Romania (Quercus cerris, Q. frainetto, Q. robur) and - EdituraSilvica.ro

Fodor et al. Mycorrhizal status of several <strong>Quercus</strong> species in <strong>Romania</strong> ...in seedling mycorrhizae as well as in maturetrees’ roots (Piggott 1982, Kranabetter &Wylie 1998) associating with 122 host species(Trappe 1964). The outer layer of the mantleconsists of thick walled cells, resembling thegelatinous walls of many lichenicolous fungi.When wet, these walls become gelatinous,providing an environment for water storage,which is of capital importance during thedrought episodes. This pecularity gives an advantageto seedlings possessing C. geophilummycorrhiza (Piggot 1982). Being ubiquitous bynature, C. geophilum links plants in a commonmycorrhizal network (Valentine at al. 2004). Itis an early stage <strong>and</strong> also a late stage associatein seral succession of the forests. Late stagefungi, such as Lactarius spp. <strong>and</strong> Russula spp.are infrequent on roots <strong>and</strong> the inoculationproduces via root connections, rather than bymycelial fragments or spores as in early stagemycorrhiza (Jones et al. 1998).The association of different morphotypes ismore or less r<strong>and</strong>om, with respect to closelyrelated hosts in the same location <strong>and</strong> showrelatively high similarity between locationsrelated to the same host species. Still the nullhypothesis of r<strong>and</strong>om association is to be carefullyveried on larger sets of data. The generaltrend is a variation of morphotypes, accordingto geographical factors (Southern versusNorth-Western <strong>Romania</strong>) <strong>and</strong> also to relatedhosts allocation (<strong>Quercus</strong> spp.). There is anevidence of within site partition of the samemorphotypes among <strong>Quercus</strong> hosts <strong>and</strong> similarityof sites from same geographical area. Itis worth to mention the dissimilarity in morphotypeallocation in Q. <strong>robur</strong> as compared toQ. <strong>cerris</strong> <strong>and</strong> Q. <strong>frainetto</strong>.Stressful conditions affect trees in urban areas,a fact reected in their mycorrhizal status,<strong>and</strong> in lower frequency of mycorrhizal apices.Also, carpophore production is a seldom eventin urban areas (Danielson & Pruden 1989, Baxteret al. 1999) never observed in present survey(from 1997 to 2008) in the city of Oradea.Drought <strong>and</strong> oil pollution reported from Tincainuenced the mycorrhizal status of Q. <strong>cerris</strong><strong>and</strong> Q. <strong>frainetto</strong>, reected in low frequenciesof mycorrhizal apices.Modern investigations on the diversity ofmycorrhiza, associated with a particular treehost, rely on DNA nger-printing. This diversityassessment takes into account all potentialmycobionts associated with a tree <strong>and</strong> notthose active at a particular moment. For activemycorrhiza at a time snapshot, the classical assessmentbased on morphotypes is a better approachon our opinion based on the presentedresults.These results lead to the idea that articialinoculation with site-adapted mycobiontswould enhance plant growth <strong>and</strong> survival afteroutplanting, an opinion shared with otherauthors (e.g. Gerhardt et al. 2007). The mycorrhizationis induced either under laboratoryconditions on dual host-fungus systems, eitherduring the seedlings growth by inoculation ofthe fungal inoculum in nursery containers, theinoculum being represented by spores, myceliaor simply, fragments of appropriate carpophores(Martinez-Amores et al. 1991). The micropropagatedplantlets of <strong>Quercus</strong> species canbe exposed to mycobionts in order to inducemycorrhization. In our opinion, a good c<strong>and</strong>idateis Cenococcum geophilum, due to its largeecological <strong>and</strong> host range, <strong>and</strong> the capacity toinduce frequent mycorrhizal tips, a hypothesisworth to test under experimental conditions.As a consequence, it is a good c<strong>and</strong>idate formycorrhization in dual systems (oak microcuttingsor micropropagated plants + mycobiont)in Petri dishes, a similar approach being proposedby Herrmann et al. (1998).ConclusionThe investigation of mycorrhizae using theclassical approach of morphotype descriptionyielded 30 types common for <strong>Quercus</strong> <strong>robur</strong>,Q. <strong>cerris</strong>, Q. <strong>frainetto</strong>. The original descriptionsof the morphotypes provide a recognition69