A research of interphase nuclei and chromosome number of Isoetes sinensis Palmer was made in the article. The chromosome number of Isoetes sinensis Palmer was 2n=4x=44. The interphase nuclei were categorized to be sim...A research of interphase nuclei and chromosome number of Isoetes sinensis Palmer was made in the article. The chromosome number of Isoetes sinensis Palmer was 2n=4x=44. The interphase nuclei were categorized to be simple chromocenter type. The metaphase chromosomes were about 5 μm in length.In addition,the mitotic process was observed. These results could supply the cytological evidence for the exploration of the biosystematics and endangerment mechanism of this species.展开更多
The genetic variation in the critically endangered speciesIsoetes hypsophila was investigated using Random Amplified Polymorphism DNA (RAPD) markers. Thirteen primers were screened from sixty primers, and a total of 1...The genetic variation in the critically endangered speciesIsoetes hypsophila was investigated using Random Amplified Polymorphism DNA (RAPD) markers. Thirteen primers were screened from sixty primers, and a total of 104 DNA fragments were scored, of which, 52 were polymorphic loci. Low-level genetic diversity within populations with PPB values ranging from 7.69%to 25.96%was found. An Anal ysis of Molecular Variance (AMOVA) indicated that the most of variance (78.30%) occurred between Yunnan and Si chuan. The variances among populations within regions and within populations were only 3.89%and 17.82%, respectively.展开更多
Isoetes sinensis Palmer (Isoetaceae) is an aquatic or amphibious plant that is critically endangered in China. Previous studies have revealed the crassulacean acid metabolism (CAM)-like photosynthetic pathway occurs c...Isoetes sinensis Palmer (Isoetaceae) is an aquatic or amphibious plant that is critically endangered in China. Previous studies have revealed the crassulacean acid metabolism (CAM)-like photosynthetic pathway occurs commonly in submerged leaves in genusIsoetes. Water chemistry parameters and the titratable acidity content of the plant extract were measured from samples obtained in the early morning (7∶00) and late afternoon (15∶00) from twoI. sinensis populations in China. One population occurs in the eulittoral zone of a freshwater tidal river at low elevation (134 m) and another occurs in a densely vegetated, high elevation (1 100 m) alpine shallow pool. Significant differences in pH and titratable acidity of the plant extract were detected between the morning and afternoon samples. These changes are associated with diurnal changes in water chemistry. Our results provide the first evidence for the existence of the CAM pathway in the East Asian endemicIsoetes sinensis Palmer. The magnitude of fluctuations in the titratable acidity of the plant extract may be correlated with the severe carbon limitation imposed on the plants by its aquatic habitat.展开更多
Using a mixed culture of megaspores and microspores from I. coreana, we established high frequency sporophyte regeneration system. After 20 days of culturing in MS basal medium, microscopic examination showed signific...Using a mixed culture of megaspores and microspores from I. coreana, we established high frequency sporophyte regeneration system. After 20 days of culturing in MS basal medium, microscopic examination showed significant morphological changes and the microspore released numerous small vesicles into the culture medium. Megaspores also showed dramatic morphological changes during its incubation time in culture. The spore wall was cracked by the expansion of the megaspore (about 2 times increase in diameter). Simultaneously, brown spots were observed on the surface of the megaspores. The frequency of female gametophytes developing from immature megaspores cultured in MS basal liquid medium (pH 7) supplemented with 1 mgl-1 GA3 was 46%. However, these female gametophytes derived from megaspore only culture could not differentiate into sporophytes. The mixed culture of microspores and megaspores resulted in successful sporophyte regeneration. The highest frequency (12.3%) of green sporophyte regeneration from mixed spore culture occurred when the cultures were maintained at 25℃ under cool-white fluorescent light (40 μmol·m-2·s-1) with a 16 h photoperiod. Regenerated sporophytes were transferred to a test tube containing vermiculite and a sand mixture and left there until they had three leaves. After root growth and the fifth leaf had emerged, more than 95% of the regenerated sporophytes were successfully transferred to the soil and grown to mature plants. The sporophyte regeneration system established in this study could be successfully used for the restoration of the endangered aquatic species, I. coreana.展开更多
Isoetes yunguiensis is an endangered and endem-ic fern in China.Field survey indicated that only one popula-tion and no more than 50 individuals occur in the wild.The genetic variation of 46 individuals from the popul...Isoetes yunguiensis is an endangered and endem-ic fern in China.Field survey indicated that only one popula-tion and no more than 50 individuals occur in the wild.The genetic variation of 46 individuals from the population remaining at Pingba(Guizhou Province,China)was assessed by Random Amplified Polymorphic DNA(RAPD)fingerprinting.Twelve primers were screened from sixty ten-bp arbitrary primers,and a total of 95 DNA fragments were scored.Of these,62.1%were polymorphic loci,which indi-cated that high level genetic variation existed in the natural population.The accumulation of genetic variation in the history of the taxon and the apparent minimal reduction effect on genetic diversity following destruction of habitat might be responsible for the high level genetic diversity presently remaining in the I.yunguiensis population.However,with the continuing decrease of population size,the genetic diversity will gradually be lost.We suggest that the materials from the extant population should be used for re-establishment of the populations.展开更多
文摘A research of interphase nuclei and chromosome number of Isoetes sinensis Palmer was made in the article. The chromosome number of Isoetes sinensis Palmer was 2n=4x=44. The interphase nuclei were categorized to be simple chromocenter type. The metaphase chromosomes were about 5 μm in length.In addition,the mitotic process was observed. These results could supply the cytological evidence for the exploration of the biosystematics and endangerment mechanism of this species.
基金Supported by the National Natural Science Foundation of China (30370098) and the State Key Basic Research and De velopment Plan (G2000046805)
文摘The genetic variation in the critically endangered speciesIsoetes hypsophila was investigated using Random Amplified Polymorphism DNA (RAPD) markers. Thirteen primers were screened from sixty primers, and a total of 104 DNA fragments were scored, of which, 52 were polymorphic loci. Low-level genetic diversity within populations with PPB values ranging from 7.69%to 25.96%was found. An Anal ysis of Molecular Variance (AMOVA) indicated that the most of variance (78.30%) occurred between Yunnan and Si chuan. The variances among populations within regions and within populations were only 3.89%and 17.82%, respectively.
基金the State Key Basic Research and Development Plan(G2000046805)
文摘Isoetes sinensis Palmer (Isoetaceae) is an aquatic or amphibious plant that is critically endangered in China. Previous studies have revealed the crassulacean acid metabolism (CAM)-like photosynthetic pathway occurs commonly in submerged leaves in genusIsoetes. Water chemistry parameters and the titratable acidity content of the plant extract were measured from samples obtained in the early morning (7∶00) and late afternoon (15∶00) from twoI. sinensis populations in China. One population occurs in the eulittoral zone of a freshwater tidal river at low elevation (134 m) and another occurs in a densely vegetated, high elevation (1 100 m) alpine shallow pool. Significant differences in pH and titratable acidity of the plant extract were detected between the morning and afternoon samples. These changes are associated with diurnal changes in water chemistry. Our results provide the first evidence for the existence of the CAM pathway in the East Asian endemicIsoetes sinensis Palmer. The magnitude of fluctuations in the titratable acidity of the plant extract may be correlated with the severe carbon limitation imposed on the plants by its aquatic habitat.
文摘Using a mixed culture of megaspores and microspores from I. coreana, we established high frequency sporophyte regeneration system. After 20 days of culturing in MS basal medium, microscopic examination showed significant morphological changes and the microspore released numerous small vesicles into the culture medium. Megaspores also showed dramatic morphological changes during its incubation time in culture. The spore wall was cracked by the expansion of the megaspore (about 2 times increase in diameter). Simultaneously, brown spots were observed on the surface of the megaspores. The frequency of female gametophytes developing from immature megaspores cultured in MS basal liquid medium (pH 7) supplemented with 1 mgl-1 GA3 was 46%. However, these female gametophytes derived from megaspore only culture could not differentiate into sporophytes. The mixed culture of microspores and megaspores resulted in successful sporophyte regeneration. The highest frequency (12.3%) of green sporophyte regeneration from mixed spore culture occurred when the cultures were maintained at 25℃ under cool-white fluorescent light (40 μmol·m-2·s-1) with a 16 h photoperiod. Regenerated sporophytes were transferred to a test tube containing vermiculite and a sand mixture and left there until they had three leaves. After root growth and the fifth leaf had emerged, more than 95% of the regenerated sporophytes were successfully transferred to the soil and grown to mature plants. The sporophyte regeneration system established in this study could be successfully used for the restoration of the endangered aquatic species, I. coreana.
基金This study was supported by the State Key Basic Research and Development Plan(No.G2000046805)the National Natural Science Foundation of China(Grant No.30370098).
文摘Isoetes yunguiensis is an endangered and endem-ic fern in China.Field survey indicated that only one popula-tion and no more than 50 individuals occur in the wild.The genetic variation of 46 individuals from the population remaining at Pingba(Guizhou Province,China)was assessed by Random Amplified Polymorphic DNA(RAPD)fingerprinting.Twelve primers were screened from sixty ten-bp arbitrary primers,and a total of 95 DNA fragments were scored.Of these,62.1%were polymorphic loci,which indi-cated that high level genetic variation existed in the natural population.The accumulation of genetic variation in the history of the taxon and the apparent minimal reduction effect on genetic diversity following destruction of habitat might be responsible for the high level genetic diversity presently remaining in the I.yunguiensis population.However,with the continuing decrease of population size,the genetic diversity will gradually be lost.We suggest that the materials from the extant population should be used for re-establishment of the populations.
