Ultrastructural demonstration of different peroxidase activities during the bean rust infection process

Abstract

During penetration and infection of the bean leaf by the rust fungus, at 22 h after artificial inoculation, the following sites of peroxidase activity were observed which might influence the interaction of the host and parasite:(I) The guard cell walls of the stoma are covered with a layer that shows peroxidase activity. This activity might influence the infection peg of the fungus.(2) Within the leaf, the infection hypha of the bean rust fungus contacts a layer of peroxidase activity at the outer surface of the host cells. In the compatible combination employcd, no differences in the peroxidase activity at this site were detected between cells which came in contact with hyphae and those which did not.(3) The penetration peg ofthe haustorial mother cell enters the host cell and differentiates to form the haustorial neck. Here, a very strong peroxidase activity was observed, which might be a defence reaction of the host against the pathogen.(4) During the development of the haustorial body, peroxidase activity was seen on the rough endoplasmic reticulum and in the Golgi bodies. It is suggested that peroxidase is synthesized on the endoplasmic reticulum and secreted towards the partly invaginated sheath by the Golgi bodies.(5) Peroxidase activity was observed on the nuclear envelope of some nuclei in infected cells. INTRODUCTIONIt seems to be weil established that an increase ofperoxidase activity can be measured in homogenates of bean leaves some days aftGr infection with viruses [2, 6, 33], bacteria [27] and bean rust [21,22,36]. These studies were made either by measuring the total peroxidase activity in extracts or by separating proteins by gel electrophoresis and staining of bands for enzyme activity. Mter incubation of bean rust infected leaves with 3,3'-diaminobenzidine, the ultrastructural localization of the oxidized substrate indicated peroxidase activities on the outside of the cell wall, on the haustorial neck at the site of fungal penetration and sometimes on the ribosomes of the endoplasmic reticulum around the haustorium [20].Recent electrophoretic studies [21] show that only a temporary increase of some peroxidase isoenzymes occurs during the first 24 h after infection.The purpose of this study was to investigate: (1) whether the increase of peroxidase activity is a contribution of the host or the pathogen; (2) if this enzyme influences the fungal penetration in the leaf as weil as the formation of the first haustorium within the leaf cells; and (3) whether synthesis of peroxidase occurs in particular cell organelles during infection.Physiological Plant Pathology (1975) 6,275-282 Ultrastructural demonstration of different peroxidase activities during the bean rust infection process KURT MENDGEN Institut jur Pjlanzenpatlwlogie und Pjlanzenschutz der Universitiit Giittingen, 31-Giittingen, Federal Republic of Gemumy (Acceptedjor publication January 1975)During penetration and infection of the bean leaf by the rust fungus, at 22 h after artificial inoculation, the following sites of peroxidase ac...

Involvement of reactive oxygen species in the response of resistant (hypersensitive) or susceptible cowpeas to the cowpea rust fungus

“…In the H # O # -untreated susceptible cv., there was no obvious DAB staining (compared with material fixed for previous experiments without DAB (M. Heath, unpublished)) at the three infection sites sectioned, other than increased staining associated with fungal mitochondrial membranes ( Fig. 3 a); a similar staining seen in haustoria of the dikaryotic stage of the bean rust fungus has been attributed to cytochrome oxidase activity (Mendgen, 1975).…”

“…In contrast to regular epidermal cells, the cytoplasm of guard cells was unstained and the only detectable DAB staining was of particles in the vacuole and the outer wall region lining the stomatal opening ( Fig. 3 e); this guard cell wall staining has also been shown for bean leaves (Mendgen, 1975).…”

Studies of the powdery-mildew fungus, Leveillula taurica, on green pepper. II. Light and electron microscopic observation of the infection process

“…4, 5). Unlike rust fungi (18), infection hyphae never formed substomatal vesicles (Fig. 5) but elongated into mesophyll tissues as intercellular hyphae (Figs.…”

Micro-autoradiographic studies on host-parasite interactions

“…The Golgi bodies are assumed to secret substances into the sheath. Around the bean rust haustorium, these secretory vesicles contain peroxidase activity (Mendgen, 1975). In older haustoria, the peroxidase activity can be detected in the sheath (Mendgen and Fuchs, 1973).…”