Immunocytochemical Analysis of the Wall Ingrowths and Cell Wall Microdomains in the Digestive Glands of Venus'...

The digestive gland of Venus flytrap consists of various types of specialized cells. Secretory cells form two layers: the first is a more external outer layer and the second is an internal layer that is connected to stalk cells. Our goal was to check whether the position/location of cells is essential in terms of cell wall composition (whether cell wall microdomains exist). We also focused on the structure of cell wall ingrowths in secretory cells. To achieve this, the localization of the cell wall components in the cell walls of gland cells was performed using the immunolabeling technique and confocal microscopy. It has been found that cells within the gland head are not equal. Their location determines the composition of their cell walls in terms of the presence of various epitopes. The cell walls of the secretory cells in the outer layer were deficient in epitopes recognized by antibodies, including JIM5 (low methylesterified homogalacturonans), CCRC-M38 (low methylesterified homogalacturonans), LM5 (galactan), and CCRC-M48 (xyloglucan), which contrasted with the cell walls of the cells in the inner layer. In terms of the occurrence of pectic homogalacturonans, cell wall ingrowths constitute cell wall microdomains. The digestive glands of Dionaea muscipula exhibit pronounced cell wall microdomain organization, with distinct distributions of pectins, hemicelluloses, and arabinogalactan proteins across different glandular layers. These compositional differences reflect functional specialization in secretion, absorption, and structural support.