Abstract
Abstract The short‐term effects of manganese (Mn) toxicity on ribulose 1,5 bisphosphate carboxylase EC 4.1.1.39 (Rubisco) activity and concentration in tobacco (Nicotiana tabacum L. 'KY 17') chloroplasts were examined. The activity of the enzyme from both Mn‐treated and control plants was determined 6,12,18, 24, and 48 h after introduction of Mn (80 mg/L). Enzyme activity was determined by monitoring rates of carbon dioxide (14CO2) fixation into acid stable products. A decrease in the enzyme's activity in experimental plants was noted after 48 h of exposure. Visible symptoms, such as chlorosis and decreased leaf size, were also observed after 48 h of Mn exposure in experimental plants. Using Rocket Immunoelectrophoresis, no appreciable differences between Rubisco concentration levels of the experimental plants and the control plants were noted indicating that the effect on Rubisco activity is a post‐translational phenomenon and that Rubisco is not being degraded at an accelerated rate. Manganese accumulated in the experimental plants to concentrations as high as 3282 μg/g dry wt as determined by atomic absorption spectrophotometry. A shuttling mechanism for Mn between young and old leaves was indicated by an observed decrease in the concentration of Mn in the young leaf tissue between 12 and 18 h after treatment.
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Claims 7
Claim · model-written summary
Manganese treatment decreased Rubisco activity in tobacco after 48 h of exposure, relative to control plants.
- Taxon
- Nicotiana tabacum
Nicotiana tabacume2 - Treatment
- Mn (80 mg/L)e3
- Gene
- Rubiscoe1
- Outcome
- enzyme's activitye4
- Direction
- decreasee4
- Qualifier
- after 48 h of exposuree4
- Comparator
- control plantse5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“manganese (Mn) toxicity on ribulose 1,5 bisphosphate carboxylase EC 4.1.1.39 (Rubisco) activity”
e2“tobacco (Nicotiana tabacum L.”
e3“after introduction of Mn (80 mg/L)”
e4“A decrease in the enzyme's activity in experimental plants was noted after 48 h of exposure”
e5“activity of the enzyme from both Mn‐treated and control plants”
Claim · model-written summary
Manganese exposure produced chlorosis and decreased leaf size in tobacco after 48 h.
- Taxon
- Nicotiana tabacumNicotiana tabacume2
- Treatment
- Mn exposuree6
- Outcome
- chlorosis and decreased leaf sizee6
- Qualifier
- after 48 he6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“tobacco (Nicotiana tabacum L.”
e6“Visible symptoms, such as chlorosis and decreased leaf size, were also observed after 48 h of Mn exposure in experimental plants”
Claim · model-written summary
Rubisco concentration did not differ between Mn-treated and control tobacco plants.
- Taxon
- Nicotiana tabacumNicotiana tabacume2
- Treatment
- Mn (80 mg/L)e3
- Outcome
- Rubisco concentration levelse7
- Direction
- no appreciable differencese7
- Comparator
- control plantse7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“tobacco (Nicotiana tabacum L.”
e3“after introduction of Mn (80 mg/L)”
e7“no appreciable differences between Rubisco concentration levels of the experimental plants and the control plants were noted”
Claim · model-written summary
The Mn-induced loss of Rubisco activity is interpreted as a post-translational effect, without accelerated Rubisco degradation.
- Taxon
- Nicotiana tabacumNicotiana tabacume2
- Gene
- Rubiscoe1
- Outcome
- effect on Rubisco activitye3
- Qualifier
- post‐translational phenomenone3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“tobacco (Nicotiana tabacum L.”
e1“manganese (Mn) toxicity on ribulose 1,5 bisphosphate carboxylase EC 4.1.1.39 (Rubisco) activity”
e3“indicating that the effect on Rubisco activity is a post‐translational phenomenon”
e4“Rubisco is not being degraded at an accelerated rate”
Claim · model-written summary
Tobacco leaves accumulated manganese to as high as 3282 μg/g dry weight.
- Taxon
- Nicotiana tabacumNicotiana tabacume2
- Outcome
- Manganese accumulatede3
- Value
- 3282 μg/g dry wte3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“tobacco (Nicotiana tabacum L.”
e3“Manganese accumulated in the experimental plants to concentrations as high as 3282 μg/g dry wt”
Claim · model-written summary
Mn concentration in the young leaf tissue of tobacco decreased between 12 and 18 h after treatment.
- Taxon
- Nicotiana tabacumNicotiana tabacume2
- Organ / stage
- young leaf tissuee3
- Outcome
- concentration of Mn in the young leaf tissuee3
- Direction
- decreasee3
- Qualifier
- between 12 and 18 h after treatmente3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“tobacco (Nicotiana tabacum L.”
e3“A shuttling mechanism for Mn between young and old leaves was indicated by an observed decrease in the concentration of Mn in the young leaf tissue between 12 and 18 h after treatment”
Claim · model-written summary
A shuttling mechanism for Mn between young and old leaves is proposed to explain the young-leaf Mn decrease.
- Taxon
- Nicotiana tabacumNicotiana tabacume2
- Outcome
- Mn between young and old leavese3
- Qualifier
- shuttling mechanisme3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“tobacco (Nicotiana tabacum L.”
e3“A shuttling mechanism for Mn between young and old leaves was indicated by an observed decrease in the concentration of Mn in the young leaf tissue between 12 and 18 h after treatment”
The same questions in other papers
manganese atom · physiology: photosynthesis · Nicotiana tabacum (tobacco)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
- 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.