Sulfur (S) is an essential element for plants, and S deficiency causes severe growth retardation. Although the catabolic process of glucosinolates (GSLs), the major S-containing metabolites specific to Brassicales including Arabidopsis, has been recognized as one of the S deficiency (-S) responses in plants, the physiological function of this metabolic process is not clear. Two β-glucosidases (BGLUs), BGLU28 and BGLU30, are assumed to be responsible for this catabolic process as their transcript levels were highly upregulated by -S. To clarify the physiological function of BGLU28 and BGLU30 and their roles in GSL catabolism, we analyzed the accumulation of GSLs and other S-containing compounds in the single and double mutant lines of BGLU28 and BGLU30 and in wild-type plants under different S conditions. GSL levels were highly increased, while the levels of sulfate, cysteine, glutathione and protein were decreased in the double mutant line of BGLU28 and BGLU30 (bglu28/30) under -S. Furthermore, transcript level of Sulfate Transporter1;2, the main contributor of sulfate uptake from the environment, was increased in bglu28/30 mutants under -S. With these metabolic and transcriptional changes, bglu28/30 mutants displayed obvious growth retardation under -S. Overall, our results indicate that BGLU28 and BGLU30 are required for -S-induced GSL catabolism and contribute to sustained plant growth under -S by recycling sulfate to primary S metabolism.

中文翻译：

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在硫缺乏下维持植物生长需要归因于两种β-葡萄糖苷酶（BGLU28和BGLU30）的硫缺乏诱导的芥子油苷分解代谢。

硫（S）是植物的必需元素，硫缺乏会严重阻碍生长。尽管芥子油苷（GSLs）的分解代谢过程已被公认为是植物中S缺乏（-S）响应之一，而芥子油苷（GSLs）是Brassicales特有的主要的含S代谢产物，是植物中S缺乏（-S）响应之一，但该代谢过程的生理功能尚不清楚。假定有两个β-葡萄糖苷酶（BGLUs）BGLU28和BGLU30负责该分解代谢过程，因为它们的转录水平被-S高度上调。为了阐明BGLU28和BGLU30的生理功能及其在GSL分解代谢中的作用，我们分析了BSL28和BGLU30的单突变和双突变系以及不同S条件下野生型植物中GSL和其他含S化合物的积累。GSL水平大大提高，在-S条件下，BGLU28和BGLU30双突变株（bglu28 / 30）的硫酸盐，半胱氨酸，谷胱甘肽和蛋白质水平降低。此外，在-S条件下，bglu28 / 30突变体中硫酸盐转运蛋白1、2（从环境中吸收硫酸盐的主要起因）的转录水平升高。通过这些代谢和转录变化，bglu28 / 30突变体在-S下显示出明显的生长迟缓。总的来说，我们的结果表明，BGLU28和BGLU30是-S诱导的GSL分解代谢所必需的，并且通过将硫酸盐再循环至主要S代谢，有助于在-S下持续植物生长。在-S条件下，bglu28 / 30突变体增加了从环境中吸收硫酸盐的主要作用。通过这些代谢和转录变化，bglu28 / 30突变体在-S下显示出明显的生长迟缓。总的来说，我们的结果表明，BGLU28和BGLU30是-S诱导的GSL分解代谢所必需的，并且通过将硫酸盐再循环至主要S代谢，有助于在-S下持续植物生长。在-S条件下，bglu28 / 30突变体增加了从环境中吸收硫酸盐的主要作用。通过这些代谢和转录变化，bglu28 / 30突变体在-S下显示出明显的生长迟缓。总的来说，我们的结果表明，BGLU28和BGLU30是-S诱导的GSL分解代谢所必需的，并且通过将硫酸盐再循环至主要S代谢，有助于在-S下持续植物生长。