Two EguCBF1 genes overexpressed in Eucalyptus display a different impact on stress tolerance and plant development

Abstract

SummaryTwo C-repeat binding factor genes (EguCBF1a ⁄ b), isolated from E. gunnii and differentially cold-regulated, were constitutively overexpressed in a cold-sensitive Eucalyptus hybrid. In addition to the expected improvement on freezing tolerance, some resulting transgenic lines (EguCBF1a-OE and EguCBF1b-OE) exhibited a decrease in stomata density and an over-accumulation of anthocyanins also observed to a lesser extent in a cold-acclimated control plant. Given that the induction of five putative CBF target genes was observed in CBF-overexpressing lines as well as in the coldacclimated control line, these phenotypes might be related to cold acclimation. In comparison with the control plant, the most altered transgenic line (EguCBF1a-OE A1 line), exhibited reduced growth and better water retention capacity. This modified phenotype includes reduced leaf area and thickness associated with a decrease in cell size, as well as a higher oil gland density and a wax deposition on the cuticle. Surprisingly, the EguCBF1b-OE B9 line, with a level of transgene expression equivalent to the A1 line, showed a less marked phenotype, suggesting a difference in transactivation efficiency between EguCBF1A and B factors. The features of these transgenic lines provide the first signs of adaptive mechanisms controlled by CBF transcription factors in an evergreen broad-leaved tree. These data also open new prospects towards genetic improvement on Eucalyptus for freezing tolerance.

An S-Domain Receptor-Like Kinase, OsSIK2, Confers Abiotic Stress Tolerance and Delays Dark-Induced Leaf Senescence in Rice

“…8B). It has been well documented that DREBs strongly enhance abiotic stress tolerance and cause dwarfism (Liu et al, 1998;Hsieh et al, 2002;Gilmour et al, 2004;Kasuga et al, 2004;Navarro et al, 2011). At present, field-grown OsSIK2-t plants exhibit a severe dwarf phenotype but strong salt tolerance compared with OsSIK2-f plants (Figs.…”

Progress on genetic modifications of pulp wood tree species relevance to India - A review

“…Shao et al, (2002) developed transgenic E. urophylla events showing an increased resistance by 35% against the bacterial wilt disease caused by the pathogen, Pseudomonas solanacearum. Navarro et al (2010) reported that two cold induced transcription factors that specifically bind to C binding factor genes namely EguCBF1a/b were isolated from E. gunni and constitutively over-expressed in a cold sensitive eucalyptus hybrids. The transgenic trees showed improved freeze tolerance and opened new avenues for freeze tolerant research in eucalyptus.…”

Chemical Defenses in Eucalyptus Species: A Sustainable Strategy Based on Antique Knowledge to Diminish Agrochemical Dependency

“…The ability to successfully grow under different kinds of abiotic stress represents an important trait in eucalypts plantations. Transgenic lines in several eucalypt species with tolerance to salinity, low temperatures and drought were obtained by YamadaWatanabe et al (2003) and Navarro et al (2011).…”