scholarly journals Differential Expression of the Ribulose Bisphosphate Carboxylase Large Subunit Gene in Bundle Sheath and Mesophyll Cells of Developing Maize Leaves Is Influenced by Light

1985 ◽  
Vol 79 (4) ◽  
pp. 1072-1076 ◽  
Author(s):  
Jenq-Yunn Sheen ◽  
Lawrence Bogorad
Keyword(s):  
Differential Expression ◽  
Large Subunit ◽  
Bundle Sheath ◽  
Ribulose Bisphosphate Carboxylase ◽  
Subunit Gene ◽  
Ribulose Bisphosphate ◽  
Mesophyll Cells ◽  
Bisphosphate Carboxylase ◽  
Maize Leaves

scholarly journals Four Mutant Alleles Elucidate the Role of the G2 Protein in the Development of C4 and C3 Photosynthesizing Maize Tissues

Genetics ◽  
2001 ◽  
Vol 159 (2) ◽  
pp. 787-797
Author(s):  
Lizzie Cribb ◽  
Lisa N Hall ◽  
Jane A Langdale
Keyword(s):  
Cell Types ◽  
Bundle Sheath ◽  
Primary Role ◽  
Ribulose Bisphosphate Carboxylase ◽  
Sheath Cell ◽  
Mesophyll Cells ◽  
Phenotypic Data ◽  
Bisphosphate Carboxylase ◽  
Bundle Sheath Cell

Abstract Maize leaf blades differentiate dimorphic photosynthetic cell types, the bundle sheath and mesophyll, between which the reactions of C4 photosynthesis are partitioned. Leaf-like organs of maize such as husk leaves, however, develop a C3 pattern of differentiation whereby ribulose bisphosphate carboxylase (RuBPCase) accumulates in all photosynthetic cell types. The Golden2 (G2) gene has previously been shown to play a role in bundle sheath cell differentiation in C4 leaf blades and to play a less well-defined role in C3 maize tissues. To further analyze G2 gene function in maize, four g2 mutations have been characterized. Three of these mutations were induced by the transposable element Spm. In g2-bsd1-m1 and g2-bsd1-s1, the element is inserted in the second intron and in g2-pg14 the element is inserted in the promoter. In the fourth case, g2-R, four amino acid changes and premature polyadenylation of the G2 transcript are observed. The phenotypes conditioned by these four mutations demonstrate that the primary role of G2 in C4 leaf blades is to promote bundle sheath cell chloroplast development. C4 photosynthetic enzymes can accumulate in both bundle sheath and mesophyll cells in the absence of G2. In C3 tissue, however, G2 influences both chloroplast differentiation and photosynthetic enzyme accumulation patterns. On the basis of the phenotypic data obtained, a model that postulates how G2 acts to facilitate C4 and C3 patterns of tissue development is proposed.

The CO2/O2 specificity of single-subunit ribulose-bisphosphate carboxylase from the dinoflagellate, Amphidinium carterae

1998 ◽  
Vol 25 (2) ◽  
pp. 131 ◽  
Author(s):  
Spencer M. Whitney ◽  
T. John Andrews
Keyword(s):  
Large Subunit ◽  
Anaerobic Bacteria ◽  
Carbon Gain ◽  
Ribulose Bisphosphate Carboxylase ◽  
Ribulose Bisphosphate ◽  
Amphidinium Carterae ◽  
Bisphosphate Carboxylase ◽  
Cell Extracts ◽  
Ribulose Bisphosphate Carboxylase Oxygenase ◽  
Alternate Substrate

Some dinoflagellates have been shown recently to be unique among eukaryotes in having a ribulose-bisphosphate carboxylase-oxygenase (Rubisco, EC 4.1.1.39) composed of only one type of subunit, the 53-kDa large subunit [reviewed by Palmer, J.D. (1996) Plant Cell 8, 343–345]. Formerly, such homomeric Rubiscos had been found only in anaerobic bacteria and are characterised by such poor abilities to discriminate against the competitive alternate substrate, O2, that they would not be able to support net carbon gain if exposed to the current atmospheric CO2/O2 ratio. The capacity of Rubiscos from aerobic organisms to discriminate more effectively against O2 appeared to correlate with the presence of additional 12- to 18-kDa small subunits. Thus the CO2/O2 specificity of the homomeric dinoflagellate Rubisco is of considerable interest from the structural, physiological and evolutionary viewpoints. However, for unknown reasons, Rubiscos from dinoflagellates studied so far are so unstable after extraction from the cells that kinetic characterisation has not been possible. We redesigned two methods for measuring Rubisco’s CO2/O2 specificity to adapt them to rapid measurement at 10°C using unfractionated cell extracts. Both methods revealed that the CO2/O2 specificity of Rubisco from the dinoflagellate, Amphidinium carterae Hulburt, was approximately twice as great as that of other homomeric Rubiscos but unlikely to be sufficient to support dinoflagellate photosynthesis without assistance from an inorganic-carbon-concentrating mechanism.

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