PDF(Pubmed)
Abstract：
Glucosinolates (GSLs) are sulfur-containing bioactive compounds usually present in Brassicaceae plants and are usually responsible for a pungent flavor and reduction of the nutritional values of seeds. Therefore, breeding rapeseed varieties with low GSL levels is an important breeding objective. Most GSLs in Brassica rapa are derived from methionine or tryptophan, but two are derived from phenylalanine, one directly (benzylGSL) and one after a round of chain elongation (phenethylGSL). In the present study, two phenylalanine (Phe)-derived GSLs (benzylGSL and phenethylGSL) were identified and quantified in seeds by liquid chromatography and mass spectrometry (LC-MS) analysis. Levels of benzylGSL were low but differed among investigated low and high GSL genotypes. Levels of phenethylGSL (also known as 2-phenylethylGSL) were high but did not differ among GSL genotypes. Subsequently, a genome-wide association study (GWAS) was conducted using 159 B. rapa accessions to demarcate candidate regions underlying 43 and 59 QTNs associated with benzylGSL and phenethylGSL that were distributed on 10 chromosomes and 9 scaffolds, explaining 0.56% to 70.86% of phenotypic variations, respectively. Furthermore, we find that 15 and 18 known or novel candidate genes were identified for the biosynthesis of benzylGSL and phenethylGSL, including known regulators of GSL biosynthesis, such as BrMYB34, BrMYB51, BrMYB28, BrMYB29 and BrMYB122, and novel regulators or structural genes, such as BrMYB44/BrMYB77 and BrMYB60 for benzylGSL and BrCYP79B2 for phenethylGSL. Finally, we investigate the expression profiles of the biosynthetic genes for two Phe-derived GSLs by transcriptomic analysis. Our findings provide new insight into the complex machinery of Phe-derived GSLs in seeds of B. rapa and help to improve the quality of Brassicaceae plant breeding.
摘要：
硫代葡萄糖苷(GSL)是通常存在于十字花科植物中的含硫生物活性化合物,并且通常负责刺鼻的味道和降低种子的营养价值。因此,选育低GSL水平的油菜品种是重要的育种目标。芸苔属油菜中的大多数GSL来自蛋氨酸或色氨酸，但有两种是来源于苯丙氨酸,一个直接（苄基GSL）和一个经过一轮链延长（苯乙基GSL）。在本研究中,通过液相色谱和质谱（LC-MS）分析鉴定和定量种子中的两种苯丙氨酸（Phe）衍生的GSL（苄基GSL和苯乙基GSL）。苄基GSL水平较低，但在所研究的低GSL基因型和高GSL基因型之间存在差异。苯乙基GSL（也称为2-苯乙基GSL）的水平很高，但在GSL基因型之间没有差异。随后，使用159个B.rapa种质进行了全基因组关联研究（GWAS），以划分与苄基GSL和苯乙基GSL相关的43和59个QTNs的候选区域，这些区域分布在10个染色体和9个支架上，解释0.56%到70.86%的表型变异，分别。此外，我们发现15和18已知或新的候选基因被鉴定为生物合成苄基GSL和苯乙基GSL，包括已知的GSL生物合成调节剂，如BrMYB34，BrMYB51，BrMYB28，BrMYB29和BrMYB122，以及新的调节子或结构基因，例如BrMYB44/BrMYB77和BrMYB60用于苄基GSL和BrCYP79B2用于苯乙基GSL。最后,我们通过转录组学分析研究了两个Phe衍生的GSL的生物合成基因的表达谱。我们的研究结果为B.rapa种子中Phe衍生的GSL的复杂机制提供了新的见解，并有助于提高十字花科植物育种的质量。
