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Assessing Structural Traits in Triticum aestivum and Zea mays for C3 and C4 Photosynthetic Differentiation Using Free-hand and Semi-thin Sections
Published on: July 12, 2024
Photorespiration and the evolution of C4 photosynthesis
Rowan F Sage1, Tammy L Sage, Ferit Kocacinar
1Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada. r.sage@utoronto.ca
Abstract:
C(4) photosynthesis is one of the most convergent evolutionary phenomena in the biological world, with at least 66 independent origins. Evidence from these lineages consistently indicates that the C(4) pathway is the end result of a series of evolutionary modifications to recover photorespired CO(2) in environments where RuBisCO oxygenation is high. Phylogenetically informed research indicates that the repositioning of mitochondria in the bundle sheath is one of the earliest steps in C(4) evolution, as it may establish a single-celled mechanism to scavenge photorespired CO(2) produced in the bundle sheath cells. Elaboration of this mechanism leads to the two-celled photorespiratory concentration mechanism known as C(2) photosynthesis (commonly observed in C(3)-C(4) intermediate species) and then to C(4) photosynthesis following the upregulation of a C(4) metabolic cycle.
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