Sudderth, Erika A. , Holbrook, Noel M. .
Physiological performance of C3, C4, and intermediate Flaveria species in the Tehuacán Valley of Mexico.
THE genus Flaveria consists of 23 species with significant variation in photosynthetic physiologies, including C3 species, C4 species, and many species which utilize a partially developed C4 cycle. The anatomy and biochemistry of Flaveria species has been extensively studied as a model system for the evolution of C4 photosynthesis. However, no previous studies have examined whether photosynthetic pathway variation in Flaveria species corresponds to physiological performance in C3, C4, and intermediate species growing under natural conditions. We measured leaf water potential, quantum yield of photosystem II, and leaf nitrogen content in field populations of two C3, three intermediate, and one C4 Flaveria species in the Tehuacán Valley of Mexico. Mid-day leaf water potential differed significantly between Flaveria species: the intermediate species operated at leaf water potentials between -0.2 to -0.3 MPa, while the C3 and C4 species had lower water potentials ranging from -0.35 to -0.4 MPa. The quantum yield of photosystem II did not vary between species, despite significant differences in leaf nitrogen content, leaf shape, plant size and life histories. Leaf nitrogen content of the C4 species was significantly higher than the two C3 species, while intermediate species were highly variable. Our results indicate that there is not a direct relationship between increasing C4 cycle characteristics and physiological performance in field populations of Flaveria.
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Erika Sudderth's Home Page
1 - Harvard University, Organismic and Evolutionary Biology, 3105 Biological Laboratories, 16 Divinity Avenue, Cambridge, Massachusetts, 02138
2 - Harvard University, Organismic and Evolutionary Biology, 3119 Biological Laboratories, 16 Divinity Avenue, Cambridge, Massachusetts, 02138
Presentation Type: Oral Paper:Papers for Topics
Date: Tuesday, August 1st, 2006
Time: 9:00 AM