Abstract
While malate and fumarate participate in a multiplicity of pathways in plant metabolism, the function of these organic acids as carbon stores in C(3) plants has not been deeply addressed. Here, Arabidopsis (Arabidopsis thaliana) plants overexpressing a maize (Zea mays) plastidic NADP-malic enzyme (MEm plants) were used to analyze the consequences of sustained low malate and fumarate levels on the physiology of this C(3) plant. When grown in short days (sd), MEm plants developed a pale-green phenotype with decreased biomass and increased specific leaf area, with thin leaves having lower photosynthetic performance. These features were absent in plants growing in long days. The analysis of metabolite levels of rosettes from transgenic plants indicated similar disturbances in both sd and long days, with very low levels of malate and fumarate. Determinations of the respiratory quotient by the end of the night indicated a shift from carbohydrates to organic acids as the main substrates for respiration in the wild type, while MEm plants use more reduced compounds, like fatty acids and proteins, to fuel respiration. It is concluded that the alterations observed in sd MEm plants are a consequence of impairment in the supply of carbon skeletons during a long dark period. This carbon starvation phenotype observed at the end of the night demonstrates a physiological role of the C(4) acids, which may be a constitutive function in plants.
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Claims 9
Claim · model-written summary
MEm plants grown in short days had decreased biomass.
- Taxon
- Arabidopsis (Arabidopsis thaliana)
Arabidopsis thalianae0 - Material
- MEm plantse1
- Treatment
- overexpressing a maize (Zea mays) plastidic NADP-malic enzymee0
- Gene
- maize (Zea mays) plastidic NADP-malic enzymee0
- Outcome
- biomasse1
- Direction
- decreasede1
- Setting
- short days (sd)e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis (Arabidopsis thaliana) plants overexpressing a maize (Zea mays) plastidic NADP-malic enzyme (MEm plants)”
e1“When grown in short days (sd), MEm plants developed a pale-green phenotype with decreased biomass and increased specific leaf area, with thin leaves having lower photosynthetic performance”
Claim · model-written summary
MEm plants grown in short days had increased specific leaf area.
- Taxon
- Arabidopsis (Arabidopsis thaliana)Arabidopsis thalianae0
- Material
- MEm plantse1
- Treatment
- overexpressing a maize (Zea mays) plastidic NADP-malic enzymee0
- Gene
- maize (Zea mays) plastidic NADP-malic enzymee0
- Outcome
- specific leaf areae1
- Direction
- increasede1
- Setting
- short days (sd)e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis (Arabidopsis thaliana) plants overexpressing a maize (Zea mays) plastidic NADP-malic enzyme (MEm plants)”
e1“When grown in short days (sd), MEm plants developed a pale-green phenotype with decreased biomass and increased specific leaf area, with thin leaves having lower photosynthetic performance”
Claim · model-written summary
MEm plants grown in short days had thin leaves with lower photosynthetic performance.
- Taxon
- Arabidopsis (Arabidopsis thaliana)Arabidopsis thalianae0
- Material
- MEm plantse1
- Treatment
- overexpressing a maize (Zea mays) plastidic NADP-malic enzymee0
- Outcome
- photosynthetic performancee1
- Direction
- lowere1
- Qualifier
- thin leavese1
- Setting
- short days (sd)e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis (Arabidopsis thaliana) plants overexpressing a maize (Zea mays) plastidic NADP-malic enzyme (MEm plants)”
e1“When grown in short days (sd), MEm plants developed a pale-green phenotype with decreased biomass and increased specific leaf area, with thin leaves having lower photosynthetic performance”
Claim · model-written summary
The pale-green phenotype of MEm plants was absent in long days.
- Taxon
- Arabidopsis (Arabidopsis thaliana)Arabidopsis thalianae0
- Treatment
- growing in long dayse2
- Outcome
- pale-green phenotypee1
- Comparator
- short days (sd)e1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis (Arabidopsis thaliana) plants overexpressing a maize (Zea mays) plastidic NADP-malic enzyme (MEm plants)”
e1“When grown in short days (sd), MEm plants developed a pale-green phenotype with decreased biomass and increased specific leaf area, with thin leaves having lower photosynthetic performance”
e2“These features were absent in plants growing in long days”
Claim · model-written summary
Rosettes of transgenic plants had very low levels of malate and fumarate in both short and long days.
- Taxon
- Arabidopsis (Arabidopsis thaliana)Arabidopsis thalianae0
- Material
- transgenic plantse3
- Outcome
- levels of malate and fumaratee3
- Qualifier
- very low levelse3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis (Arabidopsis thaliana) plants overexpressing a maize (Zea mays) plastidic NADP-malic enzyme (MEm plants)”
e3“The analysis of metabolite levels of rosettes from transgenic plants indicated similar disturbances in both sd and long days, with very low levels of malate and fumarate”
Claim · model-written summary
In the wild type, respiration at the end of the night shifted from carbohydrates to organic acids as the main substrates.
- Taxon
- Arabidopsis (Arabidopsis thaliana)Arabidopsis thalianae0
- Material
- wild typee4
- Outcome
- shift from carbohydrates to organic acids as the main substrates for respiratione4
- Qualifier
- by the end of the nighte4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis (Arabidopsis thaliana) plants overexpressing a maize (Zea mays) plastidic NADP-malic enzyme (MEm plants)”
e4“Determinations of the respiratory quotient by the end of the night indicated a shift from carbohydrates to organic acids as the main substrates for respiration in the wild type, while MEm plants use more reduced compounds, like fatty acids and proteins, to fuel respiration”
Claim · model-written summary
MEm plants used more reduced compounds, such as fatty acids and proteins, to fuel respiration at the end of the night.
- Taxon
- Arabidopsis (Arabidopsis thaliana)Arabidopsis thalianae0
- Material
- MEm plantse4
- Compound
- fatty acids and proteinse4
- Outcome
- reduced compoundse4
- Qualifier
- to fuel respiratione4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis (Arabidopsis thaliana) plants overexpressing a maize (Zea mays) plastidic NADP-malic enzyme (MEm plants)”
e4“Determinations of the respiratory quotient by the end of the night indicated a shift from carbohydrates to organic acids as the main substrates for respiration in the wild type, while MEm plants use more reduced compounds, like fatty acids and proteins, to fuel respiration”
Claim · model-written summary
The alterations in short-day MEm plants are a consequence of impaired carbon skeleton supply during a long dark period.
- Taxon
- Arabidopsis (Arabidopsis thaliana)Arabidopsis thalianae0
- Outcome
- alterations observed in sd MEm plantse5
- Qualifier
- impairment in the supply of carbon skeletons during a long dark periode5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis (Arabidopsis thaliana) plants overexpressing a maize (Zea mays) plastidic NADP-malic enzyme (MEm plants)”
e5“It is concluded that the alterations observed in sd MEm plants are a consequence of impairment in the supply of carbon skeletons during a long dark period”
Claim · model-written summary
The end-of-night carbon starvation phenotype suggests a physiological role for C4 acids that may be constitutive in plants.
- Taxon
- Arabidopsis (Arabidopsis thaliana)Arabidopsis thalianae0
- Compound
- C(4) acidse6
- Outcome
- a physiological role of the C(4) acidse6
- Qualifier
- may be a constitutive function in plantse6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis (Arabidopsis thaliana) plants overexpressing a maize (Zea mays) plastidic NADP-malic enzyme (MEm plants)”
e6“This carbon starvation phenotype observed at the end of the night demonstrates a physiological role of the C(4) acids, which may be a constitutive function in plants”
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