Genome-wide analysis of CYP in Pyrus pyrifolia and PpCYP233 as a positive regulator for lignin accumulation

Cytochrome P450 monooxygenases (CYPs), the largest enzyme family in plants, play a pivotal role in the synthesis of lignin and plant growth and development. However, the CYP family in P. pyrifolia remains largely unexplored. Our genome-wide analysis identified 283 PpCYPs classified into 41 families across 9 phylogenetic clans. Additionally, we investigated chromosomal distribution, promoter sequence analysis and expression patterns of PpCYPs in different organs and lignin-related disorders. These genes exhibited irregular chromosomal distribution patterns. PpCYP promoters contain numerous cis-elements associated with defense stress and hormone responses. Pyrus pyrifolia requires precise regulation of lignification processes to mitigate physiological disorders such as hard-end disorder. Spatiotemporal expression analysis demonstrated stage-specific transcript accumulation, with 9 PpCYPs showing significant upregulation (fold change >10) in hard-end fruit. Among these genes, PpCYP233 exhibited the highest fold change. Subcellular localization showed that PpCYP233 was localized in the endoplasmic reticulum. Functional validation demonstrated that transient overexpression of PpCYP233 in pear increased lignin content, whereas virus-induced gene silencing of PpCYP233 significantly reduced lignin accumulation, suggesting that PpCYP233 might regulate lignification affecting the formation of hard-end disorder. Our study contributes to a better understanding of CYP genes in pear.