Arabinogalactan Proteins in the Digestive Glands of Dionaea muscipula J.Ellis Traps.

Bartosz J Płachno,Piotr Świątek,Małgorzata Kapusta,Piotr Stolarczyk

doi:10.3390/cells11030586

Abstract

The arabinogalactan proteins (AGP) play important roles in plant growth and developmental processes. However, to the best of our knowledge, there is no information on the spatial distribution of AGP in the plant organs and tissues of carnivorous plants during their carnivorous cycle. The Dionaea muscipula trap forms an “external stomach” and is equipped with an effective digestive-absorbing system. Because its digestive glands are composed of specialized cells, the hypothesis that their cell walls are also very specialized in terms of their composition (AGP) compared to the cell wall of the trap epidermal and parenchyma cells was tested. Another aim of this study was to determine whether there is a spatio-temporal distribution of the AGP in the digestive glands during the secretory cycle of D. muscipula. Antibodies that act against AGPs, including JIM8, JIM13 and JIM14, were used. The localization of the examined compounds was determined using immunohistochemistry techniques and immunogold labeling. In both the un-fed and fed traps, there was an accumulation of AGP in the cell walls of the gland secretory cells. The epitope, which is recognized by JIM14, was a useful marker of the digestive glands. The secretory cells of the D. muscipula digestive glands are transfer cells and an accumulation of specific AGP was at the site where the cell wall labyrinth occurred. Immunogold labeling confirmed an occurrence of AGP in the cell wall ingrowths. There were differences in the AGP occurrence (labeled with JIM8 and JIM13) in the cell walls of the gland secretory cells between the unfed and fed traps.

Highlights

Dionaea muscipula J.Ellis (Venus flytrap) is a carnivorous plant that creates active traps that are modified leaves and that are used to attract, capture and digest invertebrates, mainly insects, and spiders [1–3]
The epitope that is recognized by the JIM14 antibody was mainly detected in the cell walls of the secretory cells of the digestive glands in both the unfed and fed traps (Figure 2a–f)
The arabinogalactan proteins (AGP) epitope that is recognized by the JIM8 antibody was present in all of the cell types of the digestive glands

Summary

Introduction

Dionaea muscipula J.Ellis (Venus flytrap) is a carnivorous plant that creates active traps that are modified leaves and that are used to attract, capture and digest invertebrates, mainly insects, and spiders [1–3]. Because of the various processes that occur in the traps (reception of the stimuli needed to close the trap, trap movement, electric signal transmission, enzyme secretion, absorption of compounds from the digested invertebrate bodies), it is a useful model for both physiological and molecular studies [7–13]. The Dionaea trap forms a special external stomach that is equipped with effective digestive-absorbing glands (Figure 1a,b). Dionaea digestive fluid contains various proteins: peroxidases, nucleases, phosphatases, phospholipases, a glucanase, chitinases and proteolytic enzymes. Some of these are used by ‘typical’ plants as stress pathway-associated proteins. For carnivory, other physiological pathways were used, e.g., Palfalvi et al [20] suggested that the genes that are used for prey-derived nutrient absorption in Dionaea are recruited from the roots

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