Phytochrome-interacting factors(PIFs)have been established as negative regulators of vascular patterning and xylem differentiation in the herbaceous plant Arabidopsis thaliana,however,the regulatory role of PIFs in se...Phytochrome-interacting factors(PIFs)have been established as negative regulators of vascular patterning and xylem differentiation in the herbaceous plant Arabidopsis thaliana,however,the regulatory role of PIFs in secondary growth in woody species remains unclear.Here,we examines the expression patterns and involvement of PtoPIF3.1 and PtoPIF3.2 during stem growth and secondary xylem development in Populus tomentosa.Overexpression of either PtoPIF3.1 or PtoPIF3.2 significantly enhances both longitudinal stem growth and radial wood development.Conversely,Ptopif3.1 and Ptopif3.2 mutants generated by CRISPR-mediated genome editing exhibit reciprocal phenotypic defects.Exogenous auxin application partially restores the phenotypes of Ptopif3.1 and Ptopif3.2 mutants,and the auxin biosynthesis-deficient mutant Ptoyuc8 exhibits developmental abnormalities similar to those observed in Ptopif3 mutants.Further analysis reveal that PtoPIF3s directly bind to and activate expression of PtoYUC8 and cell expansion-related genes PtoEXPA1.1/1.2,while modulating cambial division and expression of secondary xylem development marker genes(PtoWOX4,PtoANT,PtoCYCD3s,and PtoHB7/8)through auxin-mediated signaling.Together,our findings establish PtoPIF3.1/3.2 as key regulators that coordinate stem elongation and secondary growth in Populus,highlighting the functional divergence of PIF homologs between herbaceous and woody species.展开更多
基金upported by grants from the National Key Research and Development Program of China(2022YFD1201600)the National Natural Science Foundation of China(32371903).
文摘Phytochrome-interacting factors(PIFs)have been established as negative regulators of vascular patterning and xylem differentiation in the herbaceous plant Arabidopsis thaliana,however,the regulatory role of PIFs in secondary growth in woody species remains unclear.Here,we examines the expression patterns and involvement of PtoPIF3.1 and PtoPIF3.2 during stem growth and secondary xylem development in Populus tomentosa.Overexpression of either PtoPIF3.1 or PtoPIF3.2 significantly enhances both longitudinal stem growth and radial wood development.Conversely,Ptopif3.1 and Ptopif3.2 mutants generated by CRISPR-mediated genome editing exhibit reciprocal phenotypic defects.Exogenous auxin application partially restores the phenotypes of Ptopif3.1 and Ptopif3.2 mutants,and the auxin biosynthesis-deficient mutant Ptoyuc8 exhibits developmental abnormalities similar to those observed in Ptopif3 mutants.Further analysis reveal that PtoPIF3s directly bind to and activate expression of PtoYUC8 and cell expansion-related genes PtoEXPA1.1/1.2,while modulating cambial division and expression of secondary xylem development marker genes(PtoWOX4,PtoANT,PtoCYCD3s,and PtoHB7/8)through auxin-mediated signaling.Together,our findings establish PtoPIF3.1/3.2 as key regulators that coordinate stem elongation and secondary growth in Populus,highlighting the functional divergence of PIF homologs between herbaceous and woody species.
