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Photosynthesis in cell suspension cultures of the CAM plant Chamaecereus sylvestrii (Cactaceae)
Author(s) -
SEENI S.,
GNANAM A.
Publication year - 1980
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1980.tb03336.x
Subject(s) - photosynthesis , carbon fixation , biochemistry , chloroplast , biology , callus , photorespiration , botany , phosphoenolpyruvate carboxylase , chemistry , gene
Photosynthetic properties of cell suspension cultures derived from the callus proliferation of cladophyll explants of Chamaecereus sylvestrii Spegazzini were studied. High content of chlorophyll (105–120 μg/g fresh weight), cyanide sensitive O 2 uptake and maximal rates of O 2 evolution (100–115 μmol/mg Chl x h) and CO 2 fixation (130–150 μmol/mg Chl x h) were some of the properties of the exponential phase cells. Determination of the component reactions, viz. photosystems I and II and photophosphorylation of the chloroplasts isolated from the cells, indicated normal development and functioning of the photosynthetic machinery. Studies on the enzymatic reactions as well as the determination of the early products of 14 CO 2 fixation in light in these cells implicated the operation of both autotrophic and non‐auto‐trophic pathways, the latter being less pronounced. The diurnal oscillation of titratable acidity and malate content found in the intact cladophyll tissues was absent in the cultured cells. Evidences for a rapid and continuous drain of carbon from malate into the citrate and isocitrate components of the TCA cycle via pyruvate after decarboxylation, and then into the amino acid pool are presented. The absence of large vacuoles and the rapid turnover of malate are considered to account for the lack of diurnal fluctuation of organic acide in the cell cultures.