PARTIAL IDENTIFICATION OF DARK ¹⁴CO₂ FIXATION PRODUCTS IN LEAVES OF CATTLEYA (ORCHIDACEAE)

Abstract

SUMMARYFollowing exposure of Cattleya leaves to '^COj in the dark, labelled malate, citrate and an unidentified compound were detected by thin layer chromatography. This is interpreted to suggest the existence in Cattleya leaves of a dark COj fixation pathway which may be similar to that found in other plants which can fix large amounts of carbon in the dark.

On the Evolutionary Origin of CAM Photosynthesis

“…The resulting organic acids, canonically malic acid but also citric acid (Knauft and Arditti, 1969;Lüttge, 1988), are stored in the central vacuole and decarboxylated during the day to provide CO 2 to Rubisco and the Calvin-Benson-Bassham cycle (Silvera et al, 2010). During the night, stored carbohydrates are partially exported and partially used for organic acid synthesis (Borland and Dodd, 2002), which leads to a large proportion of storage carbohydrate cycling.…”

Crassulacean Acid Metabolism in the Gesneriaceae

“…The CAM pathway of photosynthesis occurs in tropical epiphytes of the Bromeliaceae (McWilliams, 1970;Medina and Troughton, 1974), Orchidaceae (Knauft and Arditti, 1969;McWilliams, 1970;Neales and Hew, 1975;Sinclair, 1984), Cactaceae (Wiehler, 1982), Rubiaceae (Winter et al, 1983), and the Piperaceae (Sternberg, Deniro and Ting 1984;Sipes and Ting, 1985). CAM is also found in some epiphytic ferns of the Polypodiaceae (Wong and Hew, 1976).…”

Physiological Changes During the Germination of Cattleya aurantiaca (Orchidaceae)

“…9), but the pathway being utilized by the seedlings is as yet unclear. Several orchid species, including members of Cattleya, possess the crassulacean acid metabolism carbon fixation pattern in their leaves (KNAUFT and ARDITTI 1969;WITIINER 1974). It is possible, therefore, that the same pathway may be operative i11 th~ protocorms and/ or seedlings.…”