Epicuticular wax crystalloids in rice and sugar cane leaves are reinforced by polymeric aldehydes

摘要

Epicuticular wax in sugar cane leaves is present as platelets, short furrowed rodlets and massive prominent crystalloids which consist of longitudinally aggregated rodlets. In rice, the leaf surfaces are uniformly covered by platelets in a dense, irregular arrangement. The wax crystalloids of sugar cane are affected by CHCl3 extraction at room temp. only to a little extend and less than one tenth of total epicuticular wax is obtained by this treatment. Significant disturbance of the wax structure takes place in rice, the degree of disintegration and loss of crystalloids differs between cultivars. Compared to sugar cane, the relative amounts of waxes extracted are considerably greater. Primary alcohols and esters are the compound classes of long chain wax constituents preferably extracted by CHCl3 at room temp. Complete removal of all epicuticular waxes is achieved by extraction with CHCl3 at 60degreesC in rice and sugar cane as well. Whilst the amounts of aldehydes are small in the first extracts, they are the main constituent class obtained by extraction with hot CHCl3. This suggests that aldehydes are responsible for the incomplete extraction with CHCl3 at room temp. because of their presence in an insoluble, i.e. polymeric form. They dissolve at the elevated temperature by cleavage of polymer bonds. This is in agreement with previous results on the Solubility of polymeric aldehydes in epicuticular wax from the culms of sugar cane.