Chemopreventive glucosinolate accumulation in various broccoli and collard tissues: Microfluidic-based targeted transcriptomics for by-product valorization

Floret, leaf, and root tissues were harvested from broccoli and collard cultivars and extracted to determine their glucosinolate and hydrolysis product profiles using high performance liquid chromatography and gas chromotography. Quinone reductase inducing bioactivity, an estimate of anti-cancer chemopreventive potential, of the extracts was measured using a hepa1c1c7 murine cell line. Extracts from root tissues were significantly different from other tissues and contained high levels of gluconasturtiin and glucoerucin. Targeted gene expression analysis on glucosinolate biosynthesis revealed that broccoli root tissue has elevated gene expression of AOP2 and low expression of FMOGS-OX homologs, essentially the opposite of what was observed in broccoli florets, which accumulated high levels of glucoraphanin. Broccoli floret tissue has significantly higher nitrile formation (%) and epithionitrile specifier protein gene expression than other tissues. This study provides basic information of the glucosinolate metabolome and transcriptome for various tissues of Brassica oleracea that maybe utilized as potential byproducts for the nutraceutical market.

本研究从西兰花与羽衣甘蓝栽培品种中采集花簇、叶片及根组织，经提取后采用高效液相色谱法（high performance liquid chromatography）与气相色谱法（gas chromatography）分析其硫代葡萄糖苷（glucosinolate）及其水解产物的特征谱。提取物的醌还原酶诱导生物活性——作为抗癌化学预防潜力的评估指标——通过hepa1c1c7小鼠细胞系进行检测。根组织提取物与其他组织提取物存在显著差异，且含有高水平的黑芥子苷（gluconasturtiin）与glucoerucin。针对硫代葡萄糖苷生物合成的靶向基因表达分析显示，西兰花根组织中AOP2基因表达上调，而FMOGS-OX同源基因表达水平较低，这与花簇组织的基因表达模式恰好相反：花簇组织中积累了高水平的萝卜硫苷（glucoraphanin）。西兰花的花簇组织较其他组织具有显著更高的腈类生成率（%）及环硫腈定向蛋白基因表达水平。本研究为甘蓝（Brassica oleracea）不同组织的硫代葡萄糖苷代谢组与转录组提供了基础数据，这些组织或可作为营养保健品市场的潜在副产物加以开发利用。