Enzymic Breakdown of Stigmatic Cuticula of Flowers

Abstract

ENZYME preparations from different microorganisms are able to break down the leaf cutin of different plants^1,2. Furthermore, the incompatibility reaction in Oruciferae occurs on the surface of the stigma papillae: pollen tubes are unable to penetrate the cuticle of the stigma cells³ after self-pollination. Therefore we tried to determine the activity of an enzyme preparation from Penicillium spinulosum Thom, on cutin preparations of several sources and especially on stigma cutin isolated from about 10,000 stigmata of black mustard by shaking with pectinase solution following the method in ref. 4, and treatment with ethanol. The results are listed in detail in Table 1. From this it is clear that cutin from mustard stigma is attacked more than material from the pistil of Petunia and much more than cutin from leaves and fruits. The breakdown is measured by titration of the enzymically liberated fatty acids following a new method⁵. The differences in enzymic decomposition of cutin should depend on a specific state or a special composition of the high-polymeric, reticular substrate. For the first time it has been possible to demonstrate the enzymic breakdown of stigma cutin.