Lead tolerance and accumulation in the gametophytes of the fern Athyrium yokoscense

• Published in: Journal of plant research 2005-04, Vol.118 (2), p.137-145
• Main Authors: Kamachi, H. (Toyama Univ. (Japan)), Komori, I, Tamura, H, Sawa, Y, Karahara, I, Honma, Y, Wada, N, Kawabata, T, Matsuda, K, Ikeno, S, Noguchi, M, Inoue, H
• Format: Article
• Language: English
• Subjects: Biological Transport; Dry matter; FERNS; Ferns - drug effects; Ferns - metabolism; FLAVONOIDS; GAMETES; Germination; LEAD; Lead - metabolism; Lead - toxicity; Proanthocyanidins - metabolism; Soil Pollutants; Spores - metabolism; Spores - ultrastructure; Tissue Distribution; TOLERANCE
• ISSN: 0918-9440; 1618-0860
• DOI: 10.1007/s10265-005-0202-x

The fern Athyrium yokoscense is known to be highly tolerant to lead toxicity, and is a lead hyperaccumulator that can accumulate over 1,000 micro g gE-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 micro M Pb2+ as evaluated from the prothallial growth and rhizoid development. We also showed that Athyrium gametophytes could accumulate more than 10.000 micro g gE-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.