Physiological and biochemical responses to low non-freezing temperature of two Eucalyptus globulus clones differing in drought resistance

Abstract

-We have compared the metabolic responses of leaves and roots of two Eucalyptus globulus L. clones CN5 and ST51 that differ in their sensitivity to water deficits (ST51 is more drought sensitive), with regard to the effect of chilling (10/5 • C, day/night). We studied changes in growth, osmotic potential and osmotically active compounds, soluble proteins, leaf pigments, and membrane lipid composition. Our data showed that both clones have the ability to acclimatize to chilling temperatures. As a result of 10 days of acclimation, an increase of soluble sugars in leaves of treated plants of both clones was observed that disappeared later on. Differences between clones were observed in the photosynthetic pigments and soluble protein content which were more stable in CN5 under chilling. It also was apparent that CN5 presented a less negative predawn water potential (ψ pd ) and a higher leaf turgor than ST51 throughout the chilling treatment. In the case of the CN5, increased total lipids (TFA) and concomitant increase of linolenic acid (C18:3) in leaves after acclimatization may be related to a better clone performance under chilling temperatures. Moreover, a higher constitutive investment in roots in the case of CN5 as compared to ST51 may benefit new root regeneration under low temperatures favoring growth after cold Mediterranean winter.carbohydrates / chilling / Eucalyptus globulus L. / lipids / membranes Résumé -Réponses physiologiques et biochimiques à des températures froides positives de deux clones d'Eucalyptus globulus qui diffèrent à travers leur résistance à la sécheresse. Nous avons comparé les réponses métaboliques au niveau des feuilles et racines de deux clones d'Eucalyptus globules L. CN5 et ST51 qui différent par leur sensibilité à la sécheresse (ST51 étant le plus sensible) en comparaison à l'effet de refroidissement (10 • C/5 • C, jour/nuit). Nous avons étudié les variations de croissance, de potentiel osmotique, des composés actifs osmotiquement, des protéines solubles, des pigments foliaires et de la composition de la membrane lipidique. Nos données ont montré que les deux clones ensemble ont la capacité de s'acclimater aux températures froides. À dix jours d'acclimatation, une augmentation de la teneur en sucres solubles dans les feuilles des plantes traitées des deux clones a été observée jusqu'à disparaître dans le temps. Des différences entre les clones ont été observées au niveau du contenu en pigments photosynthétiques et en protéines solubles qui d'ailleurs ont été plus stables pour le clone CN5 sous l'effet du froid. Il est aussi notable que CN5 a présenté un potentiel hydrique de base (ψ pd ) moins négatif et une turgescence foliaire plus élevée que ST51 à travers le traitement au froid. Dans le cas du clone CN5, l'augmentation concomitante des acides gras totaux (AGT) et de l'acide linolénique. (C18 :3) au niveau des feuilles après l'acclimatation peut être corrélée à une meilleure performance de ce dernier sous des températures froides. De plus, un investissement constitutif...

Variation in morpho-physiological, biochemical and molecular responses of two Eucalyptus species under short-term water stress

“…In Eucalyptus species and their hybrids, adjustments during water stress conditions are mediated by hormonal balance (Granda et al 2011), variation in pigment content (Shvaleva et al 2006(Shvaleva et al , 2008, osmotic changes (Merchant et al Tab. 2.…”

Phloem sap and leaf δ13C, carbohydrates, and amino acid concentrations in Eucalyptus globulus change systematically according to flooding and water deficit treatment

“…Major changes in the abundance of compounds transported in the phloem may arise as part of plant acclimation strategies. Regulation of osmotic potential is a common response to water limitation in leaves of Eucalyptus species via the accumulation of low molecular weight amino acids ( Shvaleva et al , 2006 ), sugars ( Shvaleva et al , 2008 ), sugar alcohols ( Merchant et al , 2006 b ), or inorganic ions ( Liu et al , 2001 ). Changes in phloem sap carbon concentration ( Cernusak et al , 2003 ), combined with the potential for changes in inorganic ions and amino acids ( Lalonde et al , 2003 ) may play a similar role in regulating osmotic potential of the phloem.…”

Effects of Combined Abiotic Stresses Related to Climate Change on Root Growth in Crops

“…Interestingly, Norway spruce plants from freezingtolerant cultivars display a larger root biomass that correlates with increase drought tolerance (Kang et al, 2003). Something similar happens in Eucaliptus globulus, where drought-tolerant cultivars that are more tolerant to freezing have also increased root biomass (Shvaleva et al, 2008). Other similar effects of both stresses are showed at the biochemical and molecular level.…”