efects of twice inoculation were much better than that of once inoculation. 7. 1 % and 4.0% of the peroxidase activities have been enhanced respectively in the seedlings which were twice inoculation with strains 3 and strains 9. 1. 1 % and 1 .2 % of the peroxidase activities have been enhanced by inoculated strains 3 and strains 9 once into seedlings.展开更多
Fungal pathogens causing poplar canker diseases are cosmopolitan in species,and have a wide range of hosts.These pathogens have diverse anamorphs and their morphology overlaps with each other;Their teleomorphs are har...Fungal pathogens causing poplar canker diseases are cosmopolitan in species,and have a wide range of hosts.These pathogens have diverse anamorphs and their morphology overlaps with each other;Their teleomorphs are hardly discovered in nature.Furthermore,the identification of these pathogens is usually limited by the geography,host and taxonomic knowledge.Therefore,a culture-independent method used to identify determine pathogens is expected to be developed for field diagnostics.Through amplifying,sequencing and analyzing multiplex nucleic acid templates and genetic marked target sequences,a multiplex PCR technique has been established and used to directly detect various environmental samples.In this study, four pathogen strains and environmental samples were amplified using fungal universal primers ITS1/ ITS4 and EF1-728F/EF1-986R by general PCR and multiplex PCR.The amplicons were sequenced,and then aligned in GenBank.The result showed that the multiplex PCR was able to successfully amplify the target gene and identify the pathogens from environmental samples in the condition of an annealing temperature of 55.6℃and primers final concentration of 0.2μmol·L<sup>-1</sup>.The multiplex PCR could amplify the target at the concentration level of approximately lng of genomic DNA.This method would provide a useful tool for the identification of canker pathogens by the multiplex PCR and the high-throughput DNA microarray detection of environmental samples.展开更多
基金supported by the twelfth five-year science and technology support program of China(2012BAD19B0801)
文摘Landscape pathology is a research approach that can provide validation of the effectiveness of regional controls of forest disease at a landscape scale. In this paper, we analyzed the effects of stand features, management approaches, and geographical locations on poplar canker disease incidence （DI） and disease severity index （DSI） of individual trees at a 10 km x 10 km mesoscale landscape in Qingfeng County, China. DI varied significantly with stand age, tree densities, and the degree of canopy closure. DI in stands younger than 4 years old was significantly lower than that in the stands over 6 years old and reached the highest value at a stand age of 8-10 years. Overall, DI was positively correlated with stand age, stand density, andthe degree of canopy closure. DI was significantly lower in agro-forest stand patches than in other three patch types, i.e. isolated patch, pure stand patch, and mixed stand patch. Poplar plantations distributed around and near to villages exhibited significantly higher DI mainly due to human activities and herbivores. Fragmentation or connectivity in this mesoscale landscape seemed not impact disease occurrence. DSI was not significantly correlated with stand density, but varied significantly with tree varieties and trees ages. DSI was highest in stands of 10-12 year trees for all poplar varieties we studied here. Plantation density and plantation age were thus critical factors in determining DI and DSI. A logistic predictive model of disease occurrence was developed for the study area, considering varieties, age, height, density, canopy cover, stand types, patch types, management status, and stand geographical locations. Our study here shows that adjustment of stand density by thinning at different plantation ages is an effective approach controlling the occurrence canker disease in short-rotation poplar plantations at the landscape scale.
基金supported by the National Key R&D Program of China(2022YFD1401000).
文摘Poplar canker,caused by the fungus Cytospora chrysosperma,results in tremendous losses in poplar plantations in China.Although NADPH oxidases(NOXs)play important roles in the development and pathogenicity of several pathogenic fungi,their roles in C.chrysosperma remain unclear.In this study,we characterized three NOX genes(CcNox1,CcNox2,and CcNoxR)in C.chrysosperma.All three genes were highly upregulated during poplar branch infection,and deletion of any of them severely reduced virulence on poplar branches.Furthermore,deletion of either CcNox1 or CcNoxR resulted in a significant increase in endogenous reactive oxygen species production in hyphae,enhanced influx of Ca^(2+),the disruption of redox homeostasis and compromised mitochondrial integrity.Moreover,biosynthesis and secretion of a known virulence factor oxalic acid was obviously defective and exogenous oxalic acid supplementation rescued the virulence of the mutants.Taken together,our findings reveal that NOXs play important roles in redox homeostasis,mitochondrial integrity and pathogenicity in C.chrysosperma.
文摘The poplar bacterial canker caused by Erwinia sp. is a serious disease spreading in most parts of Northeast China, where poplars are cultivated. The disease seriously infects those poplars belonging to section Aigeiros or the intersection hybrids of section Tacamahaca and section Aigeiros and their clones. Five fine poplar cultivars resistant to the bacterial canker have been obtained by screening tests. They are Lz2(Populus simonii × nigra var. italica), A15(P. × sp.), 613(P. × sp.), A102and A98(P. × simonii × sp.). The following chemicals are obviously effective, such as: 50% DT germicide, 40% XF-136 and 10% C.C.M.A. or 12.5% ramphencol and 50,000 ppm/ml validamycin, with which the stems or the roots can be watered.
文摘This is the first time that biological induced resistance has been used in the research of the bacterial canker on poplar. After inoculated with less-aggressive strains, middle-aggressive strains and non-aggressive strains (high-aggressive strains have been treated with 400W ultraviolet lamp for 30 min on super-clean working table) poplar seedlings have been inoculated with high-aggressive strams. the results of those experiments shown that strain 3 (from Suihua, Heilongjiang)and strain 9 (from Liaoning) can significantly enhance the activities of the peroxidase of host. and the efects of twice inoculation were much better than that of once inoculation. 7. 1 % and 4.0% of the peroxidase activities have been enhanced respectively in the seedlings which were twice inoculation with strains 3 and strains 9. 1. 1 % and 1 .2 % of the peroxidase activities have been enhanced by inoculated strains 3 and strains 9 once into seedlings.
文摘Fungal pathogens causing poplar canker diseases are cosmopolitan in species,and have a wide range of hosts.These pathogens have diverse anamorphs and their morphology overlaps with each other;Their teleomorphs are hardly discovered in nature.Furthermore,the identification of these pathogens is usually limited by the geography,host and taxonomic knowledge.Therefore,a culture-independent method used to identify determine pathogens is expected to be developed for field diagnostics.Through amplifying,sequencing and analyzing multiplex nucleic acid templates and genetic marked target sequences,a multiplex PCR technique has been established and used to directly detect various environmental samples.In this study, four pathogen strains and environmental samples were amplified using fungal universal primers ITS1/ ITS4 and EF1-728F/EF1-986R by general PCR and multiplex PCR.The amplicons were sequenced,and then aligned in GenBank.The result showed that the multiplex PCR was able to successfully amplify the target gene and identify the pathogens from environmental samples in the condition of an annealing temperature of 55.6℃and primers final concentration of 0.2μmol·L<sup>-1</sup>.The multiplex PCR could amplify the target at the concentration level of approximately lng of genomic DNA.This method would provide a useful tool for the identification of canker pathogens by the multiplex PCR and the high-throughput DNA microarray detection of environmental samples.
