Figure 2. Enrichment of gene GO terms in (a) different tissues and (b) different year-old roots relative to control (whole plant).

The number of gene GO terms categorized into each functional subcategories is present in the percentage of GO terms for that subcategory out of the total GO terms that the unigenes assigned to for whole plant (14 tissues) or each tissue, or different year-old roots (z-axis). The enrichments of the unigenes categorized into each subcategory of different tissues or different year-old roots were estimated by χ² test using the percentage of the unigenes in the subcategory in the whole plant as the expected. *, a significance level of P ≤ 0.05 (FDR ≤ 0.063 for different tissues and FDR ≤ 0.053 for different year old roots); **, a significance level of P ≤ 0.01 (FDR ≤ 0.013 for different tissues and FDR ≤ 0.011 for different year old roots).