Binucleate Rhizoctonia (Ceratorhiza spp.) induce adventitious root formation in hypocotyl cuttings of Pinus sylvestris L.

Kaparakis, George and Sen, Robin (2006) Binucleate Rhizoctonia (Ceratorhiza spp.) induce adventitious root formation in hypocotyl cuttings of Pinus sylvestris L. Scandinavian journal of forest research, 21 (6). pp. 444-449. ISSN 1400-4089

File not available for download.

Abstract

Adventitious rooting of Scots pine (Pinus sylvestris L.) hypocotyl cuttings was promoted by binucleate Rhizoctonia (BnR) and to a lesser extent by ectomycorrhizal fungi. Four BnR isolates (251, 266, 268 and 269) differentiated root meristems and significantly induced adventitious rooting in young derooted seedlings. Rooting rates were significantly higher in BnR treatments than in either indol-3-butyric acid (IBA) pretreatment (200 µm) or co-cultivation with the ectomycorrhizal fungi Suillus bovinus or Laccaria bicolor. In pre-IBA-treated cuttings, adventitious root numbers were higher in the treatments with isolates 251 and particularly 268, while more similar in other BnR treatments. In the 251, roots emerged from distal positions along the hypocotyl and not from the cut base as in the other three BnR isolate treatments. Loss of turgor and hypocotyl wilt was commonly detected up to the point of root initiation. Lateral roots and dichotomous short roots subsequently appeared at high frequency from primary adventitious roots. Mechanisms involved in root meristem differentiation, e.g. auxin production, wound response and oligosaccharide signals, are discussed with respect to host-fungal signalling mechanisms. These beneficial BnR and ectomycorrhizal fungi could provide promising new tools in the development of efficient clonal propagation methodology for this highly recalcitrant Pinus species.