Abstract
Eucalyptus species constitute the most widely planted hardwood trees in the temperate and subtropical region in the world and are used as raw materials for production of cellulose. Eucalyptus globulus is one of the most profitable trees for pulp and paper industries due to its fast growth and short harvesting cycle. However, E. globulus is well known as a woody plant which is hard to vegetative-propagate. We have so far established micropropagation method using high level of CO2 (1000 ppm) for rooting. In this study, we investigated the effect of GSSG on adventitious root formation in E. globulus. Compared to the ambient level of CO2, a high CO2 level increased adventitious root formation by 20-50%. A high CO2 level increased the expression level of rbcS. Feeding of the auxin transport inhibitor N-naphthylphtalamic acid reduced the rooting percentage, indicating that auxin transport is important. Regardless of CO2 levels, GSSG feeding increased the rooting percentage in E. globulus. GSSG feeding upregulated the GUS activity in Arabidopsis with DR5-GUS (7 days after germination), showing an importance of auxin in GSSG-dependent promotion of rooting.
