title: Lead tolerance and accumulation in the gametophytes of the fern Athyrium yokoscense.
abstract: The fern Athyrium yokoscense is known to be highly tolerant to lead toxicity, and is a lead hyperaccumulator that can accumulate over 1,000 microg g(-1) of lead in its dry matter. In this work, we examined whether the gametophytic generation of A. yokoscense also resists lead toxicity like the sporophytic generation. Spore germination in A. yokoscense was more tolerant to Pb2+, compared to that in other fern species, such as Pteridium aquilinum, Lygodium japonicum and Pteris vittata. In addition, the early gametophyte development of A. yokoscense was not much affected by 10 microM Pb2+, as evaluated from the prothallial growth and rhizoid development. We also showed that Athyrium gametophytes could accumulate more than 10,000 microg g(-1) of lead, and that the lead was localized in the cytosol and vacuole of rhizoidal cells, as determined by a transmission electron micrograph. These results indicate that Athyrium gametophytes have the ability to accumulate lead in the rhizoids. Furthermore, the gametophytes were found to include a large amount of proanthocyanidins (condensed tannins). Because proanthocyanidins have a latent ability to complex with lead ions, the possible roles of proanthocyanidins in the lead tolerance and accumulation of Athyrium gametophytes are discussed.
authors.affiliation: Department of Environmental Biology and Chemistry, Faculty of Science, Toyama University, 3190 Gofuku, Toyama, 930-8555, Japan. kamachi@sci.toyama-u.ac.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kamachi
authors.forename: Ippei
authors.initials: I
authors.lastname: Komori
authors.forename: Hideo
authors.initials: H
authors.lastname: Tamura
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Sawa
authors.forename: Ichirou
authors.initials: I
authors.lastname: Karahara
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Honma
authors.forename: Naoya
authors.initials: N
authors.lastname: Wada
authors.forename: Tokimasa
authors.initials: T
authors.lastname: Kawabata
authors.forename: Kenji
authors.initials: K
authors.lastname: Matsuda
authors.forename: Susumu
authors.initials: S
authors.lastname: Ikeno
authors.forename: Munenori
authors.initials: M
authors.lastname: Noguchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Inoue
mesh_terms: D001692:Biological Transport; D029624:Ferns / Q000187:drug effects* / Q000378:metabolism*; D018525:Germination; D007854:Lead / Q000378:metabolism* / Q000633:toxicity*; D044945:Proanthocyanidins / Q000378:metabolism; D012989:Soil Pollutants; D013170:Spores / Q000378:metabolism* / Q000648:ultrastructure; D014018:Tissue Distribution
chemical_list: D044945:Proanthocyanidins; D012989:Soil Pollutants; D007854:Lead