Poppinga et al

Poppinga et al. were different patterns of the cell wall components in the arms of the terminal cells of the quadrifids. The cell walls of the arms were especially rich in low-methyl-esterified homogalacturonan. Moreover, various arabinogalactan proteins also occurred. Cell walls in glandular cells of quadrifids were rich in low-methyl-esterified homogalacturonan; in contrast, in the aquatic carnivorous plantAldrovanda vesiculosa, cell walls in the glandular cells of digestive glands were poor in low-methyl-esterified homogalacturonan. Arabinogalactan proteins were found in the cell walls of trap gland cells in all studied carnivorous plants:Utricularia, and members of Droseraceae and Drosophyllaceae. Keywords:arabinogalactan proteins, bladderworts, carbohydrate epitopes, carnivorous plants, cell wall, digestive glands, Lentibulariaceae, trichomes == 1. Introduction == The genusUtriculariais the most diverse genus among carnivorous plants, both in terms of herb size and environmental adaptations, as well as herb body architecture. It is also the richest in number of species, with around 250 species [1,2,3,4]. All of theUtriculariaspecies are rootless herbs. Their vegetative organs go beyond the typical organ classification, i.e., either root, stem, or leaf, and they have intermixed morphological characteristics and developmental programs [5,6,7,8]. These are related to the heterotopic transfer of the function of the genes to other organs, as was shown in the root genes [9].Utriculariaproduce small hollow vesicles (bladders with elastic walls and a mobile trap door), which function as suction traps that work underwater and capture fine organisms [10,11,12,13,14,15,16]. There is agreement that these traps are of a foliar origin. UsingUtricularia gibba, Whitewoods et al. [17] showed that simple shifts in gene expression may change leaf morphogenesis, which finally results in trap formation.Utriculariatraps attract special interest because they are among the fastest moving herb organs [15,18,19,20,21,22,23]. Poppinga et al. [23] showed that animals were successfully captured byUtricularia australistraps within 9 ms. There are various types of glandular trichomes on the surface of theUtriculariatraps [24,25,26,27,28,29]. The inner part of the trap is usually densely lined by two types of large trichomes. There are trichomes with four terminal cells called quadrifids, which almost cover the entire inner surface, and trichomes with two terminal cells called bifids, which are located near the trap door. Darwin proposed the names of these trichomes [30]. Both quadrifids and bifids have the same architecture, because are formed by a basal cell, a pedestal cell, and a terminal cell. The terminal cell is usually regionally PD1-PDL1 inhibitor 2 differentiated and consists of different parts with distinct structures and functions: the basal part, stalk and arm. Quadrifids participate in PD1-PDL1 inhibitor 2 the secretion of digestive enzymes and in the resorption of released nutrients, and probably also participate in pumping out water. According to some authors, the main role of bifids is usually pumping out water [26,27,31,32,33]. Due to the extreme specialization of the quadrifids, they are an interesting model to use to study cell walls. Recently, in a series of works, we showed the major cell wall polysaccharides and glycoproteins in the various glands of carnivorous plants; however, our studies were limited toAldrovanda vesiculosa[34,35],Dionaea muscipula[36,37], andDrosophyllum lusitanicum[38]. This aim of this study is to fill in the gap in the literature concerning the immunocytochemistry of the quadrifids in the major cell wall polysaccharides and glycoproteins. Herb organs are covered by a cuticle, which is a hydrophobic and protective barrier, but is also impermeable to antibodies. However, structures such as the root hairs and pollen tubes are devoid of a cuticle, which means that the cell walls can be studied using whole-mount immunolabeled organs (without the time-consuming task of embedding them in resin and later cutting the material with a microtome). The use of this technique has produced very good results in root hairs [39,40,41] and pollen tubes [42,43]. Because cuticle discontinuities in PD1-PDL1 inhibitor 2 the glands of carnivorous plants are known [26,27,44], we wanted to try this method; therefore, we used p101 whole-mount immunolabeledUtriculariatraps. However, to what degree a cuticle with discontinuities will be a barrier to.