• Journal of Ecology and Environment
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• 제43권3호
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• pp.320-331
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• 2019

Background: Dioecious plant species having both male and female plants have been investigated regarding sex-related characteristics such as sex ratio, sex-differential resource requirements, and spatial segregation of the sexes. Habitat loss and fragmentation are major threats to the survival of plant populations, but dioecious species are particularly more prone to such habitat degradation than non-dioecious species because of their dimorphic sexual system. We examined the sex-related demographics of two Ilex cornuta populations being different regarding land use history. Methods: During 2016-2017, we examined I. cornuta trees with a basal diameter ${\geq}1.5cm$ in the Yongsu-ri population (YS population) and the Gotjawal Provincial Park population (GP population). Plant sex (male, female, or unsexed) was identified. The tree size (basal diameter and height of the main stem), clonal production (the ramet numbers per genet), and vitality for each clone were measured. The associations between population, sex, tree size, clonal production, and vitality were examined using ANOVAs and contingency table analyses. Finally, point pattern analyses using O-ring statistics were conducted to assess spatial patterns. Results: Upon excluding unsexed trees, the YS population with 74 trees was significantly male-biased (0.66), while the GP population with only 26 trees had a 1:1 sex ratio. In both populations, males and females did not differ in tree size. Although the mean number of ramets differed significantly between populations, females tended to produce more ramets than males. The proportion of weak trees was significantly higher in the YS than in the GP population. Neither population showed evidence of spatial segregation of the sexes. Conclusions: The two populations of dioecious I. cornuta are characterized by the small number of trees and relatively high frequencies of non-reproductive trees. Both indicate that these populations are quite susceptible to environmental and genetic stochasticity. On the other hand, the differences between populations in sex ratio, clonal production, and vitality suggest that conservation efforts for I. cornuta need to be population-specific. In order to help recover and enable this vulnerable species to persist, it is necessary to find ways to enhance their sexual reproduction and simultaneously reduce habitat disturbances due to anthropogenic activities.

• 식물분류학회지
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• 제47권3호
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• pp.189-195
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• 2017

Aruncus L. is a small genus which is distributed in the circumpolar regions of the Northern Hemisphere, including Europe, Asia, and North America. In Korea, there are two taxa, A. dioicus var. kamtschaticus and A. aethusifolius. Aruncus aethusifolius is a species endemic to Korea, occurring only on Jeju Island. An important characteristic of Aruncus is dioecy. However, there is some controversy regarding the sexuality of this genus, and little is known about A. aethusifolius. To characterize the sexuality of A. aethusifolius and to provide insight into the evolution of its sexual system, we investigated natural populations and herbarium specimens of A. aethusifolius. The results indicate that the species has carpellate, staminate, and bisexual flowers. Carpellate flowers are always borne on separate individuals, and staminate flowers are borne either on separate individuals or mixed with bisexual flowers on the same individuals. The sexuality of A. aethusifolius is defined as polygamo-dioecious. The polygamo-dioecious type is also found in A. dioicus var. dioicus and A. dioicus var. kamtschaticus and thus may be a general condition in Aruncus.

• Journal of Forest and Environmental Science
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• 제32권2호
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• pp.113-119
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• 2016

The long lived iteroparous conifers produce male and female gametophyte for hundreds of years once they reach the reproductive stage, however, the production of seed is not frequent. This phenomenon of infrequent seed production in conifers is yet to be understood. An attempt to study this change in cone production in Cedrus deodara of Western Himalayas -a species reported to be mainly monoecious and rarely dioecious has been made. The observations recorded on selected trees of flowering/fruiting stage for four years at four different locations have shown the species to be dioecious with higher percentage of female trees during good seed year but with no definite or predictable pattern of reproduction in the trees. A decline in production of female trees was witnessed at all but one location immediately year after reaching the maximum (good seed year). The phenomenon of seed production has been observed to be cyclic and site specific. A change in the sexual behavior of the trees from male to female or vice-versa, male or female turning monoecious or vegetative and vegetative coming to reproductive was unpredictable.

• ALGAE
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• 제26권1호
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• pp.79-86
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• 2011

Physiological studies on the hybrid by crossing between two dioecious species, Porphyra pseudolinearis and P. dentata from Korea were conducted at constant temperatures (5, 10, 15, 20, and $25^{\circ}C$), at photon flux densities (10, 20, 40, and $80\;{\mu}mol\;m^{-2}s^{-1}$) under photoperiods (14 L : 10 D and 10 L : 14 D). In the hybrid, higher growth of conchocelis was observed at 20 and $40\;{\mu}mol\;m^{-2}s^{-1}$ under 14 L : 10 D. Conchosporangial branches were produced under $10-80\;{\mu}mol\;m^{-2}s^{-1}$ at only $25^{\circ}C$, and were abundant when the conchocelis was cultured under 10 L : 14 D. Foliose thalli of the hybrid grew well at the conditions of $10-20^{\circ}C$, 10 L : 14 D and $15-20^{\circ}C$, 14 L : 10 D. The foliose thalli grew very slowly at $5^{\circ}C$ and $30^{\circ}C$, respectively. No archeospores were observed at any culture conditions. Spermatangial and zygotosporangial sori were formed at the marginal portion of mature thallus. Zygotospores from the hybrid were released at $10-2^{\circ}C$ under both photoperiods, and gave rise to form conchocelis filament. Monoecious thalli were observed at $10^{\circ}C$ under 14 L : 10 D. Neither monospores nor protothalli were produced from the conchocelis in culture.

• Journal of Plant Biotechnology
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• 제50권
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• pp.207-214
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• 2023

Lindera obtusiloba (Lauraceae) is a dioecious tree that is widely distributed in the low-altitude montane forests of East Asia, including Korea. Despite its various pharmacological properties and ornamental value, the genetic diversity and population structure of this species in Korea have not been explored. In this study, we selected 6 nuclear and 6 chloroplast microsatellite markers with polymorphism or clean cross-amplification and used these markers to perform genetic diversity and population structure analyses of L. obtusiloba samples collected from 20 geographical regions. Using these 12 markers, we identified a total of 44 alleles, ranging from 1 to 8 per locus, and the average observed and expected heterozygosity values were 0.11 and 0.44, respectively. The average polymorphism information content was 0.39. Genetic relationship and population structure analyses revealed that the natural L. obtusiloba population in Korea is composed of 2 clusters, possibly due to two different plastid genotypes. The same clustering patterns have also been observed in Lindera species in mainland China and Japan.

• 한국패류학회지
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• 제11권2호
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• pp.147-163
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• 1995

The unionid family Unionidae contains several genera in Korea, among which occru considerable variations in life histories and sexual conditions. Seven species from the Korea(Anodonta arcaeformis flavotincta, A. woodiana, Unio douglaseae, U. douglasiae sinuolatus, Lamprotula gottschei, Lanceolaria acrorhyncha, Solenaia triangularis)were stueide in order to identify and describe the seasonal gonadal activity and the visceral sex. The gonads of seven species were histologically examined by using the paraffin block technique for sectioning. All seven species were uniformly dioecious and testicular activity in six species except one species, S. triangularis, generated sperm-morulae(multinucleated cell). The annual reproductive cycle of the seven species could be classified into five successive stages; multicative, growing, mature, spent, deginerative and resting stages. The breeding season of six species was the summer and that of A. a. flavotincta was the winter.

• 식물분류학회지
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• 제46권2호
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• pp.163-174
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• 2016

Gnetum (Gnetaceae, Gnetales) is a gymnosperm genus with ca. 35 species distributed in tropical forests around the world. Due to its dioecious habit and lack of diagnostic characters from vegetative tissue, the identification of Gnetum species is not easy without seeds or reproductive structures. To identify and verify their phylogenetic positions, we applied DNA barcoding to Cambodian Gnetum collections gathered between 2010 and 2015, with previously designed cp matK gene primers. We newly sequenced partial matK sequences from 72 Gnetum collections, 43 out of 72 from Cambodia, and analyzed 115 Gnetum accessions using the neighbor-joining method. The resulting neighbor-joining tree categorized Cambodian Gnetum samples into three clades of species: G. macrostachyum, G. montanum, and G. aff. gracilipes. The recognition of G. aff. gracilipes in Cambodia is reported here for the first time. Taxonomic information for the three recognized Cambodian Gnetum species is provided and the benefits of the taxonomic reevaluation assisted by DNA barcoding are emphasized in this work.

• The Korean Journal of Ecology
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• 제10권3호
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• pp.119-127
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• 1987

On the east slope of the front ranges of the Colorado Rockies, USA, three species of Populus are distributed at different elevations from the Great Plains to the timberline. At elevations 1, 720m (P. sargentii), 2, 335m (P.angustifolia) and 3, 190m (P.tremuloides) chlorophyll cotents of leaves of thses dioecious trees were determined. Total chlorophyll content was in the range of 0.86-1.56mg/g leaf, increasing with elevation as a second-degree polynomial, and the peak content was estimated to be reached at about 2, 800m. Total chlorophyll content was greater in female than in male trees in the two higher elevation species, but not in P. sargentii, the low elevation species. Chlorophyll b content was greater than chlorophyll a content in the same two higher elevation species. The increase of chlorophyll b than to increase of chlorophyll a content. These phenomena appear to be the result of adaptation of these species to different environmental conditional at different elevation. Sequential distribution of plant populations on environmental gradients in such a way that variation in given plant characters paralell the environmental gradient must occur not only in ecotypes of a species, but also in different but closely related species.

• Journal of Plant Biotechnology
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• 제50권
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• pp.190-199
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• 2023

Date palm (Phoenix dactylifera L.: Arecaceae) is a dioecious species where only female trees bear fruits. In their natural state, date palms produce dates once a year. However, in Thailand, some trees were observed to produce dates during the off-season, despite no variations in morphology. The availability of such off-season fruits can significantly increase their market value. Interestingly, most female off-season date palms investigated in this study were obtained through micropropagation. Hence, there is an urgent need for genetic markers to distinguish female offseason flowering plantlets within tissue culture systems. In this study, we aimed to develop random amplification of polymorphic DNA-sequence characterized amplified region (RAPD-SCAR) markers for the identification of female off-season flowering date palms cultivated in Thailand. A total of 160 random decamer primers were employed to screen for specific RAPD markers in off-season flowering male and female populations. Out of these, only one primer, OPN-02, generated distinct genomic DNA patterns in female off-season flowering (FOFdp) individuals compared to female seasonal flowering genotypes. Based on the RAPD-specific sequence, specific SCAR primers denoted as FOFdpF and FOFdpR were developed. These SCAR primers amplified a single 517-bp DNA fragment, predominantly found in off-season flowering populations, with an accuracy rate of 60%. These findings underscore the potential of SCAR marker technology for tracking offseason flowering in date palms. Notably, a BLAST analysis revealed a substantial similarity between the SCAR marker sequence and the transcript variant mRNA from Phoenix dactylifera encoding the SET DOMAIN GROUP 40 protein. In Arabidopsis, this protein is involved in the epigenetic regulation of flowering time. The genetic potential of the off-season flowering traits warrants further elucidation.

• ALGAE
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• 제21권1호
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• pp.15-48
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• 2006

The genus Martensia (Delesseriaceae, Rhodophyta) is characterized by thalli composed of one to several blades that consist of proximal membranous sections and distal latticework. Nerves or veins are absent in the membranous sections. The life cycle of Martensia is accomplished by isomorphic alternation of generations. The gametophytes of Martensia are dioecious, and the male and female gametangial plants are morphologically similar. The type species of Martensia is M. elegans Hering. In this study, nine species were confirmed to occur in the subtidal regions of Jeju Island, Korea: M. albida sp. nov., M. australis Harvey, M. bibarii Y. Lee, M. elegans Hering, M. flammifolia sp. nov, M. fragilis Harvey, M. jejuensis Y. Lee, M. palmata Y. Lee, and M. projecta Y. Lee. Three of these, M. australis, M. fragilis, and M. elegans, are new records in the flora of Korea. The results of molecular analyses of the internal transcribed spacer (ITS) 1 region in the nrDNA showed that M. elegans is identical to M. australis, and M. fragilis coincides with M. bibarii. It may be a less effective tool for the species discrimination in Martensia.