role of root anatomy, organic acids and iron plaque on mercury accumulation in rice

• Published in: Plant and soil 2015-09, Vol.394 (1-2), p.301-313
• Main Authors: Wang, Xun, Tam, Nora Fung-Yee, He, Huaidong, Ye, Zhihong
• Format: Article
• Language: English
• Subjects: Accumulation; Acids; Anatomy; Bioaccumulation; Biomedical and Life Sciences; Contamination; Cultivars; Ecology; ecophysiology; endodermis; Health aspects; Hydroponics; Iron; Iron (Metal); Life Sciences; Mercury; Mercury (Metal); Methylmercury; methylmercury compounds; Organic acids; organic acids and salts; Oryza sativa; Plant Physiology; Plant Sciences; Plant-soil relationships; Regular Article; Rhizosphere; Rice; Roots; Soil pollution; Soil Science & Conservation; suberin
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-015-2537-y

BACKGROUND AND AIMS: Rice contaminated by mercury [Hg, especially methylmercury (MeHg)] has given rise to great concern in recent years. This study investigated variations in ecophysiological features (anatomy, organic acid secretions, Fe plaque formation) of rice roots and their effects on the uptake and accumulation of total mercury (THg) and MeHg by rice plants. METHODS: The development of apoplastic barriers in roots of four rice cultivars was observed by a hydroponic experiment while the concentrations of five organic acids, Fe and THg in Fe plaque were determined using a rhizobag trial with different Hg treatments. RESULTS: Cultivars with low Hg accumulation tended to develop strong apoplastic barriers in endodermis, secrete less organic acids and form more Fe plaque on root surfaces and in rhizosphere. Fe concentrations were positively correlated with THg concentrations in rhizosphere’s Fe plaque (R² = 0.60, P