Root Transcriptome of WT, SDI1 Overexpression Lines and sdi1sdi2 Double Knockouts Grown under Sulfur Sufficient and Deficient Conditions. Arabidopsis thaliana

Sulfur-deficiency-induced repressor proteins optimize glucosinolate biosynthesis in plants Glucosinolates (GSLs) in the plant order of the Brassicales are sulfur-rich secondary metabolites harboring anti-pathogenic and anti-herbivory plant-protective functions as well as possessing medicinal properties such as carcinopreventive and antibiotic activities. Plants repress GSL biosynthesis upon sulfur deficiency (–S), hence, field performance and medicinal quality are impaired by inadequate sulfate supply. The molecular mechanism linking –S to GSL biosynthesis has remained understudied. We report here the identification of the –S marker genes Sulfur deficiency induced1 and Sulfur deficiency induced2 (SDI1, SDI2) acting as major repressors controlling GSL biosynthesis in Arabidopsis under –S condition. SDI1 and SDI2 expression negatively correlated with GSL biosynthesis in both transcript and metabolite levels. Principal component analysis of transcriptome data indicated that SDI1 regulates aliphatic GSL biosynthesis as part of –S-response. SDI1 was localized to the nucleus and interacted with MYB28, a major transcription factor promoting aliphatic GSL biosynthesis, in both yeast and plant cells. SDI1 inhibited transcription of aliphatic GSL biosynthetic genes through maintaining the DNA-binding composition in a form of a SDI1-MYB28 complex, leading to down-regulate GSL biosynthesis and prioritize sulfate usage for primary metabolites under sulfur-deprived conditions. Overall design: Root tissues from WT, 2 lines of sdi1sdi2 double knockout mutants (sdi1sdi2-1 and sdi1sdi2-4) and 2 lines of SDI1 overexpression plants (SDI1ox-6 and SDI1ox-12) grown for 10 days were used for the analysis. WT and sdi1sdi2 double knockouts were grown under +S (1500 µM sulfate) or –S (15 µM sulfate) conditions and SDI1ox plants were grown under +S conditions. Experiments were duplicated for each condition. Hybridization were performed using the ATH1-121501.1 Array (Affymetrix) according to the manufacturer’s protocol.