Kan Delong, Zhao Di, Duan Pengfei
Henan Provincial Academician Workstation of Water Security for Water Source Region of Mid-line of South-to-North Diversion Project, Collaborative Innovation Center of Water Security for Water Source Region of Mid-line of South-to-North Diversion Project of Henan Province, Henan Provincial Key Laboratory of Ecological Security for Water Source Region of Mid-line of South-to-North Diversion Project, Nanyang Normal University, Nanyang, Henan Province, 473061, China.
College of Environmental Science and Tourism, Nanyang Normal University, Nanyang, Henan Province, 473061, China.
Open Life Sci. 2020 Oct 12;15(1):753-762. doi: 10.1515/biol-2020-0077. eCollection 2020.
Studies have shown that abundant and various flavonoids accumulate in chili pepper (), but there are few reports on the genes that govern chili pepper flavonoid biosynthesis. Here, we report the comprehensive identification of genes encoding type III polyketide synthase (PKS), an important enzyme catalyzing the generation of flavonoid backbones. In total, 13, 14 and 13 type III PKS genes were identified in each genome of , and , respectively. The phylogeny topology of PKSs is similar to those in other plants, as it showed two classes of genes. Within each class, clades can be further identified. Class II genes likely encode chalcone synthase (CHS) as they are placed together with the CHS gene, which experienced extensive expansions in the genomes of . Interestingly, 8 of the 11 Class II genes form three clusters in the genome of , which is likely the result of tandem duplication events. Four genes are not expressed in the tissues of , three of which are located in the clusters, indicating that a portion of genes was pseudogenized after tandem duplications. Expression of two Class I genes was complementary to each other, and all the genes in Class II were not expressed in roots of . Two Class II genes (CA00g90790 and CA05g17060) showed upregulated expression as the chili pepper leaves matured, and two Class II genes (CA05g17060 and CA12g20070) showed downregulated expression with the maturation of fruits, consistent with flavonoid accumulation trends in chili pepper as reported previously. The identified genes, sequences, phylogeny and expression information collected in this article lay the groundwork for future studies on the molecular mechanisms of chili pepper flavonoid metabolism.
研究表明，辣椒中积累了丰富多样的黄酮类化合物，但关于调控辣椒黄酮生物合成的基因报道较少。在此，我们报告了编码III型聚酮合酶（PKS）基因的全面鉴定，III型聚酮合酶是催化黄酮骨架生成的一种重要酶。在辣椒、番茄和马铃薯的每个基因组中，分别鉴定出了13个、14个和13个III型PKS基因。辣椒PKS的系统发育拓扑结构与其他植物相似，显示出两类基因。在每一类中，可以进一步鉴定出进化枝。II类基因可能编码查尔酮合酶（CHS），因为它们与番茄的CHS基因聚在一起，番茄的CHS基因在基因组中经历了广泛的扩增。有趣的是，11个II类基因中的8个在辣椒基因组中形成了三个簇，这可能是串联重复事件的结果。有4个基因在辣椒组织中不表达，其中3个位于这些簇中，表明一部分基因在串联重复后已假基因化。两个I类基因的表达相互补充，II类中的所有基因在辣椒根中均不表达。两个II类基因（CA00g90790和CA05g17060）随着辣椒叶片成熟表达上调，两个II类基因（CA05g17060和CA12g20070）随着果实成熟表达下调，这与先前报道的辣椒中黄酮类化合物积累趋势一致。本文收集的已鉴定基因、序列、系统发育和表达信息为未来研究辣椒黄酮代谢的分子机制奠定了基础。
