Plants have the capacity to form adventitious roots (ARs) from detached aerial organs, a process known as de novo root regeneration (DNRR). In Arabidopsis, wounding signals rapidly induce in leaf explants the expression of genes encoding enzymes of auxin biosynthesis, resulting in elevated
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Plants have the capacity to form adventitious roots (ARs) from detached aerial organs, a process known as de novo root regeneration (DNRR). In Arabidopsis, wounding signals rapidly induce in leaf explants the expression of genes encoding enzymes of auxin biosynthesis, resulting in elevated auxin levels and facilitating AR formation. Here, we report that DEVELOPMENT-RELATED POLYCOMB TARGET IN THE APEX 4 (DPA4/NGAL3), a well-known regulator in seed size and leaf margin development, and a repressor of
CUP-SHAPED COTYLEDON 2 (
CUC2), inhibits AR formation in detached leaves. Leaf explants of
dpa4-2 and
cuc2-1D mutants displayed both elevated
CUC2 mRNA levels and increased rooting rates. We observed reduced expression of
ULTRAPETALA1 (
ULT1), a negative regulator of DNRR, while the auxin biosynthesis genes
ASA1,
YUC4, and
YUC9 were upregulated in both mutants. Through pharmacological inhibition of YUCCA-mediated auxin biogenesis, we obtained evidence that the enhanced AR formation in both mutants is at least partially a result of increased auxin production. Genetic analysis of
dpa4-2 cuc2-1D double mutants indicates that similar mechanisms promote DNRR in both mutants. In summary, our study suggests that
DPA4 suppresses AR formation likely by repression of
CUC2 and activation of
ULT1, which, in turn, suppresses endogenous auxin biogenesis and DNRR.
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