Can C4 photosynthesis function within a single cell?

Haberle, Ines (2011) Can C4 photosynthesis function within a single cell?. Bachelor's thesis, Faculty of Science > Department of Biology.

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Abstract

Until recently, C4 photosynthesis was thought to be associated only with plants that possess two types of photosynthetic cells, mesophyll and bundle sheath cells, or so-called Kranz anatomy. The discovery of three Chenopodiaceae species, Bienertia cycloptera, Bienertia sinuspersici and Suaeda aralocaspica, which do not have these structures, and yet carry out C4 photosynthesis, showed that the C4 mechanism can be implemented within a single chlorenchyma cell that has two distinct regions. Those are peripheral and central compartments in Bienertia and distal and proximal compartments in Suaeda, respectively. Such cellular organisation is analogous to Kranz anatomy and enables compartmentalization of organelles, primarily dimorphic chloroplasts, as well as photosynthetic enzymes. A distinctive feature of the singlecell C4 photosynthesis is the positioning of dimorphic chloroplasts with respect to different compartments, which is the opposite than in common C4 plants. This is due to their role in meeting the energy requirements of the cell. The cytoskeleton, a dense network of actin filaments and microtubules, maintains the spatial organisation of cellular structures. The C4 cycle is controlled mainly through the regulation of activity of the enzyme phosphoenolpyruvate carboxylase (PEPC), either allosterically or via phosphorylation/dephosphorylation. Since PEPC isoenzymes are also found in C3 plants, they are important in elucidating the evolution of C4 plants. The comparison of these isoenzymes shows that the C4 plants probably evolved 25 – 32 million years ago from a C3 photosynthetic form. The fact that C4 plants have better photosynthetic performance on extreme habitats, such as deserts or saline soils, drives the interest for investigating single-cell C4 photosynthesis. Successful introduction of the C4 photosynthetic mechanism into C3 plants could mean a major breakthrough in the global crop cultivation.

Item Type: Thesis (Bachelor's thesis)
Supervisor: Tkalec, Mirta
Date: 2011
Number of Pages: 19
Subjects: NATURAL SCIENCES > Biology
Divisions: Faculty of Science > Department of Biology
Depositing User: Silvana Šehić
Date Deposited: 07 Oct 2014 08:41
Last Modified: 07 Oct 2014 08:41
URI: http://digre.pmf.unizg.hr/id/eprint/2958

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