QTL mapping for growth-related traits by constructing the first genetic linkage map in Simao pine.

BACKGROUND: Simao pine is one of the primary economic tree species for resin and timber production in southwest China. The exploitation and utilization of Simao pine are constrained by the relatively lacking of genetic information. Construction a fine genetic linkage map and detecting quantitative trait locis (QTLs) for growth-related traits is a prerequisite section of Simao Pine's molecular breeding program. RESULTS: In our study, a high-resolution Simao pine genetic map employed specific locus amplified fragment sequencing (SLAF-seq) technology and based on an F1 pseudo-testcross population has been constructed. There were 11,544 SNPs assigned to 12 linkage groups (LGs), and the total length of the map was 2,062.85 cM with a mean distance of 0.37 cM between markers. According to the phenotypic variation analysis for three consecutive years, a total of seventeen QTLs for four traits were detected. Among 17 QTLs, there were six for plant height (Dh.16.1, Dh16.2, Dh17.1, Dh18.1-3), five for basal diameter (Dbd.17.1-5), four for needle length (Dnl17.1-3, Dnl18.1) and two for needle diameter (Dnd17.1 and Dnd18.1) respectively. These QTLs individually explained phenotypic variance from 11.0-16.3%, and the logarithm of odds (LOD) value ranged from 2.52 to 3.87. CONCLUSIONS: In our study, a fine genetic map of Simao pine applied the technology of SLAF-seq has been constructed for the first time. Based on the map, a total of 17 QTLs for four growth-related traits were identified. It provides helpful information for genomic studies and marker-assisted selection (MAS) in Simao pine.

[Chloroplast genome phylogeny and codon preference of Docynia longiunguis].

Docynia longiunguis is a plant uniquely present in China and is of high edible and medicinal value. The analysis of its chloroplast genome will help clarify the phylogenetic relationship among Docynia and facilitate the development and utilization of D. longiunguis resources. Based on the alignment of chloroplast genome sequences of related species, the phylogeny and codon preference were analyzed. The total length of D. longiunguis chloroplast genome sequence was 158 914 bp (GenBank accession number is MW367027), with an average GC content of 36.7%. The length of the large single-copy (LSC), the small single-copy (SSC), and inverted repeats (IRs) are 87 020 bp, 19 156 bp, and 26 369 bp, respectively. A total of 102 functional genes were annotated, including 72 protein-coding genes, 26 tRNA genes, and 4 rRNA genes. The best model for constructing phylogenetic tree was TVM+F+R2. D. longiunguis and Docynia indica were clustered into a single group, while Docynia and Malus were clustered into a single group. Comparison of the chloroplast genome sequences of D. longiunguis and its five related species revealed that trnY (GUA)-psbD, ndhC-trnV (UAC), accD-psaI, psbZ-trnfM (CAU), ndhF-trnL gene regions varied greatly. The nucleic acid diversity analysis showed that there were 11 high variation areas with nucleotide variability > 0.01, all were located in the LSC and SSC regions. Except for D. longiunguis, the trnH genes in other sequences were located at the IRs/LSC junction and did not cross the boundary. Codon preference analysis showed that D. longiunguis chloroplast genome has the largest number of isoleucine (Ile) codons, up to 1 205. D. longiunguis has the closest genetic relationship with Malus baccata, Malus sieboldii, Malus hupehensis and Chaenomeles sinensis. Its chloroplast genome codon prefers to end with A/T. The chloroplast genome of D. longiunguis and other Rosaceae chloroplast genomes showed great differences in gene distribution in four boundary regions, while relatively small differences from the chloroplast genomes of Docynia delavayi and D. indica of the same genus were observed. The genome annotation, phylogenetic analysis and sequence alignment of chloroplast genome of D. longiunguis may facilitate the identification, development and utilization of this species.

Comparative Analysis of the Complete Chloroplast Genomes of Eight Ficus Species and Insights into the Phylogenetic Relationships of Ficus.

The genus Ficus is an evergreen plant, the most numerous species in the family Moraceae, and is often used as a food and pharmacy source. The phylogenetic relationships of the genus Ficus have been debated for many years due to the overlapping phenotypic characters and morphological similarities between the genera. In this study, the eight Ficus species (Ficus altissima, Ficus auriculata, Ficus benjamina, Ficus curtipes, Ficus heteromorpha, Ficus lyrata, Ficus microcarpa, and Ficus virens) complete chloroplast (cp) genomes were successfully sequenced and phylogenetic analyses were made with other Ficus species. The result showed that the eight Ficus cp genomes ranged from 160,333 bp (F. heteromorpha) to 160,772 bp (F. curtipes), with a typical quadripartite structure. It was found that the eight Ficus cp genomes had similar genome structures, containing 127 unique genes. The cp genomes of the eight Ficus species contained 89−104 SSR loci, which were dominated by mono-nucleotides repeats. Moreover, we identified eight hypervariable regions (trnS-GCU_trnG-UCC, trnT-GGU_psbD, trnV-UAC_trnM-CAU, clpP_psbB, ndhF_trnL-UAG, trnL-UAG_ccsA, ndhD_psaC, and ycf1). Phylogenetic analyses have shown that the subgenus Ficus and subgenus Synoecia exhibit close affinities and based on the results, we prefer to merge the subgenus Synoecia into the subgenus Ficus. At the same time, new insights into the subgeneric classification of the Ficus macrophylla were provided. Overall, these results provide useful data for further studies on the molecular identification, phylogeny, species identification and population genetics of speciation in the Ficus genus.

Analysis of metabolites in young and mature Docynia delavayi (Franch.) Schneid leaves using UPLC-ESI-MS/MS.

Docynia delavayi (Franch.) Schneid is a plant used both as food and traditional folk medicine. The leaves of D. delavayi are rich in polyphenols, plants with phenolic content are known to be extremely beneficial in terms of human nutrition. In the present study, we used metabolome technology (UPLC-ESI-MS/MS) to examine the young and mature D. delavayi leaves on metabolites changes, which were then analyzed and compared. As a result, 477 metabolites (including 111 flavonoids, 47 others (consisted of nine vitamin, 18 saccharides and alcohols, and 20 unassigned metabolites), 71 phenolic acids, 52 amino acids and derivatives, 18 alkaloids, 61 lipids, 24 terpenoids, 33 nucleotides and derivatives, 18 lignans and coumarins, 12 tannins, 30 organic acids) were identified, of which 281 differentially accumulated metabolites, including 146 up-regulated metabolites and 135 down-regulated metabolites. The result of clustering and PCA analyses showed that young and mature leaves were separated, which indicated that there was a great difference in metabolites between young and mature leaves. Meanwhile, we also found that both young and mature leaves displayed unique metabolites with important biological functions. KEGG enrichment analysis showed that 90 of the differential metabolites were mainly concentrated in 68 KEGG pathways. The result will greatly complement the existing knowledge on the D. delavayi leaves for lays a foundation for subsequent development and utilization.

The complete chloroplast genome of Castanopsis mekongensis A. Camus (Fagaceae).

Castanopsis mekongensis is highly valued in the furniture industry for its good wood texture, an endemic species in Yunnan province, southwest China. In our study, the chloroplast genome of C. mekongensis was assembled and characterized based on Illumina pair-end sequencing data. The total genome size of C. mekongensis was 160,699 bp, displayed a typical quadripartite structure including a pair of inverted repeat (IRs, 25,714 bp) regions separated by a large single-copy (LSC, 90,278 bp) region and a small single-copy (SSC, 18,963 bp) region. The overall guanine-cytosine (GC) content was 36.8%. We annotated 130 genes in the genome, containing 85 protein-coding genes, 37 tRNA genes, and eight rRNA genes, 12 genes contain a single intron, and two genes have two introns. The result of phylogenetic analysis based on maximum-likelihood (ML) phylogenetic tree indicated that C. mekongensis was most closely related to C. hainanensis.

Enhancing the expression of ARK1 genes in poplar leads to multiple branches and transcriptomic changes.

The ARBORKNOX1 (ARK1) gene is an important gene for regulating plant growth and development; however, transcriptomic responses of enhancing expression of ARK1 gene in poplar are poorly investigated. To provide insight into the gene function of the ARK1 gene in poplar, the ARK1 transgenic poplar '717' and '84 K' lines were obtained, the morphology of transgenic plants was observed, and transcriptome profiles were compared. The results showed that there were multiple branches in ARK1 transgenic seedlings compared with non-transgenic seedlings. The results of transcriptome analysis showed that there were significant differences in transcriptome profiles between the transgenic lines of '717' and '84 K', and between non-transgenic lines (CK) and transgenic plants. The real-time quantitative polymerase chain reaction (RT-qPCR) analysis confirmed the expression levels of the genes involved in the pathway of zeatin biosynthesis and brassinosteroid biosynthesis. The increase in expression levels of AHP and CYCD3 was related to multiple branches. Enhancing the expression of the ARK1 gene in poplar seedlings leads to multiple branches and transcriptomic changes.

The complete chloroplast genome sequence of Docynia indica (Wall.) Decne.

Docynia indica (Wall.) Decne. (Duo-Yi) is a high economic value for exploitation and utilization wild fruit tree species with edible and medicinal values in southwest China. We have sequenced the chloroplast genome to facilitate genetic improvement of this species and to assess phylogenetic relationships among major lineages. The result showed that the total chloroplast genome size of Duo-Yi was 159,546 bp in length, containing a pair of inverted repeats (IRs) of 26,369 bp, which were separated by a large single copy (LSC) and small single copy (SSC) of 87,650 bp and 19,158 bp, respectively. The overall guanine-cytosine (GC) content of the chloroplast genome was 36.6%. There were 125 genes in the chloroplast genome, which including 82 protein-coding genes, 35 transfer RNA genes, and 8 ribosomal RNA genes. Among these genes, there were 14 genes with one intron and 3 genes have two introns. The result of phylogenetic analysis indicated that the Duo-Yi was closely related to the genera of Malus doumeri.

The complete chloroplast genome of Yunnanopilia longistaminea (Opiliaceae), an endemic species in southwest China.

The complete chloroplast genome sequence of Yunnanopilia longistaminea, an endemic species in southwest China, is presented in this study. The total genome size of Y. longistaminea was 148,503 bp in length, with a typical quadripartite structure including a pair of inverted repeat (IRs, 28,075 bp) regions separated by a large single copy (LSC, 84,547bp) region and a small single copy (SSC, 7805 bp) region. The all GC content was 37.3%. The genome contains 117 genes, including 72 protein-coding genes, 37 tRNA genes, and 8 rRNA genes, 13 genes contain a single intron, and 3 genes have two introns. Further, a maximum-likelihood (ML) phylogenetic tree results that Y. longistaminea was closely related to the genera of Champereia manillana.

The complete chloroplast genome of Dipterocarpus turbinatus Gaertn. F.

Dipterocarpus turbinatus Gaertn. F., naturally distributes in Southern China, which is an elite natural tree with high economic and medicinal value. In study, all chloroplast (cp) genome of Dipterocarpus turbinatus Gaertn. F. was assembled and characterized based on Illumina pair-end sequencing data. The complete chloroplast genome length was 152,279 bp. It contained a large (LSC, 83,862 bp) and a small (SSC, 20,215 bp) single copy region, separated by a pair of inverted repeats of 24,101 bp (IRs). The overall GC content of genome was 37.3%, the corresponding values of LSC, SSC, and IR regions were 35.3, 31.6, and 43.2%, respectively. There were 128 genes in the genome including 84 protein-coding genes, 36 tRNA genes, and 8 rRNA genes. Among all genes, 14 genes contain a single intron and 1 gene has two introns. The result showed that Dipterocarpus turbinatus Gaertn. F. was closely related to Vatica mangachapoi.

Characterization of the complete chloroplast genomes of five Populus species from the western Sichuan plateau, southwest China: comparative and phylogenetic analyses.

Species of the genus Populus, which is widely distributed in the northern hemisphere from subtropical to boreal forests, are among the most commercially exploited groups of forest trees. In this study, the complete chloroplast genomes of five Populus species (Populus cathayana, P. kangdingensis, P. pseudoglauca, P. schneideri, and P. xiangchengensis) were compared. The chloroplast genomes of the five Populus species are very similar. The total chloroplast genome sequence lengths for the five plastomes were 156,789, 156,523, 156,512, 156,513, and 156,465 bp, respectively. A total of 130 genes were identified in each genome, including 85 protein-coding genes, 37 tRNA genes and eight rRNA genes. Seven genes were duplicated in the protein-coding genes, whereas 11 genes were duplicated in the RNA genes. The GC content was 36.7% for all plastomes. We analyzed nucleotide substitutions, small inversions, simple sequence repeats and long repeats in the chloroplast genomes and found nine divergence hotspots (ccsA+ccsA-ndhD, ndhC-trnV, psbZ-trnfM, trnG-atpA, trnL-ndhJ, trnR-trnN, ycf4-cemA, ycf1, and trnR-trnN), which could be useful molecular genetic markers for future population genetic and phylogenetic studies. We also observed that two genes (rpoC2 and rbcL) were subject to positive selection. Phylogenetic analysis based on whole cp genomes showed that P. schneideri had a close relationship with P. kangdingensis and P. pseudoglauca, while P. xiangchengensis was a sister to P. cathayana.

Comparative analysis of the complete chloroplast genomes of seven Populus species: Insights into alternative female parents of Populus tomentosa.

Populus tomentosa, of section Populus, is distributed mainly in northern China. This species has high resistance to many diseases and insects, and it plays key roles in shelterbelts and urban afforestation in northern China. It has long been suspected to be a hybrid, but its parents remain unknown. In the present study, we report four newly sequenced complete cp genomes from section Populus and comparative genomic analyses of these new sequences and three published cp genome sequences. The seven cp genomes ranged from 155,853 bp (P. tremula var. davidiana) to 156,746 bp (P. adenopoda) in length, and their gene orders, gene numbers and GC contents were similar. We analyzed SNPs, indels, SSRs and repeats among the seven cp genomes, and eight small inversions were detected in the ndhC-trnV, rbcL-accD, petA-psbJ, trnW-trnP, rpl16-rps3, trnL-ycf15, ycf15-trnL, and ndhF-trnL intergenic regions. Furthermore, seven divergent regions (trnH-psbA, matK, psbM-psbD, ndhC-trnV, ycf1, ndhF-ccsA and ccsA-ndhD) were found in more highly variable regions. The phylogenetic tree reveals that P. tomentosa is closely related to P. alba and P. alba var. pyramidalis. Hence, P. alba was involved in the formation of P. tomentosa.

Plastome Sequences Help to Resolve Deep-Level Relationships of Populus in the Family Salicaceae.

Populus, a core genus of Salicaceae, plays a significant ecological role as a source of pioneer species in boreal forests. However, interspecific hybridization and high levels of morphological variation among poplars have resulted in great difficulty in classifying species for systematic and comparative evolutionary studies. Here, we present phylogenetic analyses of 24 newly sequenced Populus plastomes and 36 plastomes from GenBank, which represent seven genera of Salicaceae, in combination with a matrix of eighteen morphological characters of 40 Populus taxa to reconstruct highly supported relationships of genus Populus. Relationships among the 60 taxa of Salicaceae strongly supported two monophyletic genera: Populus and Salix. Chosenia was nested within the genus Salix, and five clades within Populus were divided. Clade I included the three taxa P. euphratica, P. pruinosa, and P. ilicifolia. Clade II contained thirteen taxa [P. adenopoda, P. alba, P. bolleana, P. davidiana, P. hopeiensis, P. nigra, P. qiongdaoensis, P. rotundifolia, P. rotundifolia var. duclouxiana, P. tremula, P. tremula × alba, P. tomentosa, and P. tomentosa (NC)]. Clade III included the ten taxa P. haoana, P. kangdingensis, P. lasiocarpa, P. pseudoglauca, P. qamdoensis, P. schneideri, P. simonii, P. szechuanica, P. szechuanica var. tibetica, and P. yunnanensis. Clade IV included P. cathayana, P. gonggaensis, P. koreana, P. laurifolia, P. trinervis, P. wilsonii, and P. xiangchengensis. The last clade comprised P. angustifolia, P. balsamifera, P. deltoides, P. deltoides × nigra, P. fremontii, P. mexicana, and P. trichocarpa. This phylogeny is also supported by morphological traits, including bark smoothness, bud size, petiole shape, leaf inflorescence, male anther length and male anther tip.

Experience of minimally invasive treatment in 520 patients with intracranial aneurysms.

OBJECTIVE: To summarize the experience of minimally invasive treatment in 520 patients with intracranial aneurysms on a retrospective study. METHODS: The measures used in the treatment of 520 patients were reviewed in terms of timing of surgery, induced-hypotensive anesthesia, brain protection combined with temporal occlusion of the feeding artery, external drainage of CSF, dynamic monitoring of intracranial pressure, blood flow velocity, serum osmolality and CT scanning, anti-vasospasm therapy as well as selected interventional endovascular embolization of aneurysms. RESULTS: Of the 520 patients, 485 were treated with either direct clipping or endovascular embolization and 35 patients were treated non-surgically. In 449 patients undergoing direct clipping and 36 undergoing endovascular embolization, intraoperative rupture of aneurysm occurred in 27 (6.0%) and 0%, respectively. Death occurred in 13 (2.6%), hemiplegia in 8 (1.6%), and vegetative state in 2 (0.4%). The operative mortality of direct clipping was 3.8% in 210 patients before 1990 and 1.8% in 275 patients after 1990 (36 patients undergoing endovascular embolization, the operative mortality was 0%). CONCLUSION: The outcome of patients with intacranial aneurysms can be markedly improved and the operative mortality can be lowered by minimally invasive treatment.