title: Isolation of novel types of Arabidopsis mutants with altered reactions to cadmium: cadmium-gradient agar plates are an effective screen for the heavy metal-related mutants.
abstract: We are interested in elucidating the molecular mechanisms underlying plant reactions to the toxic heavy metal cadmium (Cd). To this end, we devised a new screening strategy using agar plates with a gradient of Cd concentrations, termed Cd-gradient agar plates (CGAPs), to isolate Arabidopsis mutants that displayed altered reactions to the metal. Arabidopsis M(2) seeds, derived from ethyl methanesulfonate (EMS) treated seeds, were germinated on the CGAPs such that the primary root of each seedling elongated against increasing concentrations of Cd on the surface of the plate. Under these conditions, the lengths of the primary roots reliably demonstrated the degree of Cd tolerance of individual seedlings. The use of CGAPs also allowed close observation of the root reaction of each seedling to Cd without causing lethal damage. The screen identified three mutant lines, MRC-32, MRC-22 and MRC-26, which showed distinctly different characteristics. MRC-32 plants exhibited enhanced tolerance to Cd and contained Cd at higher concentrations than wild-type (WT) plants treated with the heavy metal. The whole root system of MRC-22 plants showed a Cd-phobic response. MRC-26 plants accumulated less Cd in their aboveground tissues than WT plants, suggesting that they were defective in transporting the heavy metal from roots to aboveground tissues. We also determined the likely chromosomal location of each mutation.
authors.affiliation: Department of Biological Production, Faculty of Bioresource Sciences, Akita Prefectural University, Shimoshinjo-Nakano, Akita, Japan. akiowat@akita-pu.ac.jp
authors.forename: Akio
authors.initials: A
authors.lastname: Watanabe
authors.forename: Hitomi
authors.initials: H
authors.lastname: Ito
authors.forename: Megumi
authors.initials: M
authors.lastname: Chiba
authors.forename: Azumi
authors.initials: A
authors.lastname: Ito
authors.forename: Hirono
authors.initials: H
authors.lastname: Shimizu
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Fuji
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Nakamura
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Hattori
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Chino
authors.forename: Namiko
authors.initials: N
authors.lastname: Satoh-Nagasawa
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Takahashi
authors.forename: Kenji
authors.initials: K
authors.lastname: Sakurai
authors.forename: Hiromori
authors.initials: H
authors.lastname: Akagi
mesh_terms: D000362:Agar / Q000737:chemistry*; D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D002104:Cadmium / Q000378:metabolism / Q000633:toxicity*; D019216:Metals, Heavy / Q000378:metabolism / Q000633:toxicity*; D030821:Plants, Genetically Modified / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism
chemical_list: D019216:Metals, Heavy; D002104:Cadmium; D000362:Agar