Abstract
The growth of maize (Zea mays L.) kernels depends on the availability of carbon (C) and nitrogen (N) assimilates supplied by the mother plant and the capacity of the kernel to use them. Our objectives were to study the effects of N and sucrose supply levels on growth and metabolism of maize kernels. Kernel explants of Pioneer 34RO6 were cultured in vitro with varying combinations of N (5 to 30 mM) and sucrose (117 to 467 mM). Maximum kernel growth was obtained with 10 mM N and 292 mM sucrose in the medium, and a deficiency of one assimilate could not be overcome by a sufficiency of the other. Increasing the N supply led to increases in the kernel sink capacity (number of cells and starch granules in the endosperm), activity of certain enzymes (soluble and bound invertases, sucrose synthase, and aspartate aminotransaminase), starch, and the levels of N compounds (total-N, soluble protein, and free amino acids), and decreased the levels of C metabolites (sucrose and reducing sugars). Conversely, increasing the sucrose supply increased the level of endosperm C metabolites, free amino acids, and ADPG-PPase and alanine transaminase activities, but decreased the activity of soluble invertase and concentrations of soluble protein and total-N. Thus, while C and N are interdependent and essential for accumulation of maximum kernel weight, they appear to regulate growth by different means. Nitrogen supply aids the establishment of kernel sink capacity, and promotes activity of enzymes relating to sucrose and nitrogen uptake, while sucrose regulates the activities df invertase and ADPG-PPase. (C) 1999 Annals of Botany Company.
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Claims 14
Claim · model-written summary
Maximum kernel growth occurred with 10 mM N and 292 mM sucrose.
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Maximum kernel growth was obtained with 10 mM N and 292 mM sucrose in the medium”
e1“Maximum kernel growth was obtained with 10 mM N and 292 mM sucrose in the medium”
t0“Maize”
Claim · model-written summary
Sufficiency of one assimilate did not overcome deficiency of the other.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a deficiency of one assimilate could not be overcome by a sufficiency of the other.”
e1“a deficiency of one assimilate could not be overcome by a sufficiency of the other.”
t0“Maize”
Claim · model-written summary
Higher N supply increased kernel sink capacity, including endosperm cell and starch granule numbers.
- Organ / stage
- endosperme0
- Treatment
- Increasing the N supplye0
- Outcome
- kernel sink capacitye0
- Direction
- increasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increasing the N supply led to increases in the kernel sink capacity (number of cells and starch granules in the endosperm)”
e1“Increasing the N supply led to increases in the kernel sink capacity (number of cells and starch granules in the endosperm)”
t0“Maize”
Claim · model-written summary
Higher N supply increased invertase, sucrose synthase and aspartate aminotransaminase activities.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“activity of certain enzymes (soluble and bound invertases, sucrose synthase, and aspartate aminotransaminase)”
e1“activity of certain enzymes (soluble and bound invertases, sucrose synthase, and aspartate aminotransaminase)”
t0“Maize”
e2“Increasing the N supply led to increases in the kernel sink capacity (number of cells and starch granules in the endosperm)”
Claim · model-written summary
Higher N supply increased kernel starch.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“starch, and the levels of N compounds”
e1“starch, and the levels of N compounds”
t0“Maize”
e2“Increasing the N supply led to increases in the kernel sink capacity (number of cells and starch granules in the endosperm)”
Claim · model-written summary
Higher N supply increased total N, soluble protein and free amino acids.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the levels of N compounds (total-N, soluble protein, and free amino acids)”
e1“the levels of N compounds (total-N, soluble protein, and free amino acids)”
t0“Maize”
e2“Increasing the N supply led to increases in the kernel sink capacity (number of cells and starch granules in the endosperm)”
Claim · model-written summary
Higher N supply lowered sucrose and reducing sugar levels.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“and decreased the levels of C metabolites (sucrose and reducing sugars).”
e1“and decreased the levels of C metabolites (sucrose and reducing sugars).”
t0“Maize”
e2“Increasing the N supply led to increases in the kernel sink capacity (number of cells and starch granules in the endosperm)”
Claim · model-written summary
Higher sucrose supply increased endosperm carbon metabolites and free amino acids.
- Treatment
- increasing the sucrose supplye0
- Outcome
- level of endosperm C metabolites, free amino acidse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increasing the sucrose supply increased the level of endosperm C metabolites, free amino acids”
e1“increasing the sucrose supply increased the level of endosperm C metabolites, free amino acids”
t0“Maize”
Claim · model-written summary
Higher sucrose supply increased ADPG-PPase and alanine transaminase activities.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“and ADPG-PPase and alanine transaminase activities”
e1“and ADPG-PPase and alanine transaminase activities”
t0“Maize”
e2“increasing the sucrose supply increased the level of endosperm C metabolites, free amino acids”
Claim · model-written summary
Higher sucrose supply decreased soluble invertase activity.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but decreased the activity of soluble invertase”
e1“but decreased the activity of soluble invertase”
t0“Maize”
e2“increasing the sucrose supply increased the level of endosperm C metabolites, free amino acids”
Claim · model-written summary
Higher sucrose supply lowered soluble protein and total N concentrations.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“concentrations of soluble protein and total-N.”
e1“concentrations of soluble protein and total-N.”
t0“Maize”
e2“increasing the sucrose supply increased the level of endosperm C metabolites, free amino acids”
Claim · model-written summary
Authors conclude carbon and nitrogen are interdependent for maximum kernel weight but regulate growth differently.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“while C and N are interdependent and essential for accumulation of maximum kernel weight, they appear to regulate growth by different means.”
e1“while C and N are interdependent and essential for accumulation of maximum kernel weight, they appear to regulate growth by different means.”
t0“Maize”
Claim · model-written summary
Authors infer N supply establishes sink capacity and promotes sucrose and nitrogen uptake enzyme activities.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen supply aids the establishment of kernel sink capacity, and promotes activity of enzymes relating to sucrose and nitrogen uptake”
e1“Nitrogen supply aids the establishment of kernel sink capacity, and promotes activity of enzymes relating to sucrose and nitrogen uptake”
t0“Maize”
Claim · model-written summary
Authors infer sucrose regulates invertase and ADPG-PPase activities.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“sucrose regulates the activities df invertase and ADPG-PPase.”
e1“sucrose regulates the activities df invertase and ADPG-PPase.”
t0“Maize”
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