Orchestration of leaf curvature by the SBP transcription factor SPL10–<i>REVOLUTA</i> module in Arabidopsis

Leaf curvature significantly contributes to important economic traits in vegetable crops. The upward-curling leaf phenotype has been consistently observed upon overexpression of a miR156/157-resistant version of the SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 10 (SPL10) transcription factor (rSPL10). However, the role of SPL10 in regulating leaf curvature has not been well characterized. In this study, using DNA affinity purification sequencing followed by transient transactivation assays, we found that SPL10 can bind to the promoter and gene body of REVOLUTA (REV), augmenting its expression. The rSPL10 rev-6 double mutant plant displayed a downward-curling leaf phenotype similar to the rev-6 plant, supporting the notion that REV functions downstream of SPL10. Importantly, the SPL10 protein physically interacts with the REV protein, which attenuates the expression of REV promoted by SPL10, leading to the downregulation of REV-regulated genes involved in leaf curvature, such as HB2 and HB4. These findings suggest that the SPL10-REV module acts as a molecular rheostat to prevent excessive amplification of REV transcripts in Arabidopsis. Furthermore, overexpression of the BrpREV1 gene in Chinese cabbage caused the transformation of rosette leaves from flat to upward-curving and accelerated heading. Taken together, our findings reveal the role of SPL10-REV module in orchestrating leaf curvature, which could potentially be utilized for molecular breeding of economical traits in vegetable crops.