Overexpression of ATP sulfurylase in Indian mustard leads to increased selenate uptake, reduction, and tolerance

• Published in: Plant physiology (Bethesda) 1999, Vol.119 (1), p.123-132
• Main Authors: Pilon-Smits, E.A.H, Hwang, S, Lytle, C.M, Zhu, Y, Tai, J.C, Bravo, R.C, Chen, Y, Leustek, T, Terry, N
• Format: Article
• Language: English
• Subjects: Absorption. Translocation of ions and substances. Permeability; adenosine triphosphate; Agronomy. Soil science and plant productions; aps1 genes; Apsides; Arabidopsis thaliana; biochemical pathways; Biological and medical sciences; Brassica juncea; Economic plant physiology; Environmental and Stress Physiology; enzyme activity; Enzymes; Fundamental and applied biological sciences. Psychology; gene expression; gene transfer; genes; genetic variation; kinases; Mustards; nutrient uptake; Nutrition. Photosynthesis. Respiration. Metabolism; phytotoxicity; Plant roots; Plants; reduction; roots; Seedlings; Selenium; shoots; Soil water; Sulfates; tolerance; transgenic plants; Vaporizing
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.119.1.123

In earlier studies, the assimilation of selenate by plants appeared to he limited by its reduction, a step that is thought to be mediated by ATP sulfurylase. Here, the Arabidopsis APS1 gene, encoding a plastidic ATP sulfurylase, was constitutively overexpressed in Indian mustard (Brassica juncea). Compared with that in untransformed plants, the ATP sulfurylase activity was 2- to 2.5-fold higher in shoots and roots of transgenic seedlings, and 1.5- to 2-fold higher in shoots but not roots of selenate-supplied mature ATP-sulfurylase-overexpressing (APS) plants. The APS plants showed increased selenate reduction: X-ray absorption spectroscopy showed that root and shoot tissues of mature APS plants contained mostly organic Se (possibly selenomethionine), whereas wild-type plants accumulated selenate. The APS plants were not able to reduce selenate when shoots were removed immediately before selenate was supplied. In addition, Se accumulation in APS plants was 2- to 3-fold higher in shoots and 1.5-fold higher in roots compared with wild-type plants, and Se tolerance was higher in both seedlings and mature APS plants. These studies show that ATP sulfurylase not only mediates selenate reduction in plants, but is also rate limiting for selenate uptake and assimilation.