title: Cadmium-induced lignification restricts soybean root growth.
abstract: The effects of cadmium (Cd), a well-known environmental pollutant with high toxicity to plants, were tested on root growth, cell viability, phenylalanine ammonia-lyase (PAL) soluble plus cell wall-bound peroxidase (POD) activities, hydrogen peroxide (H(2)O(2)) levels, and the content and monomeric composition of lignin in soybean (Glycine max) roots. Three-day-old seedlings were cultivated in half-strength Hoagland's solution (pH 6.0), with or without 25-100 μM CdCl(2) in a growth chamber (25°C, 12/12-h light/dark photoperiod, irradiance of 280 μmolm(-2)s(-1)) for 24h. In general, root length and the fresh and dry weights decreased followed by loss of cell viability after Cd treatment. PAL activity, soluble and cell wall-bound POD activities, and H(2)O(2) and lignin contents increased significantly after Cd exposure. The lignin monomeric composition of Cd-exposed roots revealed a significant increase of p-hydroxyphenyl (H) and syringyl (S) units. These results suggest that the effects caused by Cd may be due to excessive production of monolignols forming lignin, which solidifies the cell wall and restricts root growth.
authors.affiliation: Department of Biochemistry, University of Maringá, Av. Colombo, 5790, 87020-900 Maringá, PR, Brazil.
authors.forename: Aline
authors.initials: A
authors.lastname: Finger-Teixeira
authors.forename: Maria de Lourdes Lucio
authors.initials: Mde L
authors.lastname: Ferrarese
authors.forename: Anderson Ricardo
authors.initials: AR
authors.lastname: Soares
authors.forename: Débora
authors.initials: D
authors.lastname: da Silva
authors.forename: Osvaldo
authors.initials: O
authors.lastname: Ferrarese-Filho
mesh_terms: D019256:Cadmium Chloride / Q000633:toxicity*; D002470:Cell Survival / Q000187:drug effects; D002473:Cell Wall / Q000187:drug effects / Q000378:metabolism; D004785:Environmental Pollutants / Q000737:chemistry / Q000633:toxicity*; D006861:Hydrogen Peroxide / Q000378:metabolism; D008031:Lignin / Q000378:metabolism*; D010544:Peroxidases / Q000378:metabolism; D010650:Phenylalanine Ammonia-Lyase / Q000378:metabolism; D017440:Photoperiod; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D013025:Glycine max / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D013997:Time Factors
chemical_list: D004785:Environmental Pollutants; D008031:Lignin; D006861:Hydrogen Peroxide; D010544:Peroxidases; D010650:Phenylalanine Ammonia-Lyase; D019256:Cadmium Chloride