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SHIFTS IN PHOTOSYNTHETIC CARBON LABELLING PATTERN BY ETIOLATED RICE (ORYZA SATIVA L.) SEEDLINGS DURING GREENING
Author(s) -
RAGHAVENDRA A. S.,
DAS V. S. R.
Publication year - 1977
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1977.tb02184.x
Subject(s) - etiolation , oryza sativa , greening , photosynthesis , phosphoenolpyruvate carboxykinase , botany , phosphoenolpyruvate carboxylase , sucrose , biology , labelling , sugar , biochemistry , chemistry , enzyme , gene , ecology
Summary The carbon assimilation pattern in light by dark‐grown rice (Oryza sativa) seedlings was studied during greening. After exposure of etiolated seedlings to light their capacity to synthesize the C 4 ‐acids, malate and aspartate, increased for 12 h. The labelling of 3‐phospho‐glycerate, sugar phosphates, sucrose and insolubles, did not increase until after 12 h. Thereafter a continuous steep increase in synthesis of Calvin cycle intermediates, but not of C 4 ‐acids, recurred. The levels of carboxylating enzymes (phosphoenolpyruvate and ribulose diphosphate carboxylases) in the seedlings correlated positively with the appearance of label in C 4 acids and in Calvin cycle compounds. We suggest that a β‐carboxylation mechanism was activated immediately on illumination but was persistent for only 12 h. After an 8‐h lag period following illumination, the Calvin cycle began to operate and continued during further growth of seedlings in light.