Abstract
Temporal changes in cytokinin levels, mitotic activity and cytokinin oxidase activity were determined within kernels at the same stage of physiological development in single ears of field-grown maize (Zea mays L.). Cytokinins were qualitatively and quantitatively characterized by immunoaffinity chromatography, high-performance liquid chromatography (HPLC) and radioimmunoassay (RIA). Zeatin (Z), zeatin riboside (ZR) and isopentenyladenosine (iPA) all reached their maximum concentrations 9 days after pollination (DAP). The mitotic activity within the endosperm also peaked at 9 DAP. Cytokinin oxidase was present in kernels at basal levels from 3-6 DAP, then increased substantially through 10 DAP. Comparison of oxidase activity in kernels which are maturing normally and those which will abort, revealed major differences. In aborting apical kernels, the enzyme activity remained at basal levels from 4-10 DAP and only increased slightly trough 15 DAP. In median kernels, which develop normally, oxidase activity increased significantly by 5 DAP and reached a peak 4-fold higher than the basal level by 9 DAP. The differences in cytokinin oxidase activity between kernels which are maturing normally and those which will abort was so pronounced that cytokinin oxidase levels can be considered an indicator of normal kernel development. Stem infusion of benzylaminopurine (BA), but not Z or ZR, into intact plants at pollination increased the kernel number per ear at maturity by up to 30% and in some cases the total kernel weight per ear. The increase was due to a reduction in apical kernel abortion
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Claims 10
Claim · model-written summary
Zeatin, zeatin riboside and isopentenyladenosine peaked at 9 DAP.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Zeatin (Z), zeatin riboside (ZR) and isopentenyladenosine (iPA) all reached their maximum concentrations 9 days after pollination (DAP).”
t0“Changes in cytokinins and cytokinin oxidase activity in developing maize kernels and the effects of exogenous cytokinin on kernel development”
Claim · model-written summary
Endosperm mitotic activity peaked at 9 DAP.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The mitotic activity within the endosperm also peaked at 9 DAP.”
t0“Changes in cytokinins and cytokinin oxidase activity in developing maize kernels and the effects of exogenous cytokinin on kernel development”
Claim · model-written summary
Kernel cytokinin oxidase stayed at basal levels from 3 to 6 DAP.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cytokinin oxidase was present in kernels at basal levels from 3-6 DAP”
t0“Changes in cytokinins and cytokinin oxidase activity in developing maize kernels and the effects of exogenous cytokinin on kernel development”
Claim · model-written summary
Kernel cytokinin oxidase increased substantially through 10 DAP.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“then increased substantially through 10 DAP.”
t0“Changes in cytokinins and cytokinin oxidase activity in developing maize kernels and the effects of exogenous cytokinin on kernel development”
Claim · model-written summary
In aborting apical kernels, oxidase remained basal from 4 to 10 DAP and rose only slightly through 15 DAP.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In aborting apical kernels, the enzyme activity remained at basal levels from 4-10 DAP and only increased slightly trough 15 DAP.”
t0“Changes in cytokinins and cytokinin oxidase activity in developing maize kernels and the effects of exogenous cytokinin on kernel development”
Claim · model-written summary
In normally developing median kernels, oxidase rose significantly by 5 DAP.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In median kernels, which develop normally, oxidase activity increased significantly by 5 DAP”
t0“Changes in cytokinins and cytokinin oxidase activity in developing maize kernels and the effects of exogenous cytokinin on kernel development”
Claim · model-written summary
Median-kernel oxidase peaked fourfold above basal at 9 DAP.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“reached a peak 4-fold higher than the basal level by 9 DAP.”
t0“Changes in cytokinins and cytokinin oxidase activity in developing maize kernels and the effects of exogenous cytokinin on kernel development”
Claim · model-written summary
Benzylaminopurine infusion increased mature kernel number by up to 30%.
- Treatment
- Stem infusion of benzylaminopurine (BA)e0
- Outcome
- kernel number per ear at maturitye0
- Direction
- increasede0
- Value
- up to 30%e0
- Comparator
- Z or ZRe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stem infusion of benzylaminopurine (BA), but not Z or ZR, into intact plants at pollination increased the kernel number per ear at maturity by up to 30%”
t0“Changes in cytokinins and cytokinin oxidase activity in developing maize kernels and the effects of exogenous cytokinin on kernel development”
Claim · model-written summary
Benzylaminopurine infusion increased total kernel weight in some cases.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in some cases the total kernel weight per ear.”
t0“Changes in cytokinins and cytokinin oxidase activity in developing maize kernels and the effects of exogenous cytokinin on kernel development”
t1“Stem infusion of benzylaminopurine (BA)”
Claim · model-written summary
The kernel-number increase arose from reduced apical kernel abortion.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The increase was due to a reduction in apical kernel abortion”
t0“Changes in cytokinins and cytokinin oxidase activity in developing maize kernels and the effects of exogenous cytokinin on kernel development”
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See all 10 papers →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.