Steinbrenner Jens, Linden Hartmut
Lehrstuhl für Physiologie und Biochemie der Pflanzen, Universität Konstanz, 78434 Konstanz, Germany.
Plant Mol Biol. 2003 May;52(2):343-56. doi: 10.1023/a:1023948929665.
The unicellular green alga Haematococcus pluvialis accumulates large amounts of the red ketocarotenoid astaxanthin when exposed to various stress situations such as salt stress and high light intensities. Here, the light regulation of Haematococcus carotenoid biosynthesis was examined. Isolation and characterization of the lycopene beta cyclase gene involved in carotenoid biosynthesis was carried out using a functional complementation approach. Subsequently, gene expression of lycopene cyclase, phytoene synthase, phytoene desaturase and carotenoid hydroxylase was analysed in green flagellate cells. All four genes revealed higher transcript levels in response to increased illumination. Not only the induction of astaxanthin biosynthesis but also carotenoid gene expression was found to be correlated with the redox state of the photosynthetic electron transport. In accordance with this result, increased transcript levels for carotenoid biosynthesis genes were detected under both blue and red light conditions. The application of different inhibitors of the photosynthetic electron flow indicated that the photosynthetic plastoquinone pool functions as the redox sensor for the up-regulation of carotenoid biosynthesis genes. These results suggested that in Haematococcus not only the specific astaxanthin pathway but also general carotenoid biosynthesis is subject to photosynthetic redox control.
单细胞绿藻雨生红球藻在暴露于各种胁迫条件下，如盐胁迫和高光强度时，会积累大量红色酮类胡萝卜素虾青素。在此，对雨生红球藻类胡萝卜素生物合成的光调节进行了研究。使用功能互补方法对参与类胡萝卜素生物合成的番茄红素β环化酶基因进行了分离和表征。随后，分析了绿鞭毛藻细胞中番茄红素环化酶、八氢番茄红素合酶、八氢番茄红素脱氢酶和类胡萝卜素羟化酶的基因表达。所有这四个基因在光照增加时均显示出较高的转录水平。不仅虾青素生物合成的诱导，而且类胡萝卜素基因表达也被发现与光合电子传递的氧化还原状态相关。根据这一结果，在蓝光和红光条件下均检测到类胡萝卜素生物合成基因的转录水平增加。光合电子流不同抑制剂的应用表明，光合质体醌库作为类胡萝卜素生物合成基因上调的氧化还原传感器。这些结果表明，在雨生红球藻中，不仅特定的虾青素途径，而且一般类胡萝卜素生物合成都受光合氧化还原控制。
