Transfer of C(4) Photosynthetic Characters through Hybridization of Flaveria Species |
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| Authors: | Cameron R G Bassett C L Bouton J H Brown R H |
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| Affiliation: | Department of Biochemistry, University of Georgia, Athens, Georgia 30602. |
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| Abstract: | Transfer of C4 photosynthetic traits was studied through hybridization of Flaveria trinervia (Spreng.) Mohr (C4) and Flaveria brownii A.M. Powell (C4-like) with Flaveria linearis Lag. (C3-C4) and the C3 species Flaveria pringlei Gandoger (C3). Fertility was low, based on irregular chromosome pairing and low pollen stainability, except in F. brownii × F. linearis which had bivalent pairing and 76% stainable pollen. Hybrids had apparent photosynthesis values of 71 to 148% of the midparental means, while the CO2 compensation concentration was similar to the C4 or C4-like parent, except in hybrids having the C3 species F. pringlei as a parent. Inhibition of apparent photosynthesis by O2, and phosphoenolpyruvate carboxylase and NADP-malic enzyme activities and subunit levels in the hybrids were closer to the C3 or C3-C4 parent. The species F. brownii and F. trinervia were equal in their capacity to transfer reduced O2 inhibition of AP and CO2 compensation concentration values to hybrids with F. linearis (C3-C4), although hybrids with F. trinervia had higher PEPC activity. The O2 inhibition of AP was correlated with the logarithm of activities of phosphoenolpyruvate carboxylase (r = −0.95) and NADP-malic enzyme (r = −0.87). These results confirm that C4 traits can be transferred by hybridization of C3-C4 and C4 or C4-like species, with a higher degree of C4 photosynthesis than exists in C3-C4 species, and at least in F. brownii × F. linearis, fertile progeny are obtained. |
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