Abstract: Lipoxygenase (LOX, EC1.13.11.12) is a class of non\|heme iron\|containing enzyme specifically catalyzing the dioxygenation of polyunsaturated fatty acids. Based on the tea tree genome, this study analyzed and concluded the molecular characteristics, evolution law and codon preference of 12 members in tea tree genome. The results of physiochemical nature detect showed that CsLOX6 gene had the longest open reading frame (ORF) of 2 778 bp, encoding 925 amino acids, and its protein molecular weight was 104.5 kDa. Compared with amino acid sequences of the other species, the phylogenetic tree between tea tree LOX gene family members and 37 LOX genes from 26 species(all belong to dicotyledoneae) were constructed. The results showed that 5 members belonged to 9\|LOX subtribe, 5 members belonged to 13\|LOX TypeⅠ subclass, and only 2 members belonged to 13\|LOX TypeⅡ subclass. However, as the member of 13\|LOX TypeⅡ subclass, CsLOX5 lacked of transit peptide in its leader sequence. The result of analyzing the relative synonymous codon usage (RSCU) value showed that 4 codons were high\|frequency, and 9 codons were low\|frequency. The results of the analysis of codon bias parameters showed that the bias of codon usage of tea tree LOX gene family was weak, and they prefered to use A/T as their third place of codons. In addition, cluster analysis of RSCU value was made with Neighbor\|Joinin (NJ) method, and it was found that there were differences in CsLOX10 gene clustering between phylogenetic tree based on coding sequences(CDS) and RSCU value clustering.

Key words: tea tree, lipoxygenase, genome, codon preference, clustering analysis

摘要： 脂肪氧合酶（lipoxygenase, LOX, EC 1.13.11.12）是一类含有铁离子的血红素双加氧酶，专一催化多元不饱和脂肪酸加氧反应。基于茶树基因组数据，对筛选获得的12个LOX基因家族成员的分子特性、进化规律及密码子偏好性进行分析归纳。理化性质检测结果表明，茶树LOX家族成员中以CsLOX6的开放阅读框（open reading frame, ORFs）最长(2 778 bp)，编码925个氨基酸，蛋白分子量为104.5 kDa。通过氨基酸序列同源比对，构建茶树LOX基因家族成员与26个物种（均系双子叶植物纲）的37个LOX基因的系统发育进化树，结果发现，茶树LOX基因家族成员可被分为9\|LOX亚族（5个）、13\|LOX TypeⅠ亚类（5个）及13\|LOX TypeⅡ亚类（2个），但13\|LOX TypeⅡ亚类中的CsLOX5基因，并不具有转运肽（transit peptide）前导序列。对茶树基因组LOX家族成员基因密码子相对偏好使用度（relative synonymous codon usage, RSCU）及偏好性参数进行分析，结果表明：茶树LOX基因家族成员存在着4个密码子在编码基因上被高频率选用，9个密码子被低频率选用；茶树LOX基因家族成员的密码子选用偏好性普遍较弱，并偏好以A/T作为结尾。此外，以最近邻元素法(Neighbor\|Joining, NJ)对密码子RSCU值进行聚类分析，结果发现，RSCU值的聚类与以编码序列（coding sequences, CDS）构建的系统发育进化树之间，在CsLOX10基因的聚类上存在差异。

关键词: 茶树, 脂肪氧合酶, 基因组, 密码子选用偏好性, 聚类分析