Kyushu Okinawa Agricultural Research Centre, National Agriculture and Food Research Organisation, 6651-2 Yokoichi, Miyakonojo, Miyazaki, 885-0091, Japan.
Sci Rep. 2020 Nov 26;10(1):20607. doi: 10.1038/s41598-020-77293-7.
The mechanisms of carotenoid accumulation in yellow-fleshed sweetpotato cultivars are unclear. In this study, we compared the transcriptome profiles of a yellow-fleshed cultivar, Beniharuka (BH) and two of its spontaneous white-fleshed mutants (WH2 and WH3) to reveal the genes involved in yellow flesh. As a result of RNA sequencing, a total of 185 differentially expressed genes (DEGs) were commonly detected in WH2 and WH3 compared to BH. Of these genes, 85 DEGs and 100 DEGs were commonly upregulated and downregulated in WH2 and WH3 compared to BH, respectively. g1103.t1, a paralog of zeaxanthin epoxidase (ZEP), was only DEG common to WH2 and WH3 among 38 genes considered to be involved in carotenoid biosynthesis in storage roots. The expression level of g1103.t1 was also considerably lower in five white-fleshed cultivars than in five yellow-fleshed cultivars. Analysis of carotenoid composition in the storage roots showed that the epoxidised carotenoids were drastically reduced in both WH2 and WH3. Therefore, we propose that the ZEP paralog, g1103.t1, may be involved in carotenoid accumulation through the epoxidation of β-carotene and β-cryptoxanthin in sweetpotato.
黄色果肉甘薯品种类胡萝卜素积累的机制尚不清楚。本研究比较了黄色果肉品种 Beniharuka (BH) 及其两个自发白色果肉突变体 (WH2 和 WH3) 的转录组图谱，以揭示与黄色果肉相关的基因。通过 RNA 测序，在 WH2 和 WH3 与 BH 相比共检测到 185 个差异表达基因 (DEG)。这些基因中，85 个 DEG 和 100 个 DEG 在 WH2 和 WH3 中分别相对于 BH 上调和下调。g1103.t1 是玉米黄质环氧化酶 (ZEP) 的一个基因，是在 38 个被认为参与贮藏根类胡萝卜素生物合成的基因中，在 WH2 和 WH3 中唯一共有的 DEG。g1103.t1 的表达水平在五个白色果肉品种中也明显低于五个黄色果肉品种。贮藏根中类胡萝卜素组成的分析表明，WH2 和 WH3 中的环氧化类胡萝卜素明显减少。因此，我们提出 ZEP 基因的 paralog g1103.t1 可能通过β-胡萝卜素和β-隐黄质的环氧化作用参与甘薯类胡萝卜素的积累。
