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Chloroplast movement in response to light has been known more than 100 years. Chloroplasts move towards weak light and move away from strong light. Dark-induced relocation, called dark positioning, has also been shown. However, the effects of other stimuli on chloroplast movement have not been well characterized. Here we studied low temperature-induced chloroplast relocation (termed cold positioning) in prothallial cells of the gametophytes of the fern Adiantum capillus-veneris. Under weak light chloroplasts in prothallial cells accumulated along the periclinal wall at 25degC,but they moved towards anticlinal walls when the prothalli were subsequently transferred to 40degC. A temperature shift from 25degC to 10degC or lower was enough to induce cold positioning, and high-intensity light enhanced the response. Nuclei also relocated from the periclinal position (a position along periclinal walls) to the anticlinal position (a position along anticlinal walls) under cold temperature, whereas mitochondria did not. Cold positioning was not observed in mutant fern gametophytes defective of the blue light photoreceptor, phototropin 2.

We determined the complete nucleotide sequence of the chloroplast genome of Selaginella uncinata, a lycophyte belonging to the basal lineage of the vascular plants. The circular double-stranded DNA is 144,170 bp, with an inverted repeat of 25,578 bp separated by a large single copy region (LSC) of 77,706 bp and a small single copy region (SSC) of 40,886 bp. We assigned 81 protein-coding genes including four pseudogenes, four rRNA genes and only 12 tRNA genes. Four genes, rps15, rps16, rpl32 and ycf10, found in most chloroplast genomes in land plants were not present in S. uncinata. While gene order and arrangement of the chloroplast genome of another lycophyte, Hupertzia lucidula, are almost the same as those of bryophytes, those of S. uncinata differ considerably from the typical structure of bryophytes with respect to the presence of a unique 20 kb inversion within the LSC, transposition of two segments from the LSC to the SSC and many gene losses. Thus, the organization of the S. uncinata chloroplast genome provides a new insight into the evolution of lycophytes, which were separated from euphyllophytes approximately 400 million years ago.

Six French ferns were investigated for volatile organic compounds (VOC) by GC-MS using organic solvent extraction. Seventy-seven VOC biosynthesized from the shikimic, lipidic and terpenic pathways, including isoprenoid derivatives, were identified from these putative natural resources. Asplenium trichomanes subsp. trichomanes contained mainly polyketides with an oily or waxy odor. (E)-2-Hexenal and (Z)-3-hexenol, responsible for the \"green odor\", were found in high contents in Polystichum setiferum, Dryopteris dilatata and Phegopteris connectilis. In the last, 7.4% of coumarin with a cut hay scent was highlighted from the volatile fraction. (E)-3-Hexenoic acid and (E)-2-hexenoic acid, both with herbal and fruity notes, were identified in Gymnocarpium dryopteris and Pteridium aquilinum. 1-Octen-3-ol, well-known for its mushroom-like odor, was abundant in all analyzed French ferns. While the \"fougère\" fragrance is claimed by the perfumers to be a fantasy scent, coumarin, (E)-2-hexenal, (Z)-3-hexenol and 1-octen-3-ol are the main odorous components of the perfumes belonging to the fougère accord family. This suggests that the fougère scent from the perfumers' imagination is a natural fragrance.

Flowers sensu lato are short, specialized axes bearing closely aggregated sporophylls. They are typical for seed plants (spermatophytes) and are prominent in flowering plants sensu stricto (angiosperms), where they often comprise an attractive perianth. There is evidence that spermatophytes evolved from gymnosperm-like plants with a fern-like mode of reproduction called progymnosperms. It seems plausible, therefore, that the stamens/carpels and pollen sacs/nucelli of spermatophytes are homologous to fern sporophylls and sporangia, respectively. However, the exact mode and molecular basis of early seed and flower evolution is not yet known. Comparing flower developmental control genes to their homologs from lower plants that do not flower may help to clarify the issue. We have isolated and characterized MADS-box genes expressed in gametophytes and sporophytes of the fern Ceratopteris. The data indicate that at least two different MADS-box genes homologous to floral homeotic genes existed in the last common ancestor of contemporary vascular plants, some descendants of which underwent multiple duplications and diversifications and were recruited into novel developmental networks during the evolution of floral organs

Ceratopteris thalictroides (L.) Brongn is a tetraploid fern species that contains at least three cryptic species, the south, the north and the third type. In this study we combined data from both chloroplast DNA (cpDNA) and nuclear DNA sequences of three diploid species and three cryptic species of C. thalictroides to unravel the origin of the cryptic species, particularly of the reticulate relationships among the diploid and tetraploid taxa in the genus Ceratopteris. Of the three diploid species examined, C. cornuta had cpDNA identical to that of the tetraploid third type plants, and this diploid species is a possible maternal ancestor of the tetraploid third type. Analysis of the homologue of the Arabidopsis thaliana LEAFY gene (CLFY1) identified ten alleles in the genus Ceratopteris, with six alleles found in C. thalictroides. The unrooted tree of the CLFY1 gene revealed four clusters. Each cryptic species showed fixed heterozygosity at the CLFY1 locus and had two alleles from different clusters of the CLFY1 tree. Consideration of the cpDNA sequences, CLFY1 genotypes of the cryptic species and CLFY1 gene tree in concert suggested that the cryptic species of C. thalictroides had originated through independent allopolyploidization events involving C. cornuta and two unknown hypothetical diploid species.

Rheophilous Osmunda lancea often hybridizes with a dryland ally, Osmunda japonica, to produce O. x intermedia, forming zonation in riverbanks and the adjacent dryland along flooding frequency clines. This study examined the genetic structure of populations consisting of O. x intermedia and the two parental species by analyzing ten nuclear DNA markers [six cleaved amplified polymorphic sequence (CAPS) markers and three simple sequence repeat (SSR) markers developed from an expressed sequence tag (EST) library, and the sequence of the glyceraldehyde-3-phosphate dehydrogenase gene GapCp] and chloroplast DNA sequences. The results suggest that the nuclear genes of O. japonica and O. lancea are genetically differentiated despite shared polymorphism in their chloroplast DNA sequences. This discrepancy may be attributable to natural selection and recent introgression, although it is not evident if introgression occurs between O. japonica and O. lancea in the examined populations. Our findings of putative F2 hybrids in O. x intermedia support its partial reproducibility, and also suggest that formation of later-generation hybrids generates morphological variation in O. x intermedia. O. lancea plants collected from geographically distant localities were genetically very similar, and it is suggested that O. lancea originated monotopically.

This comprehensive study of early embryology in Ceratopteris richardii combines light microscopy with the first ultrastructural evaluation of any pteridophyte embryo. Emphasis is placed on ontogeny of the foot and placental transfer cells. The embryology of C. richardii shares many similarities with that of other polypodiacious ferns while exhibiting distinctive division patterns. Formative embryonic stages have been reconstructed into three-dimensional models for ease of interpretation. The zygote divides perpendicular to the gametophyte plane and anterioposterior axis. This division establishes a prone embryological habit that maximizes rapid independent establishment of a leaf-root axis in a cordate gametophyte. After the formation of a globular eight-celled stage, initials of the first leaf, and root and shoot apical meristems are defined early by discrete formative divisions. Concomitantly, the foot expands and differentiates to transport nutrients from the gametophyte for the developing embryonic organs. Transfer cell wall ingrowth deposition begins in the gametophyte placental cells before the adjacent sporophyte cells just after the eight-celled stage. These observations provide an anatomical framework for future comparative developmental genetic studies of embryogenesis in free-sporing plants.

A knowledge of fern phenology promotes understanding of the biology and ecology of ferns. In this study, the phenology of 16 fern species in a subtropical broadleaf forest (N24deg46min,E 121deg34min) in northeastern Taiwan was monitored from August 1997 to August 2001. Every fern produced both fertile and sterile leaves in each year of the study. Most fertile leaves emerged in February and March, whereas most sterile leaves emerged from May to September. Most leaves reached full expansion during April-July and died during April-August. The average life span of leaves ranged from 4.4 months to 30.3 months. In seven species, fertile leaves lived longer than sterile leaves, but this difference was significant only in Pteris wallichiana. In the other nine species, sterile leaves lived longer than fertile leaves, but the difference was significant only in Cyathea spinulosa, Plagiogyria dunnii, and Plagiogyria adanata. The ephemeral fertile leaves of the two dimorphic species died soon after releasing their spores, at only 5 months of age. However, their sterile leaves survived for over 22 months. The fertile leaves of the other 14 species remained green for almost 2 years after releasing their spores. Sterile leaves remained sterile throughout their lives. Spores matured in May-July and were released in June-August. After spore release, the sporangia detached. No leaf produced a second cohort of sori. Several phenological events, including sterile leaf emergence, leaf expansion and senescence, and spore maturation and release, were significantly positively correlated with temperature but not with precipitation, whereas the emergence of fertile leaves was weakly negatively correlated with temperature and precipitation. However, those correlations varied among different species.

In general, phototropic responses in land plants are induced by blue light and mediated by blue light receptor phototropins. In many cryptogam plants including the fern Adiantum capillus-veneris, however, red as well as blue light effectively induces a positive phototropic response in protonemal cells. In A. capillus-veneris, the red light effect on the tropistic response is mediated by phytochrome 3 (phy3), a chimeric photoreceptor of phytochrome and full-length phototropin. Here, we report red and blue light-induced negative phototropism in A. capillus-veneris rhizoid cells. Mutants deficient for phy3 lacked red light-induced negative phototropism, indicating that under red light, phy3 mediates negative phototropism in rhizoid cells, contrasting with its role in regulating positive phototropism in protonemal cells. Mutants for phy3 were also partially deficient in rhizoid blue light-induced negative phototropism, suggesting that phy3, in conjunction with phototropins, redundantly mediates the blue light response.