Glucose enhances indolic glucosinolate biosynthesis without reducing primary sulfur assimilation

Area of Science:

• Plant molecular biology
• Plant biochemistry
• Plant signaling

Background:

• Glucose acts as a signaling molecule influencing plant metabolic pathways.
• Previous research established glucose's role in aliphatic glucosinolate biosynthesis.
• Understanding glucose regulation of indolic glucosinolates is crucial for plant defense mechanisms.

Purpose of the Study:

• To elucidate the regulatory mechanisms of indolic glucosinolate biosynthesis induced by glucose in Arabidopsis.
• To identify key genes and signaling components involved in this glucose response.

Main Methods:

• Arabidopsis thaliana genetic analysis and mutant studies (gin2-1).
• Quantitative real-time PCR (qRT-PCR) to measure gene expression levels.
• Measurement of indolic glucosinolate accumulation and sulfur assimilation.

Main Results:

• Glucose treatment significantly increased indolic glucosinolate levels and related gene expression.
• MYB34 and MYB51 are essential for basal indolic glucosinolate levels, with MYB34 critical for glucose response.
• The hexokinase 1 (HXK1) pathway, but not ABI5, is involved in glucose-induced indolic glucosinolate biosynthesis.
• Glucose enhances overall sulfur assimilation, contributing to increased glucosinolate production.

Conclusions:

• Glucose positively regulates indolic glucosinolate biosynthesis in Arabidopsis through specific MYB transcription factors and HXK1.
• The mechanism involves enhanced sulfur assimilation rather than altered sulfur partitioning.
• This study provides novel insights into the molecular basis of glucose-mediated regulation of glucosinolate pathways.