Composition of the epicuticular and intracuticular wax layers on Kalanchoe daigremontiana (Hamet et Perr. de la Bathie) leaves.

Epicuticular and intracuticular waxes from both adaxial and abaxial surfaces of the leaves of Kalanchoe daigremontiana were analyzed. All wax mixtures were found to contain approximately equal amounts of triterpenoids and very long chain fatty acid (VLCFA) derivatives. The triterpenoid fraction consisted of glutinol (8-19% of the total wax) and friedelin (4-9%), together with smaller amounts of glutanol, glutinol acetate, epifriedelanol, germanicol and beta-amyrin. The VLCFA derivatives comprised C27-C35 alkanes (19-37% of the total wax), C32-C34 aldehydes (3-7%), C32 and C34 fatty acids (0.2-3%), C26-C36 primary alcohols (4-8%), and C42-C52 alkyl esters (2-9%). The wax layers were found to differ in triterpenoid amounts, with the intracuticular wax containing higher percentages of most triterpenoids than the epicuticular wax. Friedelin, the only triterpenoid ketone present, showed the opposite distribution with higher proportions in the epicuticular wax. VLCFA derivatives also accumulated to higher percentages in the epicuticular than in the intracuticular wax layer. Epicuticular wax crystals were observed on both the adaxial and abaxial leaf surfaces.

Development of the cuticular wax during growth of Kalanchoe daigremontiana (Hamet et Perr. de la Bathie) leaves.

The goal of the present study was to monitor cuticular wax accumulation during leaf development of Kalanchoe daigremontiana. Leaves expanded linearly until they were 40-60 d old. Wax coverages of leaves on the third node increased steadily during initial leaf development, from 6.5 microg x cm(-2) on day 22 to 15.3 microg x cm(-2) on day 53, and then levelled off. Triterpenoids dominated the wax mixture throughout leaf development, but decreased from 74 to 40-45% in mature leaves, while very long-chain fatty acid (VLCFA) derivatives increased from 19 to 39-44%. The major VLCFA derivatives were alkanes, accompanied by fatty acids, primary alcohols, aldehydes and alkyl esters. In all compound classes, either C(34) or C(33) homologs predominated during leaf development. Eight different triterpenoids were identified, with glutinol constituting 70% of the fraction, and friedelin (20%) and germanicol (10%) as further major components of the young leaf wax. The glutinol percentage decreased, while the relative amounts of epifriedelanol and glutanol increased during development. Various leaf pairs upwards from the third node showed similar growth patterns and developmental time courses of cuticular wax amounts and composition. Based on these surface chemical analyses, the relative activities of biosynthetic pathways leading to various wax components can be assessed.