Abstract
Plants of Paspalum dilatatum were grown hydroponically in a phytotron under a PPFD of 600 m mol m-2s-1 and 25/18 oC (day/night) temperature. The first fully expanded leaf was excised and allowed to be rapidly dehydrated by exposure to the phytotron atmosphere. Relative water content (RWC) was monitored in a parallel sample and leaves at different RWC were frozen in liquid nitrogen. Leaf samples were later ground for enzyme extraction. RUBISCO activity was measured through the incorporation of 14CO2. The maximal RUBISCO activity increased 50% with the decrease of RWC from full-saturation to 60%, both when expressed on dry weight and soluble protein bases. On the contrary, initial activity decreased to half in severely stressed leaves. Accordingly, a sharp decrease of the % of activation was observed under stress. Lower initial activities suggest a lower carbamylation status of the enzyme of stressed leaves. Possible mechanisms will be discussed. The increase of maximal activity points to de novo synthesis of the enzyme. This hypothesis will be checked by RUBISCO protein quantification.
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Claims 5
Claim · model-written summary
Maximal Rubisco activity in Paspalum dilatatum leaves increased by 50% as relative water content decreased from full saturation to 60%.
- Taxon
- Paspalum dilatatum
_Paspalum_dilatatum_inflorescences.jpg?width=60)
Paspalum dilatatumt0 - Treatment
- decrease of RWCe1
- Outcome
- maximal RUBISCO activitye1
- Direction
- increasede1
- Value
- 50%e1
- Comparator
- full-saturatione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_Paspalum_dilatatum_inflorescences.jpg?width=500)
Verbatim
e1“The maximal RUBISCO activity increased 50% with the decrease of RWC from full-saturation to 60%”
t0“Paspalum dilatatum”
Claim · model-written summary
Initial Rubisco activity decreased to half in severely stressed leaves of Paspalum dilatatum.
- Taxon
- Paspalum dilatatumPaspalum dilatatumt0
- Organ / stage
- leavese2
- Treatment
- severely stressede2
- Outcome
- initial activitye2
- Direction
- decreasede2
- Value
- halfe2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“initial activity decreased to half in severely stressed leaves”
t0“Paspalum dilatatum”
Claim · model-written summary
The percentage of Rubisco activation decreased sharply under stress.
- Taxon
- Paspalum dilatatumPaspalum dilatatumt0
- Treatment
- stresse3
- Outcome
- % of activatione3
- Direction
- sharp decreasee3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“a sharp decrease of the % of activation was observed under stress”
t0“Paspalum dilatatum”
Claim · model-written summary
The authors suggest that lower initial activities indicate a lower carbamylation status of the enzyme in stressed leaves.
- Taxon
- Paspalum dilatatumPaspalum dilatatumt0
- Treatment
- stressed leavese4
- Outcome
- lower carbamylation statuse4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“Lower initial activities suggest a lower carbamylation status of the enzyme of stressed leaves”
t0“Paspalum dilatatum”
Claim · model-written summary
The authors suggest the increase of maximal Rubisco activity points to de novo synthesis of the enzyme, a hypothesis still to be checked.
- Taxon
- Paspalum dilatatumPaspalum dilatatumt0
- Outcome
- maximal activitye5
- Qualifier
- de novo synthesis of the enzymee5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“The increase of maximal activity points to de novo synthesis of the enzyme”
t0“Paspalum dilatatum”