In-vivo study of cutin synthesis in leaves of Clivia miniata Reg. |
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Authors: | Klaus J Lendzian Jörg Schönherr |
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Institution: | 1. Lehrstuhl für Botanik, Institut für Botanik und Mikrobiologie der Technischen Universit?t, Arcisstrasse 21, D-8000, München 2, Germany
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Abstract: | Cutin synthesis of Clivia miniata Reg. was studied by using intact leaves. Tritium-labelled hexadecanoic acid was used as precursor and was administered as droplets of micellar solutions to the upper surface of expanding leaves. Radiolabel was incorporated rapidly. Within 2 h, up to 10% of the label administered had been incorporated into cutin. Rates of 3H-cutin synthesis depended on the position of the site of precursor donation to the leaf. Highest rates were observed between 3 to 4 cm from the leaf base. From zero to 3 cm, rates increased by about one order of magnitude every centimeter. Above 4 cm, the decrease in rates of 3H-cutin synthesis was again logarithmic, such that at 10 cm from leaf base only 1%, and at 15 cm from leaf base only 0.1% of the maximum rates were observed. Rates of cutin synthesis depended on the hexadecanoic acid concentration of the droplets, according to the Michaelis-Menten equation. The maximum rate was 0.71 μg cm-2 h-1. The half-maximum rate was observed at a hexadecanoic acid concentration of 42.4 mg l-1. Maximal cutin synthesis coincided with maximal cell elongation. Microautoradiography indicated that most of the label was incorporated into the internal cuticular layer. |
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