Liu Jinyue, Xia Yaying, Jiang Wenbo, Shen Guoan, Pang Yongzhen
Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China.
Key Laboratory of Plant Resources and Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
Front Plant Sci. 2021 Jun 11;12:673337. doi: 10.3389/fpls.2021.673337. eCollection 2021.
Legume plants are rich in prenylated flavonoid compounds, which play an important role in plant defense and human health. In the present study, we identified a prenyltransferase (PT) gene, named , in white lupin (), which shows a high identity and close relationship with the other known PT genes involved in flavonoid prenylation in planta. The recombinant LaPT2 protein expressed in yeast cells exhibited a relatively strong activity toward several flavonols (e.g., kaempferol, quercetin, and myricetin) and a relatively weak activity toward flavanone (naringenin). In addition, the recombinant LaPT2 protein was also active toward several other types of flavonoids, including galangin, morin, 5-deoxyquercetin, 4'-O-methylkaempferol, taxifolin, and aromadendrin, with distinct enzymatic affinities. The gene was preferentially expressed in the roots, which is consistent with the presence of prenylated flavonoid kaempferol in the roots. Moreover, we found that the expression level of paralleled with those of and genes that were relatively higher in roots and lower in leaves, suggesting that they were essential for the accumulation of prenylated flavonoid kaempferol in roots. The deduced full-length LaPT2 protein and its signal peptide fused with a green fluorescent protein (GFP) are targeted to plastids in the protoplast. Our study demonstrated that from white lupin is responsible for the biosynthesis of prenylated flavonoids, in particular flavonols, which could be utilized as phytoalexin for plant defense and bioactive flavonoid compounds for human health.
豆科植物富含异戊烯基化黄酮类化合物,这些化合物在植物防御和人类健康中发挥着重要作用。在本研究中,我们在白羽扇豆(Lupinus albus)中鉴定出一个异戊烯基转移酶(PT)基因,命名为LaPT2,它与植物中其他已知的参与黄酮类化合物异戊烯基化的PT基因具有高度同源性和密切关系。在酵母细胞中表达的重组LaPT2蛋白对几种黄酮醇(如山奈酚、槲皮素和杨梅素)表现出相对较强的活性,而对黄烷酮(柚皮素)表现出相对较弱的活性。此外,重组LaPT2蛋白对其他几种类型的黄酮类化合物也有活性,包括高良姜素、桑色素、5-脱氧槲皮素、4'-O-甲基山奈酚、紫杉叶素和香豆素,具有不同的酶亲和力。LaPT2基因在根中优先表达,这与根中存在异戊烯基化黄酮类化合物山奈酚一致。此外,我们发现LaPT2的表达水平与根中相对较高而叶中相对较低的LaF3'H和LaF3'5'H基因的表达水平平行,表明它们对于根中异戊烯基化黄酮类化合物山奈酚的积累至关重要。推导的全长LaPT2蛋白及其与绿色荧光蛋白(GFP)融合的信号肽在L. albus原生质体中靶向质体。我们的研究表明,来自白羽扇豆的LaPT2负责异戊烯基化黄酮类化合物的生物合成,特别是黄酮醇,它们可作为植物抗毒素用于植物防御,以及作为生物活性黄酮类化合物用于人类健康。