Accumulation of iron-binding compounds in root of Pinus sylvestris challenged by Heterobasidion annosum sensu lato

We examined the interaction between the roots of Pinus sylvestris and closely related species Heterobasidion annousum s.l. (H. annosum s.s., H. parviporum, H. abietinum) that differ in host plant preference. The aim of the current study was to determine in roots the accumulation pattern of low molecular mass compounds such as catecholate and hydroxamate derivates, oxalic acid as well as iron-reduction ability of that low molecular mass compounds, that play important roles in wood degradation and they are also involved in pathogenesis. The accumulation of catechol and hydroxamate derivates increased during the early (2–6 h) and late (24–48 h) stages of interaction and similar pattern of oxalic acid accumulation were observed. The level of catecholate derivates in P. sylvestris roots that were challenged with H. parviporum or H. abietinum correlated strongly with iron reducing ability. However, when host was exposed to H. annosum s. s. hydroxamates rather than catecholates regulated iron reducing ability. The extracellular Fe3+ reducing activity was greater for H. annosum s. s. isolates than for isolates of two other species, and reduction of ferric iron may promote oxidative burst in host cell and fungal colonization. Catecholate concentration in the presence of H. annosum s.s. contributing to host cell death, confirm iron involvement in infection success.