Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China.
School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China.
Genes (Basel). 2022 Dec 9;13(12):2318. doi: 10.3390/genes13122318.
leaves are highly rich in dihydromyricetin. They have been used to make tea in China for centuries. Dihydromyricetin has many potential applications in foods and medicine. This are because it has five phenolic hydroxyl groups. However, the hydroxylases involving the biosynthesis of dihydromyricetin have not been identified and characterized. In this study, a series of hydroxylases genes, including flavanone 3-hydroxylase (F3H), flavonoid 3'-hydroxylase (F3'H), flavonoid 3',5'-hydroxylase (F3'5'H), and cytochrome P450 reductase (CPR), were identified after RNA sequencing. The full-length CDSs of , , , and genes were amplified from the cDNA library of leaves. The aforementioned enzymes were expressed and verified in . Through the substrate specificity assay, the functional F3'H, F3'5'H, and CPR in were identified. The dihydromyricetin hydroxylation process in was successfully identified. We found that substantial carbon flux occurred through the Naringenin (NAR)-Eriodictyol (ERI)-Dihydroquercetin (DHQ)-Dihydromyricetin (DHM) and NAR-Dihydrokaempferol (DHK)-DHQ-DHM pathways. This study provides some reference for the development and utilization of the germplasm resources and molecular breeding of .
树叶富含二氢杨梅素。几个世纪以来，它们在中国一直被用来泡茶。二氢杨梅素因其含有五个酚羟基，在食品和医药方面具有广泛的应用潜力。然而，涉及二氢杨梅素生物合成的羟基化酶尚未被鉴定和表征。在这项研究中，通过 RNA 测序鉴定了一系列羟基化酶基因，包括黄烷酮 3-羟化酶（F3H）、黄酮 3'-羟化酶（F3'H）、黄酮 3',5'-羟化酶（F3'5'H）和细胞色素 P450 还原酶（CPR）。从叶片 cDNA 文库中扩增了 、 、 和 基因的全长 CDS。上述酶在 中表达并验证。通过底物特异性测定，鉴定了 中的功能性 F3'H、F3'5'H 和 CPR。成功鉴定了 中二氢杨梅素的羟化过程。我们发现，大量碳通量通过橙皮素（NAR）-圣草酚（ERI）-槲皮素（DHQ）-二氢杨梅素（DHM）和 NAR-山柰酚（DHK）-DHQ-DHM 途径发生。本研究为 种质资源的开发利用和分子育种提供了一定的参考。
