Transfer of C4 Photosynthetic Characters through Hybridization of Flaveria Species

Open Access
Publisher Website
Google Scholar
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.