Abstract
The plant mitochondrial electron transport chain (ETC) includes a non-energy conserving alternative oxidase (AOX) thought to dampen reactive oxygen species (ROS) generation by the ETC and/or facilitate carbon metabolism by uncoupling it from ATP turnover. When wild-type (WT) Nicotiana tabacum grown at 28°C/22°C (light/dark) were transferred to 12°C/5°C, they showed a large induction of leaf Aox1a mRNA and AOX protein within 24 h. Transfer to cold also resulted in a large accumulation of monosaccharides, an increase in transcript level of genes encoding important ROS-scavenging enzymes and a moderate increase in lipid peroxidation. Transgenic plants with suppressed AOX level showed less cold-induced sugar accumulation than WT while transgenic plants with enhanced AOX levels showed enhanced sugar accumulation. This is inconsistent with the hypothesis that AOX acts to burn excess carbohydrate, but rather suggests a role for AOX to aid sugar accumulation, at least during cold stress. At 28°C/22°C, plants with suppressed AOX had elevated levels of lipid peroxidation compared with WT, while plants with enhanced AOX had reduced lipid peroxidation. This is consistent with the hypothesis that AOX dampens ROS generation and oxidative damage. However, this inverse relationship between AOX level and lipid peroxidation did not hold upon shift to cold. Under this stress condition, plants with strong suppression of AOX show enhanced induction of ROS-scavenging enzymes compared with WT and decline in lipid peroxidation. These data suggest that, under stress conditions, the lack of AOX enhances a mitochondrial stress-signaling pathway able to increase the ROS-scavenging capacity of the cell.
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Claims 13
Claim · model-written summary
Cold induced leaf Aox1a mRNA and AOX protein within 24 hours.
- Taxon
- Nicotiana tabacum
Nicotiana tabacume0 - Organ / stage
- leafe0
- Treatment
- 12°C/5°Ce0
- Gene
- Aox1ae0
- Outcome
- leaf Aox1a mRNA and AOX proteine0
- Direction
- inductione0
- Qualifier
- within 24 he0
- Comparator
- 28°C/22°Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When wild-type (WT) Nicotiana tabacum grown at 28°C/22°C (light/dark) were transferred to 12°C/5°C, they showed a large induction of leaf Aox1a mRNA and AOX protein within 24 h”
Claim · model-written summary
Cold caused a large accumulation of monosaccharides.
- Taxon
- Nicotiana tabacumNicotiana tabacumt0
- Treatment
- colde0
- Outcome
- monosaccharidese0
- Direction
- accumulatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transfer to cold also resulted in a large accumulation of monosaccharides”
t0“Nicotiana tabacum”
Claim · model-written summary
Cold increased transcripts of ROS scavenging enzymes.
- Taxon
- Nicotiana tabacumNicotiana tabacumt0
- Treatment
- colde1
- Outcome
- transcript level of genes encoding important ROS-scavenging enzymese0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“an increase in transcript level of genes encoding important ROS-scavenging enzymes”
t0“Nicotiana tabacum”
e1“Transfer to cold”
Claim · model-written summary
Cold moderately increased lipid peroxidation.
- Taxon
- Nicotiana tabacumNicotiana tabacumt0
- Treatment
- colde1
- Outcome
- lipid peroxidatione0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a moderate increase in lipid peroxidation”
e1“Transfer to cold”
t0“Nicotiana tabacum”
Claim · model-written summary
Suppressed AOX plants accumulated less sugar under cold than wild type.
- Taxon
- Nicotiana tabacumNicotiana tabacumt0
- Treatment
- suppressed AOX levele0
- Gene
- AOXe0
- Outcome
- cold-induced sugar accumulatione0
- Direction
- lesse0
- Comparator
- WTe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transgenic plants with suppressed AOX level showed less cold-induced sugar accumulation than WT”
t0“Nicotiana tabacum”
Claim · model-written summary
Enhanced AOX plants accumulated more sugar under cold.
- Taxon
- Nicotiana tabacumNicotiana tabacumt0
- Treatment
- enhanced AOX levelse0
- Gene
- AOXe0
- Outcome
- sugar accumulatione0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“transgenic plants with enhanced AOX levels showed enhanced sugar accumulation”
t0“Nicotiana tabacum”
Claim · model-written summary
At warm temperatures, suppressed AOX plants had elevated lipid peroxidation versus wild type.
- Taxon
- Nicotiana tabacumNicotiana tabacumt0
- Treatment
- suppressed AOXe0
- Gene
- AOXe0
- Outcome
- lipid peroxidatione0
- Direction
- elevatede0
- Qualifier
- At 28°C/22°Ce0
- Comparator
- WTe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At 28°C/22°C, plants with suppressed AOX had elevated levels of lipid peroxidation compared with WT”
t0“Nicotiana tabacum”
Claim · model-written summary
At warm temperatures, enhanced AOX plants had reduced lipid peroxidation.
- Taxon
- Nicotiana tabacumNicotiana tabacumt0
- Treatment
- enhanced AOXe0
- Gene
- AOXe0
- Outcome
- lipid peroxidatione0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“plants with enhanced AOX had reduced lipid peroxidation”
t0“Nicotiana tabacum”
Claim · model-written summary
The inverse AOX lipid peroxidation relationship did not hold after a cold shift.
- Taxon
- Nicotiana tabacumNicotiana tabacumt0
- Gene
- AOXe0
- Outcome
- relationship between AOX level and lipid peroxidatione0
- Qualifier
- upon shift to colde0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this inverse relationship between AOX level and lipid peroxidation did not hold upon shift to cold”
t0“Nicotiana tabacum”
Claim · model-written summary
Under cold, strong AOX suppression enhanced induction of ROS scavenging enzymes versus wild type.
- Taxon
- Nicotiana tabacumNicotiana tabacumt0
- Treatment
- strong suppression of AOXe0
- Outcome
- induction of ROS-scavenging enzymese0
- Direction
- enhancede0
- Comparator
- WTe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“plants with strong suppression of AOX show enhanced induction of ROS-scavenging enzymes compared with WT”
e1“Under this stress condition”
t0“Nicotiana tabacum”
Claim · model-written summary
Under cold, strongly AOX suppressed plants declined in lipid peroxidation.
- Taxon
- Nicotiana tabacumNicotiana tabacumt0
- Treatment
- strong suppression of AOXe0
- Outcome
- lipid peroxidatione0
- Direction
- declinee0
- Comparator
- WTe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“plants with strong suppression of AOX show enhanced induction of ROS-scavenging enzymes compared with WT and decline in lipid peroxidation”
t0“Nicotiana tabacum”
Claim · model-written summary
Authors infer AOX aids sugar accumulation during cold stress.
- Taxon
- Nicotiana tabacumNicotiana tabacumt0
- Gene
- AOXe0
- Outcome
- sugar accumulatione0
- Qualifier
- at least during cold stresse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“suggests a role for AOX to aid sugar accumulation, at least during cold stress”
t0“Nicotiana tabacum”
Claim · model-written summary
Authors infer a lack of AOX enhances mitochondrial stress signaling and ROS scavenging capacity.
- Taxon
- Nicotiana tabacumNicotiana tabacumt0
- Gene
- AOXe0
- Outcome
- ROS-scavenging capacity of the celle0
- Qualifier
- mitochondrial stress-signaling pathwaye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the lack of AOX enhances a mitochondrial stress-signaling pathway able to increase the ROS-scavenging capacity of the cell”
t0“Nicotiana tabacum”
The same questions in other papers
cold · physiology: oxidative · Nicotiana tabacum (tobacco)Results differ
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