Abstract
Nitrogen availability has a strong influence on developmental processes in plants. We show that the time of nitrogen supply regulates the course of leaf senescence in flag leaves of Hordeum vulgare. The senescence-specific decrease in chlorophyll content and photosystem II efficiency is clearly delayed when plants are fertilised with nitrate at the onset of leaf senescence. Concurrently, the additional supply of nitrate affects expression patterns of two marker genes of nitrogen metabolism. As shown by quantitative RT-PCR analyses, senescence-specific downregulation of plastidic glutamine synthetase (GS2) and senescence-specific upregulation of lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) are both clearly retarded. Depletion of nitrogen in experiments using hydroponic growth systems results in premature primary leaf senescence. The already started senescence processes can be even reversed by later nitrogen addition, as proved by a further increase in photosystem II efficiency and chlorophyll content, returning to the high values of controls which had not been deprived of nitrogen. Although both addition of nitrate or ammonium effectively reversed nitrogen depletion-induced primary leaf senescence, addition of urea did not. Additionally, effects of nitrogen supply on the course of leaf senescence were analysed in the model plant Arabidopsis thaliana. Leaves of A. thaliana show the same reversion of senescence processes after receiving additional nitrogen supply, indicating that the nitrogen response of leaf development is conserved in different plant species.
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Claims 9
Claim · model-written summary
Nitrate at senescence onset delayed declines in chlorophyll content and photosystem II efficiency in barley flag leaves.
- Taxon
- Hordeum vulgare
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Hordeum vulgaret0 - Organ / stage
- leaf senescencee0
- Treatment
- fertilised with nitratee0
- Outcome
- chlorophyll content and photosystem II efficiencye0
- Direction
- delayede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“The senescence-specific decrease in chlorophyll content and photosystem II efficiency is clearly delayed when plants are fertilised with nitrate at the onset of leaf senescence”
t0“flag leaves of Hordeum vulgare”
t1“Supply of nitrogen can reverse senescence processes and affect expression of genes coding for plastidic glutamine synthetase and lysine‐ketoglutarate reductase/saccharopine dehydrogenase”
Claim · model-written summary
Nitrate retarded senescence-specific downregulation of GS2.
- Taxon
- Hordeum vulgareHordeum vulgaret0
- Treatment
- nitratee1
- Gene
- plastidic glutamine synthetase (GS2)e0
- Outcome
- downregulation of plastidic glutamine synthetase (GS2)e0
- Direction
- retardede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“senescence-specific downregulation of plastidic glutamine synthetase (GS2) and senescence-specific upregulation of lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) are both clearly retarded”
t0“flag leaves of Hordeum vulgare”
t1“Supply of nitrogen can reverse senescence processes and affect expression of genes coding for plastidic glutamine synthetase and lysine‐ketoglutarate reductase/saccharopine dehydrogenase”
e1“The senescence-specific decrease in chlorophyll content and photosystem II efficiency is clearly delayed when plants are fertilised with nitrate at the onset of leaf senescence”
Claim · model-written summary
Nitrate retarded senescence-specific upregulation of LKR/SDH.
- Taxon
- Hordeum vulgareHordeum vulgaret0
- Treatment
- nitratee1
- Gene
- lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH)e0
- Outcome
- upregulation of lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH)e0
- Direction
- retardede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“senescence-specific downregulation of plastidic glutamine synthetase (GS2) and senescence-specific upregulation of lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) are both clearly retarded”
t0“flag leaves of Hordeum vulgare”
t1“Supply of nitrogen can reverse senescence processes and affect expression of genes coding for plastidic glutamine synthetase and lysine‐ketoglutarate reductase/saccharopine dehydrogenase”
e1“The senescence-specific decrease in chlorophyll content and photosystem II efficiency is clearly delayed when plants are fertilised with nitrate at the onset of leaf senescence”
Claim · model-written summary
Nitrogen depletion caused premature primary leaf senescence in hydroponic barley.
- Taxon
- Hordeum vulgareHordeum vulgaret0
- Treatment
- Depletion of nitrogene0
- Outcome
- primary leaf senescencee0
- Direction
- prematuree0
- Setting
- hydroponic growth systemse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Depletion of nitrogen in experiments using hydroponic growth systems results in premature primary leaf senescence”
t0“flag leaves of Hordeum vulgare”
t1“Supply of nitrogen can reverse senescence processes and affect expression of genes coding for plastidic glutamine synthetase and lysine‐ketoglutarate reductase/saccharopine dehydrogenase”
Claim · model-written summary
Later nitrogen addition reversed started senescence, restoring photosystem II efficiency and chlorophyll content to control values.
- Taxon
- Hordeum vulgareHordeum vulgaret0
- Treatment
- later nitrogen additione0
- Outcome
- photosystem II efficiency and chlorophyll contente0
- Direction
- increasee0
- Comparator
- controls which had not been deprived of nitrogene0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“senescence processes can be even reversed by later nitrogen addition, as proved by a further increase in photosystem II efficiency and chlorophyll content, returning to the high values of controls which had not been deprived of nitrogen”
t0“flag leaves of Hordeum vulgare”
t1“Supply of nitrogen can reverse senescence processes and affect expression of genes coding for plastidic glutamine synthetase and lysine‐ketoglutarate reductase/saccharopine dehydrogenase”
Claim · model-written summary
Nitrate reversed nitrogen depletion-induced primary leaf senescence.
- Taxon
- Hordeum vulgareHordeum vulgaret0
- Treatment
- addition of nitratee0
- Outcome
- nitrogen depletion-induced primary leaf senescencee0
- Direction
- reversede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“addition of nitrate or ammonium effectively reversed nitrogen depletion-induced primary leaf senescence”
t0“flag leaves of Hordeum vulgare”
t1“Supply of nitrogen can reverse senescence processes and affect expression of genes coding for plastidic glutamine synthetase and lysine‐ketoglutarate reductase/saccharopine dehydrogenase”
Claim · model-written summary
Ammonium reversed nitrogen depletion-induced primary leaf senescence.
- Taxon
- Hordeum vulgareHordeum vulgaret0
- Treatment
- ammoniume0
- Outcome
- nitrogen depletion-induced primary leaf senescencee0
- Direction
- reversede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“addition of nitrate or ammonium effectively reversed nitrogen depletion-induced primary leaf senescence”
t0“flag leaves of Hordeum vulgare”
t1“Supply of nitrogen can reverse senescence processes and affect expression of genes coding for plastidic glutamine synthetase and lysine‐ketoglutarate reductase/saccharopine dehydrogenase”
Claim · model-written summary
Urea did not reverse nitrogen depletion-induced primary leaf senescence.
- Taxon
- Hordeum vulgareHordeum vulgaret0
- Treatment
- addition of ureae0
- Outcome
- primary leaf senescencee1
- Direction
- did note0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“addition of urea did not”
t0“flag leaves of Hordeum vulgare”
t1“Supply of nitrogen can reverse senescence processes and affect expression of genes coding for plastidic glutamine synthetase and lysine‐ketoglutarate reductase/saccharopine dehydrogenase”
e1“Depletion of nitrogen in experiments using hydroponic growth systems results in premature primary leaf senescence”
Claim · model-written summary
Additional nitrogen reversed senescence processes in Arabidopsis leaves.
- Taxon
- A. thaliana
Arabidopsis thalianae0 - Organ / stage
- Leavese0
- Treatment
- additional nitrogen supplye0
- Outcome
- senescence processese0
- Direction
- reversione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaves of A. thaliana show the same reversion of senescence processes after receiving additional nitrogen supply”
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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.