CO₂ Exchange, Cytogenetics, and Leaf Anatomy of Hybrids between Photosynthetically Distinct Flaveria Species

Abstract

Physiological and anatomical traits associated with C4 photosynthesis have been well characterized and are known to provide certain physiological and environmental advantages to plants possessing them. Hybridization between plants which exhibit C4 photosynthesis and those which do not is a means of assessing the feasibility of incorporating C4 traits into C3 species through plant breeding. Segregating populations from fertile C3 X C4 hybrids would be useful for studying inheritance of C4 traits and their linkage. The first artificial C3 x C4 hybrids were between the C4 species Atriplex rosea and the C3 species Atriplex patula (2-4). The F, hybrid was intermediate to the parents in several anatomical and biochemical characteristics, but was similar to the C3 parent in

Degree of C4 Photosynthesis in C4 and C3-C4Flaveria Species and Their Hybrids

“…Inhibition of AP by 210 mL L' of 02 for F. trinervia x F. linearis and F. brownii x F. linearis hybrids was reported to be between that of the parents (4,12). However, in the present experiments, F. trinervia x F. linearis (Table I) (Fig.…”

“…Various aspects of CO2 exchange have been reported for these species and two of the hybrids (2,4,12). Inhibition of AP by 210 mL L' of 02 for F. trinervia x F. linearis and F. brownii x F. linearis hybrids was reported to be between that of the parents (4,12).…”

“…Four hybrids were made as described earlier (2,12). Two of the hybrids (Flaveria trinervia [C4] x Flaveria linearis and Flaveria brownii x F. linearis) have been described in terms of CO2 exchange, leaf anatomy, carboxylase activities, and cytogenetics (2,4,12).…”

“…Two of the hybrids (Flaveria trinervia [C4] x Flaveria linearis and Flaveria brownii x F. linearis) have been described in terms of CO2 exchange, leaf anatomy, carboxylase activities, and cytogenetics (2,4,12). In the following experiments, we used these two hybrids plus two hybrids made by crossing the F1, and 87-527) were selected for further study based on their contrasting response of AP to 2.…”

“…The C3-C4 species represent a gradient of C4 pathway activity: Flaveria linearis assimilates little CO2 by the C4 pathway, and Flaveria brownii is a nearly completely developed C4 type (7,17,18,21). A number of Flaveria hybrids have been made between photosynthetic types, and these hybrids also exhibit varying degrees of C4 photosynthesis as determined by CO2 exchange and activities of carboxylase enzymes (1,2,4,12). The objective of this work was to examine further the degree and coordination of C4 metabolism in C4 and C3-C4 species of Flaveria and their hybrids by examining 14CO2 assimilation and turnover of photosynthetic products, along with 02 inhibition of AP and 13C/12C isotope ratios of mature leaves.…”