MONOPTEROS (MP) mutation results in:
MONOPTEROS encodes ARF5 auxin response factor activated when high auxin promotes TIR1/AFB-mediated ubiquitination and degradation of BODENLOS/IAA12 repressor in nucleus. Liberated MP directly induces transcription of PIN1, TMO5, ATHB8, and other vascular precursor genes in basal embryo and provascular strands. In monopteros null mutants hypophysis specification fails, basal lineage divides irregularly, seedlings germinate lacking embryonic root and hypocotyl while retaining cotyledons and functional shoot meristem. This reveals essential role of ARF-mediated transcriptional activation downstre
Ref: Aida et al., Cell 2004; Taiz Plant Physiology, Chap 19: MONOPTEROS/ARF5 regulates hypophysis and root-hypocotyl formation via auxin.
