The New Zealand Institute for Plant and Food Research Ltd, Private Bag 92169, Auckland 1141, New Zealand.
Plant J. 2013 May;74(3):398-410. doi: 10.1111/tpj.12140. Epub 2013 Mar 14.
We have identified in apple (Malus × domestica) three chalcone synthase (CHS) genes. In order to understand the functional redundancy of this gene family RNA interference knockout lines were generated where all three of these genes were down-regulated. These lines had no detectable anthocyanins and radically reduced concentrations of dihydrochalcones and flavonoids. Surprisingly, down-regulation of CHS also led to major changes in plant development, resulting in plants with shortened internode lengths, smaller leaves and a greatly reduced growth rate. Microscopic analysis revealed that these phenotypic changes extended down to the cellular level, with CHS-silenced lines showing aberrant cellular organisation in the leaves. Fruit collected from one CHS-silenced line was smaller than the 'Royal Gala' controls, lacked flavonoids in the skin and flesh and also had changes in cell morphology. Auxin transport experiments showed increased rates of auxin transport in a CHS-silenced line compared with the 'Royal Gala' control. As flavonoids are well known to be key modulators of auxin transport, we hypothesise that the removal of almost all flavonoids from the plant by CHS silencing creates a vastly altered environment for auxin transport to occur and results in the observed changes in growth and development.
我们在苹果（Malus × domestica）中鉴定出三个查尔酮合酶（CHS）基因。为了了解这个基因家族的功能冗余性，我们生成了 RNA 干扰敲除系，其中这三个基因都下调。这些系没有可检测到的花青素，二氢查尔酮和类黄酮的浓度也大大降低。令人惊讶的是，CHS 的下调也导致了植物发育的重大变化，导致植物节间长度缩短，叶片变小，生长速度大大降低。显微镜分析显示，这些表型变化延伸到细胞水平，CHS 沉默系的叶片表现出异常的细胞组织。从一个 CHS 沉默系中收集的果实比“皇家 Gala”对照小，果皮和果肉中缺乏类黄酮，细胞形态也发生了变化。生长素运输实验显示，与“皇家 Gala”对照相比，CHS 沉默系中生长素的运输速度增加。由于类黄酮是众所周知的生长素运输的关键调节剂，我们假设通过 CHS 沉默从植物中去除几乎所有的类黄酮会为生长素运输创造一个完全改变的环境，并导致观察到的生长和发育变化。
