Analysis of apple epidermis in respect to ontogenic resistanceagainst Venturia inaequalis

Abstract

In order to understand mechanisms of ontogenic resistance to apple scab, we analyzed various aspects of young and old leaves. We have introduced an apple plants cultivation system where in vitro propagated and rooting explants produce a genetically uniform population of apple (Malus domestica cv. Idared) plants. In this work, we demonstrate that apple plants produced in our cultivation system showed susceptibility to Venturia inaequalis, the cause of apple scab disease in young leaves and resistance in old leaves, which is similar to orchard situation. Our analysis shows that the cessation of epidermal cell expansion and shape formation coincided with the onset of ontogenic resistance in older leaves. Formation of specific cuticular lamellar structures did not coincide with ontogenic resistance onset. Further, chemical composition analysis of wax from young susceptible and old resistant leaves did not reveal specific compounds involved in ontogenic resistance. Differences in homogalacturonan content in cell walls in susceptible and resistant cells as well as decreased methylesterification of pectin in resistant leaves suggest that polysaccharide composition of the cell wall may play a role in mycelium growth and nutrition.

Assessment of the Drought-Tolerance Criteria for Screening Peach Cultivars

“…SLA(specific leaf area) = Area Dry mass (10) To analyze stomata distribution, density, and size, leaf laminas from the adaxial and abaxial sides were varnished with a thin layer of nail polish. After complete drying, leaf surface prints were removed using forceps, mounted in water on the slides [42][43][44], and observed with AxioScope 1 (Zeiss, Jena, Germany) (20 samples × 5 microscope's field for each cultivar). The investigation was carried out at microscope magnification 200× with a coverage area of 0.24 mm 2 , and the stomata number per one mm 2 was calculated.…”