Báo cáo lâm nghiệp: Interactions between root symbionts, root pathogens and actinorhizal plants

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Interactions between root symbionts, root pathogens and actinorhizal plants...
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Báo cáo lâm nghiệp: "Interactions between root symbionts, root pathogens and actinorhizal plants"Interactions between root symbionts,root pathogens and actinorhizal plants Akkermans, D. Hahn ; F. ZoonA.Department of Microbiology, Wageningen Agricutural University, Wageningen, The Netherlands tion of plants with Frankia is dependentIntroduction upon the environmental conditions, in- cluding the interaction with other soil microorganisms (van Dijk, 1984; Houwers and Akkermans, 1981; Maas et al., 1983;Actinorhizal trees with acti- nitrogen-fixing Oremus, 1980, Oremus and Otten, 1981 ).nomycetes (Frankia sp.) microsym- as These results indicate that plant growth isbionts in root nodules play an important often limited by factors other than N fixa- 2ecological role as pioneer plants on nitro- tion.gen-poor soils. Up to 200 perennial spe-cies, alltrees and shrubs, distributed over Each soil ecosystem comprises a largeabout 20 genera, have been found to be number of different types of organismsnodulated with Frankia as the nodule sym- with a complex network of interactions.biont. Some of those, e.g., Alnus spp. in Tree growth is therefore affected by inter-temperate regions and Casuarina spp. in action with many different types of organ-subtropical and tropical regions, have isms. In soil, the roots are in close contactgreat potentials for biomass production with pathogenic fungi, nematodes andand erosion control (Silvester, 1977). The insects, but also with symbiotic organ-growth of such plants is largely dependent isms, such as mycorrhizal fungi, rhizo-upon the presence of proper Frankia bacteria and nodule-forming Frankia.strains in the soil. Although Frankia has Although the importance of such interac-been found in many types of soil, particu- tions is generally recognized in forestry,larly in soils where its host plants have little attention has been paid to their effectbeen grown previously (Fraga-Beddiar, on nitrogen-fixing actinorhizal plants. In1987; Houwers and Akkermans, 1981; the present paper, we will give an over-Rodriguez-Barrueco, 1968), inoculation of view of the interactions between root sym-the plants with selected Frankia strains bionts, pathogens and actinorhizal plants,can give a positive response with respect with special attention to Alnus and Hippo-to plant yield. Pot and field experimentshave indicated that the effect of inocula- phae spp. tion to this host-induced ineffectivity, Fran-Root symbionts kia strains which lack nitrogenase have been found in soil (van Dijk and Sluimer-Frankia Stolk, 1984) and pure cultures of these ineffective strains have been described (Hahn et aL, 1988; Hahn et aL, 1989). plants bear several types ofActinorhizal their roots. So far, mostsymbionts on After initial invasion of the cortical cells,attention has been paid to microorganisms Frankia readily develops into an endosym- nitrogen-fixing root noduleswhich induce ...