Abstract
Heat shock is considered an abiotic stress for plant growth, but the effects of heat shock on physiological responses of cucumber plant leaves with and without downy mildew disease are still not clear. In this study, cucumber seedlings were exposed to heat shock in greenhouses, and the responses of photosynthetic properties, carbohydrate metabolism, antioxidant enzyme activity, osmolytes, and disease severity index of leaves with or without the downy mildew disease were measured. Results showed that heat shock significantly decreased the net photosynthetic rate, actual photochemical efficiency, photochemical quenching coefficient, and starch content. Heat shock caused an increase in the stomatal conductance, transpiration rate, antioxidant enzyme activities, total soluble sugar content, sucrose content, soluble protein content and proline content for both healthy leaves and downy mildew infected leaves. These results demonstrate that heat shock activated the transpiration pathway to protect the photosystem from damage due to excess energy in cucumber leaves. Potential resistance mechanisms of plants exposed to heat stress may involve higher osmotic regulation capacity related to an increase of total accumulations of soluble sugar, proline and soluble protein, as well as higher antioxidant enzymes activity in stressed leaves. Heat shock reduced downy mildew disease severity index by more than 50%, and clearly alleviated downy mildew development in the greenhouses. These findings indicate that cucumber may have a complex physiological change to resist short-term heat shock, and suppress the development of the downy mildew disease.
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Claims 7
Claim · model-written summary
Heat shock significantly reduced four photosynthetic measures and starch content.
- Taxon
- cucumber
Cucumis sativust0 - Treatment
- heat shocke0
- Outcome
- net photosynthetic rate, actual photochemical efficiency, photochemical quenching coefficient, and starch contente0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“heat shock significantly decreased the net photosynthetic rate, actual photochemical efficiency, photochemical quenching coefficient, and starch content”
t0“Cucumber”
t1“Heat Shock”
Claim · model-written summary
Heat shock increased stomatal conductance, transpiration rate, and antioxidant enzyme activities in healthy and infected leaves.
- Taxon
- cucumberCucumis sativust0
- Treatment
- Heat shocke0
- Outcome
- stomatal conductance, transpiration rate, antioxidant enzyme activitiese0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Heat shock caused an increase in the stomatal conductance, transpiration rate, antioxidant enzyme activities”
t0“Cucumber”
t1“Heat Shock”
Claim · model-written summary
Heat shock increased total soluble sugar, sucrose, and soluble protein content.
- Taxon
- cucumberCucumis sativust0
- Treatment
- heat shockt1
- Outcome
- total soluble sugar content, sucrose content, soluble protein contente0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“total soluble sugar content, sucrose content, soluble protein content and proline content for both healthy leaves and downy mildew infected leaves”
t0“Cucumber”
t1“Heat Shock”
Claim · model-written summary
Heat shock increased proline content in healthy and infected leaves.
- Taxon
- cucumberCucumis sativust0
- Treatment
- heat shockt1
- Outcome
- proline contente0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“proline content for both healthy leaves and downy mildew infected leaves”
t0“Cucumber”
t1“Heat Shock”
Claim · model-written summary
The authors conclude heat shock activates transpiration to protect the photosystem.
- Taxon
- cucumberCucumis sativust0
- Treatment
- heat shocke0
- Outcome
- protect the photosystem from damage due to excess energye0
- Qualifier
- transpiration pathwaye0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“heat shock activated the transpiration pathway to protect the photosystem from damage due to excess energy”
t0“Cucumber”
t1“Heat Shock”
Claim · model-written summary
The authors propose osmotic regulation and antioxidant activity as possible heat resistance mechanisms.
- Taxon
- cucumberCucumis sativust0
- Treatment
- heat stresse0
- Outcome
- resistance mechanismse0
- Qualifier
- higher osmotic regulation capacitye0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Potential resistance mechanisms of plants exposed to heat stress may involve higher osmotic regulation capacity related to an increase of total accumulations of soluble sugar, proline and soluble protein, as well as higher antioxidant enzymes activity”
t0“Cucumber”
t1“Heat Shock”
Claim · model-written summary
Heat shock reduced downy mildew severity by more than 50% in greenhouses.
- Taxon
- cucumberCucumis sativust0
- Treatment
- Heat shocke0
- Outcome
- downy mildew disease severity indexe0
- Direction
- reducede0
- Value
- more than 50%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Heat shock reduced downy mildew disease severity index by more than 50%”
t0“Cucumber”
t1“Heat Shock”
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