A conserved AINTEGUMENTA-REVOLUTA module is a candidate to regulate carpel development in lychee

The lychee industry is vital to agricultural economies, boosting the livelihood of farmers and regional growth. However, instability of flowering causes yield fluctuations, severely limiting industry sustainability. Stable pistil development in female flowers is essential for yield improvement, yet its molecular regulation remains poorly understood. Although APETALA2 (AP2) transcription factors regulate floral organ differentiation and pistil development, their functional role in woody perennials such as lychee is uncharacterized. In this study, two AP2 genes (LITCHI007109 and LITCHI010784) were found to exhibit high and specific expression in carpels. LITCHI007109, designated as LcANT1, is an ortholog of Arabidopsis AINTEGUMENTA (ANT). We next systematically identified the direct downstream target genes of LcANT1, the set of which were significantly enriched in biological processes related to floral organ development and carpel morphology. Notably, the carpel development-related gene LITCHI024703 (LcREV) exhibited a high level of co-expression with LcANT1. We found that the LcANT1 protein can directly bind to the promoter region of LcREV. Further evolutionary analysis indicates that the ANT-REV regulatory module is highly conserved in angiosperms, especially in Sapindaceae. Our findings establish a novel theoretical framework for understanding female flower development in lychee and offer critical gene resources and regulatory networks for molecular breeding strategies aimed at developing high-yield, stable cultivars.