Báo cáo lâm nghiệp: Amplification of root—fungus interface in ectomycorrhizae by Hartig net architecture

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Amplification of root—fungus interface in ectomycorrhizae by Hartig net architecture...
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Báo cáo lâm nghiệp: "Amplification of root—fungus interface in ectomycorrhizae by Hartig net architecture"Amplification of root—fungus interfacein ectomycorrhizae by Hartig net architectureI. Kottke F. Oberwinkler FR.GUniversität Institut für Botanik, Spezielle Botanik und Mykologie, Tübingen, Tübingen, hyphae become dilated but remain inIntroduction close contact with the surface of the cortical cells. These characteristics can beIn previous investigations, it was found found when the Hartig net is in an activethat the Hartig net is formed quite similarly state. The bidirectional active exchange ofin ectomycorrhizae of different fungal spe- solutes between fungus and root iscies with diverse trees, despite charac- underlined by the results obtained fromteristic differences in mantle structure cytochemical proof of ATPase activities at(Mangin, 1910; Blasius et al., 1986; Kottke this stage (Lei and Dexheimer, 1988). Inand Oberwinkler, 1986; Haug, 1987). The ageing mycorrhizae, cortical cells are thequestion arose whether there was any first to die and their active uptake offunctional benefit for the development of solutes is no longer possible. At thisthe observed Hartig net architecture stage, hyphae of the Hartig net canimposing evolutionary pressure to equa-lize the development in different mycor-rhizal types. Transmission electron microscopystudies revealed that the scarce septationand the intimate juxtaposition of thehyphae result in a transfer cell-like struc-ture of the Hartig net, amplifying the inter-symbiont surface (Fig. 1; Kottke andOberwinkler, 1987). Hyphae do not pene-trate separately but as a lobed frontbetween the cortical cells. The tips of thefan-like branched hyphal system arecharacterized by a large number of mito-chondria and high amounts of roughendoplasmic reticulum. Cytoplasm in thisregion contains many ribosomes andlacks large vacuoles. The hind parts of the Materials and Methods Models were delineated from micrographs of the Hartig net and from possible alternatives in growth of hyphae (Fig. 3). Area, perimeter and length of hyphal walls of the models were mea- sured with Mop-Videoplan, an analytic system (Zeiss-Kontron), using standard software. The surface/volume ratios of the different systems were calculated on the basis of an average 3 pm diameter of hyhae. Results Three different models of hyphal growth in the intercellular spaces have been de- signed (Fig. 3a, b, c) and the surface/ volume ratio of hyphae calculated. The first model is delineated from the real be found from eachfrequently separated occurring Hartig net structure, the secondother. from presumed broadly dilated hyphae Hyphal growth of an active Hartig net is and the third from presumed separatelytotally different from hyphal growth on growing hyphae. Measurements fromsolid surfaces, e.g., agar media. Hyphal these models of area and perimeter ofgrowth on agar media shows apical hyphal complex and length of hyphal wallsdominance of the parent hyphae, regular, are presented in Table I.but not too frequent branching in cor- The results show that the surface/relation to se ...