Plant Products and Food Quality, Scottish Crop Research Institute, Invergowrie, Dundee, United Kingdom.
Plant Physiol. 2010 Oct;154(2):656-64. doi: 10.1104/pp.110.158733. Epub 2010 Aug 5.
The factors that regulate storage organ carotenoid content remain to be fully elucidated, despite the nutritional and economic importance of this class of compound. Recent findings suggest that carotenoid pool size is determined, at least in part, by the activity of carotenoid cleavage dioxygenases. The aim of this study was to investigate whether Carotenoid Cleavage Dioxygenase4 (CCD4) activity affects potato (Solanum tuberosum) tuber carotenoid content. Microarray analysis revealed elevated expression of the potato CCD4 gene in mature tubers from white-fleshed cultivars compared with higher carotenoid yellow-fleshed tubers. The expression level of the potato CCD4 gene was down-regulated using an RNA interference (RNAi) approach in stable transgenic lines. Down-regulation in tubers resulted in an increased carotenoid content, 2- to 5-fold higher than in control plants. The increase in carotenoid content was mainly due to elevated violaxanthin content, implying that this carotenoid may act as the in vivo substrate. Although transcript level was also reduced in plant organs other than tubers, such as leaves, stems, and roots , there was no change in carotenoid content in these organs. However, carotenoid levels were elevated in flower petals from RNAi lines. As well as changes in tuber carotenoid content, tubers from RNAi lines exhibited phenotypes such as heat sprouting, formation of chain tubers, and an elongated shape. These results suggest that the product of the CCD4 reaction may be an important factor in tuber heat responses.
尽管这类化合物具有重要的营养和经济意义，但调节贮藏器官类胡萝卜素含量的因素仍未完全阐明。最近的研究结果表明，类胡萝卜素库的大小至少部分取决于类胡萝卜素裂解双加氧酶的活性。本研究旨在探讨 Carotenoid Cleavage Dioxygenase4（CCD4）活性是否会影响马铃薯（Solanum tuberosum）块茎的类胡萝卜素含量。微阵列分析显示，与富含类胡萝卜素的黄色果肉块茎相比，白色果肉品种的成熟块茎中 CCD4 基因的表达水平升高。利用 RNA 干扰（RNAi）方法在稳定的转基因株系中下调马铃薯 CCD4 基因的表达。在块茎中下调表达导致类胡萝卜素含量增加 2-5 倍，高于对照植物。类胡萝卜素含量的增加主要是由于紫黄质含量的增加，这意味着这种类胡萝卜素可能是体内的底物。尽管在除块茎以外的植物器官（如叶片、茎和根）中的转录水平也降低，但这些器官中的类胡萝卜素含量没有变化。然而，RNAi 株系的花花瓣中的类胡萝卜素水平升高。除了块茎类胡萝卜素含量的变化外，RNAi 株系的块茎还表现出热发芽、链状块茎形成和拉长形状等表型。这些结果表明，CCD4 反应的产物可能是块茎热响应的一个重要因素。
