Abstract: Aliphatic compounds are an important part of plant aromatic substances and play an important role in the composition of white tea aroma. This study used bioinformatics methods to identify the LOX gene family in the chromosome-level tea plant genome database, and obtained 12 tea plant LOX gene family members, named CsLOX1-CsLOX12. The 12 tea plant LOXs are mainly located in the cytoplasm or chloroplast. The encoded proteins have the same characteristic domains and conserved motifs. Phylogenetic tree analysis shows that the LOX gene family is divided into two subfamilies: 9-LOX and 13-LOX. CsLOX2, CsLOX3, CsLOX4, and CsLOX7 belong to 9-LOX subtypes, and the rest belong to 13-LOX subtypes. Gene structure analysis shows that CsLOX1 contains 8 exons, the rest contain 9 exons. The transcriptome data analysis of different tissues shows that the family genes are highly expressed in the tender and mature leaves of tea plants. The upstream promoter region analysis finds a large number of cis-acting elements closely related to plant development, light response, hormone and stress response. Fluorescence quantitative PCR detection reveals that the CsLOX genes were expressed to varying degrees under drought, low temperature and MeJA hormone treatment. Under the treatment of different withering time of white tea, the expression levels of CsLOX1, CsLOX3, CsLOX5, CsLOX7, CsLOX8, CsLOX9, CsLOX11 and CsLOX12 were induced, with the peaks at 4 h (up to 27-fold increase). The results of this study show that members of the CsLOX gene family participate in the regulation of the formation of aliphatic aromas during the process of white tea withering, laying a foundation for understanding the molecular mechanism of aroma formation during tea processing.

Key words: Camellia sinensis, LOX gene, white tea withering, expression analysis