Tomato is a major source of dietary carotenoids that play an important role in human health. Improving the carotenoid profiles of tomato fruit has become a primary aspect in tomato breeding. The tomato ‘Huang Song’ landrace grows vigorously but with low contents of carotenoids in this yellowish fruit. To overcome this problem and extend lycopene to high-value astaxanthin, we co-expressed four genes encoding for phytoene synthase (crtB), β-carotene hydroxylase (BHY), β-carotene ketolase (BKT), and lycopene β-cyclase (LCYB), respectively, in the fruit of the landrace via linking the genes with 2A-sequences and driving their expression with the E8 promoter. The transgenic lines showed similar phenotypes to WT except for the fruit colors. The transgenic fruit exhibited deep red color due to the accumulation of novel ketocarotenoids including astaxanthin, canthaxanthin, and ketolutein and enhanced production of native carotenoids which were 20 ~ 44-fold of the control. The T0, T1, and T2 plants exhibited similar growing status and carotenoid profiles, indicating that the transformants were genetically stable. The transgenes resulted in upregulation of most of the endogenous carotenogenic genes in fruit at mature green stage and more plastoglobules in chromoplast. This study provides insights into metabolic engineering of tomato for enhanced production of value-added carotenoids.

番茄是膳食类胡萝卜素的主要来源，对人类健康起着重要作用。改善番茄果实的类胡萝卜素成分已成为番茄育种的主要方面。番茄'黄松'地方品种生长旺盛，但这种黄色果实中类胡萝卜素含量低。为了克服这个问题并将番茄红素扩展为高价值虾青素，我们共表达了四种编码八氢番茄红素合酶 (crtB)、β-胡萝卜素羟化酶 (BHY)、β-胡萝卜素酮醇酶 (BKT) 和番茄红素 β-环化酶 (LCYB) 的基因。 )，分别通过将基因与 2A 序列连接并用 E8 启动子驱动它们的表达在地方品种的果实中。除了果实颜色外，转基因品系显示出与 WT 相似的表型。由于虾青素、角黄素和酮叶黄素等新型酮类胡萝卜素的积累和天然类胡萝卜素产量的增加，转基因果实呈现深红色，是对照的 20~44 倍。T0、T1 和 T2 植物表现出相似的生长状态和类胡萝卜素特征，表明转化体在遗传上是稳定的。转基因导致成熟绿色阶段果实中大部分内源性类胡萝卜素基因的上调和色体中更多的质体球。这项研究提供了对番茄代谢工程的见解，以提高增值类胡萝卜素的产量。表明转化体是遗传稳定的。转基因导致成熟绿色阶段果实中大部分内源性类胡萝卜素基因的上调和色体中更多的质体球。这项研究提供了对番茄代谢工程的见解，以提高增值类胡萝卜素的产量。表明转化体是遗传稳定的。转基因导致成熟绿色阶段果实中大部分内源性类胡萝卜素基因的上调和色体中更多的质体球。这项研究提供了对番茄代谢工程的见解，以提高增值类胡萝卜素的产量。