Fecha de publicación: -- Fuente: PubMed "plant biotechnology" Int J Biol Macromol. 2026 Nov 9:155007. doi: 10.1016/j.ijbiomac.2026.155007. Online ahead of print.ABSTRACTIn Populus, xylem development is organized by a four-layer NAC-MYB regulatory network. The NAC transcription factor (TF) family plays pivotal roles in secondary cell wall formation, yet the function of NAP homologs in woody plant xylem development remains unknown. Here, we showed that PtoNAC086, a third-layer member of this network and the poplar ortholog of AtNAP (NAC-LIKE, ACTIVATED BY AP3/PI; AT1G69490.1), acted as a transcriptional activator that promoted xylem development in Populus 741. Overexpression of PtoNAC086 significantly increased xylem thickness, cambial cell layers, vessel number, and lignin deposition. Integrating RNA-seq and DNA affinity purification sequencing (DAP-seq) analyses, we identified its direct target genes and validated that PtoNAC086 directly bound to and activated the promoters of two key xylan biosynthetic genes, PtoIRX10 (IRREGULAR XYLEM 10) (involved in xylan backbone elongation) and PtoGATL1 (GALACTURONOSYLTRANSFERASE-LIKE 1) (required for reducing-end tetrasaccharide synthesis), as well as the senescence-associated genes PtoERF017 (ETHYLENE-RESPONSIVE TRANSCRIPTION FACTOR 017) and PtoSAG113 (Senescence-Related Gene 113). By contrast, PtoNAC90, another third-layer NAC factor we previously characterized, promoted wood formation by activating a distinct set of genes. Together, these two third-layer TFs positively regulated xylem development through complementary downstream targets, highlighting the functional diversification of NAC family members in vascular development. Our findings uncovered a novel function of a NAP family TF in promoting secondary vascular development, expanding the regulatory repertoire of NAP homologs beyond leaf senescence in woody perennials.PMID:43003209 | DOI:10.1016/j.ijbiomac.2026.155007