Fig. 3.

Quantification of soluble proteins in 1- and 2-year-old stems of poplar during autumnal senescence and winter. Protein concentration (A) was determined for duplicate sub-samples from each replicate. Values are expressed as the mean ± s.e. of three replicate experiments. For a given tissue, protein concentration values with the same letter are not significantly different, according to ANOVA at P < 0·05. Soluble proteins from 2-year-old (B) stems of poplar were separated by SDS–PAGE. The presence of two major proteins with a relative molecular mass of between 30 and 37 kDa is indicated by arrows.