Sulfur Deficiency-Induced Glucosinolate Catabolism Attributed to Two β-Glucosidases, BGLU28 and BGLU30, is Required for Plant Growth Maintenance under Sulfur Deficiency

• Published in: Plant and cell physiology 2020-04, Vol.61 (4), p.803-813
• Main Authors: Zhang, Liu, Kawaguchi, Ryota, Morikawa-Ichinose, Tomomi, Allahham, Alaa, Kim, Sun-Ju, Maruyama-Nakashita, Akiko
• Format: Article
• Language: English
• Subjects: Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Cellulases - metabolism; Cysteine - metabolism; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Gene Expression Regulation, Plant; Glucosinolates - metabolism; Glutathione - metabolism; Plant Development - genetics; Sulfates - metabolism; Sulfur - deficiency; Sulfur - metabolism; Transcription Factors - genetics; Transcription Factors - metabolism
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/pcaa006

Abstract 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.