A DELLA-ANAC106 reciprocal negative feedback circuit modulates gibberellin homeostasis to regulate male fertility in Arabidopsis.

While gibberellin (GA) homeostasis is critical for male fertility, the molecular mechanisms governing GA metabolic balance during pollen development remain poorly characterized. This study uncovers a regulatory network maintaining GA equilibrium to ensure male fertility in Arabidopsis thaliana. Through integrated multiomics approaches (DAP-Seq and RNA-Seq) combined with genetic analysis, we identified ANAC106 (AT3G12910), a previously unrecognized NAC (NAM; ATAF1, 2; and CUC2) transcription factor, as a key regulator to maintain GA biosynthesis and signaling homeostasis. Biochemical approaches using protein interaction assays and transcriptional activity tests elucidated a DELLA-ANAC106 feedback mechanism. Gain-of-function and loss-of-function of ANAC106 caused opposing effects on tapetum degradation, both leading to severe male sterility. ANAC106 directly activates GA biosynthetic genes (GA3ox2 and GA3ox4), elevating bioactive GA levels that promote DELLA degradation. The pollen developmental defects observed in ANAC106-overexpressing plants were effectively rescued by overexpressing the DELLA proteins in anthers or developing pollen. Furthermore, DELLA proteins physically interact with ANAC106 in a dose-dependent manner, inhibiting its transcriptional activation capacity to prevent GA over-accumulation. We reveal a DELLA-ANAC106 regulatory circuit that maintains GA homeostasis through reciprocal negative feedback. This self-correcting mechanism ensures precise spatiotemporal control of GA levels during tapetum-pollen coordination, representing a paradigm in phytohormonal regulation of plant reproduction.