National Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Horticultural Crop Biology and Genetic Improvement (East China) of Ministry of Agriculture and Rural Affairs, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China.
Key Laboratory of Biology and Genetic Improvement of Horticultural Crops, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Ministry of Agriculture and Rural Affairs, Beijing 100081, China.
Int J Mol Sci. 2022 Mar 9;23(6):2953. doi: 10.3390/ijms23062953.
Radish ( L.) is rich in specific glucosinolates (GSLs), which benefit human health and special flavor formation. Although the basic GSLs metabolic pathway in Brassicaceae plants is clear, the regulating mechanism for specific glucosinolates content in radish fleshy taproots is not well understood. In this study, we discovered that there was a significant difference in the GSLs profiles and the content of various GSLs components. Glucoraphasatin (GRH) is the most predominant GSL in radish taproots of different genotypes as assessed by HPLC analysis. Further, we compared the taproot transcriptomes of three radish genotypes with high and low GSLs content by employing RNA-seq. Totally, we identified forty-one differentially expressed genes related to GSLs metabolism. Among them, thirteen genes (, , , , , , , , , , , , and ) were significantly higher co-expressed in the high content genotypes than in low content genotype. Notably, correlation analysis indicated that the expression level of , as an R2R3 transcription factor directly regulating aliphatic glucosinolate biosynthesis, was positively correlated with the GRH content. Co-expression network showed that probably positively regulated the expression of the above genes, particularly , and consequently the synthesis of GRH. Moreover, the molecular mechanism of the accumulation of this 4-carbon (4C) GSL in radish taproots was explored. This study provides new perspectives on the GSLs accumulation mechanism and genetic improvements in radish taproots.
萝卜（L.）富含特定的硫代葡萄糖苷（GSLs），对人体健康和特殊风味的形成有益。虽然十字花科植物中基本的 GSL 代谢途径已经清楚，但萝卜肉质直根中特定 GSL 含量的调节机制尚不清楚。在这项研究中，我们发现不同基因型萝卜直根中的 GSL 图谱和各种 GSL 成分的含量存在显著差异。通过 HPLC 分析评估，萝卜直根中最主要的 GSL 是葡萄糖辣根素（GRH）。此外，我们通过 RNA-seq 比较了三个 GSL 含量高和低的萝卜基因型的直根转录组。总共鉴定出 41 个与 GSL 代谢相关的差异表达基因。其中，13 个基因（、、、、、、、、、、和）在高 GSL 含量基因型中的表达水平显著高于低 GSL 含量基因型。值得注意的是，相关性分析表明，作为直接调控脂肪族 GSL 生物合成的 R2R3 转录因子，的表达水平与 GRH 含量呈正相关。共表达网络表明，可能正向调控上述基因的表达，特别是和，从而合成 GRH。此外，还探讨了这种 4-碳（4C）GSL 在萝卜直根中积累的分子机制。本研究为萝卜直根中 GSL 积累机制和遗传改良提供了新的视角。
