Photosynthetic Characteristics of C₃-C₄ Intermediate Flaveria Species

Abstract

All available evidence suggests that C4 plants have evolved from ancestors possessing the C3 pathway of photosynthesis and this has occurred independently many times in taxonomically diverse groups (3,21). At present, the precise evolutionary transition, at the anatomical, physiological, and biochemical levels, from a C3 to a C4 plant is not clear. It is generally believed that studies of C3-C4 intermediate species might provide insight into the evolution of C4 photosynthesis. In addition, since most of the world's important crops are C3 plants, there has been considerable interest in improving their productivity by screening for mutants with reduced rates of photorespiration or by incorporating C4 characteristics into C3 plants (3,19,20). Thus, the search for naturally '

Photosynthesis, Leaf Anatomy, and Morphology of Progeny from Hybrids between C3 and C3/C4Panicum Species

“…For example, a rather well developed Kranz anatomy characterizes the C3/C4 grasses, Panicum and Neurachne (6,7,13), but the dicots Moricandia and some species of Flaveria, which have reduced PR and O2 sensitivity of AP similar to the C3/C4 grasses, have very little Kranz development (14,18). In the F2 and F5 progeny of the C3 X C3/C4 Panicum crosses some plants had well developed BSC with numerous organelles, but without F or PR which approach those ofthe C3/ C4 parents.…”

Genetic transformation of the C4 plant, Flaveria bidentis

“…Some species are C4, others are C3 and some are physiologically intermediate, ranging from C3-to C4-1ike (Edwards and Ku, 1987;Ku et al, 1991). The more C4-1ike intermediate species show some differentiation of mesophyll and bundle sheath cells with relatively high levels of C4 enzymes (Ku et al, 1983). The ability to compare closely related species with different physiological properties and different programmes of gene regulation should be a helpful experimental approach.…”

Photosynthetic Characteristics of C3-C4 Intermediate Flaveria Species

“…Naturally occurring species with photosynthetic characteristics intermediate between C3 and C4 plants have been identified in the genera Mollugo (19), Panicum (4,14), Moricandia (2,9), Flaveria (1,10,12) and, most recently, Neurachne (Hattersley, personal communication). The intermediate nature of these species includes a Kranz-like leaf anatomy, a lower r2 (indicative of reduced photorespiration), and a reduced sensitivity of net photosynthesis to 02.…”