Genome-wide identification and expression analysis of LcyAPRR2 gene family in Luffa cylindrica

Peel color is a critical agronomic trait influencing the market value of Luffa cylindrica . Recently, the white-peel variant of luffa has gained consumer preference due to its refined taste and reduced crude fiber content. Although the APRR2 gene is known to regulate peel color in various vegetable crops, its specific role in Luffa cylindrica remains unclear. In this study, five LcyAPRR2 genes ( LcyAPRR2-1 to LcyAPRR2-5 ) were identified, with protein lengths ranging from 432 to 689 amino acids and molecular weights between 48.98 and 75.73 kDa, all of which were predicted to be localized in the nucleus. Phylogenetic and collinearity analyses indicated that the evolutionary relationship of APRR2 is relatively conserved. The LcyAPRR2 genes contained two conserved domains, REC and PLN03162, and their promoter regions were enriched with light-responsive cis-acting elements. qRT-PCR analysis revealed that, compared to S1, the relative expression levels of Lcy03g018290.1 , Lcy10g010960.1 , and Lcy11g019160.1 were significantly up-regulated in the peel of Yongbai. This study provides a theoretical foundation for further investigation into the functional role of the LcyAPRR2 gene family in the formation of peel color.