Guo Rongfang, Huang Zhongkai, Deng Yanping, Chen Xiaodong, XuHan Xu, Lai Zhongxiong
Department of Horticulture, Fujian Agriculture and Forestry UniversityFuzhou, China; Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry UniversityFuzhou, China.
Department of Horticulture, Fujian Agriculture and Forestry University Fuzhou, China.
Front Plant Sci. 2016 Oct 4;7:1497. doi: 10.3389/fpls.2016.01497. eCollection 2016.
sprouts contain abundant phytochemicals, especially glucosinolates (GSs). Various methods have been used to enhance GS content in sprouts. However, the molecular basis of GS metabolism in sprouts remains an open question. Here we employed RNA-seq analysis to compare the transcriptomes of high-GS (JL-08) and low-GS (JL-09) sprouts. Paired-end Illumina RNA-seq reads were generated and mapped to the reference genome. The differentially expressed genes were analyzed between JL-08 and JL-09. Among these, 1477 genes were up-regulated and 1239 down-regulated in JL-09 compared with JL-08. Enrichment analysis of these differentially expressed genes showed that the GS biosynthesis had the smallest enrichment factor and the highest -value of all metabolic pathways in Kyoto Encyclopedia of Genes and Genomes database, indicating the main metabolic difference between JL-08 and JL-09 is the GS biosynthetic pathway. Thirty-seven genes of the sequenced data were annotated as putatively involved in GS biosynthesis, degradation, and regulation, of which 11 were differentially expressed in JL-08 and JL-09. The expression level of GS degradation enzyme myrosinase in high-GS JL-08 was lower compared with low-GS JL-09. Surprisingly, in high-GS JL-08, the expression levels of GS biosynthesis genes were also lower than those in low-GS JL-09. As the GS contents in sprouts are determined by dynamic equilibrium of seed stored GS mobilization, synthesis, degradation, and extra transport, the result of this study leads us to suggest that efforts to increase GS content should focus on either raising GS content in seeds or decreasing myrosinase activity, rather than improving the expression level of GS biosynthesis genes in sprouts.
豆芽含有丰富的植物化学物质，尤其是硫代葡萄糖苷（GSs）。人们已经使用了各种方法来提高豆芽中GS的含量。然而，豆芽中GS代谢的分子基础仍然是一个悬而未决的问题。在这里，我们采用RNA测序分析来比较高GS（JL-08）和低GS（JL-09）豆芽的转录组。生成了双末端Illumina RNA测序读数并将其映射到参考基因组。分析了JL-08和JL-09之间差异表达的基因。其中，与JL-08相比，JL-09中有1477个基因上调，1239个基因下调。对这些差异表达基因的富集分析表明，在京都基因与基因组百科全书数据库中，GS生物合成在所有代谢途径中的富集因子最小，P值最高，表明JL-08和JL-09之间的主要代谢差异是GS生物合成途径。测序数据中的37个基因被注释为可能参与GS生物合成、降解和调控，其中11个在JL-08和JL-09中差异表达。高GS的JL-08中GS降解酶黑芥子酶的表达水平低于低GS的JL-09。令人惊讶的是，在高GS的JL-08中，GS生物合成基因的表达水平也低于低GS的JL-09。由于豆芽中GS的含量是由种子储存的GS动员、合成、降解和额外运输的动态平衡决定的，本研究结果促使我们建议，提高GS含量的努力应集中在提高种子中的GS含量或降低黑芥子酶活性上，而不是提高豆芽中GS生物合成基因的表达水平。
