藏红花素(Crocins)属于脱辅基类胡萝卜素的糖苷，是名贵药材藏红花的主要活性成分，对人体健康具有重要保健功能。其生物合成是通过裂解类胡萝卜素前体玉米黄素特异合成藏红花酸及藏红花素，需多个基因。水稻胚乳不含类胡萝卜素前体。前期研究中，申请人利用高效的多基因载体系统TGSII，在水稻胚乳特异表达PSY、Crt I和BHY基因，实现了玉米黄素的合成。本研究拟用TGSII系统增加下游关键酶基因，同时利用DXS和OR基因增加上游萜类底物和扩大质体库的方式，实现水稻胚乳的藏红花素合成：(1) 用水稻愈伤转化筛选平台进行下游关键酶的体内活性筛选与藏红花素的合成验证；(2) 用整个合成途径的6~7个基因加DXS和OR的不同组合，实现胚乳中藏红花素的大量合成；(3) 用转录组和代谢组联合分析阐明其类胡萝卜素的代谢合成机制。本项目有望创制营养功能性的水稻新种质，具有重要的理论意义和应用前景。

Crocins belong to the glycosides of apocarotenoid and is the main active component of saffron (Crocus sativus) that is a traditional Chinese precious medicine. The biosynthetic pathway of crocins involves the specific synthesis of crocetin and crocin through the cleavage of the carotenoid precursor zeaxanthin, which require multiple genes. Rice endosperm contains no any carotenoid precursors. Therefore, in the preliminary study, we synthesized zeaxanthin in rice endosperm by multi-transgene stacking of three key structure genes, PSY, Crt I and BHY using the high-efficient TGSII system. In order to achieve the final synthesis of crocins in rice endosperm, we will stack the downstream key enzyme genes, and DXS and OR genes that are used to increase the upstream terpenoid substrates and expand the plastids storages by using TGSII. (1) Rice callus transformation platform was used to in vivo screen and identify key enzymes and synthesize crocins; (2) Transformation of rice using different combinations of DXS and OR with 6~7 genes of the whole pathway, to produce crocins rice with more crocins content; (3) Using conjoint analysis of transcriptome and metabolome to elucidate the metabolic mechanism of the carotenoids in endosperm of “crocins rice”. This project is expected to create new nutritionally functional rice germplasm, which has important theoretical significance and application prospects.