College of Landscape Architecture and Forestry, Qingdao Agricultural University, Qingdao, Shandong, 266109, China.
College of Resources and Environment, Qingdao Agricultural University, Qingdao, China.
J Plant Physiol. 2022 Aug;275:153753. doi: 10.1016/j.jplph.2022.153753. Epub 2022 Jun 11.
Duckweed is a kind of aquatic plant with the characteristics of high nutritional value and medicinal benefits. However, most researches focused on the natural germplasms. The underlying metabolic pathway remains to be systematically elaborated in duckweed. In our laboratory, one reddish-purple mutant with high-flavonoids was screened from a mutant library of Spirodela polyrhiza 6068, named 68-red. The content of anthocyanins and proanthocyanidins in 68-red mutant increased by 563.47% and 231.19%, respectively, compared to wild type. It is interesting that cynaroside and orientin content were significantly increased, in contrast, apigetrin and vitexin were decreased in 68-red mutant. Considering this, metabolome and transcriptome were employed to explore the flavonoids biosynthetic pathway. Here, a total of 734 metabolites were identified in the wild type and 68-red mutant. Among which, cyanidin-3-O-glucoside, cyanidin-3-O-galactoside, pelargonidin-3-O-glucoside and pelargonidin-3-O-(6″-O-malonyl)glucoside were significantly accumulated, which were positively correlated with deep reddish-purple of 68-red mutant. In addition, proanthocyanidins (B1, B2, B3, B4, C1, C2), flavonoid and its glycosides (11 luteolin and its glycosides, 14 quercetin and its glycosides, 14 kaempferol and its glycosides, 2 apigenin glycosides) were significantly accumulated, 2 apigenin glycosides were down-regulated in 68-red mutant. The transcriptome data and qRT-PCR indicated that 16 enzyme genes in flavonoids biosynthetic pathway (PAL, C4H, CHSs, F3H, ANS, ANR, F3'Hs, DFRs, LAR, GT1, BZ1) were significantly up-regulated in 68-red mutant. Correlation analysis found that three copies of F3'H gene play important roles in the synthesis of anthocyanins, luteolin and apigenin glycosides. In conclusion, the 68-red mutant is a high quality germplasm resources for food and medical industry. Metabolome and transcriptome provide new insight for exploring the enzyme genes and functional metabolites in duckweed.
浮萍是一种具有高营养价值和药用功效的水生植物。然而，大多数研究都集中在天然种质资源上，浮萍的潜在代谢途径仍需系统阐述。在我们的实验室中，从 Spirodela polyrhiza 6068 的突变体文库中筛选到一个富含类黄酮的微红突变体，命名为 68-红。与野生型相比，68-红突变体中花色苷和原花青素的含量分别增加了 563.47%和 231.19%。有趣的是，飞燕草苷和木犀草苷的含量显著增加，而荭草苷和牡荆苷的含量则降低。考虑到这一点，我们采用代谢组学和转录组学方法来探讨类黄酮的生物合成途径。在这里，共鉴定出野生型和 68-红突变体中的 734 种代谢产物。其中，矢车菊素-3-O-葡萄糖苷、矢车菊素-3-O-半乳糖苷、天竺葵素-3-O-葡萄糖苷和天竺葵素-3-O-(6″-O-丙二酰基)葡萄糖苷显著积累，这与 68-红突变体的深紫红色呈正相关。此外，原花青素（B1、B2、B3、B4、C1、C2）、类黄酮及其糖苷（11 个木樨草素及其糖苷、14 个槲皮素及其糖苷、14 个山柰酚及其糖苷、2 个芹菜素糖苷）也显著积累，而 68-红突变体中 2 个芹菜素糖苷下调。转录组数据和 qRT-PCR 表明，在 68-红突变体中，类黄酮生物合成途径中的 16 个酶基因（PAL、C4H、CHSs、F3H、ANS、ANR、F3'Hs、DFRs、LAR、GT1、BZ1）显著上调。相关性分析发现，三个 F3'H 基因拷贝在花色苷、木樨草素和芹菜素糖苷的合成中发挥重要作用。总之，68-红突变体是食品和医药工业的高质量种质资源。代谢组学和转录组学为探索浮萍中的酶基因和功能代谢物提供了新的视角。
