Overexpression of BoLSU1 and BoLSU2 Confers Tolerance to Sulfur Deficiency in Arabidopsis by Manipulating Glucosinolate Metabolism

Abstract

Sulfur is an essential element for plant growth, development and resistance to environmental stresses. Glucosinolates (GSLs), a group of sulfur rich secondary metabolites found in Brassicaceae plants, are known for their defensive properties against pathogens and herbivores. Due to their integration of a large proportion of total sulfur, their biosynthesis and degradation are closely linked to sulfur metabolism. It has been demonstrated that GSLs can be broken down to release sulfur and facilitate the production of other thio-metabolites when the plant is under stress. However, the regulation of this process is still not fully understood. In this study, we constructed two broccoli LSU (low sulfur responsive) gene overexpressing lines, 35S::BoLSU1 and 35S::BoLSU2, to detect changes in GSL metabolism after sulfur deficiency treatment. The results showed that BoLSU1 and BoLSU2 inhibit the biosynthesis of aliphatic GSLs, while also promoting their degradation and increasing the content of glutathione (GSH), leading to the reallocation of sulfur from the GSL pool to other thio-metabolites such as GSH. Furthermore, this regulation of GSL metabolism mediated by BoLSU1 and BoLSU2 is found to be dependent on myrosinases BGLU28 and BGLU30. Our study provides insight into the physiological role of LSU proteins and their regulation of sulfur metabolism.

Application of Tryptophan and Methionine in Broccoli Seedlings Enhances Formation of Anticancer Compounds Sulforaphane and Indole-3-Carbinol and Promotes Growth

“…Approximately 200 mg of fresh samples of broccoli seedlings were weighed, frozen immediately in liquid nitrogen, and stored at −80 • C. Glucosinolates were extracted with 5 mL of pre-cooled 80% methanol, and the extract was passed through DEAE Sephadex columns, followed by treatment with sulfatase (Sigma-Aldrich, Saint Louis, MO, USA). Extract solutions (5 µL) were then analyzed using ultra-high-performance liquid chromatography (UPLC) (1290 Infinity II, Agilent Technologies) according to the procedure previously described [26], and sinigrin (Sigma, USA) was used as an internal standard. The mobile phases were water (A) and methanol (B), and the gradient program was set as follows: 0 min, 0% solvent B; 7 min, 25% solvent B; 8.6 min, 60% solvent B; 9.2 min, 100% solvent B; 9.2-9.8 min, 100% solvent B; 10.6 min, 0% solvent B; and 10.6-13.0 min, 0% solvent B.…”