significance of amino acids and amino acid-derived molecules in plant responses and adaptation to heavy metal stress

• Published in: Journal of experimental botany Vol. 57; no. 4; pp. 711 - 726
• Main Authors: Sharma, Shanti S, Dietz, Karl-Josef
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.03.2006; Oxford Publishing Limited (England)
• Subjects: Acclimatization - physiology; Adaptation; Amino acids; Amino Acids - biosynthesis; Amino Acids - chemistry; Amino Acids - physiology; Animal, plant and microbial ecology; antioxidants; Applied ecology; Biological and medical sciences; Cadmium; chelating agents; chemical constituents of plants; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on plants and fungi; Fundamental and applied biological sciences. Psychology; glutathione; Glutathione - metabolism; Glutathione - physiology; heavy metal stress; Heavy metals; Histidine - metabolism; Histidine - physiology; Leaves; literature reviews; metabolic detoxification; Metal ions; metal tolerance; Metals, Heavy - metabolism; Metals, Heavy - toxicity; N-containing metabolites; Nitrogen - metabolism; oligopeptides; Phytochelatins; plant adaptation; Plant biochemistry; Plant Physiological Phenomena; Plant physiology; Plant roots; plant stress; Plants; Plants - drug effects; Plants - metabolism; Polyamines; Polyamines - metabolism; proline; Proline - chemistry; Proline - metabolism; Proline - physiology; Review Article: Perspectives in Experimental Botany; signal transduction; stress defence; Polyamine; Algae; amino acids; stress defence; Review; Antioxidant; N- containing metabolites; Stress; Heavy metal; proline; heavy metal stress; Betaine; Aminoacid; Transgenic plant; Thallophyta; Adaptation
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/erj073

Plants exposed to heavy metals accumulate an array of metabolites, some to high millimolar concentrations. This review deals with N-containing metabolites frequently preferentially synthesized under heavy metal stress such as Cd, Cu, Ni, and Zn. Special focus is given to proline, but certain other amino acids and oligopeptides, as well as betaine, polyamines, and nicotianamine are also addressed. Particularly for proline a large body of data suggests significant beneficial functions under metal stress. In general, the molecules have three major functions, namely metal binding, antioxidant defence, and signalling. Strong correlative and mechanistic experimental evidence, including work with transgenic plants and algae, has been provided that indicates the involvement of metal-induced proline in metal stress defence. Histidine, other amino acids and particularly phytochelatins and glutathione play a role in metal binding, while polyamines function as signalling molecules and antioxidants. Their accumulation needs to be considered as active response and not as consequence of metabolic dys-regulation.