CAROTENOID BIOSYNTHESIS DURING TOMATO FRUIT-DEVELOPMENT
CAROTENOID BIOSYNTHESIS DURING TOMATO FRUIT-DEVELOPMENT
复制标题
DOI：
10.1104/pp.105.1.405
复制
发表时间：
1994-05-01
期刊：
影响因子：
7.4
通讯作者：
BRAMLEY, PM
中科院分区：
文献类型：
--
作者：
FRASER, PD;TRUESDALE, MR;BRAMLEY, PM
番茄（Lycopersicon esculentum Mill.）cv Ailsa克雷格）果实的5个发育阶段，分析了其类胡萝卜素和叶绿素（Chi）含量，八氢番茄红素合成酶、八氢番茄红素去饱和酶和番茄红素环化酶的体外活性，以及八氢番茄红素合成酶（Psy）和八氢番茄红素去饱和酶（Pds）基因的表达。在成熟过程中，总类胡萝卜素的增加，同时减少志。虽然成熟果实中类胡萝卜素含量最高（主要由番茄红素和α-胡萝卜素组成），但绿色果实中的类胡萝卜素生成酶活性最高。八氢番茄红素合成酶位于质体基质中，而八氢番茄红素的代谢在果实发育的各个阶段都与质体膜有关。八氢番茄红素去饱和的体外产物从叶绿体中主要为六氢番茄红素和ζ-胡萝卜素转变为色素体中主要为番茄红素。Psy的表达在破皮果和成熟果以及花中检测到，但在叶或绿色果实中通过北方印迹分析未检测到。Pds基因转录本在绿色果实和叶片中几乎检测不到，但在花和破果中表达。这些结果表明，Psy和Pds的转录调节发育，与表达显着升高，在含质体的组织。聚球藻八氢番茄红素合成酶的抗血清与八氢番茄红素合成酶的绿色水果交叉反应，只有在西方的印迹，而不是从成熟的水果的酶。相反，Psy基因产物的单克隆抗体仅与成熟果实的八氢番茄红素合酶发生交叉反应。绿色和成熟果实中的酶分子量不同，分别为42和38 kD。使用北方印迹分析在绿色组织中没有可检测到的Psy和Pds mRNA，尽管八氢番茄红素合酶和去饱和酶活性水平高，但支持编码这些酶的不同基因的假设。
Tomato (Lycopersicon esculentum Mill. cv Ailsa Craig) fruit, at five stages of development, have been analyzed for their carotenoid and chlorophyll (Chi) contents, in vitro activities of phytoene synthase, phytoene desaturase, and lycopene cyclase, as well as expression of the phytoene synthase (Psy) and phytoene desaturase (Pds) genes. During ripening, the total carotenoids increased with a concomitant decrease in Chi. Although the highest carotenoid content (consisting mainly of lycopene and a-carotene) was found in ripe fruit, the greatest carotenogenic enzymic activities were found in green fruit. Phytoene synthase was located in the plastid stroma, whereas the metabolism of phytoene was associated with plastid membranes during all stages of fruit development. The in vitro products of phytoene desaturation altered from being predominantly phytofluene and zeta-carotene in chloroplasts to becoming mainly lycopene in chromoplasts. The expression of Psy was detected in breaker and ripe fruit, as well as flowers, but was not detectable by northern blot analysis in leaves or green fruits. The Pds gene transcript was barely detectable in green fruit and leaves but was expressed in flowers and breaker fruit. These results suggest that transcription of Psy and Pds is regulated developmentally, with expression being considerably elevated in chromoplast-containing tissues. Antiserum to the Synechococcus phytoene synthase cross-reacted with phytoene synthase of green fruit only on western blots and not with the enzyme from ripe fruit. In contrast, a monoclonal antibody to the Psy gene product only cross-reacted with phytoene synthase from ripe fruit. The enzymes from green and ripe fruit had different molecular masses of 42 and 38 kD, respectively. The absence of detectable Psy and Pds mRNA in green tissues using northern blot analyses, despite high levels of phytoene synthase and desaturase activity, lends support to the hypothesis of divergent genes encoding these enzymes.