Transgenic tobacco plants expressing a rice cysteine synthase gene are tolerant to toxic levels of cadmium

• Published in: Journal of plant physiology Vol. 158; no. 5; pp. 655 - 661
• Main Authors: Harada, Emiko, Choi, Yong-Eui, Tsuchisaka, Atsunari, Obata, Hitoshi, Sano, Hiroshi
• Format: Journal Article
• Language: English
• Published: Jena Elsevier GmbH 2001; Elsevier
• Subjects: Adaptation to environment and cultivation conditions; Agronomy. Soil science and plant productions; Biological and medical sciences; cadmium tolerance; cysteine synthase; Fundamental and applied biological sciences. Psychology; Genetics and breeding of economic plants; Nicotiana tabacum; Physiological diseases. Varia; Phytopathology. Animal pests. Plant and forest protection; sulfur; thiol; Varietal selection. Specialized plant breeding, plant breeding aims; thiol; sulfur; cysteine synthase; Nicotiana tabacum; cadmium tolerance; Monocotyledones; Cysteine; Stimulant plant; Lyases; Soil pollution; Cereal crop; Oryza sativa; Gramineae; Dicotyledones; Cysteine synthase; Angiospermae; Transgenic plant; Solanaceae; Cadmium; Enzyme; Tolerance; Detoxication; Heavy metal; Phytotoxicity; Sensitivity resistance; Limiting factor; Genetic improvement; Chelating agent; Spermatophyta; Carbon-oxygen lyases; Phytochelatin
• ISSN: 0176-1617; 1618-1328
• DOI: 10.1078/0176-1617-00314

Plants tolerate heavy metals through sequestration with cysteine-rich peptides, phytochelatins. In this reaction, the rate limiting step is considered to be the supply of cysteine, which is synthesized by cysteine synthase (CS, EC 4.2.99.8) from hydrogen sulfide and O-acetylserine. In this study, we transformed tobacco ( Nicotiana tabacum) plants with RCS1, a cytosolic cysteine synthase gene of rice ( Oryza sativa), and examined their sensitivity to cadmium. The transgenic plants had up to 3-fold higher activity of cysteine synthase than wild-type plants. Upon exposure to cadmium, they exhibited obvious tolerance with much greater growth than wild-type plants. The level of phytochelatins in shoots was higher in transgenic than in wild-type plants after cadmium treatment, suggesting that cadmium was actively trapped by phytochelatins. However, the cadmium concentration per g fresh weight of whole transgenic plants was 20 percnt; lower than that of wild-type plants, suggesting cadmium to be either actively excreted or diluted by fast growth. Genetic analysis of progenies clearly showed segregation of cadmium tolerance, indicating that the trait resulted from the introduced gene. These results suggest that introduction of a cysteine synthase gene into tobacco plants resulted not only in high level production of sulfur-containing compounds that detoxify cadmium, but also in active elimination of cadmium toxicity from plant bodies.