Abstract
Bean genotypes (Phaseolus vulgaris) selected for high or low sensitivity to oxidants showed similar stress responses to ozone, paraquat and to infection withBotrytis cinerea. The potentially oxidative nature of the fungal attack was investigated on bean leaf discs floated in diluted malt broth medium and inoculated with conidia ofB. cinereaisolates differing in aggressiveness. Hydrogen peroxide and OH* radicals were measuredin situduring infection. Additionally, peroxidases, cellulases, xylanases and polygalacturonases (PG) diffusing into the incubation medium during infection were analysed. An assay based on the oxidative degradation of 2-deoxyribose enabled the specific detection ofin situgenerated OH* radicals. The aggressiveness of six isolates ofBotrytiswas closely correlated with the amount of H2O2and OH* radicals detected in the leaf tissue during infection. Aggressive isolates induced peak signals of OH* radical formation within 24 h and strongly elevated levels of H2O2within 48 h post-inoculation (hpi), in a phase of most rapidly progressing infection. No such increases in active oxygen species (AOS) were detected in non-aggressive interactions. All fungal isolates tested suppressed plant peroxidase activity as compared to non-inoculated leaf discs. However, aggressive isolates were significantly more suppressive than non-aggressive ones, suggesting a role for peroxidases in plant resistance as scavengers of harmful AOS. Hydrogen peroxide production measured in infected leaf discs was stronger than its accumulation in the incubation medium, pointing to sources of H2O2inside the plant. The scavengers of AOS, catalase and D-mannitol significantly reduced severity of infection. Secretion of cellulases and xylanases occurred later than the start of infection, suggesting a role of these cell-wall degrading enzymes in the digestion of dead rather than the killing of living host tissue. PGs were produced by all fungal isolates much earlier (12 hpi) but the production did not reflect the isolate aggressiveness. This is the first study to directly detect toxic AOSin situduring infection of plant tissue byB. cinerea. It is concluded that AOS, besides their probable role in plant resistance, might be instrumental for necrotrophs likeB. cinereato kill the host tissue in initial stages of infection.
Abstract from the paper’s OpenAlex record; open copy licensed cc-by-nc-nd. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 15
Claim · model-written summary
Selected bean genotypes had similar responses to ozone, paraquat and Botrytis.
- Taxon
- Beane0
- Interactor
- Botrytis cinerea
Botrytis cinereae0pathogen - Outcome
- similar stress responsese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Bean genotypes (Phaseolus vulgaris) selected for high or low sensitivity to oxidants showed similar stress responses to ozone, paraquat and to infection withBotrytis cinerea”
Claim · model-written summary
Isolate aggressiveness correlated with H2O2 and OH* in infected leaves.
- Outcome
- amount of H2O2and OH* radicalse0
Not reportedTaxonDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The aggressiveness of six isolates ofBotrytiswas closely correlated with the amount of H2O2and OH* radicals detected in the leaf tissue during infection”
Claim · model-written summary
Aggressive isolates induced OH* peaks within 24 h.
Not reportedTaxon
Verbatim
e0“Aggressive isolates induced peak signals of OH* radical formation within 24 h”
Claim · model-written summary
Aggressive isolates elevated H2O2 within 48 h.
Not reportedTaxon
Verbatim
e0“strongly elevated levels of H2O2within 48 h post-inoculation”
Claim · model-written summary
Nonaggressive interactions showed no AOS increase.
Not reportedTaxon
Verbatim
e0“No such increases in active oxygen species (AOS) were detected in non-aggressive interactions”
Claim · model-written summary
All fungal isolates suppressed plant peroxidase activity.
- Treatment
- fungal isolatese0
- Outcome
- plant peroxidase activitye0
- Direction
- suppressede0
- Comparator
- non-inoculated leaf discse0
Not reportedTaxon
Verbatim
e0“All fungal isolates tested suppressed plant peroxidase activity as compared to non-inoculated leaf discs”
Claim · model-written summary
Aggressive isolates suppressed peroxidase more than nonaggressive isolates.
Not reportedTaxon
Verbatim
e0“aggressive isolates were significantly more suppressive than non-aggressive ones”
Claim · model-written summary
H2O2 production in infected leaf discs exceeded accumulation in medium.
- Outcome
- Hydrogen peroxide productione0
- Direction
- strongere0
- Comparator
- its accumulation in the incubation mediume0
Not reportedTaxon
Verbatim
e0“Hydrogen peroxide production measured in infected leaf discs was stronger than its accumulation in the incubation medium”
Claim · model-written summary
Catalase reduced infection severity.
Not reportedTaxonComparator
Verbatim
e0“catalase and D-mannitol significantly reduced severity of infection”
Claim · model-written summary
D-mannitol reduced infection severity.
Not reportedTaxonComparator
Verbatim
e0“catalase and D-mannitol significantly reduced severity of infection”
Claim · model-written summary
Cellulases were secreted after infection began.
Not reportedTaxon
Verbatim
e0“Secretion of cellulases and xylanases occurred later than the start of infection”
Claim · model-written summary
Xylanases were secreted after infection began.
Not reportedTaxon
Verbatim
e0“Secretion of cellulases and xylanases occurred later than the start of infection”
Claim · model-written summary
All isolates produced PGs early in infection.
Not reportedTaxon
Verbatim
e0“PGs were produced by all fungal isolates much earlier (12 hpi)”
Claim · model-written summary
PG production did not track aggressiveness.
Not reportedTaxon
Verbatim
e0“the production did not reflect the isolate aggressiveness”
Claim · model-written summary
Authors infer AOS might help necrotrophs kill host tissue early.
Not reportedTaxon
Verbatim
e0“AOS, besides their probable role in plant resistance, might be instrumental for necrotrophs likeB. cinereato kill the host tissue in initial stages of infection”