Carotenoids are not naturally accumulated in the endosperms of rice, which is a cereal crop. In our previous study, biofortified rice seeds accumulated two red color carotenoids, ketocarotenoids including astaxanthin and ketoxanthophylls including capsanthin, via four-step pathway engineering. Their biosynthetic pathways require zeaxanthin as a common precursor and then bifurcated. In this study, cross-fertilization between two astaxanthin (BP and sBP) and two capsanthin (C and CB) rice plants were reciprocally performed to elucidate the rice seed system’s metabolic preference. Filial seeds showed different colors in red hues between mutually interbred lines as well as from parents. The strongest driving force for metabolism was caused by the sBP line for astaxanthin regardless of the parent side and proved to be the most efficacious customized synthetic gene for rice crops. It further resulted in the highest astaxanthin levels when paternal sBP mated with maternal CB line, which has the biggest capacity of total carotenoids. Also, reciprocal crosses between CB and BP lines ascertained their metabolically balanced gene efficacy by showing the pathway preference toward either ketoxanthophylls or ketocarotenoids depending on the paternal parental side. Our study suggests that gene efficacy plays the most decisive role in leading the metabolic path and revealed the unexpectedly paternal parent-of-origin effects in the endosperm. Consequently, we simultaneously biofortified rice crops with two functional red carotenoids and finally generated new red-colored rice varieties.

类胡萝卜素不会自然积累在稻谷的胚乳中，稻谷是谷类作物。在我们之前的研究中，生物强化水稻种子通过四步通路工程积累了两种红色类胡萝卜素，包括虾青素的酮类胡萝卜素和包括辣椒红的酮叶黄素。它们的生物合成途径需要玉米黄质作为共同前体，然后分叉。在这项研究中，两种虾青素（BP 和 sBP）和两种辣椒红素（C 和 CB）水稻植物之间的交叉受精相互进行，以阐明水稻种子系统的代谢偏好。孝子的种子在互交系之间以及来自亲本的红色调中显示出不同的颜色。最强的代谢驱动力是由虾青素的 sBP 系引起的，无论亲本如何，并且被证明是最有效的水稻作物定制合成基因。当父系 sBP 与母系 CB 系交配时，它进一步导致最高的虾青素水平，母系 CB 系具有最大的总类胡萝卜素容量。此外，CB 和 BP 品系之间的互惠杂交通过显示对酮叶黄素或酮类胡萝卜素的途径偏好取决于父系亲本，从而确定了它们的代谢平衡基因功效。我们的研究表明，基因功效在引导代谢路径方面起着最决定性的作用，并揭示了胚乳中出乎意料的父本起源效应。最后，