title: Importance of plant species and external silicon concentration to active silicon uptake and transport.
abstract: Here, we characterized silicon (Si) uptake and xylem loading in Oryza sativa, Zea mays, Helianthus annuus and Benincase hispida in a series of hydroponic experiments. Both active and passive Si-uptake components co-exist in all the plants tested. The active component is the major mechanism responsible for Si uptake in O. sativa and Z. mays. By contrast, passive uptake prevails in H. annuus and B. hispida at a higher external Si concentration (0.85 mM), while the active component constantly exists and contributes to the total Si uptake, especially at a lower external Si concentration (0.085 mM). Short experiments showed that Si uptake was significantly suppressed in O. sativa and Z. mays by metabolic inhibitors or low temperature, regardless of external Si concentrations. By contrast, Si uptake in H. annuus and B. hispida was inhibited more significantly by metabolic inhibitors or low temperature at lower (for example, 0.085 mM) than at higher (for example, 1.70 mM) external Si concentrations. It can be concluded that both active and passive Si-uptake components co-exist in O. sativa, Z. mays, H. annuus and B. hispida, with their relative contribution being dependent much upon both plant species and external Si concentrations.
authors.affiliation: Institute of Soil and Fertilizer, and Ministry of Agriculture Key Laboratory of Plant Nutrition and Nutrient Cycling, Chinese Academy of Agricultural Sciences, Beijing 100081, China. ycliang@caas.ac.cn
authors.forename: Yongchao
authors.initials: Y
authors.lastname: Liang
authors.forename: Haixia
authors.initials: H
authors.lastname: Hua
authors.forename: Yong-Guan
authors.initials: YG
authors.lastname: Zhu
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.forename: Chunmei
authors.initials: C
authors.lastname: Cheng
authors.forename: Volker
authors.initials: V
authors.lastname: Römheld
mesh_terms: D001693:Biological Transport, Active / Q000187:drug effects; D019662:Cucurbitaceae / Q000187:drug effects / Q000378:metabolism*; D006368:Helianthus / Q000187:drug effects / Q000378:metabolism*; D012275:Oryza / Q000187:drug effects / Q000378:metabolism*; D012825:Silicon / Q000378:metabolism* / Q000494:pharmacology*; D003313:Zea mays / Q000187:drug effects / Q000378:metabolism*
chemical_list: D012825:Silicon