Immunodetection of Pectic Epitopes, Arabinogalactan Proteins, and Extensins in Mucilage Cells from the Ovules of Pilosella officinarum Vaill. and Taraxacum officinale Agg. (Asteraceae)

Abstract

The main aim of this study was to compare the cytological difference between ovular mucilage cells in two Asteraceae species—Pilosella officinarum and Taraxacum officinale—in order to determine whether pectic epitopes, arabinogalactan proteins, or extensins are present. The immunocytochemical technique was used. Both the Taracacum and Pilosella genera have been used recently as models for understanding the mechanisms of apomixis. Knowledge of the presence of signal molecules (pectic epitopes, arabinogalactan proteins, and extensins) can help better understand the developmental processes in these plants during seed growth. The results showed that in Pilosella officinarum, there was an accumulation of pectins in the mucilage, including both weakly and highly esterified pectins, which was in contrast to the mucilage of Taraxacum officinale, which had low amounts of these pectins. However, Taraxacum protoplasts of mucilage cells were rich in weakly methyl-esterified pectins. While the mucilage contained arabinogalactan proteins in both of the studied species, the types of arabinogalactan proteins were different. In both of the studied species, extensins were recorded in the transmitting tissues. Arabinogalactan proteins as well as weakly and highly esterified pectins and extensins occurred in close proximity to calcium oxalate crystals in both Taraxacum and Pilosella cells.

Spatio-Temporal Distribution of Cell Wall Components in the Placentas, Ovules and Female Gametophytes of Utricularia during Pollination

“…Thus, the production of AGPs in sporophytic tissues was not dependent on the occurrence of a mature gametophyte. This result is in contrast to the observation in Galanthus nivalis L. that was made by Chudzik et al [ 33 ]. These authors did not find AGPs (labeled by JIM13 and JIM8) in the sterile ovules.…”

“…[ 32 , 33 ], Quercus suber L. [ 40 ], Fragaria × ananassa Duchesne [ 41 ] and Pilosella officinarum Vaill. [ 33 ], AGPs are produced in the ovule before the pollen tube arrives. However, in other species, the production of AGPs is dependent on pollination and pollen tube growth [ 7 ].…”

“…The detailed procedures for observing the histological sections and performing the immunochemical analysis are described in Płachno et al [ 33 ]. The plant material was fixed overnight at 4 °C in 8% ( w/v ) paraformaldehyde (PFA, Sigma-Aldrich, Sigma-Aldrich Sp.…”

“…AGPs have been recorded in the styles, ovules and female gametophytes of various plant species. Their occurrence is connected with the specific stages of development, a specific tissue, organ and/or pollen tube growth e.g., [ 7 , 28 , 30 , 31 , 32 , 33 ]. In some species, the production of AGPs in ovules is triggered by pollen tube passage [ 6 , 33 , 34 ], while in others, their production is independent of pollination [ 7 ].…”

Effect of Low Temperature on Changes in AGP Distribution during Development of Bellis perennis Ovules and Anthers

“…AGPs were connected with active regulation of selection of megaspores [33], 'promotion' of viable megaspores [15], involvement in initiation of female gametogenesis [17], biochemical support for the pollen tube to reach the embryo sac in transmission track [32] and contribution to the fertilization, and the proembryo development [14,34]. Furthermore, AGPs occurred in mucilage mother cells, and their accumulation was correlated with a hypothetical role in communication between maternal tissues and the embryo [35]. The most often used antibody-JIM13-was detected in the tapetal anther layers of Brassica napus [36] and Quercus suber [37], in mature pollen grains, and in the wall of generative and sperm cells [38].…”