(a) Transcript levels of Fm4CL genes in different tissues of Fraxinus mandshurica. Tissue expression analysis of 12 Fm4CL genes in the leaf, xylem, bark, flower, bud, petiole, seed, and stem of the Fraxinus mandshurica plant. Red indicates high gene expression, green indicates low gene expression, and yellow indicates moderate gene expression. (b) qRT-PCR values of Fm4CLs/4CL-like genes in Fraxinus mandshurica tension wood. Fm4CL2, Fm4CL-like-1, Fm4CL5, Fm4CL6, Fm4CL11, and Fm4CL12 are expressed in the Fraxinus mandshurica plant. CK, TW, and OW indicate untreated as a control, tension wood, and corresponding wood, respectively.