title: Silicon modifies root anatomy, and uptake and subcellular distribution of cadmium in young maize plants.
abstract: OBJECTIVE
  Silicon (Si) has been shown to ameliorate the negative influence of cadmium (Cd) on plant growth and development. However, the mechanism of this phenomenon is not fully understood. Here we describe the effect of Si on growth, and uptake and subcellular distribution of Cd in maize plants in relation to the development of root tissues.
  
  
  METHODS
  Young maize plants (Zea mays) were cultivated for 10 d hydroponically with 5 or 50 µm Cd and/or 5 mm Si. Growth parameters and the concentrations of Cd and Si were determined in root and shoot by atomic absorption spectrometry or inductively coupled plasma mass spectroscopy. The development of apoplasmic barriers (Casparian bands and suberin lamellae) and vascular tissues in roots were analysed, and the influence of Si on apoplasmic and symplasmic distribution of (109)Cd applied at 34 nm was investigated between root and shoot.
  
  
  RESULTS
  Si stimulated the growth of young maize plants exposed to Cd and influenced the development of Casparian bands and suberin lamellae as well as vascular tissues in root. Si did not affect the distribution of apoplasmic and symplasmic Cd in maize roots, but considerably decreased symplasmic and increased apoplasmic concentration of Cd in maize shoots.
  
  
  CONCLUSIONS
  Differences in Cd uptake of roots and shoots are probably related to the development of apoplasmic barriers and maturation of vascular tissues in roots. Alleviation of Cd toxicity by Si might be attributed to enhanced binding of Cd to the apoplasmic fraction in maize shoots.
authors.affiliation: Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovakia. vaculik@fns.uniba.sk
authors.forename: Marek
authors.initials: M
authors.lastname: Vaculík
authors.forename: Tommy
authors.initials: T
authors.lastname: Landberg
authors.forename: Maria
authors.initials: M
authors.lastname: Greger
authors.forename: Miroslava
authors.initials: M
authors.lastname: Luxová
authors.forename: Miroslava
authors.initials: M
authors.lastname: Stoláriková
authors.forename: Alexander
authors.initials: A
authors.lastname: Lux
mesh_terms: D001692:Biological Transport; D002104:Cadmium / Q000493:pharmacokinetics* / Q000633:toxicity*; D018517:Plant Roots / Q000033:anatomy & histology / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism*; D012825:Silicon / Q000494:pharmacology*; D014018:Tissue Distribution; D003313:Zea mays / Q000033:anatomy & histology* / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*
chemical_list: D002104:Cadmium; D012825:Silicon