Lin Wang

Within the canonical auxin signaling pathway, Auxin Response Factors (ARFs) are transcriptionally repressed by AUX/IAA proteins under low auxin conditions, and this repression is alleviated as auxin concentrations increase. By contrast, ARF3 functions as a central regulator of gynoecium morphogenesis in Arabidopsis via a non-canonical auxin-sensing mechanism that relies on dose-dependent modulation of its protein–protein interaction network. To investigate whether an analogous regulatory mechanism operates in tomato (Solanum lycopersicum), we identified the tomato ARF3 homolog (SlARF3) and utilized it as bait in a yeast two-hybrid (Y2H) screen. This screening approach yielded 137 positive clones, corresponding to 118 putative interacting proteins. Notably, all of these interactions were abolished in the presence of 3-indoleacetic acid (IAA), indicating that SlARF3 engages in auxin-sensitive protein–protein interactions and thereby mediates auxin-dependent signal transduction. Among these, we identified an auxin-sensitive interaction between SlARF3 and TM29, a central regulator of parthenocarpy, underscoring its critical role in this developmental pathway. Functional analyses further demonstrated that silencing SlARF3 induces parthenocarpic fruit formation. Taken together, these findings define a previously uncharacterized SlARF3-centered interaction network and provide a conceptual framework for elucidating non-canonical auxin signaling pathways underlying tomato development.