Morris W L, Ducreux L, Griffiths D W, Stewart D, Davies H V, Taylor M A
Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK.
J Exp Bot. 2004 May;55(399):975-82. doi: 10.1093/jxb/erh121. Epub 2004 Mar 26.
Germplasm of Solanum tuberosum and Solanum phureja exhibit a wide (over 20-fold) variation in tuber carotenoid content. The levels of carotenoids during tuber development and storage were compared in a high carotenoid-accumulating S. phureja accession (DB375\1) with two S. tuberosum cultivars (Pentland Javelin and Desiree) that accumulate lower levels of tuber carotenoid. On a dry weight basis, total carotenoid levels were at a maximum early in tuber development. However, in the S. phureja accession, carotenoid levels remained at a high level throughout tuber development, whereas in the S. tuberosum accessions, carotenoid content decreased as dry weight increased. The carotenoid profiles of tissues during tuber development were analysed in greater detail by reverse phase HPLC. In S. phureja tubers at maturity the major carotenoids were zeaxanthin, antheraxanthin, and violaxanthin. Following 9 months storage at 4 degrees C the levels of zeaxanthin and antheraxanthin decreased, whereas the level of lutein increased; overall, however, there was only a small decrease in total carotenoid content. In order to explore the reasons for the wide variation in tuber carotenoid content, the expression patterns of the major genes encoding the enzymes of the carotenoid biosynthetic pathway were compared. Significant differences in the profiles were detected, suggesting that transcriptional control or mRNA stability gives rise to the large differences in tuber carotenoid content. In particular, there was an inverse trend between the level of zeaxanthin epoxidase transcript level and tuber carotenoid content in a range of potato germplasm, giving rise to an hypothesis for the regulation of carotenogenesis in potato tubers.
马铃薯（Solanum tuberosum）和普氏马铃薯（Solanum phureja）的种质在块茎类胡萝卜素含量上表现出广泛（超过20倍）的差异。在一个高类胡萝卜素积累的普氏马铃薯材料（DB375\1）与两个积累较低水平块茎类胡萝卜素的马铃薯品种（彭特兰标枪和德西蕾）之间，比较了块茎发育和储存期间的类胡萝卜素水平。以干重计，总类胡萝卜素水平在块茎发育早期达到最高。然而，在普氏马铃薯材料中，类胡萝卜素水平在整个块茎发育过程中都保持在较高水平，而在马铃薯品种中，类胡萝卜素含量随着干重增加而降低。通过反相高效液相色谱法更详细地分析了块茎发育过程中组织的类胡萝卜素谱。在成熟的普氏马铃薯块茎中，主要类胡萝卜素是玉米黄质、花药黄质和紫黄质。在4℃储存9个月后，玉米黄质和花药黄质水平下降，而叶黄素水平增加；然而总体而言，总类胡萝卜素含量仅略有下降。为了探究块茎类胡萝卜素含量广泛差异的原因，比较了编码类胡萝卜素生物合成途径中酶的主要基因的表达模式。检测到谱图存在显著差异，表明转录调控或mRNA稳定性导致了块茎类胡萝卜素含量的巨大差异。特别是，在一系列马铃薯种质中，玉米黄质环氧化酶转录水平与块茎类胡萝卜素含量之间存在相反趋势，从而产生了关于马铃薯块茎类胡萝卜素生物合成调控的假说。
