Sequence alignment of poplar phosphoproteins and their closest Arabidopsis homologs to identify unique phosphosites in poplar. Asterisk indicates phosphorylation site. Fine red boxes show phosphopeptides identified in this study. Phosphorylation sites identified from poplar in our study are shown in red bold font. Blue bold boxes show non-conserved phosphorylation sites. (a) Sequence alignment with all PBA1 orthologs. (b) Sequence alignment with all G6PD orthologs.