Glucosinolates (GSLs) are secondary metabolites that play important roles in plant defense and are suggested to act as storage compounds. Despite their important roles, metabolic dynamics of GSLs under various growth conditions remain poorly understood. To determine how light conditions influence the levels of different GSLs and their distribution in Arabidopsis leaves, we visualized the GSLs under different light conditions using matrix-assisted laser desorption/ionization mass spectrometry imaging. We observed the unique distribution patterns of each GSL in the inner regions of leaves and marked decreases under darkness, indicating light conditions influenced GSL metabolism. GSLs are hydrolyzed by a group of ß-glucosidase (BGLU) called myrosinase. Previous transcriptome data for GSL metabolism under light and dark conditions have revealed the highly induced expression of BGLU30, one of the putative myrosinases, which is also annotated as Dark INducible2, under darkness. Impairment of the darkness-induced GSL decrease in the disruption mutants of BGLU30, bglu30, indicated that BGLU30 mediated GSL hydrolysis under darkness. Based on the GSL profiles in the wild-type and bglu30 leaves under both conditions, short-chain GSLs were potentially preferable substrates for BGLU30. Our findings provide an effective way of visualizing GSL distribution in plants and highlighted the carbon storage GSL function.

中文翻译：

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在黑暗条件下，BGLU30参与拟南芥叶片中的芥子油苷分解代谢。

芥子油苷（GSLs）是次生代谢产物，在植物防御中起重要作用，并被建议作为储存化合物。尽管它们的重要作用，但人们对GSL在各种生长条件下的代谢动力学知之甚少。确定光照条件如何影响不同GSL的水平及其在拟南芥中的分布叶子，我们使用基质辅助激光解吸/电离质谱成像技术在不同的光照条件下观察了GSL。我们观察到每个GSL在叶片内部区域的独特分布模式，并且在黑暗下明显减少，表明光照条件影响GSL代谢。GSL被一组称为黑芥子酶的β-葡萄糖苷酶（BGLU）水解。先前在黑暗和黑暗条件下进行GSL代谢的转录组数据显示，在黑暗中高度诱导了BGLU30的表达，BGLU30是一种假定的黑芥子酶，也被称为Dark Inducible2。BGLU30，bglu30破坏突变体中黑暗诱导的GSL降低的损害，表明BGLU30在黑暗中介导了GSL水解。基于两种条件下野生型和bglu30叶片中的GSL谱，短链GSL是BGLU30的潜在底物。我们的发现提供了可视化植物中GSL分布的有效方法，并强调了碳储存GSL功能。