Functional investigation of five R2R3-MYB transcription factors associated with wood development in Eucalyptus using DAP-seq-ML.

A multi-tiered transcriptional network regulates xylem differentiation and secondary cell wall (SCW) formation in plants, with evidence of both conserved and lineage-specific SCW network architecture. We aimed to elucidate the roles of selected R2R3-MYB transcription factors (TFs) linked to Eucalyptus wood formation by identifying genome-wide TF binding sites and direct target genes through an improved DAP-seq protocol combined with machine learning for target gene assignment (DAP-seq-ML). We applied this to five TFs including a well-studied SCW master regulator (EgrMYB2; homolog of AtMYB83), a repressor of lignification (EgrMYB1; homolog of AtMYB4), a TF affecting SCW thickness and vessel density (EgrMYB137; homolog of PtrMYB074) and two TFs with unclear roles in SCW regulation (EgrMYB135 and EgrMYB122).