Abstract
Cu and Zn are common and potentially harmful heavy metals to plants, animals and humans. Herein, we investigated the effects of Cu and Zn stress on the photosynthesis and tolerance mechanism of alfalfa plants to ROS using fluorescence and biochemical methods. The results showed that Cu stress significantly reduced the chlorophyll content of the leaves, while Zn stress only reduced the Chl a content. The Fv/Fm decreased significantly under Cu stress but was not affected by Zn treatment. However, the PIABS of the leaves were sensitive to Cu and Zn stress. Both Cu and Zn stress resulted in the weakening of the ability of PQ library to accept electrons, the damage of OEC and the inhibition of the electron transfer from QA- to QB. Moreover, Cu stress also dissociated the thylakoids of leaves, but Zn stress did not significantly damage it. In Cu and Zn stressed leaves, the reduction of RC/CSm significantly increased the ABS/RC and TRo/RC values. When the stress intensified, the value of DIo/RC increased indicated a plant self-protection mechanism that eliminates excess energy in the PSII reaction center and increases the energy for heat dissipation per unit reaction center. Cu stress significantly increased the O2- production rate, H2O2 content, and MDA accumulation in the leaves. However, Zn stress exhibited a minimal effect on the ROS production and oxidative damage in the alfalfa leaves but increased the O2- production rate at the concentration of 800 μmol·L−1. Cu stress increased the activities of SOD, POD, CAT, APX, and GPX in the leaves; however, leaves adapts to Zn stress by enhancing the activities of SOD and GPX. Thus under Cu stress, the degree of photoinhibition and oxidative damage in alfalfa leaves were significantly higher than under Zn stress.
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Claims 17
Claim · model-written summary
Cu stress significantly reduced leaf chlorophyll content.
- Taxon
- alfalfa
Medicago sativat0 - Treatment
- Cu stresse0
- Outcome
- chlorophyll contente0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cu stress significantly reduced the chlorophyll content of the leaves”
t0“alfalfa (Medicago sativa)”
Claim · model-written summary
Zn stress reduced only chlorophyll a content.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- Zn stresse0
- Outcome
- Chl a contente0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Zn stress only reduced the Chl a content”
t0“alfalfa (Medicago sativa)”
Claim · model-written summary
Cu stress significantly decreased Fv/Fm.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- Cu stresse0
- Outcome
- Fv/Fme0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The Fv/Fm decreased significantly under Cu stress”
t0“alfalfa (Medicago sativa)”
Claim · model-written summary
Zn treatment did not affect Fv/Fm.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- Zn treatmente0
- Outcome
- Fv/Fme0
- Direction
- not affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The Fv/Fm decreased significantly under Cu stress but was not affected by Zn treatment”
t0“alfalfa (Medicago sativa)”
Claim · model-written summary
Leaf PIABS was sensitive to both Cu and Zn stress.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- Cu and Zn stresse0
- Outcome
- PIABS of the leavese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the PIABS of the leaves were sensitive to Cu and Zn stress”
t0“alfalfa (Medicago sativa)”
Claim · model-written summary
Cu stress weakened PQ electron acceptance, damaged OEC and inhibited QA- to QB electron transfer.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- Cue0
- Outcome
- ability of PQ library to accept electrons, the damage of OEC and the inhibition of the electron transfer from QA- to QBe0
- Direction
- weakeninge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both Cu and Zn stress resulted in the weakening of the ability of PQ library to accept electrons, the damage of OEC and the inhibition of the electron transfer from QA- to QB”
t0“alfalfa (Medicago sativa)”
Claim · model-written summary
Zn stress weakened PQ electron acceptance, damaged OEC and inhibited QA- to QB electron transfer.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- Zn stresse0
- Outcome
- ability of PQ library to accept electrons, the damage of OEC and the inhibition of the electron transfer from QA- to QBe0
- Direction
- weakeninge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both Cu and Zn stress resulted in the weakening of the ability of PQ library to accept electrons, the damage of OEC and the inhibition of the electron transfer from QA- to QB”
t0“alfalfa (Medicago sativa)”
Claim · model-written summary
Cu stress dissociated leaf thylakoids.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- Cu stresse0
- Outcome
- thylakoids of leavese0
- Direction
- dissociatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cu stress also dissociated the thylakoids of leaves”
t0“alfalfa (Medicago sativa)”
Claim · model-written summary
Zn stress did not significantly damage leaf thylakoids.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- Zn stresse0
- Outcome
- damage ite0
- Direction
- did not significantly damagee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Zn stress did not significantly damage it”
t0“alfalfa (Medicago sativa)”
Claim · model-written summary
Under Cu and Zn stress, reduced RC/CSm significantly increased ABS/RC and TRo/RC.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- Cu and Zne0
- Outcome
- ABS/RC and TRo/RC valuese0
- Direction
- increasede0
- Qualifier
- reduction of RC/CSme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In Cu and Zn stressed leaves, the reduction of RC/CSm significantly increased the ABS/RC and TRo/RC values”
t0“alfalfa (Medicago sativa)”
Claim · model-written summary
DIo/RC increased as stress intensified, indicating greater heat dissipation.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- stress intensifiede0
- Outcome
- value of DIo/RCe0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When the stress intensified, the value of DIo/RC increased indicated a plant self-protection mechanism that eliminates excess energy in the PSII reaction center and increases the energy for heat dissipation per unit reaction center”
t0“alfalfa (Medicago sativa)”
Claim · model-written summary
Cu stress significantly increased leaf O2- production, H2O2 content and MDA accumulation.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- Cu stresse0
- Outcome
- O2- production rate, H2O2 content, and MDA accumulatione0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cu stress significantly increased the O2- production rate, H2O2 content, and MDA accumulation in the leaves”
t0“alfalfa (Medicago sativa)”
Claim · model-written summary
Zn stress had minimal effect on ROS production and oxidative damage.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- Zn stresse0
- Outcome
- ROS production and oxidative damagee0
- Direction
- minimal effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Zn stress exhibited a minimal effect on the ROS production and oxidative damage in the alfalfa leaves”
Claim · model-written summary
At 800 μmol·L−1, Zn stress increased O2- production.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- Zn stresse0
- Outcome
- O2- production ratee0
- Direction
- increasede0
- Qualifier
- 800 μmol·L−1e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Zn stress exhibited a minimal effect on the ROS production and oxidative damage in the alfalfa leaves but increased the O2- production rate at the concentration of 800 μmol·L−1”
Claim · model-written summary
Cu stress increased SOD, POD, CAT, APX and GPX activity.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- Cu stresse0
- Outcome
- activities of SOD, POD, CAT, APX, and GPXe0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cu stress increased the activities of SOD, POD, CAT, APX, and GPX in the leaves”
t0“alfalfa (Medicago sativa)”
Claim · model-written summary
Zn stress enhanced SOD and GPX activity.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- Zn stresse0
- Outcome
- activities of SOD and GPXe0
- Direction
- enhancinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“leaves adapts to Zn stress by enhancing the activities of SOD and GPX”
t0“alfalfa (Medicago sativa)”
Claim · model-written summary
Cu caused significantly more photoinhibition and oxidative damage than Zn.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- Cu stresse0
- Outcome
- degree of photoinhibition and oxidative damagee0
- Direction
- highere0
- Comparator
- Zn stresse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“under Cu stress, the degree of photoinhibition and oxidative damage in alfalfa leaves were significantly higher than under Zn stress”
The same questions in other papers
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1 in the opposite direction
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zinc atom · physiology: oxidative · Medicago sativa (alfalfa)Positive and negative results
1 in the opposite direction
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copper atom · physiology: oxidative · Medicago sativa (alfalfa)Positive and negative results
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zinc atom · disease · Medicago sativa (alfalfa)Positive and negative results
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zinc atom · molecular: metabolites · Medicago sativa (alfalfa)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- positive
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copper atom · disease · Medicago sativa (alfalfa)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- positive
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copper atom · physiology: antioxidant enzymes · Medicago sativa (alfalfa)Results agree
1 paper in the same direction as this paper
- positive
heavy metal · physiology: antioxidant enzymes · Medicago sativa (alfalfa)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
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8 of 13 groups shown: named compounds and organisms first, then groups whose results differ (checked claim by claim), then those with positive and negative results, then the smaller groups.
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.