The Decay of Cutin and Cuticular Components by Soil Microorganisms in Their Natural Environment

Abstract

The cuticular components cellulose and cutin are decomposed in a period of 3-8 months (depending on the season) by soil microorganisms under natural conditions. The cellulose is attacked prior to the cutin layer. The latter is invaded by microorganisms which settle first in the cellulose layer. If purified cutin strips with the cellulose removed, are exposed to the action of soil microorganisms, the degradation also starts from the "inside" of the layer.The progress of degradation depends on the soil used, active garden soil giving the best, and poor sand soil the slowest attack. The degradation of the cutin layers starts with a swelling of the former boundaries of the epidermal cells, then follows the removal of successive sub-layers and finally the detachment of entire subunits from the weakened structure, ultimately leading to a total decay of the structure. The detachment of the lamellae within the cutin layer could be shown in cross sections of the exposed material by electron microscopical examination.Halo-formation around the invading microorganisms, and the lipid accumulation as a result of fatty acid release from the cutin by far-distance decomposition, showed that cutin decay by exo-enzyme action is a widespread property of soil microorganisms.

COMPARATIVE ULTRASTRUCTURAL STUDY OF THE DEGRADATION IN SOIL OF ISOLATED CUTIN FROM ILEX LEAVES AND MALUS FRUIT

“…5] may be due to localized differences in the monomeric composition and structural configuration of the polymer. A similar phenomenon was also observed in Gasteria cutin that had been buried in soil (de Vries et aL, 1967). However, there does appear to be a difference in the pattern of microbial colonization between adaxial and abaxial leaf cutin [compare Fig.…”

“…Cc •V. Previous workers have been unable to clean efficiently buried strips of cellulose or cutin retrieved from soil (Tribe, 1957;de Vries et al, 1967), but the ultrasonic treattnent used in this study removed virtually all traces of debris from the cutin surface. Although this procedure also removed micro-organisms, it allowed the surface topography to be examined in detail with the SEM.…”

“…It is possible that this, and other hydrolytic reagents used in the present study, could not easily penetrate the thicker cutin of Ilex leaves and Malus fruits and thus any ennbedded polysaccharides were shielded from their action. Previous workers have been unable to clean efficiently buried strips of cellulose or cutin retrieved from soil (Tribe, 1957;de Vries et al, 1967), but the ultrasonic treattnent used in this study removed virtually all traces of debris from the cutin surface. Although this procedure also removed micro-organisms, it allowed the surface topography to be examined in detail with the SEM.…”

“…The degradation of complex plant polymers, such as cellulose, cutin and lignin, by soil micro-organisms has mostly been studied under in vitro conditions (Heinen, 1963;Reese, 1977). In one of the rare experiments where such material has been examined after burial in soil, Tribe (1957) placed cellulose (cellophane) strips on glass slides in a range of different soils and examined them at intervals with the light microscope (LM) for signs of microbial degradation, De Vries et al (1967) used a similar procedure to follow the degradation of leaf cutin of Gasteria verrucosa in the soil, examining samples with both the LM and, to a limited extent, the TEM,…”

Development of the Structure of the Normal, Smooth Cuticle of the Apple “Golden Delicious”

“…The cuticle has a very fine lamella structure in Ficus elastica (SITTE 1962;SITTE & RENNIER 1963). It has dotted bead-like structures arranged to parallel lamellae in Gasteria verrucosa (DE VRIES, BREDEMEIJER & HEINEN 1967). c. fruits…”