Mycorrhizal status of several Quercus species in Romania (Quercus cerris, Q. frainetto, Q. robur) and the optimization perspective of growth conditions for in vitro propagated plants transplanted in the field

There is an increasing interest for important tree species conservation in the context of climate change, anthropogenic pressure and invasion of alien tree species. A key factor in the survival of trees is represented by the mycorrhizal association. The success of micropropagated trees also depends on the acquisition of mycorrhizal mutualists. Ectomycorrhizal roots samples from several Quercus species (Q. cerris, Q. frainetto, Q. robur) were examined for mycorrhizal morphotypes’ characterization. The samples were collected during the vegetation season from stands located in Southern and North-Western Romania. 30 morphotypes of active mycorrhizaewere identified with Cenococcum geophilum Fr. (Ascomycota) asdominating morphotype. Previous studies on somatic embryogenesis inQ. robur and Q. frainetto demonstrated the utility of in vitro techniques in obtaining plants from these recalcitrant seed producing species, considered at risk in various areas of the country, due to increasingly stressful conditions. The success rate of the acclimatization process depends on the mycorrhization performed either artificially, in the laboratory, either naturally, in the field. Ex situ mycorrhization solutions are considered as less costly, yet efficient alternative to improve the ex vitro survival ofmicropropagated plants or endangered tree species or for those with economic importance, in vitro propagation is an important conservation tool combined with the acquisition of appropriate mycorrhizal mutualists.