AgCl precipitates in isolated cuticular membranes reduce rates of cuticular transpiration

Abstract

Counter diffusion of chloride, applied as NaCl at the inner side of isolated cuticles, and silver, applied as AgNO(3) at the outer side, lead to the formation of insoluble AgCl precipitates in isolated cuticles. AgCl precipitates could be visualized by light and scanning electron microscopy. The presence of AgCl precipitates in isolated cuticles was verified by energy dispersive X-ray analysis. It is argued that insoluble AgCl precipitates formed in polar pores of cuticles and as a consequence, cuticular transpiration of 13 out of 15 investigated species was significantly reduced up to three-fold. Water as a small and uncharged but polar molecule penetrates cuticles via two parallel paths: a lipophilic path, formed by lipophilic cutin and wax domains, and a aqueous pathe, formed by polar pores. Thus, permeances P (m s(-1)) of water, which is composed of the two quantities P (Lipid) and P (Pore), decreased, since water transport across polar pores was affected by AgCl precipitates. Cuticles with initially high rates of cuticular transpiration were generally more sensitive towards AgCl precipitates compared to cuticles with initially low rates of transpiration. Results presented here, significantly improves the current model of the structure of the cuticular transpiration barrier, since the pronounced heterogeneity of the cuticular transport barrier, composed of lipophilic as well as polar paths of diffusion, has to be taken into account in future.

Comparative characteristics of anatomical and morphological adaptations of plants of two subgenera Haworthia Duval to arid environmental conditions

“…It is well-known that the epidermis with a thick layer of cuticle fulfils various protective functions and displays numerous xeromorphic traits in its structure [17,18].…”

Barriers, pathways and processes for uptake, translocation and accumulation of nanomaterials in plants – Critical review

“…regions permeable to water and other polar solutes (Figure 5;Schreiber, 2005;Schreiber et al, 2006). Thinned, permeable regions of the cuticle exist in various plant tissues possessing secretory/uptake functions, such as trichomes, mucilage-covered root hairs and tips, and hydathodes (refer the ''Plant loopholes'' section; Fahn, 1982).…”

“…as protection against pests, or excessive light irradiance (Fahn, 1982;Sánchez-Serrano, 2001;Wagner, 1991). Due to the secretory properties, glandular trichomes are permeable for diffusion of polar substances (polar paths, refer the ''Cuticle'' section; Schreiber, 2005;Schreiber et al, 2006). Glandular trichomes can accumulate large quantities (up to 10% of leaf dry weight) of metabolic substances between the pectin layer and the cuticle.…”

Foliar Iron Fertilization of Peach (Prunus persica (L.) Batsch): Effects of Iron Compounds, Surfactants and Other Adjuvants

“…Recently, it has been observed that the size of molecular Ca species was less limiting for ionic species (entering through aqueous pores) than for neutral species (entering through cutin and waxes) (Schö nherr and Schreiber 2004). The process of cuticular water transport has been recently investigated using an experimental design based on the formation of AgCl precipitates in the cuticle polar pores (Schreiber et al 2006). Cuticular water sorption has also been attributed to a polysaccharide fraction with a high-hydration capacity (Domínguez and Heredia 1999), which may consist of a reticulum of microfibrils ramifying and stretching through the cuticular membrane (Jeffree 1996).…”