Seedlings of Norway spruce were exposed to fungal infection and drought in order to investigate d... more Seedlings of Norway spruce were exposed to fungal infection and drought in order to investigate differences in their stress responses on the enzymatic level. Six-week-old seedlings were infected with the root rot fungus Rhizoctonia, or subjected to drought, respectively. Changes at the enzymatic level were more rapid and significantly higher in infected plants in comparison with drought-stressed spruce plants. Rhizoctonia infection resulted in early local and systemic increase in peroxidase and chitinase activity. The most prominent isoforms responding were highly basic peroxidases and chitinases (pI 9-9.5) and several acidic chitinases (pI3-4). An increased intensity of similar peroxidase isoforms was found in drought-affected plants. Two peroxidase isoforms (with pI < 9) accumulated exclusively in response to drought. These results suggest that at an early stage of infection and drought stress, the two stresses can be distinguished by the temporal appearance and isoform profile of peroxidases and chitinases. Changes in enzyme activity appeared before changes in physiological parameters, thus these isoform profiles could be used as early markers of stress conditions in spruce. Periodic acid Schiff's; Spi2, Spruce pathogen induced number 2.
1 Neodiprion sertifer nucleopolyhedrovirus (NeseNPV) is widely used as a viral bio-insecticide ag... more 1 Neodiprion sertifer nucleopolyhedrovirus (NeseNPV) is widely used as a viral bio-insecticide against larvae of the European pine sawfly N. sertifer (Geoff.) (Hymenoptera: Diprionidae), which is one of the most harmful defoliators of pines in Northern Europe. A major obstacle to studying this pathogenic virus in nature is the difficulty of confirming and quantifying the presence of NeseNPV. 2 In the present study, we developed real-time polymerase chain reaction (PCR) primers, based on the caspid gene 39 sequence, for the specific and quantitative detection of NeseNPV. The quantitative real-time PCR (qPCR) assay can detect virus from any substrate tested, including different insect life stages (egg, larval, adult), pine foliage, and litter or ground vegetation. The reproducible detection limit for the real-time assay is 0.013 pg of viral DNA (0.013 × 10 −12 g), corresponding to 136 viral genomes or approximately one to seven virus occlusion bodies per sample. 3 qPCR is a specific, quantitative, sensitive, reliable and flexible procedure, and is a good supplement to conventional microscopy-or bioassay-based methods for detection of the virus. We have used qPCR to quantify the level of NeseNPV in samples collected in the field after aerial application of the virus, and demonstrated significantly higher virus levels in sawfly larvae from sprayed areas compared with unsprayed control areas 4 weeks after spraying. 4 This qPCR assay can be used to determine important aspects of the biology of NeseNPV (e.g. virus levels in different insect life stages and in their microhabitats on pine foliage and in forest litter).
Seedlings of Norway spruce were exposed to fungal infection and drought in order to investigate d... more Seedlings of Norway spruce were exposed to fungal infection and drought in order to investigate differences in their stress responses on the enzymatic level. Six-week-old seedlings were infected with the root rot fungus Rhizoctonia, or subjected to drought, respectively. Changes at the enzymatic level were more rapid and significantly higher in infected plants in comparison with drought-stressed spruce plants. Rhizoctonia infection resulted in early local and systemic increase in peroxidase and chitinase activity. The most prominent isoforms responding were highly basic peroxidases and chitinases (pI 9-9.5) and several acidic chitinases (pI3-4). An increased intensity of similar peroxidase isoforms was found in drought-affected plants. Two peroxidase isoforms (with pI < 9) accumulated exclusively in response to drought. These results suggest that at an early stage of infection and drought stress, the two stresses can be distinguished by the temporal appearance and isoform profile of peroxidases and chitinases. Changes in enzyme activity appeared before changes in physiological parameters, thus these isoform profiles could be used as early markers of stress conditions in spruce. Periodic acid Schiff's; Spi2, Spruce pathogen induced number 2.
Seedlings of Norway spruce were exposed to fungal infection and drought in order to investigate d... more Seedlings of Norway spruce were exposed to fungal infection and drought in order to investigate differences in their stress responses on the enzymatic level. Six-week-old seedlings were infected with the root rot fungus Rhizoctonia, or subjected to drought, respectively. Changes at the enzymatic level were more rapid and significantly higher in infected plants in comparison with drought-stressed spruce plants. Rhizoctonia infection resulted in early local and systemic increase in peroxidase and chitinase activity. The most prominent isoforms responding were highly basic peroxidases and chitinases (pI 9-9.5) and several acidic chitinases (pI3-4). An increased intensity of similar peroxidase isoforms was found in drought-affected plants. Two peroxidase isoforms (with pI < 9) accumulated exclusively in response to drought. These results suggest that at an early stage of infection and drought stress, the two stresses can be distinguished by the temporal appearance and isoform profile of peroxidases and chitinases. Changes in enzyme activity appeared before changes in physiological parameters, thus these isoform profiles could be used as early markers of stress conditions in spruce. Periodic acid Schiff's; Spi2, Spruce pathogen induced number 2.
1 Neodiprion sertifer nucleopolyhedrovirus (NeseNPV) is widely used as a viral bio-insecticide ag... more 1 Neodiprion sertifer nucleopolyhedrovirus (NeseNPV) is widely used as a viral bio-insecticide against larvae of the European pine sawfly N. sertifer (Geoff.) (Hymenoptera: Diprionidae), which is one of the most harmful defoliators of pines in Northern Europe. A major obstacle to studying this pathogenic virus in nature is the difficulty of confirming and quantifying the presence of NeseNPV. 2 In the present study, we developed real-time polymerase chain reaction (PCR) primers, based on the caspid gene 39 sequence, for the specific and quantitative detection of NeseNPV. The quantitative real-time PCR (qPCR) assay can detect virus from any substrate tested, including different insect life stages (egg, larval, adult), pine foliage, and litter or ground vegetation. The reproducible detection limit for the real-time assay is 0.013 pg of viral DNA (0.013 × 10 −12 g), corresponding to 136 viral genomes or approximately one to seven virus occlusion bodies per sample. 3 qPCR is a specific, quantitative, sensitive, reliable and flexible procedure, and is a good supplement to conventional microscopy-or bioassay-based methods for detection of the virus. We have used qPCR to quantify the level of NeseNPV in samples collected in the field after aerial application of the virus, and demonstrated significantly higher virus levels in sawfly larvae from sprayed areas compared with unsprayed control areas 4 weeks after spraying. 4 This qPCR assay can be used to determine important aspects of the biology of NeseNPV (e.g. virus levels in different insect life stages and in their microhabitats on pine foliage and in forest litter).
Seedlings of Norway spruce were exposed to fungal infection and drought in order to investigate d... more Seedlings of Norway spruce were exposed to fungal infection and drought in order to investigate differences in their stress responses on the enzymatic level. Six-week-old seedlings were infected with the root rot fungus Rhizoctonia, or subjected to drought, respectively. Changes at the enzymatic level were more rapid and significantly higher in infected plants in comparison with drought-stressed spruce plants. Rhizoctonia infection resulted in early local and systemic increase in peroxidase and chitinase activity. The most prominent isoforms responding were highly basic peroxidases and chitinases (pI 9-9.5) and several acidic chitinases (pI3-4). An increased intensity of similar peroxidase isoforms was found in drought-affected plants. Two peroxidase isoforms (with pI < 9) accumulated exclusively in response to drought. These results suggest that at an early stage of infection and drought stress, the two stresses can be distinguished by the temporal appearance and isoform profile of peroxidases and chitinases. Changes in enzyme activity appeared before changes in physiological parameters, thus these isoform profiles could be used as early markers of stress conditions in spruce. Periodic acid Schiff's; Spi2, Spruce pathogen induced number 2.
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