Abstract
Nodulated soybeans ( Glycine max L. Merr, cv. Maple Arrow) were exposed to various physiological and environmental treatments to determine the relationship between nodule adenylate pools and the degree of O 2 limitation of nitrogenase. Adenylate energy charge (AEC = [ATP + 0.5 ADP]/[ATP + ADP + AMP]) and ATP/ADP ratios declined under conditions of decreased (10%) external pO 2 but increased in nodules exposed to elevated (30%) external pO 2 . Nitrogenase activity was inhibited by both pO 2 treatments, but recovered towards initial levels within 45 min. AEC also returned to initial levels during this period. To account for these and related data in the literature, it was hypothesized that 1) legume nodules regulate infected cell O 2 concentration (Oi) to maintain adenylate pools at levels which limit respiratory metabolism: 2) treatments which decrease Oi alter the adenylate pools and further limit nodule metabolism; 3) treatments which increase Oi to levels in excess of a narrow range alter the adenylate pools and activate biochemical pathways which are not conducive to nitrogenase activity. In a preliminary test of these hypotheses, changes in AEC and ATP/ADP ratio were studied in nodules in which nitrogenase activity was inhibited by stem girdling, nitrate fertilization and exposure to an Ar:O 2 atmosphere. All three treatments caused an increased O 2 limitation of nodule respiration and nitrogenase activity. However, decreases in AEC were observed only in the stem girdling and nitrate fertilization treatment: Ar:O 2 exposure had no effect on whole nodule AEC. While this result challenged the hypotheses suggesting a central role for adenylates in the regulation of O 2 ‐limited metabolism, it was noted that the Ar:O 2 treatment would differ from the other treatments in that it would have a specific effect on the ATP demands for NH 3 assimilation in the plant fraction. Since AEC and ATP/ADP ratio would be affected by both the rate of ATP synthesis (potentially an O 2 ‐limited process) and the demand for ATP, changes in these parameters in the whole nodule may not be a reliable indicator of adenylate‐mediated O 2 limitation. Futher studies are needed to examine in vivo changes in adenylate pools in the plant and bacteroid fractions in nodules which vary in their degree of O 2 ‐limited metabolism.
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Claims 8
Claim · model-written summary
Decreased external pO2 (10%) lowered the ATP/ADP ratio and adenylate energy charge in soybean nodules.
- Taxon
- Glycine max
Glycine maxe0 - Material
- Maple Arrowe0
- Treatment
- decreased (10%) external pO 2e1
- Outcome
- ATP/ADP ratiose1
- Direction
- declinede1
- Qualifier
- Adenylate energy chargee1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nodulated soybeans ( Glycine max L. Merr, cv. Maple Arrow)”
e1“Adenylate energy charge (AEC = [ATP + 0.5 ADP]/[ATP + ADP + AMP]) and ATP/ADP ratios declined under conditions of decreased (10%) external pO 2 but increased in nodules exposed to elevated (30%) external pO 2”
Claim · model-written summary
Elevated external pO2 (30%) increased the ATP/ADP ratio in soybean nodules.
- Taxon
- Glycine maxGlycine maxe0
- Material
- Maple Arrowe0
- Treatment
- elevated (30%) external pO 2e1
- Outcome
- ATP/ADP ratiose1
- Direction
- increasede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nodulated soybeans ( Glycine max L. Merr, cv. Maple Arrow)”
e1“Adenylate energy charge (AEC = [ATP + 0.5 ADP]/[ATP + ADP + AMP]) and ATP/ADP ratios declined under conditions of decreased (10%) external pO 2 but increased in nodules exposed to elevated (30%) external pO 2”
Claim · model-written summary
Both pO2 treatments inhibited nitrogenase activity in soybean nodules.
- Taxon
- Glycine maxGlycine maxe0
- Treatment
- both pO 2 treatmentse2
- Outcome
- Nitrogenase activitye2
- Direction
- inhibitede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nodulated soybeans ( Glycine max L. Merr, cv. Maple Arrow)”
e2“Nitrogenase activity was inhibited by both pO 2 treatments, but recovered towards initial levels within 45 min”
Claim · model-written summary
Nitrogenase activity recovered towards initial levels within 45 min after both pO2 treatments.
- Taxon
- Glycine maxGlycine maxe0
- Treatment
- both pO 2 treatmentse2
- Outcome
- Nitrogenase activitye2
- Direction
- recoverede2
- Qualifier
- within 45 mine2
- Comparator
- initial levelse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nodulated soybeans ( Glycine max L. Merr, cv. Maple Arrow)”
e2“Nitrogenase activity was inhibited by both pO 2 treatments, but recovered towards initial levels within 45 min”
Claim · model-written summary
AEC returned to initial levels after both pO2 treatments.
- Taxon
- Glycine maxGlycine maxe0
- Treatment
- both pO 2 treatmentse2
- Outcome
- AECe3
- Direction
- returnede3
- Comparator
- initial levelse3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nodulated soybeans ( Glycine max L. Merr, cv. Maple Arrow)”
e2“Nitrogenase activity was inhibited by both pO 2 treatments, but recovered towards initial levels within 45 min”
e3“AEC also returned to initial levels during this period”
Claim · model-written summary
Stem girdling, nitrate fertilization and Ar:O2 exposure each increased O2 limitation of nodule respiration.
- Taxon
- Glycine maxGlycine maxe0
- Treatment
- stem girdling, nitrate fertilization and exposure to an Ar:O 2 atmospheree5
- Outcome
- O 2 limitation of nodule respiratione4
- Direction
- increasede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nodulated soybeans ( Glycine max L. Merr, cv. Maple Arrow)”
e4“All three treatments caused an increased O 2 limitation of nodule respiration and nitrogenase activity”
e5“nodules in which nitrogenase activity was inhibited by stem girdling, nitrate fertilization and exposure to an Ar:O 2 atmosphere”
Claim · model-written summary
AEC decreased in nodules under stem girdling and nitrate fertilization.
- Taxon
- Glycine maxGlycine maxe0
- Treatment
- stem girdling and nitrate fertilization treatmente6
- Outcome
- AECe6
- Direction
- decreasese6
- Comparator
- Ar:O 2 exposuree7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nodulated soybeans ( Glycine max L. Merr, cv. Maple Arrow)”
e6“decreases in AEC were observed only in the stem girdling and nitrate fertilization treatment”
e7“Ar:O 2 exposure had no effect on whole nodule AEC”
Claim · model-written summary
Ar:O2 exposure had no effect on whole nodule AEC.
- Taxon
- Glycine maxGlycine maxe0
- Treatment
- Ar:O 2 exposuree7
- Outcome
- whole nodule AECe7
- Direction
- no effecte7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nodulated soybeans ( Glycine max L. Merr, cv. Maple Arrow)”
e7“Ar:O 2 exposure had no effect on whole nodule AEC”
The same questions in other papers
fertilization · physiology: respiration · Glycine max (soybean)Positive and negative results
1 in the opposite direction
- positive
nitrogen · physiology: respiration · Glycine max (soybean)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- positive
- negative
- no effect
pruning · physiology: respiration · Glycine max (soybean)Results agree
1 paper in the same direction as this paper
- negative
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.