Endocytosis of 1,3-?-glucans by broad bean cells at the penetration site of the cowpea rust fungus (haploid stage)

Abstract

Abstract. The penetration hypha of basidiospore-derived infection structures of the cowpea rust fungus (Uromyces vignae Barclay) in epidermal cells of the nonhost, broad bean (Viciafaba L.), was studied with the electron microscope after high-pressure freezing and freeze substitution. After fungal invasion of the epidermis, a plug in the penetration hypha separated the infection structures on the cuticle from the intraepidermal vesicle of the fungus. The plug and the fungal cell wall reacted with a polyclonal 1,3-13-glucan antibody. The plug in the haploid stage seems to have a task similar to the septum formed in the diploid stage of the fungus. Around the penetration hypha, the plant wall stained darkly and a papilla was deposited by the plant. In the papilla, 1,3-]3-glucans were labelled by a monoclonal and a polyclonal antibody. In the infected epidermal cell, clathrin-coated pits, coated vesicles, partially coated reticula and multivesicular bodies were found. The contents of the coated pits, coated vesicles, partially coated reticula and multivesicular bodies bound to monoclonal and polyclonal 1,3-f3-glucan antibodies. Accumulation and uptake of this paramural material into the plant cell by endocytosis is concentrated at the fungal penetration site. It may influence the host-parasite interaction.

Cell wall synthesis in cotton roots after infection with Fusarium oxysporum

“…Deposition of callose is a typical wound response of plants (Aist and Bushnell 1991;Smart 1991). Using antibodies, it has been detected around the penetration site of the ring nematode Cricomella xenoplax in the root cortex (Hussey et al 1992), in contact cells surrounding vessels of tomato and cotton infected with Fusarium oxysporum (Mueller et al 1994), and in plant leaves around the penetration site of Uromyces vicia-fabae (Xu and Mendgen 1994). In addition, we observed label over plasmodesmata and spots in the cell plate but not over the Golgi apparatus.…”

“…In barley epidermal cells infected by Erysiphe graminis the wall apposition is produced soon after fungal contact with the plant cuticle (Kunoh 1982). Such appositions are produced by a cytoplasmic aggregate that accumulates within a few minutes at the site of fungal penetration (Bushnell 1984;Aist and Bushnell 1991;Xu and Mendgen 1994;Freytag et al 1994).…”

Plant nuclear migrations as indicators of critical interactions between resistant or susceptible cowpea epidermal cells and invasion hyphae of the cowpea rust fungus

“…The part of the IEV closest to the plant began to focus on the fungus, and particularly on the wall becomes sealed with a plug of y^-glucan (Xu & fungal apex, as a hyphal tip developed. The plant Mendgen, 1994) and, more distally, the fungus nucleus migrated to this hyphal tip when the invasion establishes tip growth and the resulting primary hypha was 15-20/^m long ( Fig. 1 tf) and remained at hypha elongates linearly.…”

Knocking on the heaven’s wall: pathogenesis of and resistance to biotrophic fungi at the cell wall

“…Exocytosis is typically balanced by endocytosis events to prevent net growth of the plasma membrane [58]. Indeed, clathrin-coated pits and coated vesicles, which serve as endocytosis markers, were detected by immunolabelling in high numbers at U. vignae penetration sites in broad bean epidermal cells [59,60]. An excess rate of exocytosis compared to endocytosis would inevitably result in the invagination of the plasma membrane.…”