design: Immediately after soil removal, seedling roots were cut off from the rest of the plant, placed in homemade foil packets and flash frozen in liquid nitrogen.  They were then stored at -80 degrees C until shipped in a liquid nitrogen dry shipping container to the Marden Lab at Penn State where they were transferred without thawing to a -80 freezer for storage.  In the Marden Lab, Roots were never allowed to thaw as they were ground under liquid nitrogen to a powder in a porcelain mortar and pestle.  The powder was transferred under liquid nitrogen to a sterile plastic tube and then without thawing to a -80 freezer for storage.  An aliquot of about 100 mg of powder from each individual seedling root was used for isolated total RNA (mean RIN numbers 7.5 - 8.4) via a CTAB protocol (details available from H. W. Fescemyer on request).  Pools of RNA were prepared using equal amounts of total RNA from each of 5 individual seedling roots within each combination of parent (mother) tree (N = 5) and seedling treatment (N = 3) to yield 15 pools per species submitted for sequencing.  For each tree species, the Penn State Genomics Core Facility prepared 15 bar coded libraries using the TruSeq Stranded mRNA Sample Preparation Kit and combined equimolar quantities for one lane of 2 x 150 bp paired-end sequencing on Penn States Illumina HiSeq 2500 or NextSeq 550 (high capacity flow cell).