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Photosynthetic carbon fixation in the corollas of Petunia hybrida
Author(s) -
Weiss David,
ShomerIlan Adiva,
Vainstein Alexander,
Halevy Abraham H.
Publication year - 1990
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.1399-3054.1990.tb09046.x
Subject(s) - photosynthesis , botany , carbon fixation , rubisco , biology , chloroplast , petunia , horticulture , biochemistry , gene
Corollas of Petunia hybrida (cv. Hit Parade Rosa) flowers fixed 14 CO 2 under both light and dark conditions. Rates of light fixation were much higher in mature pink corollas than in young, green corollas [57 and 9 nmol (ngchl) 1 min ‐1 ], paralleling the development of chloroplasts in these tissues. Stomatal conductance in corollas was only 12% of that in green leaves, mainly due to the presence of few, and non‐functioning stomata in the corolla. The activity and concentration of ribulose bisphosphate carboxylase (EC 4.1.1.39) in corolla extracts were only about 30% (per unit Chi) of those in extracts from green leaves. These results, together with previous results, might indicate a coordinated reduction in activity of systems participating in photosynthesis in corollas. The fixation products following a 6 s pulse with 14 CO 2 , were typical of C, plants in both corollas and green leaves, but a higher level of β‐carboxylation products was found in the corollas. The activity of phosphoenol‐pyruvate carboxylase (EC 4.1.1.31) (per unit protein) was similar in both tissues. Although the total carbon fixed by the corolla constituted only a small part of the metabolites required for flower development, certain photosynthetic metabolites might have a regulatory role in flower development.