Abstract
BACKGROUND: Salinity-alkalinity stress is known to adversely affect a variety of processes in plants, thus inhibiting growth and decreasing crop yield. Polyamines protect plants against a variety of environmental stresses. However, whether exogenous spermidine increases the tolerance of tomato seedlings via effects on chloroplast antioxidant enzymes and chlorophyll metabolism is unknown. In this study, we examined the effect of exogenous spermidine on chlorophyll synthesis and degradation pathway intermediates and related enzyme activities, as well as chloroplast ultrastructure, gene expression, and antioxidants in salinity-alkalinity-stressed tomato seedlings. RESULTS: Salinity-alkalinity stress disrupted chlorophyll metabolism and hindered uroorphyrinogen III conversion to protoporphyrin IX. These effects were more pronounced in seedlings of cultivar Zhongza No. 9 than cultivar Jinpengchaoguan. Under salinity-alkalinity stress, exogenous spermidine alleviated decreases in the contents of total chlorophyll and chlorophyll a and b in seedlings of both cultivars following 4 days of stress. With extended stress, exogenous spermidine reduced the accumulation of δ-aminolevulinic acid, porphobilinogen, and uroorphyrinogen III and increased the levels of protoporphyrin IX, Mg-protoporphyrin IX, and protochlorophyllide, suggesting that spermidine promotes the conversion of uroorphyrinogen III to protoporphyrin IX. The effect occurred earlier in cultivar Jinpengchaoguan than in cultivar Zhongza No. 9. Exogenous spermidine also alleviated the stress-induced increases in malondialdehyde content, superoxide radical generation rate, chlorophyllase activity, and expression of the chlorophyllase gene and the stress-induced decreases in the activities of antioxidant enzymes, antioxidants, and expression of the porphobilinogen deaminase gene. In addition, exogenous spermidine stabilized the chloroplast ultrastructure in stressed tomato seedlings. CONCLUSIONS: The tomato cultivars examined exhibited different capacities for responding to salinity-alkalinity stress. Exogenous spermidine triggers effective protection against damage induced by salinity-alkalinity stress in tomato seedlings, probably by maintaining chloroplast structural integrity and alleviating salinity-alkalinity-induced oxidative damage, most likely through regulation of chlorophyll metabolism and the enzymatic and non-enzymatic antioxidant systems in chloroplast. Exogenous spermidine also exerts positive effects at the transcription level, such as down-regulation of the expression of the chlorophyllase gene and up-regulation of the expression of the porphobilinogen deaminase gene.
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Claims 13
Claim · model-written summary
Salinity-alkalinity stress disrupted chlorophyll metabolism.
- Taxon
- tomato
Solanum lycopersicumt0 - Treatment
- Salinity-alkalinity stresse0
- Outcome
- chlorophyll metabolisme0
- Direction
- disruptede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Salinity-alkalinity stress disrupted chlorophyll metabolism and hindered uroorphyrinogen III conversion to protoporphyrin IX.”
t0“tomato”
Claim · model-written summary
Salinity-alkalinity stress hindered conversion of uroorphyrinogen III to protoporphyrin IX.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- Salinity-alkalinity stresse0
- Outcome
- uroorphyrinogen III conversion to protoporphyrin IXe0
- Direction
- hinderede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Salinity-alkalinity stress disrupted chlorophyll metabolism and hindered uroorphyrinogen III conversion to protoporphyrin IX.”
t0“tomato”
Claim · model-written summary
Stress effects were more pronounced in Zhongza No. 9 than Jinpengchaoguan.
- Taxon
- tomatoSolanum lycopersicumt0
- Material
- Zhongza No. 9e0
- Outcome
- effectse0
- Direction
- more pronouncede0
- Comparator
- Jinpengchaoguane0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These effects were more pronounced in seedlings of cultivar Zhongza No. 9 than cultivar Jinpengchaoguan.”
t0“tomato”
Claim · model-written summary
Spermidine alleviated declines in total chlorophyll and chlorophyll a and b after four days of stress.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- exogenous spermidinee0
- Outcome
- contents of total chlorophyll and chlorophyll a and be0
- Direction
- alleviated decreasese0
- Qualifier
- following 4 days of stresse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under salinity-alkalinity stress, exogenous spermidine alleviated decreases in the contents of total chlorophyll and chlorophyll a and b in seedlings of both cultivars following 4 days of stress.”
t0“tomato”
Claim · model-written summary
With extended stress, spermidine reduced three chlorophyll precursors.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- exogenous spermidinee0
- Outcome
- accumulation of δ-aminolevulinic acid, porphobilinogen, and uroorphyrinogen IIIe0
- Direction
- reducede0
- Qualifier
- extended stresse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“With extended stress, exogenous spermidine reduced the accumulation of δ-aminolevulinic acid, porphobilinogen, and uroorphyrinogen III and increased the levels of protoporphyrin IX, Mg-protoporphyrin IX, and protochlorophyllide”
t0“tomato”
Claim · model-written summary
With extended stress, spermidine increased protoporphyrin IX, Mg-protoporphyrin IX and protochlorophyllide.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- exogenous spermidinee0
- Outcome
- levels of protoporphyrin IX, Mg-protoporphyrin IX, and protochlorophyllidee0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“With extended stress, exogenous spermidine reduced the accumulation of δ-aminolevulinic acid, porphobilinogen, and uroorphyrinogen III and increased the levels of protoporphyrin IX, Mg-protoporphyrin IX, and protochlorophyllide”
t0“tomato”
Claim · model-written summary
The spermidine effect occurred earlier in Jinpengchaoguan than Zhongza No. 9.
- Taxon
- tomatoSolanum lycopersicumt0
- Material
- Jinpengchaoguane0
- Outcome
- effect occurrede0
- Direction
- earliere0
- Comparator
- Zhongza No. 9e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effect occurred earlier in cultivar Jinpengchaoguan than in cultivar Zhongza No. 9.”
t0“tomato”
Claim · model-written summary
Spermidine alleviated stress-induced increases in malondialdehyde, superoxide generation and chlorophyllase activity.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- Exogenous spermidinee0
- Outcome
- malondialdehyde content, superoxide radical generation rate, chlorophyllase activitye0
- Direction
- alleviatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exogenous spermidine also alleviated the stress-induced increases in malondialdehyde content, superoxide radical generation rate, chlorophyllase activity, and expression of the chlorophyllase gene”
t0“tomato”
Claim · model-written summary
Spermidine alleviated stress-induced chlorophyllase gene expression.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- Exogenous spermidinee0
- Gene
- chlorophyllase genee0
- Outcome
- expression of the chlorophyllase genee0
- Direction
- alleviatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exogenous spermidine also alleviated the stress-induced increases in malondialdehyde content, superoxide radical generation rate, chlorophyllase activity, and expression of the chlorophyllase gene”
t0“tomato”
Claim · model-written summary
Spermidine alleviated stress-induced decreases in antioxidant enzyme activity and antioxidants.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- Exogenous spermidinee0
- Outcome
- activities of antioxidant enzymes, antioxidantse0
- Direction
- decreasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exogenous spermidine also alleviated the stress-induced increases in malondialdehyde content, superoxide radical generation rate, chlorophyllase activity, and expression of the chlorophyllase gene and the stress-induced decreases in the activities of antioxidant enzymes, antioxidants, and expression of the porphobilinogen deaminase gene.”
t0“tomato”
Claim · model-written summary
Spermidine alleviated decreased expression of the porphobilinogen deaminase gene.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- Exogenous spermidinee0
- Gene
- porphobilinogen deaminase genee0
- Outcome
- expression of the porphobilinogen deaminase genee0
- Direction
- decreasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exogenous spermidine also alleviated the stress-induced increases in malondialdehyde content, superoxide radical generation rate, chlorophyllase activity, and expression of the chlorophyllase gene and the stress-induced decreases in the activities of antioxidant enzymes, antioxidants, and expression of the porphobilinogen deaminase gene.”
t0“tomato”
Claim · model-written summary
Spermidine stabilized chloroplast ultrastructure under stress.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- Exogenous spermidinee0
- Outcome
- chloroplast ultrastructuree0
- Direction
- stabilizede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exogenous spermidine stabilized the chloroplast ultrastructure in stressed tomato seedlings.”
t0“tomato”
Claim · model-written summary
The authors propose chloroplast structure, oxidative damage and chlorophyll and antioxidant regulation as mechanisms of spermidine protection.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- Exogenous spermidinee0
- Outcome
- protection against damage induced by salinity-alkalinity stresse0
- Qualifier
- probably by maintaining chloroplast structural integrity and alleviating salinity-alkalinity-induced oxidative damagee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exogenous spermidine triggers effective protection against damage induced by salinity-alkalinity stress in tomato seedlings, probably by maintaining chloroplast structural integrity and alleviating salinity-alkalinity-induced oxidative damage, most likely through regulation of chlorophyll metabolism and the enzymatic and non-enzymatic antioxidant systems in chloroplast.”
t0“tomato”
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