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PLASTIDS IN LATICIFERS OF PAPAVER. II. ENZYME CYTOCHEMISTRY OF MEMBRANE‐BOUND INCLUSIONS OF LATICIFER PLASTIDS IN P. BRACTEATUM LINDL. (PAPAVERACEAE)
Author(s) -
Nessler Craig L.,
Mahlberg Paul G.
Publication year - 1979
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1979.tb06224.x
Subject(s) - cytochemistry , catalase , biology , plastid , papaveraceae , papaver , peroxidase , biochemistry , hydrogen peroxide , enzyme , botany , chloroplast , alkaloid , gene
Membrane‐bound inclusions in laticifer plastids of Papaver bracteatum Lindl. were examined by electron microscopic enzyme cytochemistry. Electron‐opaque reaction products were observed in the plastid inclusions of laticifers in tissues incubated in 3,4 dihydroxyphenylalanine (dopa), tyrosine, or 3,3 diaminobenzidine (DAB). The enzymatic basis for substrate oxidation was confirmed by the absence of reaction product in boiled controls. Oxidation of dopa and tyrosine in plastid inclusions was not inhibited by sodium diethyldithiocarbamate (DDC), although DDC did inhibit the formation of reaction product between chloroplast lamellae in non‐laticiferous cells. Reaction product was also observed in tissues incubated in dopa and subsequently treated with catalase or catalase plus DDC. DAB oxidation was observed at pH 9.0 and 7.3, in tissues preincubated in aminotriazole (AT) and when hydrogen peroxide was omitted from the DAB medium. The results suggest that peroxidases in the inclusions of laticifer plastids may be responsible for substrate oxidation, even though exogenously applied catalase failed to inhibit dopa oxidation.