Figure 6.

A, Comparison of cold tolerance-related genes in the early and late hybrid poplar clones after SD treatment. Expression patterns of cold tolerance-related transcripts whose levels changed significantly in the early and late clones (Supplemental Table S4) were clustered using the K-means method. The nonlinear x axis represents the duration of the SD treatment in days, and the y axis represents relative transcript levels expressed as a ratio (log₁₀ scale). The number of transcripts and mean expression profile are shown for each cluster. B, Expression patterns of DREB and DRTY in the early and late clones. The x axis represents the duration of the SD treatment in days, and the y axis represents relative transcript levels expressed as a ratio (log₂ scale).