Chinese Tree Research Articles

Chinese sapindaceous tree species (Sapindus mukorosii) exhibits lead tolerance and long-term phytoremediation potential for moderately contaminated soils

Heavy metal pollution in metropolitan soils poses significant risks to human health and the entire ecosystem. Effective mitigation strategies and technologies are crucial for addressing these environmental issues. Fast-growing trees are an essential part of phytoremediation projects all over the world and provide long-term ecological benefits to mankind. This study assessed the lead tolerance and phytoremediation potential of a fast-growing soapberry tree species (Sapindus mukorossi) in moderately contaminated soil. Two independent experiments were conducted to assess its tolerance at (i) germination level and (ii) prolonged growth stage. In the germination experiments, seeds were exposed to lead (II) nitrate Pb (NO₃)₂ at various concentrations (0, 5, 10, 20, 50, 100, 200, 300, 400 and 500 μM) for 120 days. Results showed significant differences in germination time, germination index, seedling vigor index, energy of germination, final germination, germination inhibition, seedling height and root/shoot weight compared to the control experiments. In the prolonged growth experiments, seedlings were grown for six months in soils amended/spiked with different Pb concentrations (T0 = 0, T1 = 20, T2 = 50, T3 = 100, T4 = 150 and T5 = 200 mg kg−1 soil) and their biomass was determined. The highest biomass achieved in six months (T0: 12.62 g plant−1), followed by (T1: 12.33 g plant−1), (T2: 12.42 g plant−1), (T3: 11.86 g plant−1), (T4: 10.86 g plant−1) and (T5: 10.06 g plant−1) respectively. S. mukorossi showed no visible signs of Pb toxicity over a six-month period. During six months of exposure, the total Pb content in S. mucrossi tissues were classified as roots > leaves > stems. The highest cumulative absorption of Pb occurred between the fourth and fifth months of exposure. Maximum transfer factor (TF) was detected during the fourth month ranging from 0.888 to 1.012 for the different Pb concentrations. Furthermore, the growth behavior, lead accumulation, bioconcentration factors (BCF) and tolerance index (TI) indicated that S. mucrossi may tolerate moderate Pb concentrations for longer periods. These findings suggest that S. mukorossi may be deployed for long-term phytoremediation coupled with urban forest applications in the future.

Chemical constituents variation of seed oil of the Chinese tallow tree (Sapium sebiferum (L.) Roxb) at different harvesting time

Sapium sebiferum (L.) Roxb, has a long history of being used as an oil-producing plant due to its high oil content of the seeds. In recent years, the seed oil of this tree has gained considerable interest as an ideal material to produce biodiesel. To optimize the harvesting time of the seed, we tracked the variation of chemical constituents of seed oil harvested in different days (from October 1, 2021 to November 30, 2021). Firstly, the chemical constituents and fatty acid profile of external wax and internal kernel oil were studied, using nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS) as structure elucidation tools. Secondly, the constituent variation of external wax and kernel oil from different harvesting time was analyzed by 1H NMR and chemometrics tool. The results showed that unsaturated fatty acids in the kernel oil accumulated during harvesting time, while the external wax was progressively oxidized to formic acid due to exposure to air. Since the kernel oil was seal off from oxygen, no oxidation process was observed in it. Considering for the quality and total weight of lipids for biodiesel manufacturing, we suggest that the optimal harvesting time for seeds of S. sebiferum should be early November, when the fruit undergo complete cracking and the seeds are initially exposure to air. This information is practically helpful for optimizing the production of biodiesel from S. sebiferum and other similar oil-producing plants.

Research on the Estimation of Chinese Fir Stand Volume Based on UAV-LiDAR Technology

Chinese fir (Cunninghamia lanceolata) is the main fast-growing timber species in China, and studies of its stand volume are important for evaluating the effectiveness of forest management. However, it is difficult to accurately estimate stand volume from the perspective of a single tree due to the mutual concealment among Chinese fir trees. Therefore, in this study, we propose a method for identifying different forms of Chinese fir. The specific idea is to realize the accurate identification of a single Chinese fir tree, two Chinese fir trees, and three Chinese fir trees, and construct their respective stand volume estimation models to obtain an estimate of the forest stand volume. The key results are as follows: (1) the overall accuracy of recognition of different forms of Chinese fir is 79%, and the construction of different forms of Chinese fir units is beneficial for identifying forest trees; (2) a multiunit volume equation for different forms of Chinese fir is constructed; (3) based on predictions obtained with the constructed stand volume model, the difference between the estimated stand volume and the measured stand volume is small, and the average accuracy reaches 89.19%; and (4) compared to traditional volume estimation methods based on individual tree scale, the research method in this study shows a significant improvement (about 9.96%) in overall accuracy. In summary, this method can weaken the influence of erroneous individual tree segmentation on the accuracy of stand volume estimation, and can greatly reduce the working time of single tree segmentation to achieve the fast and accurate estimation of fir plantation stand volume.

Identification and Characterization of Diplodia parva and Diplodia crataegicola Causing Black Rot of Chinese Quince.

Fungal isolates from infected Chinese quince trees were found to cause black rot in Yeongcheon, Gyeongsangbuk Province, Korea. The quince leaves withered and turned reddish-brown and fruits underwent black mummification. To elucidate the cause of these symptoms, the pathogen was isolated from infected leaf and fruit tissues on potato dextrose agar and Levan media. Several fungal colonies forming a fluffy white or dark gray mycelium and two types of fungi forming an aerial white mycelium, growing widely at the edges, were isolated. Microscopic observations, investigation of fungal growth characteristics on various media, and molecular identification using an internal transcribed spacer, β-tubulin, and translation elongation factor 1-α genes were performed. The fungal pathogens were identified as Diplodia parva and Diplodia crataegicola. Pathogenicity tests revealed that the pathogen-inoculated fruits exhibited a layered pattern, turning brown rotting; leaves showed circular brown necrotic lesions. The developed symptoms were similar to those observed in the field. Fungal pathogens were reisolated to fulfill Koch's postulates. Apples were inoculated with fungal pathogens to investigate the host range. Strong pathogenicity was evident in the fruits, with browning and rotting symptoms 3 days after inoculation. To determine pathogen control, a fungicidal sensitivity test was conducted using four registered fungicides. Thiophanate-methyl, propineb, and tebuconazole inhibited the mycelial growth of pathogens. To the best of our knowledge, this is the first report on the isolation and identification of the fungal pathogens D. parva and D. crataegicola from infected fruits and leaves of Chinese quince, causing black rot disease in Korea.

New host records of the reptile tick Amblyomma helvolum Koch (Ixodida: Ixodidae: Amblyomminae) in Taiwan

Amblyomma helvolum Koch is an Asiatic reptile-associated tick that usually inhabits tropical forests and is primarily parasitic on varanids, skinks, and snakes. In Taiwan, A. helvolum has been reported on Elaphe carinata (Taiwan stink snake) and Ptyas mucosa (Oriental rat snake). Herein, we report new host records of A. helvolum in Taiwan from the following squamate species: Diploderma swinhonis (Swinhoe's japalure), Eutropis longicaudata (Long-tailed sun skink), Oligodon formosanus (Taiwan kukri), Sphenomorphus incognitus (Brown forest skink), and Trimeresurus stejnegeri (Chinese green tree viper). In addition, we present an overview of the distribution of A. helvolum across its range and its association with reptilian microbial agents.

Long-term effects of planting density and site quality on timber assortment structure based on a 41-year plantation trial of Chinese fir

Stand density control coupled with site control is a key technique for cultivating large-diameter timber of Chinese fir trees, whose yield can be effectively increased by the optimal density and site management mode employed. This study aimed to evaluate the dynamic changes in timber assortment structure under differing initial planting densities and site quality based on growth data of a 41-year trial of Chinese fir plantations. Our results showed that the total timber yield and both large-diameter timber outturn and the outturn rate all increased with better site quality under the same initial planting density. Further, the outturn peak as well as outturn rate peak for both medium- and small-diameter timber was reached sooner with improved site quality. For the same site class, a lower initial planting density augmented the total timber outturn rate, and also resulted in less time required for the total timber outturn rate to reach a constant or maximum value. Finally, the total timber outturn rate of all density plots tended to be nearly identical. Using a high planting density increased the outturn of small-diameter timber, whose outturn peak was delayed in the denser plots. The bolstering effect of low density upon the growth of large-diameter timber was enhanced by higher site quality, with density-induced differences in large-diameter timber more pronounced; conversely, that promoting effect weakened under poor site quality conditions. The interaction between planting density and site index significantly influenced the growth of any timber assortment of Chinese fir in the early stage following its formation. Notably, the significant effect of site index on large-diameter timber lasted longer than that of other timber assortments. The optimal site conditions for cultivating large-diameter timber trees of Chinese fir consist of a site class ≥ 20 with a planting density limited to no more than 1667 trees/ha, whose stand rotation period must be over 26 years, so as to maximize the output of large-diameter timber yield. Our empirical findings will be helpful for the construction of an optimal cultivation mode for the density, site, and rotation age of large-diameter timber in Chinese fir plantations.

Drought dampens the positive acclimation responses of leaf photosynthesis to elevated [CO2] by altering stomatal traits, leaf anatomy, and Rubisco gene expression in Pyrus

The responses of Chinese pear plantations to rising atmospheric CO2 concentration ([CO2]) and drought are crucial for accurately estimating pear production and forest carbon sink of China under future climate change. Here, we investigated the effect of CO2 enrichment on plant growth and leaf photosynthesis of Chinese pear trees grown under full irrigation and different levels of drought. We identified that leaf photosynthetic capacity and stomatal conductance increased by high [CO2] acclimation. However, such positive effects disappeared when drought occurred, especially under moderate and severe drought. This down-regulation of high [CO2] acclimation responses in leaf photosynthesis by drought was mainly caused by the decline in stomatal diffusional efficiency, thinner mesophyll tissues and smaller mesophyll cells. The decrease of stomatal diffusional efficiency was further caused by the reduced stomatal density and decreased regularity of stomatal distribution pattern under drought. Moreover, the down-regulation of those positive acclimation responses was relevant with the declines of carboxylation and photochemical efficiency of Rubisco, which was confirmed by the down-regulated expression levels of Rubisco coding genes. Overall, our results demonstrated that drought dampened the positive acclimation responses of leaf photosynthesis to elevated [CO2] by modifying stomatal morphology and distribution, leaf anatomy, and Rubisco gene expression. Therefore, under future climate change where CO2 enrichment is coupled with higher frequency of drought events, drought limitations should be incorporated into the current coupled climate-carbon models to avoid overestimation of the positive responses of Chinese pear plantations to elevated [CO2] and to accurately predict forest carbon sequestration.

Comparative Chloroplast Genome Analysis of Chinese Lacquer Tree (Toxicodendron vernicifluum, Anacardiaceae): East-West Divergence within Its Range in China

Chinese lacquer tree (Toxicodendron vernicifluum) is an important commercial arbor species known for the production of raw lacquer. Here, we investigated the intraspecific chloroplast (cp) genome variability of T. vernicifluum using two available and five newly sequenced cp genomes. We found that each of the seven cp genomes encoded 87 protein-coding genes, 37 tRNA genes, and eight rRNA genes. Phylogenetic analyses based on protein-coding genes indicated that the four individuals from western China formed a monophyletic group sister to the cluster containing the three individuals from eastern China. The cp genomes from western China exhibited a larger genome length and longer large single-copy (LSC), small single-copy (SSC), and inverted repeat (IR) regions than those from eastern China. A total of 466 single nucleotide polymorphisms (SNPs) and 141 insertion-deletion mutations were detected among the seven cp genomes, most of which were found between the eastern and western lineages. The two groups exhibited a similar number of microsatellites, long repeats, and tandem repeats. Notably, complementary repeat sequences were only found in the IRs of the individuals from eastern China, while reverse repeat sequences were only detected in the LSC of the individuals from western China. Eight intraspecific mutational hotspots were also identified, including six intergenic regions (trnF-ndhJ, rpl32-trnL, ccsA-ndhD, trnH-psbA, psbC-trnS, and trnL-trnF) and two gene regions (rpl32 and rps19). The genomic resources presented in this study will be useful for further studies on evolutionary patterns and resource protection of T. vernicifluum.

An Estimation Model of the Ultimate Shear Strength of Root-Permeated Soil, Fully Considering Interface Bonding

Roots can be seen as natural soil reinforcement material. The prediction and quantitative evaluation of the shear strength of root-permeated soil is the focus of vegetation slope protection, in which the bonding effect of the root–soil interface is the key factor. Taking the roots of Chinese fir trees as an example, the shear resistance test of root–soil interface bonding strength and the direct shear test of root-permeated soil with different root area ratios and inclination angles were carried out. The results indicated that the bonding strength of the root–soil interface could be quantified by interfacial cohesion and friction angle. The shear strength of root-permeated soil increased with the root area ratio, and its relationship with the inclination angle of root relative shear direction was: 45° > 90°. In addition, an estimation model of the ultimate shear strength of root-permeated soil was developed, in which the bonding effect of the root–soil interface was quantified by the interface bonding strength parameters. The soil stress, root diameter, root length, and the initial angle between the root and shear direction can be considered in the estimation model. The rationality and accuracy of the estimated model were verified through the comparison of experimental results and Wu’s model. The proposed model can be used to calculate the stability of the biotechnical reinforcement landslides and evaluate the shear strength of the root-permeated soil.

Description of Laimaphelenchus shanxiensis sp. n. (Rhabditida: Aphelenchoididae) from Shanxi province, P.R. China

Summary Laimaphelenchus shanxiensis sp. n. was recovered from the bark samples of Chinese pine tree (Pinus tabuliformis) in Shanxi province, China. The new species is characterised by having 888-1049 μm long females, the cephalic region with six labial sectors divided by ribs, stylet 11-13 μm long, the excretory pore located at the same level with, or slightly posterior to nerve ring, lateral field with four incisures, post-vulval uterine sac 54-83 μm long, vulva with a well-developed anterior flap, tail having a single stalk at terminus ending to a flat structure with 4-7 finger-like appendages in scanning electron microscopy; male spicules 20-22 μm long and two pairs of caudal papillae present. In addition, molecular phylogenetic trees inferred from the partial small subunit (SSU) and D2-D3 segments of large subunit (LSU) of rRNA genes, revealed that this nematode belongs to the Laimaphelenchus and is different from all currently sequenced species of Laimaphelenchus for their SSU and LSU markers.

Genome-Wide Identification and Expression Analysis of TPS Gene Family in Liriodendron chinense.

Terpenoids play a key role in plant growth and development, supporting resistance regulation and terpene synthase (TPS), which is the last link in the synthesis process of terpenoids. Liriodendron chinense, commonly called the Chinese tulip tree, is a rare and endangered tree species of the family Magnoliaceae. However, the genome-wide identification of the TPS gene family and its transcriptional responses to development and abiotic stress are still unclear. In the present study, we identified a total of 58 TPS genes throughout the L. chinense genome. A phylogenetic tree analysis showed that they were clustered into five subfamilies and unevenly distributed across six chromosomes. A cis-acting element analysis indicated that LcTPSs were assumed to be highly responsive to stress hormones, such as methyl jasmonate (MeJA) and abscisic acid (ABA). Consistent with this, transcriptome data showed that most LcTPS genes responded to abiotic stress, such as cold, drought, and hot stress, at the transcriptional level. Further analysis showed that LcTPS genes were expressed in a tissue-dependent manner, especially in buds, leaves, and bark. Quantitative reverse transcription PCR (qRT-PCR) analysis confirmed that LcTPS expression was significantly higher in mature leaves compared to young leaves. These results provide a reference for understanding the function and role of the TPS family, laying a foundation for further study of the regulation of TPS in terpenoid biosynthesis in L. chinense.

Visual Simulation Research on Growth Polymorphism of Chinese Fir Stand Based on Different Comprehensive Grade Models of Spatial Structure Parameters

Since tree morphological structure is strongly influenced by internal genetic and external environmental factors, accurate simulation of individual morphological–structural changes in trees is the premise of forest management and 3D simulation. However, existing studies have few descriptions, and the research on the impact of growth environments and stand spatial structures on tree morphological structure and growth is still limited. In our study, we constructed a comprehensive grade model of spatial structure (CGMSS) to comprehensively evaluate individual tree growth states of the stands and grade them from 0 to 10 correspondingly. In addition, we developed a Chinese fir morphological structure growth model based on CGMSS, and dynamically simulate the growth variations of Chinese fir stands. The results showed that the overall stand prediction accuracy of CGMSS-based Chinese fir diameter at breast height, tree height, crown width and under-living branch height growth models was more than 94%. According to the analysis of the comprehensive grade of spatial structure (CGSS) of trees in the stand, except for the prediction accuracy and systematic error of the under-living branch height growth model at the CGSS = 3–5 levels, the systematic error of the Chinese fir growth model at each level was lower than 21.2%, and the prediction accuracy was greater than 73%. Compared with the spatial structural unit (SSU)-based Chinese fir growth model proposed by Ma et al., all growth models fit better at all levels, except for the CGMSS-based Chinese fir tree height and under-living branch height growth models that fit significantly lower than the SSU-based Chinese fir growth model at CGSS = 3–5 levels. In this study, the main conclusion is that the simulation results of CGMSS’s Chinese fir morphological structure growth model are closer to the real growth state of trees, achieving accurate simulation of differential growth of trees in different growth dominance degrees and spatial structure states in forest stands, making visualized forest management more effective and realistic.

The complete chloroplast genome and phylogenetic analysis of Stewartia sichuanensis (Theaceae), a Chinese endemic tree with narrow distribution

Stewartia sichuanensis is a rare plant species of Theaceae and is endemic to China. Its distribution area is highly restricted, and genomic information is extremely limited. The present study reports the first complete chloroplast of S. sichuanensis. The chloroplast genome length was 158,903 bp, with a GC content of 37.3%. The chloroplast genome was comprised of an 87,736 bp long large single copy (LSC), an 18,435 bp long small single copy (SSC), and two copies of inverted repeat (IR) regions of 26,366 bp. It contained 129 genes, including 85 encoding, 36 transfer RNA, and eight ribosomal RNA genes. The phylogenetic analysis suggested that S. sichuanensis was closely related to S. laotica and S. pteropetiolata.

Phenotypic Variation in Leaf, Fruit and Seed Traits in Natural Populations of Eucommia ulmoides, a Relict Chinese Endemic Tree

Eucommia ulmoides Oliver is a dioecious, pharmaceutically and economically important, and precious relict tree species endemic to China, and has been listed as a key protected tree species of national level II. Phenotypic variation in ten natural populations in some key traits is still obscure. In order to study the relationship between population variation in phenotypic traits and geoclimatic factors, 15 traits were analyzed in 117 female sampled tree from ten natural populations. The results showed that the coefficients of variation for all of the 15 traits widely ranged from 9.7% (fruit vertical diameter) to 49.0% (leaf thickness), with an average of 19.7%. The nested ANOVA revealed plentiful phenotypic variations within and among populations. The variation within population was the main source, with an average proportion of 42.8%, greater than that among the population (16.6%). The 15 traits were reduced to four principal components, which collectively accounted for 70.1% of phenotypic variation among trees. The ten populations were mainly divided into two groups: Group A included eight populations throughout the Wuling Mountains occurring in relatively close proximity to each other, and Group B which comprises two geographically distant populations in mountains further northern. There were significant level correlations between phenotypic differentiation among population of E. ulmoides and both geographic (r = 0.65, p < 0.05) and climatic (r = 0.73, p < 0.01) distance. Step-wise regression indicates average annual temperature and rainfall accounted for most of the phenotypic variation among populations, and mainly associated with differences in leaf, fruit and seed size. These results can have an important implication for genetic improvement, diversity conservation and resource management of the species in the future.

Functional identification of anthocyanin glucosyltransferase genes: a Ps3GT catalyzes pelargonidin to pelargonidin 3-O-glucoside painting the vivid red flower color of Paeonia.

Glycosylation from an anthocyanidin 3-O-glucosyltransferase Ps3GT (PsUGT78A27) facilitates the accumulation of pelargonidin 3-O-glucoside, which defines the vivid red flower color and occurs only in specific peony tree cultivars. Although tree peony cultivars of Chinese and Japanese both originated from China, vivid red color is only found in flowers of Japanese cultivars but not of Chinese cultivar groups. In this study, a Japanese tree peony cultivar 'Taiyoh' with vivid red petals and a Chinese tree peony cultivar 'Hu Hong' with reddish pink petals were chosen as the experimental materials. Flavonoids profiling indicated that pelargonidin 3-O-glucoside (Pg3G) detected only in Japanese cultivar contributed to vivid red color of tree peony petals, while pelargonidin 3,5-di-O-glucoside (Pg3G5G) found in both of Japanese and Chinese cultivars was responsible for pink flower color. Through the integration of full-length transcriptome sequencing and in vitro enzymatic activity analysis, two anthocyanin glucosyltransferase genes PsUGT78A27 and PsUGT75L45 were isolated from the petals of tree peony, and their encoding products exhibited enzymatic activities of pelargonidin 3-O-glucosyltransferase and anthocyanin 5-O-glucosyltransferase, respectively. Further quantitative real-time PCR revealed that PsUGT78A27 displayed high expression in petals of both cultivars and PsUGT75L45 was expressed at high levels in cultivar 'Hu Hong' only. Using a gene gun technique, the GFP fusion proteins of PsUGT78A27 and PsUGT75L45 were visualized to be cytoplasmic and nuclear localization in the epidermal cells of tree peony petals, and the glucosylation function of PsUGT78A27 and PsUGT75L45 to alter petal color of tree peony and herbaceous peony had been directly validated in vivo. These results demonstrated that PsUGT78A27 and PsUGT75L45 are key players for the presence or absence of vivid red flower color in tree peony cultivars. Our findings further elucidated the chemical and molecular mechanism of petal pigmentation of Paeonia and could help breed the Paeonia cultivars possessing novel flower colors.

First report of mume virus A infecting Prunus salicina worldwide and Prunus mume in Korea.

Mume virus A (MuVA) of the genus Capillovirus in the family Betaflexiviridae was first isolated from a Japanese apricot tree (Prunus mume) exhibiting symptoms of diffuse chlorotic spots (Marais et al. 2018). MuVA infection has been reported in Japanese apricot trees in Japan as well as in peach (P. persica) and Japanese apricot trees in China (Marais et al. 2018; Zhang et al. 2021; Zheng et al. 2020). In the present study, the diversity of viruses and viroids infecting Chinese plum trees (P. salicina) was investigated using high-throughput sequencing (HTS). Ten flowers each from 50 trees without obvious symptoms related to virus and/or viroid infection were randomly collected from five orchards in Gimcheon, Korea, in April 2020. The samples from each Chinese plum tree were pooled, and the same amounts of 50 individual samples prepared in advance were pooled for the extraction of total RNA using the RNeasy Plant Mini Kit (QIAGEN, Hilden, Germany). Removal of ribosomal RNA and construction of cDNA library from the extracted total RNA were conducted using the TruSeq Stranded Total RNA with Ribo-Zero Plant kit (Illumina, San Diego, CA, USA). Paired-end RNA sequencing using Illumina NovaSeq 6000 System (paired-end reads of 101 bp and a total of 162,845,322 reads) and data analysis were performed at Macrogen (Daejeon, Korea). Adaptor and low-quality sequences of reads were removed using Trimmomatic program. Trimmed reads were assembled into contigs using Trinity program, and several databases including NCBI Nucleotide and Kyoto Encyclopedia of Genes and Genomes were used for functional annotation. HTS identified plum bark necrosis stem pitting-associated virus (PBNSPaV; four contigs ranging from 2081 to 3202 nucleotides) and hop stunt viroid (HSVd; one contig of 618 nucleotides). PBNSPaV and HSVd were also detected by RT-PCR (PBNSPaV det-F and PBNSPaV det-R for PBNSPaV [Al Rwahnih et al. 2007]; VP-19 and VP-20 for HSVd [Astruc et al. 1996]) and confirmed by Sanger sequencing of the amplified products. Interestingly, one contig derived from MuVA, which was not previously reported in Korea, was also detected. The contig was 7,618-nucleotide long (15,205 reads), and NCBI BLASTN search revealed 98.74% homology (100% query coverage) with the MuVA isolate pm14 (GenBank accession number MG783575). To design diagnostic primers for reverse transcription (RT)-polymerase chain reaction (PCR), the contig sequence and MuVA sequences available in NCBI GenBank (GenBank accession numbers MG783575 and MN412555) were aligned using CLC Main Workbench 6.9.1 (QIAGEN, Redwood, CA, USA). The following primer set (expected size of 1,143 bp) was prepared: MuVA-2F (5'-CAGCTTTGTGACTCYAACCC-3') and MuVA-2R (5'-AATGGCTTGAGGRCCTGCAG-3'). The primers target a partial region (nt position 1185 to 2327 on the basis of the reference genome sequence of MuVA, GenBank accession no. NC_040568) of the polyprotein gene (ORF1). Each of the 50 samples was tested for the presence of MuVA using the above-mentioned RT-PCR primers with SuPrimeScript RT-PCR Premix (GeNet Bio, Daejeon, Korea). MuVA was detected in three samples collected from the same orchard. The three amplicons were inserted into a T&A cloning vector (RBC Bioscience, Taipei, Taiwan) and sequenced at Macrogen. Three consensus sequences obtained by Sanger sequencing were registered in NCBI GenBank under accession numbers MW589492, MW589493, and MW589494. NCBI BLASTN search revealed that the Korean isolates of MuVA shared high homology with isolate pm14 [98.16%, 98.08%, and 98.16% (100% query coverage), respectively]. To confirm additional MuVA infections, leaf samples of Chinese plum trees were collected from orchards in Uiseong (70 trees) and Seongju (50 trees) as well as a Japanese apricot tree in Chuncheon, from April to July 2021. RT-PCR confirmed additional MuVA infections from Uiseong (one tree) and Seongju (one tree) as well as from the Japanese apricot tree in Chuncheon. NCBI BLASTN search of the three additional amplicons (GenBank accession numbers OM210030, OM210031, and OM210032) revealed high homology with isolate pm14 [98.25%, 98.08%, and 97.90% (100% query coverage)]. To the best of our knowledge, this is the first report of MuVA infecting P. mume in Korea and P. salicina worldwide. Further research is needed to investigate MuVA infections on various Prunus spp. including P. persica in Korea.

Cyanidin-3-O-glucoside Contributes to Leaf Color Change by Regulating Two bHLH Transcription Factors in Phoebe bournei

Anthocyanins produce different-colored pigments in plant organs, which provide ornamental value. Thus, this study was conducted to understand the mechanism of anthocyanin synthesis in ornamental plants. Phoebe bournei, a Chinese specialty tree, has high ornamental and economic value due to its rich leaf color and diverse metabolic products. Here, the metabolic data and gene expression of red P. bournei leaves at the three developmental stages were evaluated to elucidate the color-production mechanism in the red-leaved P. bournei species. First, metabolomic analysis identified 34 anthocyanin metabolites showing high levels of cyanidin-3-O-glucoside (cya-3-O-glu) in the S1 stage, which may suggest that it is a characteristic metabolite associated with the red coloration of the leaves. Second, transcriptome analysis showed that 94 structural genes were involved in anthocyanin biosynthesis, especially flavanone 3'-hydroxy-lase (PbF3'H), and were significantly correlated with the cya-3-O-glu level. Third, K-means clustering analysis and phylogenetic analyses identified PbbHLH1 and PbbHLH2, which shared the same expression pattern as most structural genes, indicating that these two PbbHLH genes may be regulators of anthocyanin biosynthesis in P. bournei. Finally, overexpression of PbbHLH1 and PbbHLH2 in Nicotiana tabacum leaves triggered anthocyanin accumulation. These findings provide a basis for cultivating P. bournei varieties that have high ornamental value.

Estimation of Biomass Dynamics and Allocation in Chinese Fir Trees Using Tree Ring Analysis in Hunan Province, China

Studying tree biomass dynamics and allocation is crucial to understanding the forest carbon cycle and the adaptation of trees to the environment. However, traditional biomass surveys are time-consuming and labor-intensive, so few studies have specifically examined biomass formation in terms of the increase in individual tree biomass, and the role that tree age and site conditions play in this process, especially tree roots, is unclear. We studied the tree ring characteristics of 87 sample trees (8–40 years old) from 29 Chinese fir plantations with different site conditions and measured the biomass of their stems, crowns, and roots. The biomass increment at various age stages during tree growth was determined via using tree ring analysis, and a generalized additive mixed model (GAMM) was used to analyze biomass formation and allocation, as well as the specific impact of site conditions on them. The results showed that the biomass increment of Chinese fir trees first increased and then decreased with age, and improving site conditions delayed the carbon maturation of the trees. The proportion of stem biomass increased with age, while the proportion of crown biomass decreased and the proportion of root biomass increased and then decreased. The effect of the site conditions on the tree biomass allocation showed a nonlinear trend. Tree ring analysis provides a feasible and effective method for assessing tree growth and biomass dynamics. Forest managers can use the findings of this study to scientifically optimize the management of increasing forest carbon sequestration.

Molecular Characterization and Function of the Nogo-66 Receptor (NgR1) Gene in the Chinese Tree Shrew

Nogo-66 receptor (NgR1) is a glycosylphosphatidylinositol-linked cell surface receptor with high affinity for Nogo-66. The binding of Nogo-66 to NgR1 plays a key role in inhibiting neurite growth, limiting synaptic plasticity and mediating Mammalian Reovirus (MRV) infection. The Chinese tree shrew (Tupaia belangeri chinensis) is, a new and valuable experimental animal that is widely used in biomedical research. Although susceptible to MRV, little is known about tree shrew NgR1 and its role in MRV infection. In this study, we cloned NgR1 form the Chinese tree shrew by RACE technology and analyzed its characteristics, spatial structure and its tissue expression. We also examined the expression pattern of NgR1 in the response of tree shrew primary nerve cells (tNC) to MRV1/TS/2011 infection. Tree shrew NgR1 was found to have a closer relationship to human NgR1 (90.34%) than to mouse NgR1. Similar to the protein structure of human NgR1, the tree shrew NgR1 has the same leucine-rich repeat (LRR) domain structure that is capped by C-terminal and N-terminal cysteine-rich modules. The tree shrew NgR1 mRNAs were predominantly detected in the central nervous system (CNS), and tree shrew NgR1 can mediate infection by MRV1/TS/2011. Taken together, these results help to elucidate the function of NgR1 and provide a basis for using the tree shrew as an animal model for studies of the nervous system and infectious diseases.

Camptothecin Effectively Regulates Germline Differentiation through Bam-Cyclin A Axis in Drosophila melanogaster.

Camptothecin (CPT), first isolated from Chinese tree Camptotheca acuminate, produces rapid and prolonged inhibition of DNA synthesis and induction of DNA damage by targeting topoisomerase I (top1), which is highly activated in cancer cells. CPT thus exhibits remarkable anticancer activities in various cancer types, and is a promising therapeutic agent for the treatment of cancers. However, it remains to be uncovered underlying its cytotoxicity toward germ cells. In this study we found that CPT, a cell cycle-specific anticancer agent, reduced fecundity and exhibited significant cytotoxicity toward GSCs and two-cell cysts. We showed that CPT induced GSC loss and retarded two-cell cysts differentiation in a niche- or apoptosis-independent manner. Instead, CPT induced ectopic expression of a differentiation factor, bag of marbles (Bam), and regulated the expression of cyclin A, which contributed to GSC loss. In addition, CPT compromised two-cell cysts differentiation by decreasing the expression of Bam and inducing cell arrest at G1/S phase via cyclin A, eventually resulting in two-cell accumulation. Collectively, this study demonstrates, for the first time in vivo, that the Bam-cyclin A axis is involved in CPT-mediated germline stem cell loss and two-cell cysts differentiation defects via inducing cell cycle arrest, which could provide information underlying toxicological effects of CPT in the productive system, and feature its potential to develop as a pharmacology-based germline stem cell regulation agent.