Cupressus Gigantea Research Articles

Genetic Diversity Assessment of Cupressus gigantea W. C. Cheng & L. K. Fu Using Inter-Simple Sequence Repeat Technique

Cupressus gigantea W. C. Cheng & L. K. Fu is an endemic conifer tree species that is distributed widely along the northern portion of the deep gorge of the Yarlung Tsangbo River on the Tibetan Plateau. However, as a key plant species growing on the Tibetan plateau, C. gigantea has since become an endangered species due to habitat loss and degradation, overexploitation, and other factors. It has been listed as a first-grade national protected wild plant species in China. Accordingly, to conserve this plant species, we should obtain more information on its genetic structure. In this study, the genetic diversity and structure among 67 samples were evaluated by the inter-simple sequence repeat (ISSR) technique. Overall, 78 bands were produced with a molecular length of 200 bp to 3100 bp using 10 ISSR primers. The mean values for the average number of alleles (Na), effective number of alleles (Ne), Nei’s gene diversity (H), and Shannon’s information index (I) were 1.529, 1.348, 0.199, and 0.293, respectively. Additionally, the number of polymorphic loci (NPLs) and percentage of polymorphic loci (PPLs) averaged 41.25 and 52.90, respectively. Further, total variation among populations was 14.2%, while that within populations was 85.8%; accordingly, the within-population genetic differentiation was found to be significant (p < 0.001). These results demonstrated that a genetic structure model with K = 3 fitted the data best, which agreed with the unweighted pair group method with arithmetic average (UPGMA) cluster and the principal coordinate analysis (PCoA). These findings are beneficial for ensuring the development and genetic protection of C. gigantea populations in the future.

Proteomic characterization of the different stages of seed germination in Cupressus gigantea

Abstract Seed germination is a pivotal period of plant growth and development. This process can be divided into four major stages, swelling absorption, seed coat dehiscence, radicle emergence and radicle elongation. Cupressus gigantea, a tree native to Tibet, China, is characterized by its resistance to stresses such as cold, and drought, and has a high economic and ecological value. Nevertheless, given its unique geographic location, its seeds are difficult to germinate. Therefore, it is crucial to explore the mechanisms involved in seed germination in this species to improve the germination efficiency of its seeds, thereby protecting this high-quality resource. Here, our findings indicate that seed germination was enhanced when exposed to a 6-h/8-h light/dark photoperiod, coupled with a temperature of 20°C. Furthermore, the application of exogenous GA3 (1 mg/ml, about 2.9 mM) stimulated the germination of C. gigantea seeds. Subsequently, proteomics was used to detect changes in protein expression during the four stages of seed germination. We identified 34 differentially expressed proteins (DEPs), including 13 at the radicle pre-emergence stage, and 17 at the radicle elongation stage. These DEPs were classified into eight functional groups, cytoskeletal proteins, energy metabolism, membrane transport, stress response, molecular chaperones, amino acid metabolism, antioxidant system and ABA signalling pathway. Most of them were found to be closely associated with amino acid metabolism. Combined, these findings indicate that, along with temperature and light, exogenous GA3 can increase the germination efficiency of C. gigantea seeds. Our study also offers insights into the changes in protein expression patterns in C. gigantea seeds during germination.

Efficient purging of deleterious mutations contributes to the survival of a rare conifer.

Cupressaceae is a conifer family rich in plants of horticultural importance, including Cupressus, Chamaecyparis, Juniperus, and Thuja, yet genomic surveys are lacking for this family. Cupressus gigantea, one of the many rare conifers that are threatened by climate change and anthropogenic habitat fragmentation, plays an ever-increasing role in ecotourism in Tibet. To infer how past climate change has shaped the population evolution of this species, we generated a de novo chromosome-scale genome (10.92Gb) and compared the species' population history and genetic load with that of a widespread close relative, C. duclouxiana. Our demographic analyses, based on 83 re-sequenced individuals from multiple populations of the two species, revealed a sharp decline of population sizes during the first part of the Quaternary. However, populations of C. duclouxiana then started to recover, while C. gigantea populations continued to decrease until recently. The total genomic diversity of C. gigantea is smaller than that of C. duclouxiana, but contrary to expectations, C. gigantea has fewer highly and mildly deleterious mutations than C. duclouxiana, and simulations and statistical tests support purifying selection during prolonged inbreeding as the explanation. Our results highlight the evolutionary consequences of decreased population size on the genetic burden of a long-lived endangered conifer with large genome size and suggest that genetic purging deserves more attention in conservation management.

Prediction of Potential Suitable Areas and Priority Protection for Cupressus gigantea on the Tibetan Plateau.

Cupressus gigantea (C. gigantea) is an endemic endangered species on the Tibetan Plateau; its potential suitable areas and priority protection in the context of global climate change remain poorly predicted. This study utilized Biomod2 and Marxan to assess the potential suitable areas and priority protection for C. gigantea. Our study revealed that the suitable areas of C. gigantea were concentrated in the southeastern Tibetan Plateau, with the center in Lang County. Temperature was identified as a crucial environmental factor influencing the distribution of C. gigantea. Over the coming decades, the suitable range of C. gigantea expanded modestly, while its overall distribution remained relatively stable. Moreover, the center of the highly suitable areas tended to migrate towards Milin County in the northeast. Presently, significant areas for improvement are needed to establish protected areas for C. gigantea. The most feasible priority protected areas were located between the Lang and Milin counties in Tibet, which have more concentrated and undisturbed habitats. These results provide scientific guidance for the conservation and planning of C. gigantea, contributing to the stability and sustainability of ecosystems.

Prediction of suitable habitat distribution and potential impact of climate change on distribution patterns of <i>Cupressus gigantea</i>

Prediction of suitable habitat distribution and potential impact of climate change on distribution patterns of <i>Cupressus gigantea</i>

Genomic insights into the genotype-environment mismatch and conservation units of a Qinghai-Tibet Plateau endemic cypress under climate change.

Habitat loss induced by climate warming is a major threat to biodiversity, particularly to threatened species. Understanding the genetic diversity and distributional responses to climate change of threatened species is critical to facilitate their conservation and management. Cupressus gigantea, a rare conifer found in the eastern Qinghai–Tibet Plateau (QTP) at 3000–3600 m.a.s.l., is famous for its largest specimen, the King Cypress, which is >55 m tall. Here, we obtained transcriptome data from 96 samples of 10 populations covering its whole distribution and used these data to characterize genetic diversity, identify conservation units, and elucidate genomic vulnerability to future climate change. After filtering, we identified 145,336, 26,103, and 2833 single nucleotide polymorphisms in the whole, putatively neutral, and putatively adaptive datasets, respectively. Based on the whole and putatively neutral datasets, we found that populations from the Yalu Tsangpo River (YTR) and Nyang River (NR) catchments could be defined as separate management units (MUs), due to distinct genetic clusters and demographic histories. Results of gradient forest models suggest that all populations of C. gigantea may be at risk due to the high expected rate of climate change, and the NR MU had a higher risk than the YTR MU. This study deepens our understanding of the complex evolutionary history and population structure of threatened tree species in extreme environments, such as dry river valleys above 3000 m.a.s.l. in the QTP, and provides insights into their susceptibility to global climate change and potential for adaptive responses.

Integration of the Physiology, Transcriptome and Proteome Reveals the Molecular Mechanism of Drought Tolerance in Cupressus gigantea

Drought stress can dramatically impair woody plant growth and restrict the geographical distribution of many tree species. To better understand the dynamics between the response and mechanism of Cupressus gigantea to drought and post-drought recovery, a comparative analysis was performed, relying on physiological measurements, RNA sequencing (RNA-Seq) and two-dimensional gel electrophoresis (2-DE) proteins. In this study, the analyses revealed that photosynthesis was seriously inhibited, while osmolyte contents, antioxidant enzyme activity and non-enzymatic antioxidant contents were all increased under drought stress in seedlings. Re-watering led to a recovery in most of the parameters analyzed, mainly the photosynthetic parameters and osmolyte contents. Transcriptomic and proteomic profiling suggested that most of the differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) were specifically altered, and a few were consistently altered. Drought induced a common reduction in the level of DEGs and DEPs associated with photosynthesis. Notably, DEGs and DEPs involved in reactive oxygen species (ROS) scavenging, such as ascorbate oxidase and superoxide dismutase (SOD), showed an inverse pattern under desiccation. This study may improve our understanding of the underlying molecular mechanisms of drought resistance in C. gigantea and paves the way for more detailed molecular analysis of the candidate genes.

Ancient introgression drives adaptation to cooler and drier mountain habitats in a cypress species complex

Introgression may act as an important source of new genetic variation to facilitate the adaptation of organisms to new environments, yet how introgression might enable tree species to adapt to higher latitudes and elevations remains unclear. Applying whole-transcriptome sequencing and population genetic analyses, we present an example of ancient introgression from a cypress species (Cupressus gigantea) that occurs at higher latitude and elevation on the Qinghai-Tibet Plateau into a related species (C. duclouxiana), which has likely aided the latter species to extend its range by colonizing cooler and drier mountain habitats during postglacial periods. We show that 16 introgressed candidate adaptive loci could have played pivotal roles in response to diverse stresses experienced in a high-elevation environment. Our findings provide new insights into the evolutionary history of Qinghai-Tibet Plateau plants and the importance of introgression in the adaptation of species to climate change.

In-depth transcriptome characterization uncovers distinct gene family expansions for Cupressus gigantea important to this long-lived species\u2019 adaptability to environmental cues

BackgroundCupressus gigantea, a rare and endangered tree species with remarkable medicinal value, is endemic to the Tibetan Plateau. Yet, little is known about the underlying genetics of the unique ecological adaptability of this extremely long-lived conifer with a large genome size. Here, we present its first de novo and multi-tissue transcriptome in-depth characterization.ResultsWe performed Illumina paired-end sequencing and RNA libraries assembly derived from terminal buds, male and female strobili, biennial leaves, and cambium tissues taken from adult C. gigantea. In total, large-scale high-quality reads were assembled into 101,092 unigenes, with an average sequence length of 1029 bp, and 6848 unigenes (6.77%) were mapped against the KEGG databases to identify 292 pathways. A core set of 41,373 genes belonging to 2412 orthologous gene families shared between C. gigantea and nine other plants was revealed. In addition, we identified 2515 small to larger-size gene families containing in total 9223 genes specific to C. gigantea, and enriched for gene ontologies relating to biotic interactions. We identified an important terpene synthases gene family expansion with its 121 putative members.ConclusionsThis study presents the first comprehensive transcriptome characterization of C. gigantea. Our results will facilitate functional genomic studies to support genetic improvement and conservation programs for this endangered conifer.

Genetic diversity and population structure of two endemic Cupressus (Cupressaceae) species on the Qinghai-Tibetan plateau

Cupressus gigantea and C. torulosa are ecologically and economically important endemic species of the conifer family Cupressaceae on the Qinghai-Tibetan plateau. C. gigantea was previously classified as a subspecies of C. torulosa because of their similar morphological characteristics and close distribution. In this study, 401 individuals were sampled from 16 populations of the two Cupressus species. The specimens were genotyped using 10 polymorphic microsatellite loci through fluorescence polymerase chain reaction (PCR). The genetic diversity of C. gigantea and C. torulosa populations was generally low, with the highest genetic diversity detected in the population LLS of C. gigantea. Distance-based phylogenetic and principal co-ordinates analyses indicated a clear genetic structures for the 16 populations of the two Cupressus species. Moreover, Mantel test results showed indistinctive correlations between population-pairwise Fst values and geographic distances, as well as between genetic distances and geographic distances in C. gigantea and C. torulosa, respectively. AMOVA suggested that genetic variation mostly resided within populations. Sixteen naturalpopulations were evidently clustered into two major groups in the constructed neighbour-joining tree. The results demonstrated that C. gigantea and C. torulosa are different Cupressus species. The genetic information provided important theoretical references for conservation and management of the two endangered Cupressus species.

The complete chloroplast genome of Cupressus gigantea, an endemic conifer species to Qinghai-Tibetan Plateau

The complete chloroplast genome of the wild Cupressus gigantea (Cupressaceae) is determined in this study. The circular genome is 128 244 bp in length with 115 single copy genes and two duplicated genes (trnI-CAU and trnQ-UUG). This genome contains 82 protein-coding genes, four ribosomal RNA genes and 31 transfer RNA genes. In these genes, eight genes (atpF, rpoC1, ndhA, ndhB, petB, petD, rpl16 and rpl2) harbor a single intron and two genes (rps12 and ycf3) harbor two introns. This genome does not contain canonical IRs, and the overall GC content is 34.7%. A maximum parsimony phylogenetic analysis revealed that C. gigantea and C. sempervirens are more closely related.

Isolation and characterization of polymorphic microsatellites in the Tibetan cypress Cupressus gigantea using paired-end Illumina shotgun sequencing

Cupressus gigantea Cheng et L. K. Fu is an endangered conifer endemic to Tibet of China. In this study, 16 polymorphic microsatellite markers were developed using paired-end Illumina shotgun sequencing. The number of alleles varied between 3 and 18, with an average of 8.063 alleles per locus. The observed (H O) and expected heterozygosities (H E) ranged from 0.227 to 0.902 and from 0.000 to 1.000, respectively. Following the false discovery rate controlling procedure, six loci showed significant deviations from Hardy–Weinberg equilibrium, and linkage disequilibrium was only detected between a pair of loci. These informative microsatellite markers can be readily used for genetic analyses of this endangered plant.

Terpenoids from Stems and Leaves of <I>Cupressus gigantea</I>

Terpenoids from Stems and Leaves of <I>Cupressus gigantea</I>

Terpenoids from Stems and Leaves of Cupressus gigantea

AimTo study the chemical constituents of Cupressus gigantea. MethodsThe chemical constituents were isolated by various chromatographic methods, and the chemical structures were elucidated on the basis of spectral analysis (NMR, MS). ResultsA new labdane-type diterpenoid, fourteen known diterpenoids, and two known sesquiterpenoids were isolated from the stems and leaves of Cupressus gigantea. The structure of the new compound (1) was elucidated on the basis of the analysis of spectroscopic data. ConclusionCompound 1 is a new sesquiterpenoid, compounds 1–17 were isolated from this plant for the first time.

A 622-year regional temperature history of southeast Tibet derived from tree rings

A tree ring-width record spanning from AD 1377—1998 was developed from Tibetan juniper ( Cupressus gigantea) growing at sites north of the deep gorge of the Yarlung Tsangbo River of southeast Tibet. A linear regression model between ring width and mean January—June temperature accounts for 35% of January—June temperature variance for the period 1961—1998. Based on this model, we reconstructed January—June temperature variation history for the study region during the past 622 years. Warm conditions occurred during AD 1385—1418, 1443—1466, 1482—1501, 1523—1548, 1570s, 1705—1759, 1770—1790, 1851—1888, 1910s, and 1938—1965, and periods of relatively cold years are identified for AD 1419—1442, 1470s, 1502—1522, 1550—1569, 1610—1640, 1680—1700, 1760s, 1791—1850, 1900s and 1965—1995. Spatial correlation between tree rings and observed temperatures indicates that the reconstruction is representative of temperature change for southeast Tibet. Regional cold conditions during AD 1625, 1685, 1760, 1800—1850, 1890—1930 and 1965—1995, and warm conditions during 1710, 1730—1750, 1850—1890 and 1930—1960 can be identified in the eastern Tibetan Plateau. Our reconstruction shows good agreement with modelled regional temperatures derived from an ECHO-G model simulation. Common cold periods around 1470, 1685 and 1845 corresponding to the Spörer Minimum, the Maunder Minimum and the Dalton Minimum periods of low solar activity and increased volcanic activity were identified, indicating that solar and volcanic activity played an important role in temperature change of this region. The discrepancy between modelled and reconstructed temperatures was noted around 1965, reflecting that temperature decrease in the late 20th century (1965—1995) is anomalous.

Genetic Variation in the Qinghai-Tibetan Plateau Endemic and Endangered Conifer Cupressus gigantea, Detected Using RAPD and ISSR Markers

AbstractAssessing the level and distribution of genetic diversity of rare tree species is essential for their management and the development of effective conservation strategies. Cupressus gigantea is a long-lived endemic cypress of the west Qinghai-Tibetan Plateau and the tallest tree in its genus. The current populations of this species are fragmented and highly disturbed. We used RAPD (Random Amplified Polymorphic DNA) and ISSR (Inter-Simple Sequence Repeat amplification) markers to assess the genetic variation and population structure of this endangered cypress. The 15 RAPD primers used in this study amplified 108 reproducible bands, 49 (45.4%) of which were polymorphic, while the 12 ISSR primers amplified 94 bands, 65 (69.2%) of which were polymorphic. Analysis of Molecular Variance (AMOVA) indicated that 49.7% and 38.3% of the variation was attributable to differences between populations for the RAPD and ISSR markers, respectively; relatively high compared to values reported for other conifer species. These estimates were also similar to Gst values obtained from Nei’s gene diversity analyses (RAPD = 0.41 and ISSR = 0.36), and suggest that there is a high degree of population differentiation in this narrowly-distributed conifer. The genetic structure of this species has probably been shaped by its long life cycle and climatic changes during the Quaternary. The high degree of population differentiation in this species highlights the need for additional conservation measures, including measures to protect of all of the remaining populations. The substantial similarities between the results of the RAPD and ISSR analyses of samples from the same individuals indicate that they can be interpreted with high levels of confidence.

Quantitative assessment on endangerment degree of rare animal and plant species in Tibet, China

It is of profound theoretical and practical significance to study endangerment status of rare species in Tibet. Index system is firstly set down for quantitative assessment of rare animal and plant species, then endangerment degree of wildlife under special state protection are calculated, which is expressed by value E. The results reveal that Yunnan snub-nosed monkey (Rhinopithecus bieti), Himalayan tahr (Hemitragus jemlahicus) and Gigantic Cypress (Cupressus gigantea) have the highest E respectively in animals and plants. According to value E, all species are categorized into 4 ranks: critically endangered (0.6–0.8), endangered (0.4–0.6), vulnerable (0.2–0.4) and lower risk (E ⩽ 0.2). By comparison of the first five animals and plants of the highest E, each sub-ecozone bears a distinct identity.

Palaeoecological and experimental evidence of former forests and woodlands in the treeless desert pastures of Southern Tibet (Lhasa, A.R. Xizang, China)

Palaeoecological and palaeopedological investigations around Lhasa (3650 m, 29°40′N/91°04′E, A.R. Xizang, China) provide evidence of human induced environmental changes which have occurred over the past 4600 years. The present desert pastures of Southern Tibet most probably replaced forests of Juniperus convallium, J. tibetica and Cupressus gigantea along with Prunus mira and Buddleja crispa in the understorey. Paleosol investigations and determined charcoal indicate a likeliness of forest destruction followed by increased erosion and sedimentation of colluvial soils. For the first time cereal pollen types could be clearly distinguished in southern Tibet. Juniperus pollen has been proved to have only a short dispersal range. The presence of cereal pollen and other human indicator pollen proves that it is more likely that human activity rather than climatic changes caused the forest decline during the younger Holocene. Successful non-irrigated reforestation trial experiments since 1997 on southern slopes around Lhasa with indigenous Cupressaceae have demonstrated that desertification of southern Tibet is a reversible process. As Lhasa receives 443 mm annual precipitation and has summer temperatures of above 10 °C it follows that the natural vegetation should be a forest, as opposed to the desert status quo that presides at present.