Introduction of Specific Carbohydrates into Eucalyptus gunnii Cells Increases their Freezing Tolerance

Abstract

The comparison of soluble sugar content in various cell lines of Eucalyptus gunnii exhibiting different freezing resistances revealed that the most resistant cell line contained the highest soluble sugar content. It was possible to increase the freezing resistance of the sensitive cell line by progressive exposure to low temperatures (acclimation). During the early stage of cold acclimation, an increase of soluble sugar concentration was observed in the cells confirming the correlation between freezing resistance and soluble carbohydrate content in this species. In addition, feeding experiments on the sensitive cell line were performed to introduce specific sugars into the cells. Both electropulsation and long‐term incubation in the presence of fructose and raffinose led to an increase in the tolerance of the cells during a freezing programme. Using radioactive fructose, the uptake of the sugar into cells and protoplasts was checked. In the light of these results, hypotheses are presented concerning the possible role of intracellular sugars in cryoprotection.

Regulation of tocopherol biosynthesis through transcriptional control of tocopherol cyclase during cold hardening in Eucalyptus gunnii

“…Contrary to the acclimation observed at 16 C for cell suspension culture or at 12 C for plantlets, this loss of frost tolerance after a direct culture at 13 C may be associated with the additional stressful effect of chilling and freezing. These results, in accordance with our previous data (Leborgne et al 1995a(Leborgne et al , 1995b, show that cold hardening of Eucalyptus cell suspension cultures occurs only after a very specific, progressive and gentle decrease in culture temperature. The rapid chilling program, when the cell suspension culture fails to cold acclimate, is appropriate for use as a negative acclimation control in these molecular studies, and the cold acclimation program can be used to study gene expression associated with an increase in freezing tolerance.…”

“…4A). This spectacular induced-frost tolerance, known as cold acclimation, has already been described for other Eucalyptus lines (Leborgne et al 1995b, Teulières et al 1989, Travert et al 1997. These results show that this biological system is well adapted to the study of gene expression associated with this strong adaptive response.…”

Resistance to freezing in three Eucalyptus globulus Labill subspecies

“…In contrast, the cell suspension that was unable to acclimate did not accumulate soluble sugars in response to the same cold treatment. Also Leborgne et al (1995) made a comparison of soluble sugar content in various cell lines of E. gunnii exhibiting different freezing resistances revealed that the most resistant cell line contained the highest soluble sugar content.…”

Rustificação de plantas de Eucalyptus dunnii Maiden e a relação entre as concentrações de carboidratos solúveis totais e de prolina foliar e a tolerância ao frio

“…Hekneby et al (2006), em leguminosas, também observaram que a aclimatação ao frio diminuiu o TL 50 e aumentou a concentração de carboidratos solúveis totais nas folhas de todas as espécies avaliadas. Correlação negativa entre o conteúdo de carboidratos solúveis e a temperatura letal de 50% (TL 50 ) também foi obtida em E. gunnii (LEBORGNE et al, 1995). Da mesma forma, Bravo et al (1998) Nas análises de prolina, identificou-se nos tecidos das plantas concentração média de 48,5 mg g -1 MS, a qual não foi influenciada pelo período de aclimatação (dados não apresentados).…”