Selective autophagy receptor VISP1 enhances cytokinin signaling by modulating the Type-A/B ARR feedback loop during root development.

Abstract

Selective autophagy maintains intracellular homeostasis by selectively targeting cytoplasmic components through autophagy receptors. While virus-induced small peptide 1 (VISP1) has been identified as an autophagy receptor regulating plant-virus interactions, its function in phytohormone responses remains poorly understood. Here, we demonstrate that VISP1 positively regulates cytokinin responses during root development by modulating the feedback loop between type-A and -B <i>Arabidopsis</i> Response Regulators (ARRs). <i>VISP1</i> overexpression transgenic lines displayed shorter primary roots, fewer lateral roots, and elongated root hairs, accompanied with an induced cytokinin response compared to wild-type plants. Conversely, the <i>visp1</i> mutant exhibited attenuated cytokinin sensitivity. Mechanistically, cytokinin induces <i>VISP1</i> transcription, with the type-B ARR1 transcription factor directly binding to the <i>VISP1</i> promoter to activate its expression. VISP1 physically interacts with multiple type-A ARRs and promotes their autophagic degradation, thereby alleviating their repression on type-B ARRs. Collectively, our findings reveal a regulatory mechanism in which VISP1 amplifies cytokinin signaling by disrupting the negative feedback loop of type-A and type-B ARRs.