摘要:

The parasitic phase of the uredial stage of rust fungus infection is characterized by the formation of a specialized structure—the haustorium. The haustorial neck contains a band of darkly staining wall material, the length of which is dependent on the fungal species. In older infected tissues a collar sometimes develops at the site of penetration. In such cells, the host plasmalemma appears to double back on itself between the collar and the haustorial neck. The mitochondria of the haustorium contain many plate-like cristae and, less frequently, concentric whorls of membranes. Cytoplasmic microtubules are also observed in both the neck and body of the haustorium. Centriolar plaques are found appressed to the nuclear envelopes in both the hyphae and haustoria. They frequently consist of two amorphous regions which are connected by a rod-shaped, layered structure. The septal pore of the intercellular hyphae contains a plug of electron-transparent material. Surrounding it is a matrix of dense amorphous cytoplasm devoid of organelles which is bordered by a hemispherical array of microbodies containing crystals. Axenic cultures ofMelampsora linimycelium were examined and found to contain similar septal pore regions. These cultures also show some differences from the parasitic hyphae. The septa-associated microbodies in these cells appear to derive from an aggregate of tubular endoplasmic reticulum cisternae. Their mitochondria differ from those of the intercellular hyphae in having more and longer, plate-like cristae and a denser staining matrix. They therefore represent a type intermediate between those of the intercellular hyphae and the haustoria. The pseudoparenchymatous stroma of the axenic cultures contains cells of widely divergent ages. Some are young as determined by their dense cytoplasmic contents and large lobed nuclei. However, others are older, with large vacuoles and many lipid bodies. In some cases they have thick cell walls consisting of many layers.

ISSN:0008-4026    

DOI:10.1139/b72-031

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Qualitative histochemical assays localized lipids, carbohydrates, succinate dehydrogenase, and acid phosphatase inTriticum aestivumseedlings. Starch was present in the base of the shoot apex and near vascular tissues throughout the seedlings. Succinate dehydrogenase activity was located in the apical summit, apical base, young leaf primordia, and very young axillary buds. Acid phosphatase was localized at the base of the apex, scutellum, and aleurone tissues. Thicker cell walls were noted in the epidermis of the apical dome and at the base of the apex. This combination of histochemical staining patterns suggests initiation of provascular tissue very early in leaf initiation.

ISSN:0008-4026    

DOI:10.1139/b72-032

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Boron autoradiographs of plant material may be obtained on a new commercially available "film." Samples and film are placed in a neutron source. The film records the location of boron atoms by detecting alpha particles emitted from boron after neutron capture. The film is completely insensitive to gamma rays, which usually cause undesirable darkening when this technique is used with conventional photographic film. Variation in content of boron in sunflowers grown at varying boron concentrations was easily detected. Boron tends to accumulate at the tip and along the margins of the leaf.

ISSN:0008-4026    

DOI:10.1139/b72-033

出版商:NRC Research Press    

年代:1972

数据来源: NRC