Abstract
<title>Abstract</title> <p>Leaf size directly determines photosynthetic efficiency, plant architecture, and yield components. However, the molecular regulatory mechanism underlying leaf size in pepper (Capsicum spp.) remains unclear. Previous GWAS analysis revealed that the CcF-box SNE gene is significantly associated with leaf size in pepper. In this study, we systematically characterized the pepper F-box gene family and cloned CcF-box SNE from the Hainan Yellow Lantern pepper. qPCR analysis showed that CcF-box SNE expression was significantly upregulated in small-leaf pepper accessions and exhibited a significant negative correlation with chlorophyll content and net photosynthetic rate. Its expression level first decreased and then increased with leaf age and could be induced by multiple hormones. Functional analysis demonstrated that silencing CcF-box SNE significantly increased leaf area and leaf cell size in pepper, while also enhancing photosynthetic parameters and the levels of growth-promoting hormones such as IAA and GA₃. In contrast, overexpression of CcF-box SNE significantly inhibited leaf development in Arabidopsis, reducing the corresponding hormone levels and photosynthetic efficiency. Collectively, these findings indicate that CcF-box SNE is a key negative regulator of leaf size in pepper, participating in leaf development by mediating endogenous hormone homeostasis, cell expansion, and photosynthetic efficiency. This study provides theoretical support for elucidating the regulatory mechanisms of leaf size in pepper.</p>