Genome assembly of Ottelia alismoides, a multiple-carbon utilisation aquatic plant.

OBJECTIVES: Ottelia Pers. is in the Hydrocharitaceae family. Species in the genus are aquatic, and China is their centre of origin in Asia. Ottelia alismoides (L.) Pers., which is distributed worldwide, is a distinguishing element in China, while other species of this genus are endemic to China. However, O. alismoides is also considered endangered due to habitat loss and pollution in some Asian countries. Ottelia alismoides is the only submerged macrophyte that contains three carbon dioxide-concentrating mechanisms, i.e. bicarbonate (HCO3-) use, crassulacean acid metabolism and the C4 pathway. In this study, we present its first genome assembly to help illustrate the various carbon metabolism mechanisms and to enable genetic conservation in the future. DATA DESCRIPTION: Using DNA and RNA extracted from one O. alismoides leaf, this work produced ∼ 73.4 Gb HiFi reads, ∼ 126.4 Gb whole genome sequencing short reads and ∼ 21.9 Gb RNA-seq reads. The de novo genome assembly was 6,455,939,835 bp in length, with 11,923 scaffolds/contigs and an N50 of 790,733 bp. Genome assembly completeness assessment with Benchmarking Universal Single-Copy Orthologs revealed a score of 94.4%. The repetitive sequence in the assembly was 4,875,817,144 bp (75.5%). A total of 116,176 genes were predicted. The protein sequences were functionally annotated against multiple databases, facilitating comparative genomic analysis.

Draft genome of Brasenia schreberi, a worldwide distributed and endangered aquatic plant.

OBJECTIVES: Brasenia is a monotypic genus in the family of Cabombaceae. The only species, B. schreberi, is a macrophyte distributed worldwide. Because it requires good water quality, it is endangered in China and other countries due to the deterioration of aquatic habitats. The young leaves and stems of B. schreberi are covered by thick mucilage, which has high medical value. As an allelopathic aquatic plant, it can also be used in the management of aquatic weeds. Here, we present its assembled and annotated genome to help shed light on medial and allelopathic substrates and facilitate their conservation. DATA DESCRIPTION: Genomic DNA and RNA extracted from B. schreberi leaf tissues were used for whole genome and RNA sequencing using a Nanopore and/or MGI sequencer. The assembly was 1,055,148,839 bp in length, with 92 contigs and an N50 of 22,379,495 bp. The repetitive elements in the assembly were 555,442,205 bp. A completeness assessment of the assembly with BUSCO and compleasm indicated 88.4 and 90.9% completeness in the Eudicots database and 95.4 and 96.6% completeness in the Embryphyta database. Gene annotation revealed 67,747 genes that coded for 73,344 proteins.

Soil microbial community structure, function and network along a mangrove forest restoration chronosequence.

Mangrove forests have high ecological, social and economic values, but due to environmental changes and human activities, natural mangrove forests have experienced serious degradations and reductions in distribution area worldwide. In the coastal zones of southern China, an introduced mangrove species, Sonneratia apetala, has been extensively used for mangrove restoration because of its rapid growth and strong environmental adaptability. However, little is known about how soil microorganisms vary with the restoration stages of the afforested mangrove forests. Here, we examined the changes in soil physicochemical properties and microbial biomass, community structure and function, and network in three afforested S. apetala forests with restoration time of 7, 12, and 18 years and compared them with a bare flat and a 60-year-old natural Kandelia obovata forest in a mangrove nature reserve. Our results showed that the contents of soil salinity, organic carbon, total nitrogen, ammonium nitrogen, and microbial biomass increased, while soil pH and bacterial alpha diversity decreased with afforestation age. Soil microbial community structure was significantly affected by soil salinity, organic carbon, pH, total nitrogen, ammonium nitrogen, available phosphorus, and available kalium, and susceptibility to environmental factors was more pronounced in bacterial than fungal community structure. The relative abundances of aerobic chemoheterotrophy were significantly higher in 12- and 18-year-old S. apetala than in K. obovata forest, while that of sulfate-reducing bacteria showed a decreasing trend with afforestation age. The abundance of dung saprotroph was significantly higher in 12- and 18-year-old S. apetala forests than in the natural forest. With the increasing afforestation age, the modularity of microbial networks increased, while stability and robustness decreased. Our results suggest that planting S. apetala contributes to improving soil fertility and microbial biomass but may make soil microbial networks more vulnerable.

Chromosome-level genome assembly and demographic history of Euryodendron excelsum in monotypic genus endemic to China.

Euryodendron excelsum is in a monotypic genus Euryodendron, endemic to China. It has intermediate morphisms in the Pentaphylacaceae or Theaceae families, which make it distinct. Due to anthropogenic disturbance, E. excelsum is currently found in very restricted and fragmented areas with extremely small populations. Although much research and effort has been applied towards its conservation, its long-term survival mechanisms and evolutionary history remain elusive, especially from a genomic aspect. Therefore, using a combination of long/short whole genome sequencing, RNA sequencing reads, and Hi-C data, we assembled and annotated a high-quality genome for E. excelsum. The genome assembly of E. excelsum comprised 1,059,895,887 bp with 99.66% anchored into 23 pseudo-chromosomes and a 99.0% BUSCO completeness. Comparative genomic analysis revealed the expansion of terpenoid and flavonoid secondary metabolite genes, and displayed a tandem and/or proximal duplication framework of these genes. E. excelsum also displayed genes associated with growth, development, and defence adaptation from whole genome duplication. Demographic analysis indicated that its fluctuations in population size and its recent population decline were related to cold climate changes. The E. excelsum genome assembly provides a highly valuable resource for evolutionary and ecological research in the future, aiding its conservation, management, and restoration.

Draft genome of Castanopsis chinensis, a dominant species safeguarding biodiversity in subtropical broadleaved evergreen forests.

OBJECTIVES: Castanopsis is the third largest genus in the Fagaceae family and is essentially tropical or subtropical in origin. The species in this genus are mainly canopy-dominant trees, and the key components of evergreen broadleaved forests play a crucial role in the maintenance of local biodiversity. Castanopsis chinensis, distributed from South China to Vietnam, is a representative species. It currently suffers from a high disturbance of human activity and climate change. Here, we present its assembled genome to facilitate its preliminary conservation and breeding on the genome level. DATA DESCRIPTION: The C. chinensis genome was assembled and annotated by Nanopore and MGI whole-genome sequencing and RNA-seq reads using leaf tissues. The assembly was 888,699,661 bp in length, consisting of 133 contigs and a contig N50 of 23,395,510 bp. A completeness assessment of the assembly with Benchmarking Universal Single-Copy Orthologs (BUSCO) indicated a score of 98.3%. Repetitive elements comprised 471,006,885 bp, accounting for 55.9% of the assembled sequences. A total of 51,406 genes that coded for 54,310 proteins were predicted. Multiple databases were used to functionally annotate the protein sequences.

Genome assembly of Erythrophleum Fordii, a special "ironwood" tree in China.

OBJECTIVES: Erythrophleum is a genus in the Fabaceae family. The genus contains only about 10 species, and it is best known for its hardwood and medical properties worldwide. Erythrophleum fordii Oliv. is the only species of this genus distributed in China. It has superior wood and can be used in folk medicine, which leads to its overexploitation in the wild. For its effective conservation and elucidation of the distinctive genetic traits of wood formation and medical components, we present its first genome assembly. DATA DESCRIPTION: This work generated ~ 160.8 Gb raw Nanopore whole genome sequencing (WGS) long reads, ~ 126.0 Gb raw MGI WGS short reads and ~ 29.0 Gb raw RNA-seq reads using E. fordii leaf tissues. The de novo assembly contained 864,825,911 bp in the E. fordii genome, with 59 contigs and a contig N50 of 30,830,834 bp. Benchmarking Universal Single-Copy Orthologs (BUSCO) revealed 98.7% completeness of the assembly. The assembly contained 471,006,885 bp (54.4%) repetitive sequences and 28,761 genes that coded for 33,803 proteins. The protein sequences were functionally annotated against multiple databases, facilitating comparative genomic analysis.

Seed rain composition responds to climate change in a subtropical forest.

Recent climate change has been shown to alter aspects of forest plant demography, such as growth and mortality, but less attention has been focused on how climate change alters the reproduction of plant populations through time. We hypothesized that the plant seed production would respond to climate change, and that the response would differ according to plant life form and functional traits. We tested this hypothesis by examining climate change from 2005 to 2020 and by determining the temporal trends of seed rain and seed production from plants with different life forms (e.g., herbs, vines, trees, palms) and of tree species with different statures as well as leaf, seed and wood traits during 2014-2020. We also tested the correlation between meteorological variables and time series of seed rain using cross correlation analysis. We found increasing wetness (lower vapor pressure deficit) through time but with decreasing minimum relative humidity, which is a pattern consistent with trends seen in many other parts of the world. During the study period, seed production of shrubs and relative contribution of woody vines to total seed rain decreased, while relative contribution of palms to total seed rain and tree species with more conservative leaf traits increased their contribution to total seed rain. Overall, these trends were well explained by the trends of meteorological variables and the responses of these life forms to climate change in previous studies. Additionally, the increasingly conservative leaf traits were also consistent with shifts in traits following recovery from disturbance. Our results suggest that a trait-based approach may help to unveil trends that are not readily apparent by examining seed counts alone. The compositional change found in the seed rain may indicate future shifts in forest species composition and should be incorporated into future studies of forest modelling and projections under climate change.

Draft genome and transcriptome of Nepenthes mirabilis, a carnivorous plant in China.

OBJECTIVES: Nepenthes belongs to the monotypic family Nepenthaceae, one of the largest carnivorous plant families. Nepenthes species show impressive adaptive radiation and suffer from being overexploited in nature. Nepenthes mirabilis is the most widely distributed species and the only Nepenthes species that is naturally distributed within China. Herein, we reported the genome and transcriptome assemblies of N. mirabilis. The assemblies will be useful resources for comparative genomics, to understand the adaptation and conservation of carnivorous species. DATA DESCRIPTION: This work produced ~ 139.5 Gb N. mirabilis whole genome sequencing reads using leaf tissues, and ~ 21.7 Gb and ~ 27.9 Gb of raw RNA-seq reads for its leaves and flowers, respectively. Transcriptome assembly obtained 339,802 transcripts, in which 79,758 open reading frames (ORFs) were identified. Function analysis indicated that these ORFs were mainly associated with proteolysis and DNA integration. The assembled genome was 691,409,685 bp with 159,555 contigs/scaffolds and an N50 of 10,307 bp. The BUSCO assessment of the assembled genome and transcriptome indicated 91.1% and 93.7% completeness, respectively. A total of 42,961 genes were predicted in the genome identified, coding for 45,461 proteins. The predicted genes were annotated using multiple databases, facilitating future functional analyses of them. This is the first genome report on the Nepenthaceae family.

Potential inhibitors of microglial activation from the roots of Vernicia montana Lour.

During our continuous investigation of natural, herbal inhibitors of microglial over-activation in the Euphorbiaceae family, two plants of the Vernicia genus showed remarkable inhibitory effects on nitric oxide (NO) production in over-activated microglia. In this study, bioactivity-guided phytochemical research on the active fraction of the roots of V. montana was carried out. As a result, seven undescribed terpenoids and lignans, together with thirty-one known components, were isolated and identified using comprehensive spectral analysis. All the identified compounds were evaluated for their inhibitory effects on NO production in lipopolysaccharide-stimulated BV-2 cells. Combined with our previous research on the Vernicia genus, the effective material basis of different plants and medicinal components was analyzed systematically.

The complete chloroplast genome of Ormosia purpureiflora (Fabaceae).

Ormosia purpureiflora is endemic to China. It is named after its purple flowers. It is a small tree only up to 3 m. It has leathery leaves, racemose inflorescences. The seeds are elliptic and red in coat. It is only confined to Luofushan Provincial Nature Reserve in Huizhou of Guangdong Province. Herein, we first reported on its complete chloroplast genome sequence as genomic resource for conservation purposes. The chloroplast genome of O. purpureiflora was 173,364 bp in length, with a large single-copy region of 73,465 bp, a small single-copy region of 18,751 bp, and a pair of inverted repeat regions that were 40,574 bp each. A total of 90 protein-coding genes, 38 transfer RNA genes, and eight ribosomal RNA genes were predicted, while 106 simple sequence repeats were recorded throughout the genome. Phylogenetic analysis revealed that O. purpureiflora was sister to O. emarginata.

The complete chloroplast genome of Rhododendron kawakamii (Ericaceae).

Rhododendron kawakamii is endemic in Taiwan island and is a unique and epiphytic species. Here, we report its complete chloroplast genome. The length of the R. kawakamii chloroplast genome is 230,777 bp, with a large single-copy region of 146,155 bp, a small single-copy region of 72,082 bp, and a pair of inverted repeat regions (IRA) of 6,270 bp each. The genome contains 77 protein-coding genes, 29 transfer RNA genes, and four ribosomal RNA genes. In addition, the genome contains 81 simple sequence repeats. Phylogenetic analysis revealed that R. kawakamii is genetically related to R. datiandingense.

The complete mitochondrial genome of Ormosia boluoensis.

Ormosia is a particular genus in the Fabaceae family with its striking seeds. The genus Ormosia boluoensis is a newly reported and critically endangered species, and field investigations have indicated that there are only hundreds of it. For the effective conservation, we report its complete mitochondrial genome. The length of the O. boluoensis mitochondrial genome is 248,619 bp, including 28 protein-coding genes, 14 transfer RNA genes, 3 ribosomal RNA genes, and 45 simple sequence repeats. Phylogenetic analysis revealed that O. boluoensis was a sister to the clade including Sophora flavescens, Ammopiptanthus nanus, and Ammopiptanthus mongolicus.

The complete chloroplast genome of Rhododendron datiandingense (Ericaceae).

Rhododendron datiandingense is newly reported and endemic to China. The genome of R. datiandingense is 207,311 bp in length, including a large single-copy region of 190,689 bp and a small single-copy region of 2582 bp, a pair of inverted repeat regions (IRA) of 7020 bp each. The genome encodes 110 genes, comprising 77 protein-coding genes, four ribosomal RNA genes, and 29 transfer RNA genes. Repeat analysis revealed 62 simple sequence repeats (SSRs) in the genome. Phylogenetic analysis revealed that R. datiandingense is clearly separated from the other Rhododendron species and shown in the basal position.

The complete mitochondrial genome sequence of Aquilaria sinensis.

Aquilaria sinensis, endemic to China, is an economically important evergreen tree species and a source of agarwood. Due to the high market demand for agarwood, this species is heavily overexploited in the wild and is now listed as an endangered species. Although its nuclear and chloroplast genomes have been previously reported, little is known about its mitochondrial genome. Using the paired-end short reads generated by the Illumina sequencing platform, we assembled and herein report the mitochondrial genome of A. sinensis for future phylogenetic, evolutionary, and preservative studies. The length of the A. sinensis mitochondrial genome was found to be 341,829 bp and the GC content was 45.01%. A total of 32 protein-coding genes, 19 tRNA genes, and three rRNA genes were annotated. The phylogenetic tree indicated that A. sinensis is most closely genetically related to Vigna radiata.

The complete chloroplast genome of Aganope dinghuensis (Fabaceae).

Aganope is a genus in the family Fabaceae, with only 11 species. They are distributed throughout Asia and Africa. Aganope dinghuensis, a newly reported species, is native to China with a restricted distribution. We, therefore, report its complete chloroplast genome for better future conservation. The chloroplast genome of A. dinghuensis is 143,690 bp, with a GC content of 35.32%. In the genome, a pair of inverted repeat regions of 13,015 bp each, a large single-copy region of 98,824 bp, and a small single-copy region of 18,836 bp were identified. Genome annotation identified 115 genes, comprising 74 protein-coding genes, 8 ribosomal RNA genes, and 33 transfer RNA genes. Repeat analysis indicates that the chloroplast genome of A. dinghuensis contains 126 simple sequence repeats (SSR), of which the majority are A/T mononucleotides. Phylogenetic analysis revealed that A. dinghuensis is a sister to the clade that includes Indigofera tinctoria, Desmodium uncinatum, Sarcodum scandens, Wisteria brachybotrys, and Callerya nitida.

The complete chloroplast genome sequence of Begonia coptidifolia.

Begonia (Begoniaceae) is a large, pantropically distributed genus, comprising more than 1900 species. Due to poorly available genome resources, the phylogeny of this species-rich genus is still challenged. B. coptidifolia is a newly discovered species of restricted distribution in Southern China, and its genetic relationship with the other Begonia species has not been reported. Therefore, in this study, we report for the first time its chloroplast genome for future phylogenetic analysis. The circular chloroplast genome of B. coptidifolia is 169,412 bp in length, with a GC content of 35.57%. Its large single-copy region is 75,937 bp, a small single-copy region is 18,362 bp, and two inverted repeat regions are 37,556 bp and 37,557 bp, respectively. The genome encodes 82 protein-coding genes, 8 ribosomal RNA genes, and 40 transfer RNA genes. Phylogenetic analysis indicated that B. coptidifolia is genetically closest to B. pulchrifolia.

The complete chloroplast genome sequence of Ormosia boluoensis.

Ormosia boluoensis is a critically Endangered species that is exclusively distributed in Xiangtoushan National Nature Reserve in Guangdong province, China. At present, the population of the species is made up of less than 100 adult individuals. Here, we are the first to report the complete chloroplast genome sequence of O. boluoensis. The chloroplast genome of O. boluoensis is 175,760 bp long and includes a large single-copy region that is 74,613 bp, a small, 18,719 bp single copy region and a pair of inverted repeat regions that are 40,771 bp and 41,657 bp in length, respectively. The overall GC content of the O. boluoensis chloroplast genome is 35.58% and contains a total of 134 genes, including 89 protein-coding genes, 8 ribosomal RNA genes, and 37 transfer RNA genes. Phylogenetic analysis revealed that O. boluoensis is genetically similar to O. xylocarpa and O. emarginata genera.

The complete chloroplast genome sequence of Ormosia formosana.

Ormosia formosana is an important hardwood species and its seeds are popular as decorative jewelry. Currently, this species is threatened in the natural forests due to habitat destruction. Here, we first report the chloroplast genome of O. formosana for future studies in ecology, phylogeny, and conservation. The chloroplast genome of O. formosana is 173,587 bp in length with a GC content of 35.80%. It includes a large single-copy region of 73,550 bp, a small single-copy region of 18,683 bp, and two inverted repeat regions of 40,696 bp and 40,658 bp, respectively. The genome was totally annotated with 135 genes, including 90 protein-coding genes, eight ribosomal RNA genes, and 37 transfer RNA genes. Phylogenetic analysis indicated that O. formosana is most genetically similar to O. boluoensis.

Testing the competition-colonization trade-off and its correlations with functional trait variations among subtropical tree species.

The competition-colonization trade-off, by which species can partition spatial niches, is a potentially important mechanism allowing the maintenance of species diversity in plant communities. We examined whether there was evidence for this trade-off among tree species in a subtropical forest and how it correlated with eight functional traits. We developed and estimated a metric for colonization ability that incorporates both fecundity and seed dispersal based on seed trap data and the sizes and distributions of adult trees. Competitive ability was estimated as survival probability under high crowding conditions based on neighborhood models. Although we found no significant relationship between colonization and competitive abilities, there was a significant negative correlation between long distance dispersal ability and competitive ability at the 5 cm size class. Colonizers had traits associated with faster growth, such as large leaves and low leaf lamina density, whereas competitors had traits associated with higher survival, such as dense wood. Our results imply that any trade-off between competition and colonization may be more determined by dispersal ability than by fecundity, suggesting that seed dispersal is an important contributor to diversity maintenance. Future work should test how competitive ability covaries with the components of colonization ability, as we did here.

Endangered but genetically stable-Erythrophleum fordii within Feng Shui woodlands in suburbanized villages.

Feng Shui woodlands are naturally or artificially formed green areas in southern China. They are precious for maintaining ecosystem balance in modern semiurban environments. However, they are generally small and geographically isolated from each other, and the status of genetic diversity of the plant species within them has been almost neglected. Therefore, we studied the genetic diversity of the endangered Erythrophleum fordii in eight Feng Shui woodlands (a total of 1,061 individuals) in Guangzhou, a large city in southern China, using microsatellites. For comparison, one population with 33 individuals sampled in a nature reserve was also studied. Although our results indicate that significant demographic declines occurred historically in E. fordii, such declines have not resulted in consistent reductions in genetic variation over generations in Feng Shui populations in the recent past, and the levels of genetic variation in these populations were higher than or comparable to the genetic variation of the population in the nature reserve. In addition, our parentage and paternity analyses indicated widespread and potential long-distance pollen flow within one Feng Shui woodland, indicating the presence of an unbroken pollination network, which would at least partially alleviate the genetic erosion due to habitat fragmentation and the unequal gene contributions of E. fordii parents to their progenies when favorable recruitment habitats are absent under most of the parent trees. Overall, our results suggest that E. fordii in Feng Shui woodlands may not be driven to extinction in the near future. Nevertheless, uncontrolled fast urban development with a lack of awareness of Feng Shui woodlands will cause the local extinction of E. fordii, which has already happened in some Feng Shui woodlands.