Sulfur assimilation and metabolism in brassica species under drought and salinity stress: Biochemical responses and adaptation mechanisms

Abstract

Brassica crops require substantial sulfur for synthesizing glucosinolates and stress-protective compounds. This research examined sulfur assimilation pathway responses to drought and salinity stress in Brassica juncea and Brassica napus. Experiments conducted at Bangkok Institute of Applied Sciences from October 2023 to February 2025 measured sulfate uptake, assimilatory enzyme activities, and sulfur-containing metabolite concentrations under controlled stress conditions. Results showed that drought stress increased ATP sulfurylase activity by 2.3-fold and cysteine content by 67% in B. juncea, while salinity elevated glutathione levels 2.8-fold. The sulfur assimilation pathway was upregulated under both stresses, with serine acetyltransferase activity increasing 1.9-fold. B. juncea demonstrated superior stress tolerance correlated with higher basal sulfur metabolite pools. These findings reveal sulfur metabolism as an important component of abiotic stress adaptation in Brassica species with implications for crop improvement.