| Popis: |
If Albert Einstein had investigated ectomycorrhizal symbiosis, he might well have devised a formula for same to read as follows: E = mc2, where the efficiency (E) of the symbiosis is somehow related to the mass (m) of mycelium colonizing the cortex (c) of the plant root. Granted such a formula is far too empirical to be taken seriously, but nonetheless it does summarily describe what is an essential feature of ectomycorrhizal symbiosis — the Hartig net, an intercellular and tissue-specific mutualism between assimilative and nonaggressive fungal cells (mycobiont) and cortical parenchyma cells of the primary root (phytobiont). The extent of mutualistic interdependence between such specialized soil fungi and plant root systems, while of overall benefit to both partners, limits considerably the ability to study mycorrhizal fungi as experimental or genetic systems. The genetic basis for such mutualism has thus eluded investigation. This is true in large part because the fungal component(s) or mycobionts of ectomycorrhizas have resisted detailed or molecular genetic study. The development of DNA-mediated transformation systems for ectomycorrhizal fungi (Barrett et al. 1990; Marmeisse et al. 1992b) provides much opportunity for investigations into the genetic basis for mutualistic association between mycobiont and phytobiont. Transformation procedures may also prove useful to improve the symbiosis, provided genes important to the formation and function of ectomycorrhizas can be identified. |
