Abstract
The effects of osmotic dehydration in wheat leaves (Triticum aestivum L. cv. Long chun No. 10) on the photochemical function and protein metabolism of PSII were studied with isolated thylakoid and PSII membranes. The results indicated that PSII was rather resistant to water stress as mild water deficit in leaves did not significantly affect its activity. However, extreme stress conditions such as 40% decrease in relative water content (RWC) or 1.8 MPa in water potential (Psi(w)) caused ca 50% reduction in O-2 evolution and ca 25% inhibition of DCIP (2,6-dichlorophenol indophenol) photoreduction of PSII. In addition, it was found that the inhibited DCIP photoreduction of PSII could not be reversed by DPC (2,2-diphenylcarbazide), a typical electron donor to PSII, suggesting that water stress did not affect electron donation to PSII. Urea-SDS-PAGE and western blot analysis showed that the steady state levels of major PSII proteins, including the DI and D2 proteins in the PSII reaction center, declined on a chlorophyll basis with increasing water stress, possibly as a result of increased degradation. In vitro translation experiments and quantitative analysis of chloroplast RNAs indicated that the potential synthesis of chloroplast proteins from their mRNAs was impaired by water stress. From the results it is concluded that the effects of water stress on PSII protein metabolism, especially on the reaction center proteins, may account for the damage to PSII photochemistry.
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Claims 7
Claim · model-written summary
Mild water deficit did not significantly affect PSII activity in wheat leaves.
- Taxon
- wheat
Triticum aestivume0 - Material
- Long chun No. 10e0
- Treatment
- mild water deficite1
- Outcome
- activitye1
- Direction
- did not significantly affecte1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“effects of osmotic dehydration in wheat leaves (Triticum aestivum L. cv. Long chun No. 10)”
e1“PSII was rather resistant to water stress as mild water deficit in leaves did not significantly affect its activity”
Claim · model-written summary
Extreme water stress reduced O2 evolution of PSII by about 50%.
- Taxon
- wheatTriticum aestivume0
- Treatment
- extreme stress conditions such as 40% decrease in relative water content (RWC)e2
- Outcome
- O-2 evolutione2
- Direction
- reductione2
- Value
- ca 50%e2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“effects of osmotic dehydration in wheat leaves (Triticum aestivum L. cv. Long chun No. 10)”
e2“extreme stress conditions such as 40% decrease in relative water content (RWC) or 1.8 MPa in water potential (Psi(w)) caused ca 50% reduction in O-2 evolution and ca 25% inhibition of DCIP (2,6-dichlorophenol indophenol) photoreduction of PSII”
Claim · model-written summary
Extreme water stress inhibited DCIP photoreduction of PSII by about 25%.
- Taxon
- wheatTriticum aestivume0
- Treatment
- extreme stress conditions such as 40% decrease in relative water content (RWC)e2
- Outcome
- DCIP (2,6-dichlorophenol indophenol) photoreduction of PSIIe2
- Direction
- inhibitione2
- Value
- ca 25%e2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“effects of osmotic dehydration in wheat leaves (Triticum aestivum L. cv. Long chun No. 10)”
e2“extreme stress conditions such as 40% decrease in relative water content (RWC) or 1.8 MPa in water potential (Psi(w)) caused ca 50% reduction in O-2 evolution and ca 25% inhibition of DCIP (2,6-dichlorophenol indophenol) photoreduction of PSII”
Claim · model-written summary
Water stress is suggested not to affect electron donation to PSII, since DPC did not reverse the inhibited DCIP photoreduction.
- Taxon
- wheatTriticum aestivume0
- Treatment
- water stresse3
- Outcome
- electron donation to PSIIe3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“effects of osmotic dehydration in wheat leaves (Triticum aestivum L. cv. Long chun No. 10)”
e3“the inhibited DCIP photoreduction of PSII could not be reversed by DPC (2,2-diphenylcarbazide), a typical electron donor to PSII, suggesting that water stress did not affect electron donation to PSII”
Claim · model-written summary
Steady-state levels of major PSII proteins, including D1 and D2, declined with increasing water stress.
- Taxon
- wheatTriticum aestivume0
- Treatment
- increasing water stresse4
- Outcome
- steady state levels of major PSII proteinse4
- Direction
- declinede4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“effects of osmotic dehydration in wheat leaves (Triticum aestivum L. cv. Long chun No. 10)”
e4“the steady state levels of major PSII proteins, including the DI and D2 proteins in the PSII reaction center, declined on a chlorophyll basis with increasing water stress, possibly as a result of increased degradation”
Claim · model-written summary
Potential synthesis of chloroplast proteins from their mRNAs was impaired by water stress.
- Taxon
- wheatTriticum aestivume0
- Treatment
- water stresse5
- Outcome
- potential synthesis of chloroplast proteinse5
- Direction
- impairede5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“effects of osmotic dehydration in wheat leaves (Triticum aestivum L. cv. Long chun No. 10)”
e5“the potential synthesis of chloroplast proteins from their mRNAs was impaired by water stress”
Claim · model-written summary
Water-stress effects on PSII protein metabolism may account for the damage to PSII photochemistry.
- Taxon
- wheatTriticum aestivume0
- Outcome
- damage to PSII photochemistrye6
- Qualifier
- effects of water stress on PSII protein metabolisme6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“effects of osmotic dehydration in wheat leaves (Triticum aestivum L. cv. Long chun No. 10)”
e6“the effects of water stress on PSII protein metabolism, especially on the reaction center proteins, may account for the damage to PSII photochemistry”