Glucosinolate catabolism maintains glucosinolate profiles and transport in sulfur-starved Arabidopsis.

Glucosinolates (GSL) are sulfur (S)-rich specialized metabolites presented in Brassicales order plants. Our previous study found that GSL can function as S source in Arabidopsis seedlings via its catabolism catalyzed by two ß-glucosidases, BGLU28 and BGLU30. However, as GSL profiles in plants vary among growth stages and organs, the potential contribution of BGLU28/30-dependent GSL catabolism at the reproductive growth stage needs verification. Thus, in this study, we assessed growth, metabolic, and transcriptional phenotypes of mature bglu28/30 double mutants grown under different S conditions. Our results showed that compared to wild-type plants grown under -S, mature bglu28/30 mutants displayed impaired growth and accumulated increased levels of GSL in their reproductive organs and rosette leaves of before bolting plants. In contrast, the levels of primary S-containing metabolites, glutathione, and cysteine decreased in mature seeds. Furthermore, the transport of GSL from rosette leaves to the reproductive organs was stimulated in the bglu28/30 mutants under -S. Transcriptome analysis revealed that genes related to other biological processes, such as ethylene response, defense response, and plant response to heat, responded differentially to -S in the bglu28/30 mutants. Altogether, these findings broadened our understanding of the roles of BGLU28/30-dependent GSL catabolism in plant adaptation to nutrient stress.