Unraveling the functional and adaptive role of Eucalyptus wood: what do we know and what do we still ignore.

FERNÁNDEZ M.E.; MARTÍNEZ MEIER A; BAROTTO, JA; GYENGE JE; BARIGAH T; TESÓN N; ALARCÓN P.; QUIÑONES MARTORELLO, A.; SALLESSES, L.; DALLA SALDA, G.; ROZENBERG P; MONTEOLIVA S

Orleans

Conferencia; Wood formation and tree adaptation to climate; 2018

Le Studium-INRA

A synthesisis presented about advances and gaps in knowledge in relation to the functionaland adaptive role of wood in Eucalyptusgenus. Interdisciplinary studies were focused on four Eucalyptus species differing in wood density and abiotic stressresistance. Anatomical and functional measurements showed that there is notrade-off between xylem hydraulic efficiency and safety, both within andbetween species. In relative terms, species can have mean large vessels and lowvulnerability to  cavitation (E. viminalis), mean small vessels andhigh vulnerability to cavitation (E.grandis terminal branches), together with other size-function combinations.Study of the role of different cell types regarding efficiency versus safetysuggested that the complex matrix of cells around vessels should be consideredto interpret the trade-off between anatomy and function in these solitaryvesselled species. It seems that vasicentric tracheids have a dual function: increasinghydraulic efficiency by connecting functional vessels, and hampering embolismspreading in case of cavitated ones. Some general trends were observed between averagewood density and  xylem function at theinterspecific level, but not always at the intraspecific level. Thus, the valueof wood density as a proxy of wood safety for within-species screening needsstill to be proved considering a larger range of genetic variability (i.e.provenances). In addition, no plasticity in vulnerability to cavitation hasbeen observed in plants subjected to different water regimes. The functionalrole of Eucalyptus wood is now betterunderstood than its real adaptive role. More research is needed consideringwood function and environmental conditions of provenances, as well as theimpact of density and anatomical plasticity in terms of droughtresistance.