scholarly journals The Involvement of Aspartate and Glutamate in the Decarboxylation of Malate by Isolated Bundle Sheath Chloroplasts from Zea mays

1986 ◽  
Vol 81 (1) ◽  
pp. 115-119 ◽  
Author(s):  
Stuart Boag ◽  
Colin L. D. Jenkins
Keyword(s):  
Zea Mays ◽  
Bundle Sheath

Some Effects of Buthidazole on Corn (Zea mays) Photosynthesis, Respiration, Anthocyanin Formation, and Leaf Ultrastructure

Weed Science ◽  
1980 ◽  
Vol 28 (1) ◽  
pp. 97-100 ◽  
Author(s):  
Kriton K. Hatzios ◽  
Donald Penner
Keyword(s):  
Zea Mays ◽  
Flow System ◽  
Dark Respiration ◽  
Bundle Sheath ◽  
Herbicide Application ◽  
Leaf Ultrastructure ◽  
Anthocyanin Formation ◽  
Transmission Electron ◽  
Corn Plants ◽  
Whole Plants

The effect of the herbicide buthidazole {3-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-4-hydroxy-1-methyl-2-imidazolidinone} on photosynthesis, respiration, anthocyanin formation and leaf ultrastructure of corn (Zea mays L. ‘Pioneer 3780’) was studied following pre- or postemergence applications. Total photosynthesis and dark respiration were measured with an infrared CO2 analyzer in an open air flow system 12, 18, and 24 days after preemergence treatment with 0, 0.56, 1.12, and 2.24 kg/ha of buthidazole. The 0.56 and 1.12 kg/ha preemergence treatments had no effect on total corn photosynthesis even 24 days after treatment, whereas buthidazole at 2.24 kg/ha inhibited photosynthesis as early as 12 days. Total photosynthesis and dark respiration were also measured in whole plants, 30 cm tall, before herbicide application and 4, 24, 48, and 96 h after postemergence treatment with buthidazole at 0, 0.28, 0.56, 0.84, and 1.12 kg/ha. Following postemergence treatment, buthidazole inhibited total corn photosynthesis at any rate examined as early as 4 h after treatment. Neither pre- or postemergence buthidazole applications influenced respiration with the exception of a transitory increase caused by 0.56 kg/ha 12 days after preemergence treatment and by 0.84 and 1.12 kg/ha 4 h after postemergence treatment. Transmission electron micrographs revealed that buthidazole applied postemergence at 0.28 and 1.12 kg/ha reduced or prevented the accumulation of starch in bundle sheath chloroplasts as early as 24 h after treatment. Ultrastructural disruptions in some mesophyll chloroplasts of treated corn plants were also evident. Preemergence application of buthidazole at rates of 0.28, 0.42, 0.56, and 1.12 kg/ha inhibited anthocyanin formation indicating an alteration in corn metabolism.

The photosynthetic carbon metabolism of Zea mays and Gomphrena globosa: the location of the CO2 fixation and the carboxyl transfer reactions

1970 ◽  
Vol 48 (4) ◽  
pp. 777-786 ◽  
Author(s):  
J. A. Berry ◽  
W. J. S. Downton ◽  
E. B. Tregunna
Keyword(s):  
Zea Mays ◽  
Bundle Sheath ◽  
Oxidative Decarboxylation ◽  
Gomphrena Globosa ◽  
Phosphorylated Compounds ◽  
Bundle Sheath Cells ◽  
Phosphoglyceric Acid ◽  
Photosynthetic Carbon Metabolism ◽  
Gradient Separation ◽  
Density Gradient Separation

Zea mays and Gomphrena globosa form labeled aspartate and malate (C4-acids) via β-carboxylation of P-enolpyruvate during photosynthesis. Studies of the redistribution of 14C in pulse- and chase-type feedings of 14CO2 indicate that most labeled phosphorylated compounds are formed from the C4-acids. A mechanism involving CO2 as a transitory intermediate is advanced to explain the carboxyl transfer from the C4-acids to 3-phosphoglyceric acid (3-PGA). In this model, CO2 is generated through the oxidative decarboxylation of malic acid by "malic" enzyme, and is refixed by RuDP carboxylase to form 3-PGA. The pattern of labeling of photosynthetic products, the extractable enzyme activities, and the gas exchange properties of these plants appear to be consistent with this proposed sequence of reactions. The location of 14C-labeled compounds was determined by radioautography, and by nonaqueous density gradient separation. Differential grinding was used to study the location of some photosynthetic enzymes. These indicate that CO2 fixation by β-carboxylation occurs in the leaf mesophyll. The carboxyl transfer and the reactions leading to the photosynthesis of starch appear to be confined predominantly to the bundle sheath cells. Rapid transport of C4-acids from the site of CO2 fixation in the mesophyll to the bundle sheath may occur by plasmodesmata.

A fundamental thermostable cyanide-sensitive phosphoenolpyruvate acid carboxylase in photosynthetic and other organisms

1971 ◽  
Vol 49 (4) ◽  
pp. 631-643 ◽  
Author(s):  
David Pan ◽  
E. Roy Waygood
Keyword(s):  
Heat Treatment ◽  
Zea Mays ◽  
Acid Phosphatase ◽  
Plant Species ◽  
Phosphoenolpyruvate Carboxylase ◽  
Deae Cellulose ◽  
Bundle Sheath ◽  
Evolutionary Significance ◽  
Optimum Temperature ◽  
Optimum Ph

A thermostable 'phosphoenolpyruvate carboxylase' has been isolated from leaves of Zea mays different from phosphoenolpyruvate carboxylase (EC. 4.1.1.31) in that its optimum pH is 5.4, it does not liberate orthophosphate during the reaction, and it is inhibited by cyanide. The enzymic reaction has an optimum temperature of 70–75C and has been purified through steps including acidification to pH 4.6, heat treatment to 50C, and DEAE-cellulose and Sephadex G-200 column chromatography. Three fractions were active in the Sephadex eluate, but only fraction III was free from a thermostable acid phosphatase which catalyzes the liberation of orthophosphate from the substrate and the end product which is suggested to be a C4 phosphocarbonyl compound, although phosphohydroxypyruvate appears by either spontaneous or enzymic decarboxylation. The enzyme is assayed by the formation of a phenyl-hydrazone at 325 nm. The enzyme is localized and tightly bound in both the parenchyma bundle sheath and mesophyll chloroplasts, which are free from the thermostable acid phosphatase. Similar concentrations of the enzyme have been found in all plant species tested including C3 plants, ferns, bryophytes, algae, fungi, and even in calf liver. The enzyme must have considerable evolutionary significance.

Studies of the Ndh complex and photosystem II from mesophyll and bundle sheath chloroplasts of the C4-type plant Zea mays

2006 ◽  
Vol 163 (8) ◽  
pp. 800-808 ◽  
Author(s):  
Costel C. Darie ◽  
Luca De Pascalis ◽  
Bettina Mutschler ◽  
Wolfgang Haehnel
Keyword(s):  
Zea Mays ◽  
Photosystem Ii ◽  
Bundle Sheath
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