Key Laboratory of Plant Resources/Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
College of Landscape and Forestry, Qingdao Agricultural University, Qingdao, China.
Physiol Plant. 2021 May;172(1):64-76. doi: 10.1111/ppl.13293. Epub 2020 Dec 10.
Chalcone synthase (CHS) is the key enzyme in the flavonoid biosynthetic pathway and has been studied in many plants, but the function of the CHS gene has not been well characterized in Paeonia ostii. In this study, we obtained a CHS homolog gene from P. ostii, which possessed the putative conserved amino acids of chalcone synthase by multiple alignment analysis and demonstrated the highest expression in developing seeds. In vitro assays of the recombinant PoCHS protein confirmed enzymatic activity using malonyl-CoA and 4-coumaroyl-CoA as substrates, and the optimal pH and reaction temperature were 7.5 and 40 °C, respectively. Furthermore, ectopic over-expression of PoCHS in Arabidopsis up-regulated the expression levels of genes involved in seed development (ABI), glycolysis (PKp2, PDH-E1a, and SUS2/3), and especially fatty acid biosynthesis (BCCP2, CAC2, CDS2, FatA, and FAD3). This resulted in an increased unsaturated fatty acid content, especially α-linolenic acid, in transgenic Arabidopsis seeds. In this study, we examined the functions of CHS homolog of P. ostii and demonstrated its new function in seed fatty acid biosynthesis.
查尔酮合酶（CHS）是类黄酮生物合成途径中的关键酶，已在许多植物中进行了研究，但在牡丹中，CHS 基因的功能尚未得到很好的表征。本研究从牡丹中获得了一个 CHS 同源基因，通过多重比对分析表明该基因具有类黄酮合酶的假定保守氨基酸，并在发育中的种子中表达最高。体外实验表明，重组 PoCHS 蛋白具有酶活性，以丙二酰辅酶 A 和 4-香豆酰辅酶 A 为底物，最适 pH 值和反应温度分别为 7.5 和 40°C。此外，在拟南芥中异位过表达 PoCHS 可上调参与种子发育的基因（ABI）、糖酵解（PKp2、PDH-E1a 和 SUS2/3），特别是脂肪酸生物合成（BCCP2、CAC2、CDS2、FatA 和 FAD3）的表达水平。这导致转基因拟南芥种子中不饱和脂肪酸含量增加，尤其是α-亚麻酸。本研究检验了牡丹 CHS 同源基因的功能，并证明了其在种子脂肪酸生物合成中的新功能。
