Crocins and picrocrocin are glycosylated apocarotenoids responsible, respectively, for the color and the unique taste of the saffron spice, known as red gold due to its high price. Several studies have also shown the health-promoting properties of these compounds. However, their high costs hamper the wide use of these metabolites in the pharmaceutical sector. We have developed a virus-driven system to produce remarkable amounts of crocins and picrocrocin in adult Nicotiana benthamiana plants in only two weeks. The system consists of viral clones derived from tobacco etch potyvirus that express specific carotenoid cleavage dioxygenase (CCD) enzymes from Crocus sativus and Buddleja davidii. Metabolic analyses of infected tissues demonstrated that the sole virus-driven expression of C. sativus CsCCD2L or B. davidii BdCCD4.1 resulted in the production of crocins, picrocrocin and safranal. Using the recombinant virus that expressed CsCCD2L, accumulations of 0.2% of crocins and 0.8% of picrocrocin in leaf dry weight were reached in only two weeks. In an attempt to improve apocarotenoid content in N. benthamiana, co-expression of CsCCD2L with other carotenogenic enzymes, such as Pantoea ananatis phytoene synthase (PaCrtB) and saffron β-carotene hydroxylase 2 (BCH2), was performed using the same viral system. This combinatorial approach led to an additional crocin increase up to 0.35% in leaves in which CsCCD2L and PaCrtB were co-expressed. Considering that saffron apocarotenoids are costly harvested from flower stigma once a year, and that Buddleja spp. flowers accumulate lower amounts, this system may be an attractive alternative for the sustainable production of these appreciated metabolites.

藏红花素和大藏红花素是糖基化的类胡萝卜素，分别决定了藏红花香料的颜色和独特的味道，因其价格昂贵而被称为红色黄金。几项研究还表明这些化合物具有促进健康的特性。然而，它们的高成本阻碍了这些代谢物在制药领域的广泛使用。我们开发了一种病毒驱动的系统，可以在短短两周内在本塞姆氏烟草成年植物中产生大量的藏红花素和苦藏红花素。该系统由源自烟草蚀刻马铃薯病毒的病毒克隆组成，这些病毒克隆表达来自藏红花和醉鱼花的特定类胡萝卜素裂解双加氧酶（CCD）。对感染组织的代谢分析表明， C. sativus CsCCD2L 或B. davidii BdCCD4.1 的唯一病毒驱动表达导致了藏红花素、苦藏红花素和藏红花醛的产生。使用表达CsCCD2L的重组病毒，仅两周内就达到了叶片干重中0.2%的藏红花素和0.8%的苦藏红花素的积累。为了提高本塞姆氏烟草中的类胡萝卜素含量，使用相同的病毒系统进行了 CsCCD2L 与其他胡萝卜素生成酶的共表达，例如菠萝泛菌八氢番茄红素合酶 (PaCrtB) 和藏红花 β-胡萝卜素羟化酶 2 (BCH2)。这种组合方法使 CsCCD2L 和 PaCrtB 共表达的叶子中藏红花素额外增加了 0.35%。考虑到藏红花类胡萝卜素每年从花柱头中收获一次，成本高昂，而醉鱼草属。 花朵积累的量较少，该系统可能是可持续生产这些有价值的代谢物的有吸引力的替代方案。