1974. Studies on nuclear division in basidia of Poria Iriternrrrgirlcrto. Can. J . Bot. 52: 2323-2333.Nuclear division in basidia of Poria Irrternrrrgir~~ta was studied comparatively by light and electron microscopy. Premeiotic mitosis occurred in the lower half of the basidi~~m and was oriented parallel to the longitudinal axis of the basidium. Mitosis was not observed with the light microscope and only late anaphase figures of mitosis were seen with the electron microscope. Mitosis was intranuclear w~t h microtubules oriented between two spindle pole bodies (SPBs). The SPBs were spherical with a central core of material slightly more electron opaque than the surrounding SPB material. The nuclear envelope remained intact except at the SPBs.Divisions I and I1 of meiosis were chiastobasidial and occurred at the apices of basidia. The major features of meiosis observed by both light and electron microscopy were ( I ) karyogamy followed by the presence of one or two nucleoli in the prophase nucleus; (2) elongated chromosomes and synapsis at late zygotene-pachytene; (3) occurrence of a spindle at laetaphase-anaphase composed of chromosomal and continuous microtubules associated with the SPBs; (4) absence of a metaphase plate with chromosomes arranged randomly around a zone of continuous microtubules; (5) condensation of chromosomes and asynchronous separation at anaphase; (6) kinetochores at anaphase; (7) the nuclear envelope remaining intact throughout meiosis except for discontinuities at the SPBs; (8) membrane-bound vesicles assoclared with chromosomes during division; and (9) separation of daughter nuclei at telophase. Sta es of division I1 meiosis were observed less frequently and were similar to division I. The k u r postmeiotic nuclei then migrated back toward the central part of the basidium. Sterigmata developed at this time. Postmeiotic nuclei were surrounded by one or two envelopes of perinuclear endoplasmic reticulum before their migration into basidiospores. Electron-opaque inclusions occurred within the nuclei at this stage. -SETLIFF, E. C., H. C. HOCH et R. F. PATTON. 1974. Studies on nuclear division in basidia of Poriu laternargirrnto. Can. J . Bot. 52: 2323-2333. La division nucleaire dans les basides de Poria loietnrrrginutu a CtC CtudiCe en microscopie photonique et electronique. La mitose premeiotique a lieu dans la moitiC inferieure de la baside et est orientee parallklement B l'axe longitudinal de la baside. La mitose n'a pas kt6 observee au microscope photonique et seules des configurations mitotiques de fin d'anaphase ont Cte vues au microscope electronique. La mitose est intranucliaire et les microtubules sont orientes entre deux corps polaires du fuseau (SPB). Les SPB sont sphCriques avec une masse centrale de materiel legkrement plus opaque aux electrons que le materiel environnant. L'enveloppe nucleaire demeure intacte sauf au niveau des SPB. Les divisions I et I1 de la miiose sont chiastobasidiennes et se produisent B l'apex des basides.Les principales caracteristiques de la meiose, obse...
Since Percival's inoculation studies in 1902 with the wound pathogen Chondrostereum purpureum (Pers.�:�Fr.) Pouz. on plum trees in England, this fungus has become well known as the cause of silver-leaf disease of rosaceous fruit trees. However, its pathological impact on forest trees has been little studied and appreciated. Therefore, the question is raised about the pathogenic role and incidence of C. purpureum on other trees in damaged forests. A survey of 561 collections of this fungus in herbaria of Canada and the United States found that the highest incidence occurred in the Betulaceae (45%), especially Betula (27%) and Alnus (15%). The second-most favoured host family was the Salicaceae (20%) with a 15 and 5% occurrence on Populus and Salix, respectively. The third-most favoured substrate was apparently the Rosaceae at 11%, but this reflected a bias of agricultural research in orchards. A 6% incidence was found in the Fagaceae, 4% in the Aceraceae and 3% in the Ulmaceae. From 1 to 3% of the collections occurred for each of the Cornaceae, Juglandaceae, Magnoliaceae and Pinaceae. Incidences <1% were indicated for each of the Aquifoliaceae, Caprifoliaceae, Cupressaceae, Grossulariaceae, Hamamelidaceae, Hippocastanaceae, Myrtaceae, Oleaceae, Rhamnaceae and Tiliaceae. The host survey data indicate that C.�purpureum is an important pathogen with epidemic potential in forest trees, especially species in the Betulaceae and Salicaceae. The silvering symptom is inconspicuous in birch and other non-rosaceous trees. Forests with greatest vulnerability are those subjected (1) to physical forces that cause stem injuries to susceptible trees, (2) to environmental conditions conducive for infection and (3) to high levels of basidiospore inoculum from fruiting bodies on hardwood slash that result from timber harvesting and storm damage. Silver-leaf is an important fungal disease of many tree species in North America and is largely responsible for the birch dieback in North American forests. Control data from several mycoherbicide experiments support this conclusion.
Brassicaceae plants are nonmycorrhizal. They were found to inhibit VA mycorrhizal infection in their host plants. We tested if they can influence growth of ectomycorrhizal (ECM) fungi. When roots and leaves of Brassicaceae plants and ECM fungi were cultured together in the same petri dishes, the root exudates of turnip (Brassica rapa), swede (B. napobrassica), cabbage (B. oleracea, var. capitata), broccoli (B. oleracea, var. italica Plenck), kohlrobi (B. caulorapa Pasq.), mustard (B. juncea), radish (Raphanus sativus), and choy (B. napus) significantly stimulated hyphal growth of the ectomycorrhizal fungus Paxillus involutus. Root exudates of turnip and cabbage stimulated hyphal growth of Pisolithus tinctorius and two isolates of P. involutus. Colony area of P. involutus was increased by 452 and 414%, respectively, in the presence of turnip and cabbage germinants. Root exudates of turnip increased the biomass of P. involutus and P. tinctorius by 256 and 122% and cabbage by 220 and 82%, respectively. The stimulatory effect was not affected by autoclaving the root exudates. Root exudates had chemical reactions with glutathione and lysine, which resulted in a reduction of the growth stimulation of ECM fungi. Myrosinase enhanced further the stimulatory effects of turnip on the ECM colony diameter growth by 23%. Autoclaved roots and leaves of turnip did not stimulate fungal growth, but mechanically ground roots and leaves of turnip stimulated growth of P. involutus by 147 and 135%, respectively. After desulfuration with aryl sulphatuse, the glucosinolates (GLSs) in turnip roots and leaves were identified by HPLC. The major ones were indole GLSs. Prominent compounds identified were 1-methoxy-3-indolymethyl GLS and4-methoxy-3-indolymethyl GLS. The finding provides an opportunity to field test the use of Brassicaceae plants in enhancing ectomycorrhizal formation in conifers by interplanting conifers with Brassicaceae plants in forest tree nursery and agroforestry systems.
The septal pore apparatus was studied in Poria latemarginata, Polyporus tomentosus, and Rhizoctonia solani. Fixation by potassium permanganate was compared with fixation by glutaraldehyde – osmium tetroxide. Potassium permanganate reduced the size of the septal swelling about 50% and destroyed much of the internal integrity of the septal swelling. In glutaraldehyde – osmium tetroxide fixed material, a fibrillar network extended from the cross wall throughout the septal swelling. Except for this network, the septal swelling was electron transparent and similar in appearance to a vacuole. A rim of electronopaque material, attached to the septal swelling, surrounded the pore mouth in Polyporus tomentosus and Rhizoctonia solani.
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