Endangered Plants In China Research Articles

Genetic Diversity and Population Differentiation of a Chinese Endangered Plant Ammopiptanthus nanus (M. Pop.) Cheng f.

Ammopiptanthus nanus (M. Pop.) Cheng f. is a very important resource plant that integrates soil and water conservation, afforestation of barren mountains, and ornamental, medicinal, and scientific research functions and is also a critically endangered plant in China, remaining in only six small fragmented populations in the wild. These populations have been suffering from severe anthropomorphic disturbances, causing further losses in genetic diversity. However, its genetic diversity level and genetic differentiation degree among the fragmented populations are still unclear. Inthis study, DNA was extracted from fresh leaves from the remnant populations of A. nanus, and the inter-simple-sequence repeat (ISSR) molecular marker system was used to assess its level of genetic diversity and differentiation. The result was that its genetic diversity is low at both species and population levels, with only 51.70% and 26.84% polymorphic loci, respectively. The Akeqi population had the highest genetic diversity, whereas the Ohsalur and Xiaoerbulak populations had the lowest. There was significant genetic differentiation among the populations, and the value of the genetic differentiation coefficient (Gst) was as high as 0.73, while the gene flow value was as low as 0.19 owing to spatial fragmentation and a serious genetic exchange barrier among the populations. It is suggested that a nature reserve and germplasm banks should be established as soon as possible for elimination of the anthropomorphic disturbances, and mutual introductions between the populations and introduced patches of the species, such as with habitat corridors or stepping stones, should be performed simultaneously to improve the genetic diversity of the isolated populations for the conservation of this plant.

Flowering characteristics and mating system of Fritillaria cirrhosa (Liliaceae), an endangered plant in China

Flowering characteristics and mating system of Fritillaria cirrhosa (Liliaceae), an endangered plant in China

Endangerment of Ostrya rehderiana Chun and its relationship with rhizosphere soil microflora

AbstractOstrya rehderiana Chun (Or) is an endangered plant in China. The rhizosphere microbial community is one of the key factors influencing the growth and development of plants. Soil samples in the rhizosphere of wild Or (W_Or), cultivated Or (C_Or) and the predominant plant species Cryptomeria fortunei Hooibrenk ex Otto et Diet (CfH) all growing in the same habitat were investigated. We performed polymerase chain reaction (PCR) in 16S rDNA region for bacteria and internal transcribed spacer (ITS) rDNA regions for fungi in the rhizosphere. At genus level the predominant bacteria in the rhizosphere of both W_Or and CfH were higher, and the species distribution profiles exhibited higher similarities. The distribution profiles of fungal species at the genus level in the rhizosphere of W_Or and C_Or also exhibited higher similarities. The similarity in bacterial diversity at the genus levels between W_Or and C_Or exhibited higher similarities, whereas that of fungal diversity at the genus levels between W_Or and CfH exhibited higher similarities. There existed Rhizophlyctis and Termitomyces species capable of degrading cellulose and lignin in the rhizosphere of both W_Or and C_Or. These species may affect the normal formation of the cell wall of Or. Bacterial species Mycena were capable of enhancing the growth of plant root system, Suillus, Geomyces, Gigaspora and Phlebia were capable of degrading many types of wastes were only present in CfH. The absence of these beneficial strains in both W_Or and C_Or may be one of the causes of the growth and development retardation of Or.

Stem Canker on Cyclocarya paliurus Is Caused by Botryosphaeria dothidea.

Cyclocarya paliurus, an important endangered plant in China, has considerable medicinal, timber, and horticultural value. However, little is known about diseases that affect its health. In recent years, stem canker diseases on C. paliurus have been observed frequently in newly established nurseries in Jiangsu Province, China. Symptomatic trees showed elliptical, sunken lesions on the bark, with internal discoloration, leading to enlarging cankers with delineated margins. Pathogenicity tests with fungi isolated from symptomatic samples reproduced typical canker symptoms on both detached branches and potted plants of C. paliurus. Moreover, conidia from pycnidia of isolate ZB-23 could also cause stem canker on C. paliurus. Through combined morphological observation and DNA sequences of ITS region, β-tubulin, and translation elongation factor 1-α genes, the pathogen was identified as Botryosphaeria dothidea. Multigene maximum likelihood and maximum parsimony phylogenetic analyses further supported the identification of the pathogen. To our knowledge, this is the first report of B. dothidea causing stem canker on C. paliurus in China.

De Novo Transcriptome Assembly and Population Genetic Analyses for an Endangered Chinese Endemic Acer miaotaiense (Aceraceae).

Acer miaotaiense (P. C. Tsoong) is a rare and highly endangered plant in China. Because of the lack of genomic information and the limited number of available molecular markers, there are insufficient tools to determine the genetic diversity of this species. Here, 93,305 unigenes were obtained by multiple assembled contigs with a transcriptome sequencing program. Furthermore, 12,819 expressed sequence tag-derived simple sequence repeat (EST-SSR) markers were generated, 300 were randomly selected and synthesized, 19 primer pairs were identified as highly polymorphic (average number of alleles (Na) = 8, expected heterozygosity (He) = 0.635, polymorphism information content (PIC) = 0.604) and were further used for population genetic analysis. All 261 samples were grouped into two genetic clusters by UPGMA, a principal component analyses and a STRUCTURE analyses. A moderate level of genetic differentiation (genetic differentiation index (Fst) = 0.059–0.116, gene flow = 1.904–3.993) among the populations and the major genetic variance (81.01%) within populations were revealed by the AMOVA. Based on the results, scientific conservation strategies should be established using in situ and ex situ conservation strategies. The study provides useful genetic information for the protection of precious wild resources and for further research on the origin and evolution of this endangered plant and its related species.

Structural diversity of naturally regenerating Chinese yew (Taxus wallichiana var. mairei) populations in ex situ conservation

The Chinese yew (Taxus wallichiana var. mairei) is ranked in the first class of important wild endangered plants in China. Due to overexploitation, it now occurs scattered only in the forest undergrowth along the Yangtze River Valley. To improve the conservation management of the species, we applied structural indices to investigate the structural diversity of naturally regenerating yew populations that have established via ex situ conservation. The results show that most yews had larger non‐yew tree neighbors; these were 30–70% larger than their reference trees. Collectively, the average distances between the yews and the three nearest‐neighboring trees were short ( 3 m), suggesting that the yews face strong interspecific competition from neighbors. In these two forest stands, most of the pole‐sized yews were found beneath a single tall neighboring tree (height  10 m), and their growth was enhanced under a single neighboring tree but not under two, three or zero neighboring trees. Finally, we recommend simple silvicultural measures to reduce interspecific competition and improve the vitality of the yew population; specifically, the cutting or pruning of branches of large neighboring trees in tandem with the thinning of canopy trees growing next to the mother yews.

Genetic diversity in intraspecific hybrid populations of Eucommia ulmoides Oliver evaluated from ISSR and SRAP molecular marker analysis.

Eucommia ulmoides Oliver, the only extant species of Eucommiaceae, is a second-category state-protected endangered plant in China. Evaluation of genetic diversity among some intraspecific hybrid populations of E. ulmoides Oliver is vital for breeding programs and further conservation of this rare species. We studied the genetic diversity of 130 accessions from 13 E. ulmoides intraspecific hybrid populations using inter-simple sequence related (ISSR) and sequence-related amplified polymorphism (SRAP) markers. Of the 100 ISSR primers and 100 SRAP primer combinations screened, eight ISSRs and eight SRAPs were used to evaluate the level of polymorphism and discriminating capacity. A total number of 65 bands were amplified using eight ISSR primers, in which 50 bands (76.9%) were polymorphic, with an average of 8.1 polymorphic fragments per primer. Alternatively, another 244 bands were observed using eight SRAP primer combinations, and 163 (66.8%) of them were polymorphic, with an average of 30.5 polymorphic fragments per primer. The unweighted pair-group method (UPGMA) analysis showed that these 13 populations could be classified into three groups by the ISSR marker and two groups by the SRAP marker. Principal coordinate analysis using SRAP was completely identical to the UPGMA-based clustering, although this was partly confirmed by the results of UPGMA cluster analysis using the ISSR marker. This study provides insights into the genetic background of E. ulmoides intraspecific hybrids. The progenies of the variations "Huazhong-3", "big fruit", "Yanci", and "smooth bark" present high genetic diversity and offer great potential for E. ulmoides breeding and conservation.

Genetic effects of different mating modes in Sinocalycanthus chinensis (Cheng et S.Y. Chang) Cheng et S.Y. Chang, an endangered species endemic to Zhejiang Province, China

The tertiary relict plant Sinocalycanthus chinensis, endemic to Zhejiang province with small populations and fragmented distribution, is an endangered plant in China. A relatively high species-level genetic diversity and low population-level genetic diversity exist in this species, and large genetic differentiation exists between two main populations with significant geographical isolation. Based on a previous artificial simulation mating test, amplified fragment length polymorphism (AFLP) marker was used in the present study to assess genetic diversity of filial generation colonies generated by different mating modes and to clarify genetic effects of various mating modes. The filial generation colonies generated by natural pollination and by geitonogamy were found to be similar to each other in terms of their relatively low genetic parameters and minimum genetic differentiation. This indicated that under natural conditions, selfing might occur at a higher proportion leading to the low genetic diversity within the population. The degree of genetic diversity of the filial generation colonies generated by outbreeding was highest, followed by inbreeding (xenogamy) and selfing (geitonogamy). Moreover, genetic differentiation between filial generation colonies generated by selfing (geitonogamy) and inbreeding (i.e., xenogamy) was much smaller than that between filial generation colonies generated by selfing and outbreeding. The results indicated that the genetic effect of outbreeding was much more dominant than other mating modes. Therefore, artificially promoting outbreeding between the two isolated geographically populations contributed to the enhancement of genetic diversity in populations in S. chinensis.

Plant regeneration via somatic embryogenesis and shoot organogenesis from immature cotyledons of Camellia nitidissima Chi

Camellia nitidissima Chi (Theaceae) is a world-famous economic and ornamental plant with golden-yellow flowers. It has been classified as one of the rarest and most endangered plants in China. Our objective was to induce somatic embryogenesis, shoot organogenesis and plant regeneration for C. nitidissima. Three types of callus (whitish, reddish and yellowish) were induced from immature cotyledons on improved woody plant medium (WPM) with different plant growth regulators (PGRs). Among the callus, whitish callus was induced by 4.5μM 2,4-dichlorophenoxyacetic acid (2,4-D) and reddish and yellowish callus were induced by strongly active cytokinins, thidiazuron (TDZ) or 6-benzylaminopurine (BAP), singly or combined with weakly active auxin, α-naphthaleneacetic acid (NAA). The embryogenic callus could differentiate into somatic embryos, nodular embryogenic structures (large embryo-like structures) or adventitious shoots depending on the PGR used in WPM. BAP was best for adventitious buds and zeatin was best for somatic embryogenesis while kinetin (Kt) was best for the formation of nodular embryogenic structures. The three regeneration pathways often occurred in the same embryogenic callus clumps. Most shoots (80.0%) developed roots in WPM supplemented with 24.6μM IBA and 0.3μM NAA while 47.5% of somatic embryos could germinate directly and develop into plantlets on induction medium supplemented with 0.9μM BAP and 0.1μM NAA. The nodular embryogenic structures could be sub-cultured and cyclically developed in one of two differentiation pathways: shoot organogenesis or somatic embryogenesis. Plantlets derived from shoot buds rooted and somatic embryos germinated when transplanted into soil in a greenhouse; 66.7% of plantlets from shoot culture and 78.6% of plantlets from somatic embryos survived after 8 weeks’ acclimatization.