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Cyclitols and carbohydrates in leaves and roots of 13 Eucalyptus species suggest contrasting physiological responses to water deficit
Author(s) -
MERCHANT ANDREW,
TAUSZ MICHAEL,
ARNDT STEFAN K.,
ADAMS MARK A.
Publication year - 2006
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2006.01577.x
Subject(s) - deserts and xeric shrublands , eucalyptus , biology , botany , sucrose , water content , acclimatization , sugar , mannitol , osmoprotectant , horticulture , ecology , biochemistry , amino acid , geotechnical engineering , habitat , engineering , proline
ABSTRACT In many tree species, physiological adaptations to drought include the accumulation of osmotically active substances and/or the presence of particular compatible solutes, among them cyclitols. Recently, the cyclitol quercitol was identified in species of Eucalyptus , a diverse genus whose speciation is probably driven by adaptation to water availability. We subjected seedlings of 13 Eucalyptus species from different ecosystems (‘mesic’ and ‘xeric’) and different sub‐generic taxonomic groups to 10 weeks of water deficit (WD) treatment. Pre‐dawn water potentials (ψ pdwn ) and relative water content (RWC) were determined in shoots, and total osmolality, soluble low‐molecular‐weight carbohydrates and cyclitols were measured in leaves and roots. Responses to water deficit followed two distinct patterns: Eucalyptus species from ‘mesic’ environments adjusted concentrations of sucrose (through increased levels of sucrose and decreases in RWC) in response to water deficit, whereas ‘xeric’ species increased concentrations of quercitol (through reductions in RWC). In root tissues, only species from xeric environments contained high levels of quercitol and mannitol, increasing under WD conditions. We suggest that the former (mesic) strategy may be beneficial to respond to short‐lasting drought conditions, because sucrose is easily metabolized, whereas the latter (xeric) strategy may relate to an effective acclimation to longer‐lasting drought. These physiological response groups are also related to taxonomic groups within the genus.