Exogenous nitric oxide enhances cadmium tolerance of rice by increasing pectin and hemicellulose contents in root cell wall

• Published in: Planta Vol. 230; no. 4; pp. 755 - 765
• Main Authors: Xiong, Jie, An, Lingyao, Lu, Han, Zhu, Cheng
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Berlin/Heidelberg : Springer-Verlag 01.09.2009; Springer-Verlag; Springer; Springer Nature B.V
• Subjects: Accumulation; Adaptation, Physiological - drug effects; Agriculture; Atomic absorption spectroscopy; Biological and medical sciences; Biomedical and Life Sciences; Cadmium; Cadmium - toxicity; Cell Wall - drug effects; Cell Wall - metabolism; Cell walls; Cellulose; Ecology; Forestry; Fundamental and applied biological sciences. Psychology; Leaves; Life Sciences; Microscopy, Fluorescence; Nitric oxide; Nitric Oxide - metabolism; Nitric Oxide - pharmacology; Nitroprusside - pharmacology; Original Article; Oryza - cytology; Oryza - drug effects; Oryza - growth & development; Oryza - metabolism; Oxides; Pectins - metabolism; Photosynthesis - drug effects; Plant roots; Plant Roots - cytology; Plant Roots - drug effects; Plant Roots - growth & development; Plant Roots - metabolism; Plant Sciences; Plant Shoots - drug effects; Plant Shoots - metabolism; Plant Transpiration - drug effects; Plantlets; Plants; Pollution tolerance; Polysaccharides - metabolism; Rice; Roots; Sodium; Spectral analysis; Spectrometry; Tissue Distribution - drug effects; Toxicity; Transpiration; Cadmium; Hemicellulose; Pectin; Nitric oxide; Cellulose; Exogenous; Monocotyledones; Root; Plant biology; Tolerance; Cell wall; Oryza; Gramineae; Content; Angiospermae; Herbaceous plant; Spermatophyta
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s00425-009-0984-5

To study the mechanisms of exogenous NO contribution to alleviate the cadmium (Cd) toxicity in rice (Oryza sativa), rice plantlets subjected to 0.2-mM CdCl₂ exposure were treated with different concentrations of sodium nitroprusside (SNP, a NO donor), and Cd toxicity was evaluated by the decreases in plant length, biomass production and chlorophyll content. The results indicated that 0.1 mM SNP alleviated Cd toxicity most obviously. Atomic absorption spectrometry and fluorescence localization showed that treatment with 0.1 mM SNP decreased Cd accumulation in both cell walls and soluble fraction of leaves, although treatment with 0.1 mM SNP increased Cd accumulation in the cell wall of rice roots obviously. Treatment with 0.1 mM SNP in nutrient solution had little effect on the transpiration rate of rice leaves, but this treatment increased pectin and hemicellulose content and decreased cellulose content significantly in the cell walls of rice roots. Based on these results, we conclude that decreased distribution of Cd in the soluble fraction of leaves and roots and increased distribution of Cd in the cell walls of roots are responsible for the NO-induced increase of Cd tolerance in rice. It seems that exogenous NO enhances Cd tolerance of rice by increasing pectin and hemicellulose content in the cell wall of roots, increasing Cd accumulation in root cell wall and decreasing Cd accumulation in soluble fraction of leaves.