| Species / dataset | Gene | Locus / identifier | Predominant expression pattern | Inferred functional association |
|---|---|---|---|---|
| *Populus trichocarpa* | PtrPAL1 | Potri.006G126800 | More broadly expressed; grouped with PtrPAL3 rather than xylem-enriched clade (pqac-00000003, pqac-00000000) | Predominantly associated with condensed tannins, flavonoids, and other phenolic metabolites rather than lignin (pqac-00000000) |
| *Populus trichocarpa* | PtrPAL2 | Potri.008G038200 | Mainly expressed in xylem and root tips; group A (pqac-00000003, pqac-00000000) | Predominantly associated with lignin production / monolignol flux (pqac-00000000) |
| *Populus trichocarpa* | PtrPAL3 | Potri.016G091100 | More broadly expressed; grouped with PtrPAL1 (pqac-00000003, pqac-00000000) | Predominantly associated with condensed tannins, flavonoids, and other phenolic metabolites (pqac-00000000) |
| *Populus trichocarpa* | PtrPAL4 | Potri.010G224100 | Mainly expressed in xylem and root tips; group A (pqac-00000003, pqac-00000000) | Predominantly associated with lignin production / monolignol flux (pqac-00000000) |
| *Populus trichocarpa* | PtrPAL5 | Potri.010G224200 | Mainly expressed in xylem and root tips; group A (pqac-00000003, pqac-00000000) | Predominantly associated with lignin production / monolignol flux (pqac-00000000) |
| *Populus* (quaking aspen) | PtPAL1 | cDNA-defined isoform; no Potri locus given in cited study | Expressed in CT-accumulating, non-lignifying cells of stems, leaves, and roots; strong in palisade/epidermal/hypodermal/cortical/root epidermis-exodermis domains (pqac-00000002, pqac-00000006, pqac-00000010) | Associated with condensed tannin sink strength and non-lignin phenylpropanoid metabolism; co-expression pattern parallels 4CL2 (pqac-00000002, pqac-00000006) |
| *Populus* (quaking aspen) | PtPAL2 | cDNA-defined isoform; no Potri locus given in cited study | Associated with heavily lignified structural shoot cells, xylem vessels/fibers, and root tips; localized to lignifying xylem domains (pqac-00000002, pqac-00000006, pqac-00000010) | Associated with lignifying tissues / structural phenylpropanoid metabolism; expression pattern parallels 4CL1 (pqac-00000002, pqac-00000006) |


*Table: This table summarizes the five *Populus trichocarpa* PAL family members with Potri locus IDs and their inferred partitioning between lignin-associated versus condensed tannin/flavonoid-associated functions, based on de Jong et al. 2015. It also adds the classic quaking aspen PtPAL1/PtPAL2 cell-type specialization from Kao et al. 2002 to help interpret likely functional differentiation within poplar PAL genes.*