Gametophyte and embryonic ontogeny: understanding the reproductive calendar of Cypripedium japonicum Thunb. (Cypripedoideae, Orchidaceae), a lady's slipper orchid endemic to East Asia.

BACKGROUND: The genus Cypripedium L. is one of the five genera of the subfamily Cypripedioideae, members of which are commonly known as lady's slipper orchids. Cypripedium japonicum is a perennial herb native to East Asia, specifically China, Japan, and Korea. Due to its limited distribution, the species is included in the Endangered category of the IUCN Red List. RESULTS: We investigated gametophyte development, including complete embryogenesis, in C. japonicum. The complete reproductive cycle is presented based on our observations. Anther development begins under the soil, and meiosis of pollen mother cells begins 3 weeks before anthesis, possibly during early April. The megaspore mother cells develop just after pollination in early May and mature in mid-late June. The pattern of embryo sac formation is bisporic, and there are six nuclei: three forming the egg apparatus, two polar nuclei, and an antipodal cell in the mature embryo sac. Triple fertilization results in the endosperm nucleus, which degenerates when the proembryo reaches the eight-to-sixteen-cell stage. CONCLUSION: Our overall comparisons of the features of gametophyte and embryo development in C. japonicum suggest that previous reports on the embryology of Cypripedium are not sufficient for characterization of the entire genus. Based on the available information, a reproductive calendar showing the key reproductive events leading to embryo formation has been prepared.

The embryological insight into the relationship between Forsythia and Abeliophyllum (Forsythieae, Oleaceae).

Forsythia saxatilis, a Korean native Forsythia, is recognized as an endangered species in the Korean Red List. We carried out a comprehensive embryological investigation, including a study of the pericarp development, of F. saxatilis and compared it with previously acquired information on the family Oleaceae and also with Abeliophyllum distichum, a close relative of Forsythia. Our results revealed that several embryological features of Forsythia are exclusively comparable with the family Oleaceae, particularly in relation to A. distichum. Despite the differences in fruit types and pericarp ontogeny, Forsythia shares some unique embryological features with Abeliophyllum, for instance the basic type of anther wall development, formation of the nucellar cap, a long micropyle, formation of the obturator and hypostase, and the crushed endotesta. Furthermore, the loculicidal capsule of Forsythia seems to be primitive within the tribe Forsythieae and samara of Abeliophyllum might be evolved from it. In conclusion, a considerable number of synapomorphies of embryological characters supports recent molecular reports and provide additional embryological evidence for the sister-group relationship of Forsythia and Abeliophyllum.

Correction to: The embryological insight into the relationship between Forsythia and Abeliophyllum (Forsythieae, Oleaceae).

In the original publication of the article, species name.

Taxonomic study of amanita subgenus lepidella and three unrecorded amanita species in Korea.

Amanita Pers. is a well-known monophyletic mushroom genus with a broad distribution. However, the diversity of Korean Amanita species has been underestimated, and most taxonomic studies conducted in Korea have only investigated their morphological characteristics. This approach is frequently insufficient for correct identification in fungal classification; therefore, we constructed a phylogeny of Amanita subgen. Lepidella in order to understand the phylogenetic placements of 16 Amanita specimens collected in Korea in 2012. The phylogeny constructed using the sequence data of the internal transcribed spacers and the partial large subunit of ribosomal RNA identified nine Amanita species (A. citrina, A. excelsa var. spissa, A. flavipes, A. fritillaria, A. oberwinklerana, A. pallidorosea, A. rubescens, A. subjunquillea, and A. volvata); of these, A. fritillaria, A. oberwinklerana, and A. pallidorosea are new to Korea.