Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; College of Horticulture, South China Agricultural University, Guangzhou 510642, China; Lingnan Guangdong Laboratory of Modern Agriculture, Guangzhou, 510642, China.
College of Horticulture, South China Agricultural University, Guangzhou 510642, China.
Plant Sci. 2021 Apr;305:110835. doi: 10.1016/j.plantsci.2021.110835. Epub 2021 Feb 5.
Anthocyanins are important flavonoid pigments in plants. Malonyl CoA is an important intermediate in anthocyanin synthesis, and citrate, formed by citrate synthase (CS) catalysing oxaloacetate, is the precursor for the formation of malonyl-CoA. CS is composed of two isoforms, mitochondrial citrate synthase (mCS), a key enzyme of the tricarboxylic acid (TCA) cycle, and citrate synthase (CSY) localizated in microbodies in plants. However, no CS isoform involvement in anthocyanin synthesis has been reported. In this study, we identified the entire CS family in petunia (Petunia hybrida): PhmCS, PhCSY1 and PhCSY2. We obtained petunia plants silenced for the three genes. PhmCS silencing resulted in abnormal development of leaves and flowers. The contents of citrate and anthocyanins were significantly reduced in flowers in PhmCS-silenced plants. However, silencing of PhCSY1 and/or PhCSY2 did not cause a visible phenotype change in petunia. These results showed that PhmCS is involved in anthocyanin synthesis and the development of leaves and flowers, and that the citrate involved in anthocyanin synthesis mainly derived from mitochondria rather than microbodies in petunia.
花色素苷是植物中重要的类黄酮色素。丙二酰辅酶 A 是花色素苷合成的重要中间产物，而柠檬酸是由柠檬酸合酶 (CS) 催化草酰乙酸形成的，是丙二酰辅酶 A 形成的前体。CS 由两种同工酶组成，线粒体柠檬酸合酶 (mCS)，是三羧酸 (TCA) 循环的关键酶，和位于植物微体中的柠檬酸合酶 (CSY)。然而，目前尚未有 CS 同工酶参与花色素苷合成的报道。在这项研究中，我们鉴定了矮牵牛中的整个 CS 家族：PhmCS、PhCSY1 和 PhCSY2。我们获得了三种基因沉默的矮牵牛植物。PhmCS 沉默导致叶片和花朵发育异常。PhmCS 沉默植物的花朵中柠檬酸和花色素苷的含量显著降低。然而，PhCSY1 和/或 PhCSY2 的沉默并没有引起矮牵牛可见的表型变化。这些结果表明 PhmCS 参与花色素苷合成和叶片及花朵的发育，并且参与花色素苷合成的柠檬酸主要来自于线粒体，而不是微体。
