Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:1.2.1.13 (
glyceraldehyde-3-phosphate dehydrogenase
)
6,511
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
To determine whether the sun-exposed peel of apple fruit has a higher photosynthetic capacity than the shaded peel, fruit peel samples were taken in both early July and early September from the exterior part of the canopy of mature 'Liberty'/M.9 trees for measuring oxygen evolution, key enzymes and metabolites involved in photosynthesis, and chlorophyll fluorescence. Compared with the shaded peel, the sun-exposed peel had higher light-saturated oxygen evolution rate and higher light saturation point, but lower apparent and true quantum yields. The activity of ribulose-1,5-bisphosphate carboxylase/oxygenase,
glyceraldehyde-3-phosphate dehydrogenase
, phosphoribulokinase, stromal
fructose-1,6-bisphosphatase
, ADP-glucose pyrophosphorylase and sucrose-phosphate synthase (SPS) were higher in the sun-exposed peel than in the shaded peel on both sampling dates except that no significant difference was found in SPS activity between the two peel types in September. No significant difference was detected in the concentration of key metabolites (G6P, F6P, G1P, and PGA) between the sun-exposed peel and the shaded peel, suggesting that the response of the key enzymes to light exposure is well coordinated. Chlorophyll fluorescence quenching analysis showed that the sun-exposed peel had higher PSII quantum efficiency than the shaded peel at each given PFD, which resulted mainly from the higher photochemical quenching coefficient (qP). The sun-exposed peel had higher thermal dissipation capacity, as indicated by larger NPQ and F
o
quenching, than the shaded peel at high PFD. In conclusion, the sun-exposed peel of apple fruit has higher activities of the Calvin cycle enzymes and higher rate of electron transport, leading to higher photosynthetic O
2
evolution capacity. It appears that the acclimation of the Calvin cycle activities, thermal dissipation, and electron transport in apple peel are well coordinated in response to light exposure.
...
PMID:The sun-exposed peel of apple fruit has a higher photosynthetic capacity than the shaded peel. 3268 32
The limited availability of nitrogen (N) is a fundamental challenge for many crop plants. We have hypothesized that the relative crop photosynthetic rate (
P
) is exponentially constrained by certain plant-specific enzyme activities, such as ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), NADP-
glyceraldehyde-3-phosphate dehydrogenase
(NADP-G3PDH), 3-phosphoglyceric acid (PGA) kinase, and chloroplast
fructose-1,6-bisphosphatase
(cpFBPase), in
Triticum aestivum
and
Oryza sativa
. We conducted a literature search to compile information from previous studies on C
3
and C
4
crop plants, to examine the photosynthetic rate responses to limited leaf [N] levels. We found that in
Zea may
s, NADP-malic enzyme (NADP-ME), PEP carboxykinase (PCK), and Rubisco activities were positively correlated with
P
. A positive correlation was also observed between both phosphoenolpyruvate carboxylase (PEPC) and Rubisco activity with leaf [N] in
Sorghum bicolor
. Key enzyme activities responded differently to
P
in C
3
and C
4
plants, suggesting that other factors, such as leaf [N] and the stage of leaf growth, also limited specific enzyme activities. The relationships followed the best fitting exponential relationships between key enzymes and the
P
rate in both C
3
and C
4
plants. It was found that C
4
species absorbed less leaf [N] but had higher [N] assimilation rates (
A
rate
) and higher maximum photosynthesis rates (
P
max
), i.e., they were able to utilize and invest more [N] to sustain higher carbon gains. All C
3
species studied herein had higher [N] storage (N
store
) and higher absorption of [N], when compared with the C
4
species. N
store
was the main [N] source used for maintaining photosynthetic capacity and leaf expansion. Of the nine C
3
species assessed, rice had the greatest
P
max
, thereby absorbing more leaf [N]. Elevated CO
2
(eCO
2
) was also found to reduce the leaf [N] and
P
max
in rice but enhanced the leaf [N] and N use efficiency of photosynthesis in maize. We concluded that eCO
2
affects [N] allocation, which directly or indirectly affects
P
max
. These results highlight the need to further study these physiological and biochemical processes, to better predict how crops will respond to eCO
2
concentrations and limited [N].
...
PMID:Validation of an Enzyme-Driven Model Explaining Photosynthetic Rate Responses to Limited Nitrogen in Crop Plants. 3310 24
<< Previous
1
2
3
4
