Appearance and Accumulation of C<sub>4</sub> Carbon Pathway Enzymes in Developing Wheat Leaves

Aoyagi, Kazuko; Bassham, James A.

doi:10.1104/pp.80.2.334

Cited by 28 publications

(15 citation statements)

References 21 publications

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“…Protein turnover in leaves is slow (Huffaker 1982), and protein-bound aspartic acid bears the isotopic signature of the time of protein synthesis. These data require that PEP-carboxylase activity is higher relative to RuBPcarboxylase activity early in leaf development, and this is consistent with a number of measurements of PEPcarboxylase activity (Hampp et al 1987;Aoyagi and Bassham 1986;Hedley and Rowland 1975).…”

Section: C3 Plantssupporting

confidence: 78%

Aspartic-acid synthesis in C3 plants

Melzer

O’Leary

1991

Planta

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In a previous study (Melzer and O'Leary, 1987, Plant Physiol. 84, 58-60), we used isotopic methods to show that a substantial fraction of protein-bound aspartic acid in tobacco is derived from anaplerotic synthesis via phosphoenolpyruvate (PEP) carboxylase. Similar studies in soybean (Glycine max L.) and spinach (Spinacia oleracea L.) showed a similar pattern, and this pattern persists with age because of slow protein turnover. A more quantitative analysis indicates that about 40% of protein-bound aspartate is derived in this manner. Analyses of free aspartic and malic acids show that contribution of PEP carboxylase to the synthesis of these acids decreases with increasing age. The C4 plant Zea mays L. did not show this pattern.

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Section: C3 Plantssupporting

confidence: 78%

Aspartic-acid synthesis in C3 plants

Melzer

O’Leary

1991

Planta

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“…The results and scheme presented in Fig. 3 are also consistent with young or photosynthetically developing leaves fixing a relative high percentage of ~4CO2 into malate and metabolites of the TCA cycle in comparison to more mature leaves (Tamas et al 1970, Aoyagi andBassham 1986). There is also evidence in some species that the synthesis of malic acid is linked to nitrate assimilation as a means of neutralizing the base generated in protein synthesis (see Edwards and Walker 1983).…”

Section: Resultssupporting

confidence: 66%

Leaf development and the role of NADP-malate dehydrogenase in C3 plants

Vivekanandan

Edwards

1987

Photosynth Res

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The activity of NADP-malate dehydrogenase (NADP-MDH) was determined in the developing first leaf of the C3 plants wheat, barley and pea. Light dependent activation of the enzyme was observed in all three species following rapid extraction and immediate assay. Maximum activity was obtained following extraction from preilluminated leaves and incubation on ice for 45 min in the presence of dithiothreitol. In all three species, maximum activity was obtained in the young leaf 4 days after emergence of the seedling (about 2.5 to 3 μmoles per milligram chlorophyll per min in wheat and barley, and 6 μmoles per milligram chlorophyll per min in pea). On a chlorophyll basis there was an approximate five-fold decrease in NADP-MDH activity as the leaf matured. A similar pattern was found for phospho-enolpyruvate carboxylase and NADP-malic enzyme which had maximum activity in younger leaf tissue. Similarly, the activity of nitrate reductase in wheat and barley was high in the young leaf and it rapidly declined as the leaf matured. In contrast, the capacity for photosynthesis was relatively low in the young leaf, reaching a maximum 6 to 8 days after seedling emergence. The pattern of change in activity of phosphoribulokinase, an enzyme of the reductive pentose phosphate pathway, was similar to that of photosynthesis. The results suggest NADP-MDH and phospho-enolpyruvate carboxylase have important function(s) in the young leaf, which are not directly linked to C3 photosynthesis, and which, in part, may be linked to nitrate assimilation and provision of malate to mitochondria.

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“…These differing characteristics are not really surprising since photoautotrophic cultured cells are growing and dividing unlike a mature leaf. Thus, the cultured cells should be compared to developing leaves which do have high respiration rates and a lower ratio of RuBPcase to PEPcase activity (1,14). Probably because of these characteristics all photoautotrophic cultures described thus far require elevated CO2 levels, usually 1 to 5%, for growth and have CO2 compensation concentrations higher than that ofmature leaves (reviewed in 11, 20).…”

mentioning

confidence: 99%

Characteristics of Five New Photoautotrophic Suspension Cultures Including Two Amaranthus Species and a Cotton Strain Growing on Ambient CO₂ Levels

Xu¹,

Blair²,

Rogers³

et al. 1988

Plant Physiol.

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Suspension cultures of cotton (Gossypium hirsutum), Amaranthus cruentus, A. powellii, Datura innoxia, and a Nicotiana tabacum-N. glutinosa fusion hybrid were adapted to grow photoautotrophically under continuous light. The cotton strain grew with an atmosphere of ambient CO2 (about 0.06 to 0.07% in the culture room) while the other strains required elevated CO2 levels (5%). Photoautotrophy was indicated by the requirement for CO2 and for light for growth. The strains grew with doubling times near 14 days and had from 50 to 600 micrograms of chlorophyll per gram of fresh weight. The cells grew in small to moderate sized clumps with cell sizes from 40 to 70 micrometers (diameter). Like most photoautotrophic cultures described so far the ribulose 1,5-bisphosphate carboxylase (RuBPcase) activity levels were well below those of mature leaves. The phosphoenolpyruvate carboxylase levels were not elevated in the C4 Amaranthus species. The cells showed high dark respiration rates and had lower net CO2 fixation under high 02 conditions. Dark CO2 fixation rates ranged from near 10 to 30% of that in light.Fluorescence emission spectra measurements show that the cell antenna pigments systems of the four strains examined are similar to that of chloroplasts of green plants. The cotton strain which was capable of growth under ambient CO2 conditions showed the unique properties of a high RuBPcase activation level in ambient CO2 and a stable ability to show net CO2 fixation in 21% 02 conditions. The first higher plant tissue culture described as being photoautotrophic, i.e. growing with CO2 and light as the sole carbon and energy source, respectively, was that of Bergmann (3) lower RuBPcase2 activity which often leads to RuBPcase to PEPcase activity ratios near one. These differing characteristics are not really surprising since photoautotrophic cultured cells are growing and dividing unlike a mature leaf. Thus, the cultured cells should be compared to developing leaves which do have high respiration rates and a lower ratio of RuBPcase to PEPcase activity (1,14). Probably because of these characteristics all photoautotrophic cultures described thus far require elevated CO2 levels, usually 1 to 5%, for growth and have CO2 compensation concentrations higher than that ofmature leaves (reviewed in 11, 20).To date, no species with the C4 photosynthesis pathway has been grown photoautotrophically. Photoheterotrophic, green cultures of the C4 species, Gisekia pharnaceoides (25), Portulaca oleracea (12, 13) and Froelichia gracilis (15) have been initiated and used in photosynthesis studies, but these cultures were grown with 2 to 2.5% sucrose in the culture medium.Photoautotrophic cultures can be used for many purposes including the selection of mutants resistant to photosynthetic herbicides, for screening for herbicidal activity, and for herbicide mechanism ofaction studies. The photoautotrophic cultures may be valuable for producing desired compounds if chloroplasts are involved in the biosynthesis. Studies of chloroplast dev...

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Appearance and Accumulation of C₄ Carbon Pathway Enzymes in Developing Wheat Leaves

Cited by 28 publications

References 21 publications

Aspartic-acid synthesis in C3 plants

Aspartic-acid synthesis in C3 plants

Leaf development and the role of NADP-malate dehydrogenase in C3 plants

Characteristics of Five New Photoautotrophic Suspension Cultures Including Two Amaranthus Species and a Cotton Strain Growing on Ambient CO₂ Levels

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Appearance and Accumulation of C4 Carbon Pathway Enzymes in Developing Wheat Leaves

Cited by 28 publications

References 21 publications

Aspartic-acid synthesis in C3 plants

Aspartic-acid synthesis in C3 plants

Leaf development and the role of NADP-malate dehydrogenase in C3 plants

Characteristics of Five New Photoautotrophic Suspension Cultures Including Two Amaranthus Species and a Cotton Strain Growing on Ambient CO2 Levels

Contact Info

Product

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Appearance and Accumulation of C₄ Carbon Pathway Enzymes in Developing Wheat Leaves

Characteristics of Five New Photoautotrophic Suspension Cultures Including Two Amaranthus Species and a Cotton Strain Growing on Ambient CO₂ Levels