Different drought‑adaptive capacity of a native Patagonian tree species (Nothofagus pumilio) resulting from local adaptation.

MATTERA MG; DALLA SALDA G; MARCHELLI P; SOLIANI C; AZPILICUETA M M

EUROPEAN JOURNAL OF FOREST RESEARCH

SPRINGER

Lugar: Berlin; Año: 2021

1612-4669

The resistance of diferent genotypes to abiotic stress may be due to genetic efects and/or to phenotypic plasticity allowingthem to acclimate to variable conditions. The contribution of one or the other mechanism determines diferent strategies withimplications for the species conservation and adaptive management. In this study, the ecophysiological response to droughtof Nothofagus pumilio provenance sites (humid, mesic and xeric) from contrasting precipitation regimes was evaluated in acommon garden trial. Seedlings were submitted to progressive drought by withdrawing irrigation (control vs water defcit).Assuming a genetic base determined by selection pressures, populations from more xeric sites are expected to show higherresistance to drought, e. g., higher resistance to xylem cavitation and safety margin, stronger stomatal control and osmoticadjustment. Vulnerability to cavitation curves were performed, and the percentage loss of conductivity (P12, P50, P88 andslope) was obtained. The water potential at turgor loss point (TLP) and the osmotic potential at full turgor (π100) were calculated from pressure?volume curves. The humid site showed a signifcantly higher P50 value than the mesic and the xericsites. Pre-dawn water potential difered between the provenances from xeric and mesic conditions under severe water defcit.Natural selection was inferred from the comparison of diferentiation at neutral markers and phenotypic traits (FST vs. PST),with signals of adaptive variation (PST> FST) for stomatal density, specifc leaf area, TLP, π100 and stomatal conductance.Results suggest a diferential adaptive capacity to drought of N. pumilio provenance sites that could be evidencing localadaptation to their home environment.