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Expression of C 4 ‐like photosynthesis in several species of Flaveria
Author(s) -
MOORE B. D.,
KU M. S. B.,
EDWARDS G. E.
Publication year - 1989
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1989.tb02127.x
Subject(s) - rubisco , phosphoenolpyruvate carboxylase , photosynthesis , botany , biology , carbon fixation , c4 photosynthesis , protoplast , pyruvate carboxylase , vascular bundle , biochemistry , enzyme
Photosynthetic metabolism was investigated in leaves of five species of Flaveria (Asteraceac), all previously considered to be C 4 plants. Leaves were exposed to 14 CO 2 for different intervals up to 16s. Extrapolation of 14 C‐product curves to zero time indicated that only F. trinervia and F.bidentis assimilated atmospheric CO 2 exclusively through phosphoenolpyruvate carboxylase. The proportion of direct fixation of 14 CO 2 by ribulose‐I, 5‐bisphosphate carboxylase/oxygenase (Rubisco) ranged from 5 to 10% in leaves of F. australasica . F. palmeri and F. vaginata. Protoplasts of leaf mesophyll and bundle sheath cells were utilized to examine the intercellular compartmentation of principal photosynthetic enzymes. Leaves of F. australasica, F. palmeri and F. vaginata contained 5 to 7% of the leaf's Rubisco activity in the mesophyll cells, while leaves of F. trinervia and F. bidentis contained at most 0.2 to 0.8% of such activity in their mesophyll cells. Thus, F. trinervia and F. bidentis have the complete C 4 syndrome, while F. australasica, F. palmeri and F. vaginata are less advanced, C 4 ‐like species.