Plasticity of vulnerability to leaf hydraulic dysfunction during acclimation to drought in grapevines: An osmotic-mediated process

11 páginas.-- 5 figuras.-- 3 tablas.-- 68 referencias© 2014 Scandinavian Plant Physiology Society. Previous studies have reported correlation of leaf hydraulic vulnerability with pressure-volume parameters related to cell turgor. This link has been explained on the basis of the effects of turgor on connectivity among cells and tissue structural integrity, which affect leaf water transport. In this study, we tested the hypothesis that osmotic adjustment to water stress would shift the leaf vulnerability curve toward more negative water potential (Ψleaf) by increasing turgor at low Ψleaf. We measured leaf hydraulic conductance (Kleaf), Kleaf vulnerability [50 and 80% loss of Kleaf (P50 and P80); |Ψleaf| at 50 and 80% loss of Kleaf, respectively), bulk leaf water relations, leaf gas exchange and sap flow in two Vitis vinifera cultivars (Tempranillo and Grenache), under two water treatments. We found that P50, P80 and maximum Kleaf decreased seasonally by more than 20% in both cultivars and watering treatments. However, Kleaf at -2MPa increased threefold, while osmotic potential at full turgor and turgor loss point decreased. Our results indicate that leaf resistance to hydraulic dysfunction is seasonally plastic, and this plasticity may be mediated by osmotic adjustment.Spanish Ministry of Science and innovation. Grant Numbers: AGL2008-04525-C02-01, AGL2009-11310/AGR, AGL2011-30408-C04-01, BES-2009-016906Peer Reviewe