Italian National Agency for New Technologies, Energy, and Sustainable Development (ENEA), Biotechnology Laboratory, Casaccia Research Centre, Rome, Italy.
Instituto Botánico. Departamento de Ciencia y Tecnología Agroforestal y Genética. Universidad de Castilla-La Mancha, Campus Universitario s/n, Albacete, Spain.
J Exp Bot. 2021 Apr 2;72(8):3200-3218. doi: 10.1093/jxb/erab053.
Crocetin biosynthesis in Buddleja davidii flowers proceeds through a zeaxanthin cleavage pathway catalyzed by two carotenoid cleavage dioxygenases (BdCCD4.1 and BdCCD4.3), followed by oxidation and glucosylation reactions that lead to the production of crocins. We isolated and analyzed the expression of 12 genes from the carotenoid pathway in B. davidii flowers and identified four candidate genes involved in the biosynthesis of crocins (BdALDH, BdUGT74BC1, BdUGT74BC2, and BdUGT94AA3). In addition, we characterized the profile of crocins and their carotenoid precursors, following their accumulation during flower development. Overall, seven different crocins, crocetin, and picrocrocin were identified in this study. The accumulation of these apocarotenoids parallels tissue development, reaching the highest concentration when the flower is fully open. Notably, the pathway was regulated mainly at the transcript level, with expression patterns of a large group of carotenoid precursor and apocarotenoid genes (BdPSY2, BdPDS2, BdZDS, BdLCY2, BdBCH, BdALDH, and BdUGT Genes) mimicking the accumulation of crocins. Finally, we used comparative correlation network analysis to study how the synthesis of these valuable apocarotenoids diverges among B. davidii, Gardenia jasminoides, and Crocus sativus, highlighting distinctive differences which could be the basis of the differential accumulation of crocins in the three species.
藏红花酸在宿根亚麻花花中的生物合成是通过两种类胡萝卜素裂解双加氧酶（BdCCD4.1 和 BdCCD4.3）催化的叶黄素裂解途径进行的，然后通过氧化和糖基化反应产生西红花酸。我们从宿根亚麻花花中分离并分析了 12 条类胡萝卜素途径的基因表达，并鉴定了 4 个参与西红花酸生物合成的候选基因（BdALDH、BdUGT74BC1、BdUGT74BC2 和 BdUGT94AA3）。此外，我们还研究了西红花酸及其类胡萝卜素前体在花发育过程中的积累情况。总的来说，本研究共鉴定出七种不同的西红花酸、藏红花酸和 picrocrocin。这些类胡萝卜素降解产物的积累与组织发育平行，在花朵完全开放时达到最高浓度。值得注意的是，该途径主要在转录水平上受到调控，一大组类胡萝卜素前体和类胡萝卜素降解产物基因（BdPSY2、BdPDS2、BdZDS、BdLCY2、BdBCH、BdALDH 和 BdUGT 基因）的表达模式与西红花酸的积累相似。最后，我们使用比较相关网络分析来研究这些有价值的类胡萝卜素降解产物在宿根亚麻、栀子和番红花中的合成如何发生分歧，突出了三者之间的明显差异，这些差异可能是三种植物中西红花酸积累差异的基础。
