Sopper forårsaker mange alvorlige sykdommer på trær. For å gjøre de rette tiltakene må en vite hv... more Sopper forårsaker mange alvorlige sykdommer på trær. For å gjøre de rette tiltakene må en vite hvilke sopper som er årsak til skaden. Dette kan ofte være vanskelig da forskjellige patogener kan forårsake lignende symptomer. Skogforsk har nå utviklet DNA-baserte metoder som påviser og registrerer mengden av viktige skadesopper i gran. Disse metodene er basert på artsspesifikke DNA-sekvenser. Ved hjelp av disse metodene kan vi oppdage svært små soppmengder i en vevsprøve, ja helt ned til en soppcelle i prøven. I ...
To identify differentially expressed genes of the white-rot fungus Heterobasidion parviporum, two... more To identify differentially expressed genes of the white-rot fungus Heterobasidion parviporum, two cDNA libraries were constructed using suppressive subtraction hybridization (SSH) technique with RNA extracted from an advanced stage of decay area and from colonization front next to the reaction zone of the stem of a mature Norway spruce naturally colonized by the fungus. Besides several cytochrome P450s and hypothetical proteins with unknown function, the SSH libraries constructed contained, among others, genes involved in basic cellular processes, and lignin and cellulose degradation. To examine the role of selected candidate genes for each functional group, three trees, each colonized by a different genotype of the pathogen and showing a variable degree of wood decay, were used for real-time RT-PCR profiling of candidate genes. In the decay transition areas the study revealed activity centers that showed remarkable similarity in the transcript profiles of the monitored genes.
The GH61 represents the most enigmatic Glycoside Hydrolase family (GH) regarding enzymatic activi... more The GH61 represents the most enigmatic Glycoside Hydrolase family (GH) regarding enzymatic activity and importance in cellulose degradation. Heterobasidion irregulare is a necrotizing pathogen and white-rot fungus that causes enormous damages in conifer forests. The genome of H. irregulare allowed identification of ten HiGH61 genes. qRT-PCR analysis separate the HiGH61 members into two groups; one that show up regulation on lignocellulosic substrates (HiGH61A, HiGH61B, HiGH61D, HiGH61G, HiGH61H, and HiGH61I) and a second showing either down-regulation or constitutive expression (HiGH61C, HiGH61E, HiGH61F, and HiGH61J). HiGH61H showed up to 17,000-fold increase on spruce heartwood suggesting a pivotal role in cellulose decomposition during saprotrophic growth. Sequence analysis of these genes reveals that all GH61s except HiGH61G possess the conserved metal-binding motif essential for activity. The sequences also divide into groups having either an insert near the N terminus or an insert near the second catalytic histidine, which may represent extensions of the substrate-binding surface. Three of the HiGH61s encode cellulose-binding modules (CBM1). Interestingly, HiGH61H and HiGH61I having CBM1s are up-regulated on pure cellulose. There was a common substrate-specific induction patterns of the HiGH61s with several reference cellulolytic and hemicellulolytic GHs, this taken together with their low transcript levels on media lacking lignocellulose, reflect the concerted nature of cell wall polymer degradation.
Heterobasidion parviporum, a common pathogenic white-rot fungus in managed Norway spruce forests ... more Heterobasidion parviporum, a common pathogenic white-rot fungus in managed Norway spruce forests in northern and central Europe, causes extensive decay columns within stem heartwood of the host tree. Infected trees combat the lateral spread of decay by bordering the heartwood with a fungistatic reaction zone characterized by elevated pH and phenol content. To examine the mode of fungal feeding in the reaction zone of mature Norway spruce trees naturally infected by H. parviporum, we conducted spatial profiling of pectin and hemicellulose composition, and established transcript levels of candidate fungal genes encoding enzymes involved in degradation of the different cell wall components of wood. Colonized inner heartwood showed pectin and hemicellulose concentrations similar to those of healthy heartwood, whereas the carbohydrate profiles of compromised reaction zone, irrespective of the age of fungal activity in the tissue, indicated selective fungal utilization of galacturonic acid, arabinose, xylose and mannose. These data show that the rate of wood decay in the reaction zone is slow. While the up-regulation of genes encoding pectinases and hemicellulases preceded that of the endoglucanase gene during an early phase of fungal interaction with xylem defense, the manganese peroxidase gene showed similar transcript levels during different phases of wood colonization. It seems plausible that the reaction zone components of Norway spruce interfere with both lignin degradation and the associated co-hydrolysis of hemicelluloses and pectin, resulting in a prolonged phase of selective decay.
Sopper forårsaker mange alvorlige sykdommer på trær. For å gjøre de rette tiltakene må en vite hv... more Sopper forårsaker mange alvorlige sykdommer på trær. For å gjøre de rette tiltakene må en vite hvilke sopper som er årsak til skaden. Dette kan ofte være vanskelig da forskjellige patogener kan forårsake lignende symptomer. Skogforsk har nå utviklet DNA-baserte metoder som påviser og registrerer mengden av viktige skadesopper i gran. Disse metodene er basert på artsspesifikke DNA-sekvenser. Ved hjelp av disse metodene kan vi oppdage svært små soppmengder i en vevsprøve, ja helt ned til en soppcelle i prøven. I ...
To identify differentially expressed genes of the white-rot fungus Heterobasidion parviporum, two... more To identify differentially expressed genes of the white-rot fungus Heterobasidion parviporum, two cDNA libraries were constructed using suppressive subtraction hybridization (SSH) technique with RNA extracted from an advanced stage of decay area and from colonization front next to the reaction zone of the stem of a mature Norway spruce naturally colonized by the fungus. Besides several cytochrome P450s and hypothetical proteins with unknown function, the SSH libraries constructed contained, among others, genes involved in basic cellular processes, and lignin and cellulose degradation. To examine the role of selected candidate genes for each functional group, three trees, each colonized by a different genotype of the pathogen and showing a variable degree of wood decay, were used for real-time RT-PCR profiling of candidate genes. In the decay transition areas the study revealed activity centers that showed remarkable similarity in the transcript profiles of the monitored genes.
The GH61 represents the most enigmatic Glycoside Hydrolase family (GH) regarding enzymatic activi... more The GH61 represents the most enigmatic Glycoside Hydrolase family (GH) regarding enzymatic activity and importance in cellulose degradation. Heterobasidion irregulare is a necrotizing pathogen and white-rot fungus that causes enormous damages in conifer forests. The genome of H. irregulare allowed identification of ten HiGH61 genes. qRT-PCR analysis separate the HiGH61 members into two groups; one that show up regulation on lignocellulosic substrates (HiGH61A, HiGH61B, HiGH61D, HiGH61G, HiGH61H, and HiGH61I) and a second showing either down-regulation or constitutive expression (HiGH61C, HiGH61E, HiGH61F, and HiGH61J). HiGH61H showed up to 17,000-fold increase on spruce heartwood suggesting a pivotal role in cellulose decomposition during saprotrophic growth. Sequence analysis of these genes reveals that all GH61s except HiGH61G possess the conserved metal-binding motif essential for activity. The sequences also divide into groups having either an insert near the N terminus or an insert near the second catalytic histidine, which may represent extensions of the substrate-binding surface. Three of the HiGH61s encode cellulose-binding modules (CBM1). Interestingly, HiGH61H and HiGH61I having CBM1s are up-regulated on pure cellulose. There was a common substrate-specific induction patterns of the HiGH61s with several reference cellulolytic and hemicellulolytic GHs, this taken together with their low transcript levels on media lacking lignocellulose, reflect the concerted nature of cell wall polymer degradation.
Heterobasidion parviporum, a common pathogenic white-rot fungus in managed Norway spruce forests ... more Heterobasidion parviporum, a common pathogenic white-rot fungus in managed Norway spruce forests in northern and central Europe, causes extensive decay columns within stem heartwood of the host tree. Infected trees combat the lateral spread of decay by bordering the heartwood with a fungistatic reaction zone characterized by elevated pH and phenol content. To examine the mode of fungal feeding in the reaction zone of mature Norway spruce trees naturally infected by H. parviporum, we conducted spatial profiling of pectin and hemicellulose composition, and established transcript levels of candidate fungal genes encoding enzymes involved in degradation of the different cell wall components of wood. Colonized inner heartwood showed pectin and hemicellulose concentrations similar to those of healthy heartwood, whereas the carbohydrate profiles of compromised reaction zone, irrespective of the age of fungal activity in the tissue, indicated selective fungal utilization of galacturonic acid, arabinose, xylose and mannose. These data show that the rate of wood decay in the reaction zone is slow. While the up-regulation of genes encoding pectinases and hemicellulases preceded that of the endoglucanase gene during an early phase of fungal interaction with xylem defense, the manganese peroxidase gene showed similar transcript levels during different phases of wood colonization. It seems plausible that the reaction zone components of Norway spruce interfere with both lignin degradation and the associated co-hydrolysis of hemicelluloses and pectin, resulting in a prolonged phase of selective decay.
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