Comprehensive Identification of Auxin Response Factor Gene Family and Their Expression Profiles Under Lanthanum Stress in Amorphophallus konjac

Amorphophallus konjac is an economically important horticultural crop, valued for its corms as both a traditional medicine and a food source. The auxin transcription factor (ARF) family plays pivotal roles in auxin signaling and the processes of the morphogenesis of tissues and organs. However, the specific role of the ARF gene family in the regulation of corms remains unknown. In this study, we identified 23 AkARF genes unevenly distributed across 11 chromosomes in A. konjac. Phylogenetic analysis classified these proteins into four distinct clades, with members of the same group sharing conserved gene structures. Expression profiling demonstrated AkARF genes were expressed in a tissue-specific and spatio-temporal manner. Furthermore, lanthanum treatment significantly increased corm biomass and endogenous auxin levels (peak at 20 mg·L−1; p < 0.05). Transcriptome and qRT-PCR analyses revealed coordinated expression of AkARF6/13/14/16/20 with corm biomass accumulation. Pearson’s correlation analysis further confirmed positive correlations of AkARF6/13 with auxin content (p < 0.05). These results suggested the potential regulatory roles of AkARF6/13 in auxin-mediated corm development. This study provides the potential functional role of ARF-mediated growth and development of corms in A. konjac.