Cytological Study of Cypripedium japonicum Thunb. (Orchidaceae Juss.): An Endangered Species from Korea

Abstract

Changes in chromosome number and karyotype evolution are important to plant diversification, as they are both major drivers of speciation processes. Herein, chromosome number, karyotype, and genome size of the Korean lady’s slipper orchid Cypripedium japonicum Thunb., an endangered species, were investigated in natural populations. Furthermore, all cytological data from this species are reported herein for the first time. The chromosome number of all investigated C. japonicum plants was diploid (2n = 2x = 22), with x = 11 as base chromosome number, whereby the species can now be clearly distinguished from the Japanese lady’s slipper orchid. The karyotypes of all studied individuals were of similar length, symmetrical, and rather unimodal. Flow cytometry of the C. japonicum revealed that the genome size ranged from 28.38 to 30.14 pg/1C. Data on chromosome number and karyotypes were largely consistent with previous results indicating that Korean (x = 11) populations of C. japonicum are more closely related to Chinese populations (x = 11) compared to Japanese (x = 10) populations. These comprehensive cytological results will benefit the efforts to discriminate the geographically isolated and endangered Eastern Asian (China, Japan, and Korea) lady’s slipper orchid species.

Does the evolution of micromorphology accompany chromosomal changes on dysploid and polyploid levels in the Barnardia japonica complex (Hyacinthaceae)?

“…Genome sizes of 42 selected individuals of the B. japonica complex were measured using flow cytometry with Pisum sativum “Kleine Rheinländerin” (4.42 pg/1 C) for diploids and Vicia faba L. “Inovec” (13.45 pg/1 C) for polyploids as internal standards [ 62 – 65 ]. The methodology used for the measurement of the genome sizes followed [ 64 , 66 ].…”

Phylogeography of the endangered orchids Cypripedium japonicum and Cypripedium formosanum in East Asia: Deep divergence at infra‐ and interspecific levels

“…japonicum have a low germination rate, compromising survival and development (Liu & al., 2012). The species has chromosome numbers of 2 n = 22 in China (Qian & al., 2013; Choi & al., 2021) and Korea (Choi & al., 2021) and 2 n = 20 in Japan (Tanaka, 1965; Karasawa & Aoyama, 1986; Kondo & al., 1994).…”

Does the evolution of micromorphology accompany chromosomal changes on dysploid and polyploid levels in the Barnardia japonica complex (Hyacinthaceae)?

“…Genome sizes of 42 selected individuals of the B. japonica complex were measured using ow cytometry with Pisum sativum "Kleine Rheinländerin" (4.42 pg/1C) for diploids and Vicia faba L. "Inovec" (13.45 pg/1C) for polyploids as internal standards [54][55][56][57]. The coe cient of variation (CV) for the internal standard and sample peaks ranged from 0.92-4.49%.…”