SlTCP24 regulates tomato leaf morphology, fruit quality, and productivity via the auxin signaling pathway

The transcription factor TEOSINTE BRANCHED1, CYCLOIDEA, PROLIFERATING CELL FACTOR (TCP) plays an important role in plant growth and development. SlTCP24 influences tomato leaf morphogenesis; however, the underlying regulatory mechanisms are not clear. In this study, SlTCP24 was found to play a role in tomato leaf development by mediating the auxin signaling pathway. The findings revealed that CRISPR-mediated knockout of SlTCP24 (CR- Sltcp24 ) resulted in more complex leaf phenotypes, characterized by a higher number of leaflets and more pronounced leaf lobing. Treatment with exogenous indole-3-acetic acid (IAA) induced the expression of SlTCP24 in leaves, while overexpression of SlTCP24 (OE- SlTCP24 ) was correlated with high levels of auxin and its metabolites. These results suggest a reciprocal regulatory relationship between SlTCP24 and IAA, wherein SlTCP24 modulates the biosynthesis of IAA via the tryptophan-dependent pathway. Moreover, SlTCP24 physically interacts with the auxin response factor SlARF10. These findings support the hypothesis that SlTCP24 mediates auxin signaling to influence the development of tomato leaves and subsequently regulates the yield and quality of fruits. This study provides novel insights into the interplay between TCP transcription factors and auxin signaling during the morphogenesis of tomato leaves.