Dark fixation of CO2 by flowers of cut roses

Summary Complete flower heads of cut roses (cv. Baccara) were exposed to ¹⁴CO₂ for 1–4 h. The flower tissue was able to fix CO₂ via PEP carboxylase (E.C. 4.1.1.31) in the dark; various TCA products were identified in petals, ovary and anthers, including malate, aspartate, citrate, serine/glycine, glutamate and asparagine. The concentrations of these labelled products were similar in the petals and anthers, but lower in the ovary. After removal of the petals the amounts of these components were reduced in the anthers to a relatively high extent (to 1/6), whereas the amounts in the ovary increased slightly. It is suggested that the petals are necessary for supplying the anthers with the described components.Abbreviations DTT dithiothreitol - EDTA ethylenediaminetetra-acetate - MDH malate dehydrogenase - NADH nicotinamideade-ninedinucleotide - PEP phosphoenolpyruvate - PVP polyvinylpyrrolidone - TCA tricarboxylic acid