Oligo-carrageenan (OC) kappa increases net photosynthesis, and basal and secondary metabolism enzyme activities in Eucalyptus globulus trees. Here, trees were sprayed on leaves with water (control) or with OC kappa 1 mg ml-1, once a week, four times in total, and cultivated for 17 additional weeks (21 weeks in total). Height, level of glucose, trehalose, TOR phosphorylated in Ser2448 (TOR-P) and transcripts encoding TOR and S6 kinase (S6K) as well as the level of transcripts encoding proteins and enzymes involved in glucose accumulation, photosynthesis, C, N and S assimilation, and synthesis of phenylpropanoid compounds (PPCs) and terpenes were determined. Treated trees showed an increase in height of 105% compared to controls at week 21. Treated trees showed an increase in glucose and trehalose level having an oscillatory pattern with maximal levels for glucose at week 1, 9-11 and 17-19, and for trehalose at weeks 1-3, 5, 8-9, 12, 15-16 and 18-21. TOR-P showed increases from week 1 until the end of the experiment with peaks at weeks 2, 6, 12 and 16. The level of tor transcripts showed peaks at weeks 3, 6, 10-11 and 13 whereas the level of s6k transcripts remained unchanged. In addition, transcripts encoding proteins involved in photosynthesis, and enzymes involved in glucose accumulation, C, N and S assimilation, and synthesis of secondary metabolites showed an oscillatory pattern with increases mainly at weeks 3-4, 5-6, 10-11, and in some cases at weeks 13-14 and 16-18. Thus, the increases in trehalose levels better correlate with increases in TOR-P and transcript levels. Therefore, OC kappa induced an increase in the levels of glucose, trehalose, TOR-P and expression of genes involved in photosynthesis, and basal and secondary metabolism which may explain, at least in part, the increase in growth and defense responses in E. globulus trees.
CHEMICAL DEFENSE RESPONSES IN Eucalyptus globulus (Labill) PLANTS
