Abstract
Pretreatment of maize (Zea mays L.) seeds withCaCl2 solution significantly raised calcium andcalmodulin levels and enhanced intrinsic heat tolerance in maize seedlings.This enhancement is specific to Ca2+ and cannot besubstituted by Mg2+. In contrast, treatments with theCa2+ chelator EGTA or plasma membraneCa2+ channel blockers La3+ orverapamil lowered the intrinsic heat tolerance. Concurrent treatment withCa2+ and Ca2+ -channel blockers(La3+, verapamil) also decreased theCa2+ -enhanced heat tolerance. In addition, calmodulinantagonists chlorpromazine or W7 treatment eliminated theCa2+ -enhanced heat tolerance, whilst W5, a less activeanalogue of W7, had little effect on the Ca2+ -enhancedheat tolerance. Measurement of antioxidant enzyme activities and lipidperoxidation showed that heat stress induced an oxidative stress in maizeseedlings. External Ca2+ treatment enabled the seedlingsto keep relatively higher activities of superoxide dismutase (SOD), catalase(CAT) and ascorbate peroxidase (APX) and lower levels of lipid peroxidationthan Ca2+ -deficient treatments; on the contrary, EGTAtreatment led to more rapid loss of SOD, CAT and APX activities and higherlevels of lipid peroxidation in the seedlings under heat stress. In addition,concurrent Ca2+ and W7 treatment weakened the effects ofCa2+ treatment on SOD, CAT and APX activities and causedmore severe lipid peroxidation. These results suggested that externalCa2+ can enhance the intrinsic heat tolerance of maizeseedlings. This enhancement requires the entry of externalCa2+ into cells across plasma membranes and themediation of intracellular calmodulin, and is associated with the increase ofantioxidant system activity.
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Claims 15
Claim · model-written summary
Calcium chloride pretreatment raised calcium and calmodulin levels and enhanced maize heat tolerance.
- Treatment
- withCaCl2 solutione0
- Outcome
- calcium andcalmodulin levels and enhanced intrinsic heat tolerancee0
- Direction
- raisede0
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pretreatment of maize (Zea mays L.) seeds withCaCl2 solution significantly raised calcium andcalmodulin levels and enhanced intrinsic heat tolerance in maize seedlings.”
e1“Pretreatment of maize (Zea mays L.) seeds withCaCl2 solution”
Claim · model-written summary
Mg2+ could not substitute for Ca2+ in enhancing heat tolerance.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This enhancement is specific to Ca2+ and cannot besubstituted by Mg2+.”
e1“Pretreatment of maize (Zea mays L.) seeds withCaCl2 solution”
Claim · model-written summary
EGTA lowered intrinsic heat tolerance.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“treatments with theCa2+ chelator EGTA or plasma membraneCa2+ channel blockers La3+ orverapamil lowered the intrinsic heat tolerance.”
e1“Pretreatment of maize (Zea mays L.) seeds withCaCl2 solution”
Claim · model-written summary
Calcium channel blockers La3+ and verapamil lowered heat tolerance.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“plasma membraneCa2+ channel blockers La3+ orverapamil lowered the intrinsic heat tolerance.”
e1“Pretreatment of maize (Zea mays L.) seeds withCaCl2 solution”
Claim · model-written summary
Co-treatment with calcium and channel blockers decreased calcium-enhanced heat tolerance.
- Treatment
- withCa2+ and Ca2+ -channel blockers(La3+, verapamil)e0
- Outcome
- heat tolerancee0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Concurrent treatment withCa2+ and Ca2+ -channel blockers(La3+, verapamil) also decreased theCa2+ -enhanced heat tolerance.”
e1“Pretreatment of maize (Zea mays L.) seeds withCaCl2 solution”
Claim · model-written summary
Chlorpromazine or W7 eliminated calcium-enhanced heat tolerance.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“calmodulinantagonists chlorpromazine or W7 treatment eliminated theCa2+ -enhanced heat tolerance”
e1“Pretreatment of maize (Zea mays L.) seeds withCaCl2 solution”
Claim · model-written summary
W5 had little effect on calcium-enhanced heat tolerance.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“W5, a less activeanalogue of W7, had little effect on the Ca2+ -enhancedheat tolerance.”
e1“Pretreatment of maize (Zea mays L.) seeds withCaCl2 solution”
Claim · model-written summary
Heat stress induced oxidative stress in maize seedlings.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“heat stress induced an oxidative stress in maizeseedlings.”
e1“Pretreatment of maize (Zea mays L.) seeds withCaCl2 solution”
Claim · model-written summary
External calcium maintained higher SOD, CAT and APX activities under heat stress.
Verbatim
e0“External Ca2+ treatment enabled the seedlingsto keep relatively higher activities of superoxide dismutase (SOD), catalase(CAT) and ascorbate peroxidase (APX) and lower levels of lipid peroxidationthan Ca2+ -deficient treatments”
Claim · model-written summary
External calcium reduced lipid peroxidation relative to calcium-deficient treatments.
Verbatim
e0“External Ca2+ treatment enabled the seedlingsto keep relatively higher activities of superoxide dismutase (SOD), catalase(CAT) and ascorbate peroxidase (APX) and lower levels of lipid peroxidationthan Ca2+ -deficient treatments”
Claim · model-written summary
EGTA accelerated loss of SOD, CAT and APX activity under heat stress.
- Taxon
- seedlingse0
- Treatment
- EGTAtreatmente0
- Outcome
- SOD, CAT and APX activitiese0
- Direction
- more rapid losse0
Not reportedComparator
Verbatim
e0“EGTAtreatment led to more rapid loss of SOD, CAT and APX activities and higherlevels of lipid peroxidation in the seedlings under heat stress.”
Claim · model-written summary
EGTA increased lipid peroxidation under heat stress.
Not reportedComparator
Verbatim
e0“EGTAtreatment led to more rapid loss of SOD, CAT and APX activities and higherlevels of lipid peroxidation in the seedlings under heat stress.”
Claim · model-written summary
Calcium plus W7 weakened calcium effects on SOD, CAT and APX activities.
- Treatment
- concurrent Ca2+ and W7 treatmente0
- Outcome
- SOD, CAT and APX activitiese0
- Direction
- weakenede0
- Comparator
- Ca2+ treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“concurrent Ca2+ and W7 treatment weakened the effects ofCa2+ treatment on SOD, CAT and APX activities and causedmore severe lipid peroxidation.”
e1“Pretreatment of maize (Zea mays L.) seeds withCaCl2 solution”
Claim · model-written summary
Calcium plus W7 caused more severe lipid peroxidation.
- Treatment
- concurrent Ca2+ and W7 treatmente0
- Outcome
- lipid peroxidatione0
- Direction
- more severee0
- Comparator
- Ca2+ treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“concurrent Ca2+ and W7 treatment weakened the effects ofCa2+ treatment on SOD, CAT and APX activities and causedmore severe lipid peroxidation.”
e1“Pretreatment of maize (Zea mays L.) seeds withCaCl2 solution”
Claim · model-written summary
The authors infer that calcium-mediated heat tolerance requires calcium entry and intracellular calmodulin and relates to antioxidant activity.
- Outcome
- enhancemente0
- Qualifier
- entry of externalCa2+ into cells across plasma membranes and themediation of intracellular calmoduline0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This enhancement requires the entry of externalCa2+ into cells across plasma membranes and themediation of intracellular calmodulin, and is associated with the increase ofantioxidant system activity.”
e1“Pretreatment of maize (Zea mays L.) seeds withCaCl2 solution”
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See all 23 papers →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.