目的 鉴定虎杖Polygonum cuspidatum PKS III基因组家族成员，对其进行生物信息学分析、表达特征分析，并明确其表达量与虎杖药材有效成分含量的关系。方法 依据虎杖基因组数据，鉴定虎杖PKS III基因家族成员，分析其蛋白理化性质、二级结构、系统发育和保守基序等特征，利用转录组数据分析其表达特征，研究表达量与药材有效成分相关性。结果 虎杖全基因组中共鉴定出73个PKS III成员，不均匀地分布在20条染色体上；亚细胞定位预测显示，大部分PKS III定位于细胞质中，小部分定位于质膜上。系统发育分析表明，73个PKS III被分为3大类，同一类中的PKS III拥有相同的保守结构域。通过启动子顺式作用元件分析，虎杖PKS III基因具有多种激素响应、光响应和生长发育响应元件。表达特征分析显示，PKS III基因在虎杖药材根及根茎的5个组织中存在较大表达差异，PKS32、PKS42在所有组织中的表达量均显著高于其他基因，在根茎髓部表达量最高；相关性分析发现PKS3、PKS8、PKS21、PKS44、PKS58、PKS61与虎杖苷、大黄素甲醚含量呈显著正相关；PKS27、PKS56、PKS69与白藜芦醇和大黄素含量呈显著正相关；PKS32和PKS42与大黄素甲醚含量呈显著正相关。结论 鉴别出73个虎杖PKS III家族成员，部分成员基因表达量与虎杖药材有效成分含量具有显著相关性，为后续研究虎杖PKS III基因功能、阐明虎杖蒽醌类、二苯乙烯类及黄酮类成分的生物合成机制提供基础。

Objective To identify the genome-wide family members of type III polyketide synthase (PKS III) and conduct bioinformatics analysis and expression profile analysis and clarify the relationship between their expression and the content of active components of Huzhang (Polygonum cuspidatum). Methods Based on the genome data of P. cuspidatum, the members of PKS III gene family were identified. Subsequently, the characteristics of these members were analyzed, including the physicochemical properties of their encoded proteins, secondary structure, phylogeny, and conserved motifs. Transcriptome data were further used to analyze their expression profiles, and the correlation between the expression levels of these PKS III genes and the active components was investigated. Results A total of 73 PKS III members were identified in the whole genome of P. cuspidatum, which were unevenly distributed on 20 chromosomes. Subcellular localization prediction indicated that most PKS III members were localized in the cytoplasm, while a small portion were localized on the plasma membrane. Phylogenetic analysis revealed that they were clustered into three major groups, and members within the same group shared identical conserved domains. Analysis of promoter cis-acting elements demonstrated that the PKS III genes contained various elements responsive to hormones, light, and growth and development. Expression profile analysis showed significant differences in the expression of PKS III genes among five tissues of roots and rhizomes of P. cuspidatum. Specifically, the expression levels of PKS32 and PKS42 were significantly higher than those of other genes in all tissues, with the highest expression detected in the rhizome pith. Correlation analysis indicated that PKS3, PKS8, PKS21, PKS44, PKS58, and PKS61 exhibited a significant positive correlation with the contents of polydatin and physcion, and PKS27, PKS56, and PKS69 showed a significant positive correlation with the contents of resveratrol and emodin; and PKS32 and PKS42 displayed a significant positive correlation with the content of physcion. Conclusion A total of 73 PKS III family members were identified, and the expression levels of some members correlated significantly with the contents of active components in P. cuspidatum roots and rhizomes. This study provides a foundation for subsequent research on the functions of PKS III genes and for elucidating the biosynthetic mechanisms of anthraquinones, stilbenes, and flavonoids in P. cuspidatum.

R282.12

湖北省自然科学基金资助项目（2023AFD122）；湖北省高等学校优秀中青年科技创新团队计划（T2022020）