Abstract
ABSTRACT Penicillium expansum, P. digitatum, and P. italicum acidify the ambient environments of apple and citrus fruit during decay development. They use two mechanisms for this: the production of organic acids, mainly citric and gluconic, and NH(4)(+) utilization associated with H(+) efflux. Exposure of P. expansum and P. digitatum hyphae to pH 5.0 increased their citric acid production, compared with the production of organic acids at acidic ambient pH. In decayed fruit, both pathogens produced significant amounts of citric and gluconic acids in the decayed tissue and reduced the host pH by 0.5 to 1.0 units. Ammonium depletion from the growth medium or from the fruit tissue was directly related to ambient pH reduction. Analysis of transcripts encoding the endopolygalacturonase gene, pepg1, from P. expansum accumulated under acidic culture conditions from pH 3.5 to 5.0, suggesting that the acidification process is a pathogenicity enhancing factor of Penicillium spp. This hypothesis was supported by the finding that cultivars with lower pH and citric acid treatments to reduce tissue pH increased P. expansum development, presumably by increasing local pH. However, organic acid treatment could not enhance decay development in naturally acidic apples. Conversely, local alkalinization with NaHCO(3) reduced decay development. The present results further suggest that ambient pH is a regulatory cue for processes linked to pathogenicity of postharvest pathogens, and that specific genes are expressed as a result of the modified host pH created by the pathogens.
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Claims 10
Claim · model-written summary
Three Penicillium species acidified apple and citrus fruit environments during decay.
- Taxon
- apple and citrus fruit
Citrus
Malus domesticae0 - Interactor
- Penicillium expansum
Penicillium expansume0pathogen - Outcome
- acidify the ambient environmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Penicillium expansum, P. digitatum, and P. italicum acidify the ambient environments of apple and citrus fruit during decay development”
Claim · model-written summary
Exposure to pH 5.0 increased citric acid production by P. expansum and P. digitatum hyphae.
- Taxon
- Apple and Citrus FruitCitrusMalus domesticat0
- Interactor
- P. expansumPenicillium expansume0pathogen
- Second interactor
- P. digitatum
Penicillium digitatume0pathogen - Outcome
- citric acid productione0
- Direction
- increasede0
- Comparator
- acidic ambient pHe0
- Setting
- pH 5.0e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exposure of P. expansum and P. digitatum hyphae to pH 5.0 increased their citric acid production, compared with the production of organic acids at acidic ambient pH”
t0“Apple and Citrus Fruit”
Claim · model-written summary
The pathogens produced significant citric and gluconic acids in decayed fruit.
- Taxon
- Apple and Citrus FruitCitrusMalus domesticat0
- Outcome
- citric and gluconic acids in the decayed tissuee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In decayed fruit, both pathogens produced significant amounts of citric and gluconic acids in the decayed tissue”
t0“Apple and Citrus Fruit”
Claim · model-written summary
The pathogens reduced host fruit pH by 0.5 to 1.0 units.
- Taxon
- Apple and Citrus FruitCitrusMalus domesticat0
- Outcome
- host pHe0
- Direction
- reducede0
- Value
- 0.5 to 1.0 unitse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“reduced the host pH by 0.5 to 1.0 units”
t0“Apple and Citrus Fruit”
Claim · model-written summary
Ammonium depletion was directly related to ambient pH reduction.
- Taxon
- Apple and Citrus FruitCitrusMalus domesticat0
- Compound
- Ammoniume0
- Outcome
- ambient pH reductione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ammonium depletion from the growth medium or from the fruit tissue was directly related to ambient pH reduction”
t0“Apple and Citrus Fruit”
Claim · model-written summary
P. expansum pepg1 transcripts accumulated under acidic culture conditions.
- Taxon
- Apple and Citrus FruitCitrusMalus domesticat0
- Interactor
- P. expansumPenicillium expansume0pathogen
- Gene
- pepg1e0
- Outcome
- transcriptse0
- Direction
- accumulatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“transcripts encoding the endopolygalacturonase gene, pepg1, from P. expansum accumulated under acidic culture conditions from pH 3.5 to 5.0”
t0“Apple and Citrus Fruit”
Claim · model-written summary
Lower-pH cultivars increased P. expansum development.
- Taxon
- Apple and Citrus FruitCitrusMalus domesticat0
- Material
- cultivars with lower pHe0
- Interactor
- P. expansumPenicillium expansume0pathogen
- Outcome
- P. expansum developmente0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“cultivars with lower pH and citric acid treatments to reduce tissue pH increased P. expansum development”
t0“Apple and Citrus Fruit”
Claim · model-written summary
Citric acid treatment increased P. expansum development.
- Taxon
- Apple and Citrus FruitCitrusMalus domesticat0
- Treatment
- citric acid treatmentse0
- Interactor
- P. expansumPenicillium expansume0pathogen
- Outcome
- P. expansum developmente0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“citric acid treatments to reduce tissue pH increased P. expansum development”
t0“Apple and Citrus Fruit”
Claim · model-written summary
Organic acid treatment did not enhance decay development in naturally acidic apples.
- Taxon
- applesMalus domesticae0
- Treatment
- organic acid treatmente0
- Outcome
- decay developmente0
- Direction
- could not enhancee0
- Qualifier
- naturally acidice0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“organic acid treatment could not enhance decay development in naturally acidic apples”
Claim · model-written summary
Local alkalinization with NaHCO(3) reduced decay development.
- Taxon
- Apple and Citrus FruitCitrusMalus domesticat0
- Treatment
- local alkalinization with NaHCO(3)e0
- Outcome
- decay developmente0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“local alkalinization with NaHCO(3) reduced decay development”
t0“Apple and Citrus Fruit”
The same questions in other papers
organic acid · disease · Malus domestica (apple)Positive and negative results
2 in the opposite direction
- positive
- positive
sodium hydrogencarbonate · disease · CitrusResults agree
2 papers in the same direction as this paper
- positive
- positive
sodium hydrogencarbonate · disease · Malus domestica (apple)Results agree
3 papers in the same direction as this paper
- positive
- positive
- positive
alkalinity · disease · Malus domestica (apple)Results agree
1 paper in the same direction as this paper
- positive
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.