%0 Journal Article %A Chun-Mei GONG %A Peng-Bo NING %A Gen-Xuan WANG %A Zong-Suo LIANG %T A REVIEW OF ADAPTABLE VARIATIONS AND EVOLUTION OF PHOTOSYNTHETIC CARBON ASSIMILATING PATHWAY IN C3 AND C4 PLANTS %D 2009 %R 10.3773/j.issn.1005-264x.2009.01.023 %J Chinese Journal of Plant Ecology %P 206-221 %V 33 %N 1 %X

Three photosynthetic pathways are used by plants: C3, which most plants use, C4 and crassulacean acid metabolism (CAM). C3 is the ancestral pathway, with C4 and CAM representing recently diverged forms. We conclude that the variation and evolution of photosynthetic pathway of C3 and C4 are adaptations to environmental stresses. First, we discuss the evolutional future of photosynthetic pathways. It has been suggested that low atmosphere CO2, enhanced temperatures, drought and salinity are external drivers of C4 photosynthetic evolution. Second, we analyze the possibility of evolution from C3 to C4. The polyphyletic evolution of the C4 pathway suggests that the transition from C3 to C4 was relatively simple. This suggestion is supported by the observation that both C3 and C4 plants possess inherent plasticity in their photosynthetic characteristics. The stress causing the shift from C3 to C4 was involved in the environmental regulation of plants, and the C4 pathway in C3 plants evolved as an adaptation. The environmental stresses may have involved plant capacities for survivorship and competition in arid areas. Third, we present a simplistic model of the main phases of C4 photosynthetic evolution and discuss the variation and evolution of C3 and C4 photosynthetic carbon assimilating pathways. Evolution was not directly to C4 photosynthesis, so each step had to be stable, beginning with numerous preconditions needed for an evolutionary lineage to begin evolving C4 characteristics. A current complication of C4 photosynthetic evolution is global climate change and human manipulation of the biosphere. It is possible that C4 photosynthesis can be used to resist adversity and increase the yield of C3 crops. In conclusion, study of the evolution of photosynthetic pathway in plants provided insight into the photosynthetic physiology of plants under stress and provided new theory to reconstruct vegetation, enhance crop yield, and explain adaptation of C3 species in arid areas.

%U https://www.plant-ecology.com/EN/10.3773/j.issn.1005-264x.2009.01.023