Abstract
Abstract Vacuum infiltration of inorganic nitrogen ions affected the photosynthetic rate and CO2 compensation point of Themeda triandra and Zea mays in a similar way. However these two plants differed markedly in their photorespiratory mechanisms in response to inorganic nitrogen. Increased nitrogen levels in the in vitro reaction mixture stimulated T. triandra RuBP oxygenase activity (500%), but the similar enzyme from Z. mays showed no response to nitrogen. Using metabolic inhibitors it appears that glycolate and glyoxylate may serve as substrates for photorespiratory CO2, producing formate. T. triandra leaf formate levels increased considerably with infiltration of increased inorganic nitrogen levels. This was not the case in Z. mays. In T triandra an alternative photorespiratory pathway appears to be operating under high nitrogen: this pathway would utilize inorganic nitrogen more efficiently with a greater loss of photorespiratory CO2, resulting in decreased productivity. Z mays did not exhibit any of these responses to nitrogen, suggesting that the observed responses of T. triandra to nitrogen could in part account for its sensitivity to nitrogen inhibition of growth.
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Claims 9
Claim · model-written summary
Nitrogen infiltration affected photosynthetic rate similarly in both plants.
- Taxon
- Themeda triandra
Themeda triandrae0 - Treatment
- inorganic nitrogen ionse0
- Outcome
- photosynthetic ratee0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Vacuum infiltration of inorganic nitrogen ions affected the photosynthetic rate and CO2 compensation point of Themeda triandra and Zea mays in a similar way”
Claim · model-written summary
Nitrogen infiltration affected CO2 compensation point similarly in both plants.
Zea maysNot reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Vacuum infiltration of inorganic nitrogen ions affected the photosynthetic rate and CO2 compensation point of Themeda triandra and Zea mays in a similar way”
Claim · model-written summary
Increased nitrogen stimulated T. triandra RuBP oxygenase activity by 500%.
- Taxon
- T. triandraThemeda triandrae0
- Treatment
- Increased nitrogen levelse0
- Gene
- T. triandra RuBP oxygenasee0
- Outcome
- RuBP oxygenase activitye0
- Direction
- stimulatede0
- Value
- 500%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increased nitrogen levels in the in vitro reaction mixture stimulated T. triandra RuBP oxygenase activity (500%)”
Claim · model-written summary
Z. mays RuBP oxygenase did not respond to nitrogen.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the similar enzyme from Z. mays showed no response to nitrogen”
Claim · model-written summary
Glycolate and glyoxylate may serve as substrates for photorespiratory CO2 production of formate.
- Taxon
- Themeda triandraThemeda triandrat0
- Compound
- glycolate and glyoxylatee0
- Outcome
- photorespiratory CO2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“glycolate and glyoxylate may serve as substrates for photorespiratory CO2, producing formate”
t0“themeda triandra”
t1“themeda triandra”
Claim · model-written summary
T. triandra leaf formate levels rose with increased nitrogen infiltration.
- Taxon
- T. triandraThemeda triandrae0
- Treatment
- increased inorganic nitrogen levelse0
- Outcome
- leaf formate levelse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“T. triandra leaf formate levels increased considerably with infiltration of increased inorganic nitrogen levels”
Claim · model-written summary
Z. mays leaf formate did not rise with nitrogen infiltration.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This was not the case in Z. mays”
t0“themeda triandra”
t1“themeda triandra”
e1“T. triandra leaf formate levels increased considerably with infiltration of increased inorganic nitrogen levels”
Claim · model-written summary
An alternative photorespiratory pathway may operate in T. triandra under high nitrogen.
- Taxon
- T triandraThemeda triandrae0
- Treatment
- high nitrogene0
- Outcome
- alternative photorespiratory pathwaye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In T triandra an alternative photorespiratory pathway appears to be operating under high nitrogen”
Claim · model-written summary
The proposed pathway may increase nitrogen use and photorespiratory CO2 loss, decreasing productivity.
- Taxon
- themeda triandraThemeda triandrat0
- Outcome
- decreased productivitye0
- Qualifier
- greater loss of photorespiratory CO2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this pathway would utilize inorganic nitrogen more efficiently with a greater loss of photorespiratory CO2, resulting in decreased productivity”
t0“themeda triandra”
t1“themeda triandra”
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