Akademik Veri Yönetim Sistemi
PLANTS-BASEL, cilt.14, sa.19, 2025 (SCI-Expanded, Scopus)
Tea, a widely consumed beverage globally, is a vital agricultural product for many countries. Polyphenol oxidases (PPOs), copper-containing enzymes found in plants, fungi, and animals, are essential for physiological metabolism and enzymatic browning in tea plants (Camellia sinensis). Codon usage bias (CUB), a key evolutionary characteristic, offers valuable insights into species evolution and gene function. However, the codon usage patterns of Camellia sinensis polyphenol oxidase (CsPPO) genes remain undocumented. In this study, we conducted, for the first time, a comprehensive analysis of CUB in 24 CsPPO genes, comparing their CUB profiles with those of other Camellia species (Camellia lanceoleosa, Camellia nitidissima, Camellia ptilophylla) and non-Camellia species (Actinidia chinensis, Cornus florida, Rhododendron vialii) to elucidate potential evolutionary relationships and functional constraints influencing CUB. Nucleotide composition analysis revealed an AT-rich bias, with a preference for G/C-ending codons at the third position. Codon usage indices indicated low expression levels and weak CUB. RSCU and RFSC analyses revealed that the preferred and high-frequency codons were mostly G/C-ending. Codon usage frequency analysis suggested Zea mays as a suitable host for CsPPO gene expression. ENC-GC3s, PR2, and neutrality plots showed natural selection had a stronger impact than mutation on CUB. Additionally, measure independent of length and composition (MILC) values confirmed low PPO gene expression levels, and correlation analyses demonstrated that both nucleotide composition and gene expression affect CUB. Overall, codon usage in CsPPO genes is mainly shaped by natural selection, with weak bias and low expression potential, providing useful insights for future genetic engineering and heterologous expression.