Search

Camellia japonica, an evergreen ornamental plant in the Theaceae family, has a natural range that is now shrinking. This is evident by the fact that the species is on the verge of extinction in Laoshan Mountain (Qingdao), the northernmost area of China known to have a natural population of C. japonica. Little is known about the genetic diversity and relationships among cultivated and wild C. japonica populations. One hundred and eighty samples of six C. japonica populations were tested for genetic diversity with simple sequence repeat (SSR) markers; these included three cultivated populations, two natural populations in Qingdao, and one natural population in Daqingshan. The average values of polymorphism information content (PIC), expected heterozygosity (He), and Shannon’s information index (I) were 0.5849, 0.6385 and 1.3170, respectively, indicating that C. japonica has a high genetic diversity. The genetic diversities of the six populations in rank order were as follows: Daqingshan > Zhongshan Park > Changmenyan Island > Daguan Island > Botanical Garden > May Fourth Square. The geographical isolation of the islands had no significant influence on the genetic diversity of C. japonica. Clustering results showed that the six C. japonica populations could be grouped into three categories, and most populations were clustered according to their geographical origin and genetic background. These results also reconfirmed that the C. japonica (Naidong) population in Qingdao originated from Changmenyan Island. Genetic variation was highest within populations (89%), indicating that C. japonica can be protected at the population level. These findings will prove useful for the genetic analysis, protection, and horticultural use of C. japonica.

Ailanthus altissima is a deciduous tree native to China and introduced to other parts of the world as an ornamental plant. It exhibits resistance to both abiotic and biotic stress factors and has various pharmacological effects and strong allelopathy, generating significant research interests. However, the genome sequence of this species has not been reported, limiting its research development. The purpose of the study was to determine the genome size and characteristics of A. altissima to conduct its genomic survey. Next-generation sequencing and K-mer analysis were employed to measure the genome size of A. altissima. Overall, a total of 61.93 Gb high-quality clean data were acquired, representing approximately 64.09× coverage of the A. altissima genome. The genomic characteristics of A. altissima include a genome size of 966.38 Mbp, a heterozygosis rate of 0.78 %, and a repeat rate of 41.22 %. A total of 735,179 genomic SSRs markers were identified based on genome survey sequences. Alignment analysis showed that A. altissima was closely related to Citrus sinensis and Leitneria florida-na. This study provides basic information for future whole-genomic sequencing of A. altissima. This will facilitate a knowledge of the population structure, genetic diversity, long distance-gene transfer, and pollen-based gene flow analyses of A. altissima populations from its known distribution ranges in China, focusing on planted and natural forest stands.

Hybrid tuliptree (Liriodendron sion-americanum P.C. Yieh ex Shang et Z.R. Wang) has good wood quality and been widely used in furniture and other fields. Compared with parental species, hybrid tuliptree displayed faster growth rate, better wood quality and wider adaptability. But the morphological properties of hybrid tuliptree and parental species are highly similar, its identification has become an urgent problem. This study aims to evaluate the capabilities of near infrared hyperspectral imaging (NIR-HSI) technique to identify hybrid tuliptree, Chinese tuliptree, and tuliptree. For this purpose, the building models were carried out using Partial least squares discriminant analysis (PLS-DA) and support vector machine (SVM) after different data treatment. The results demonstrated that NIR-HSI spectroscopy combined with successive projections algorithm (SPA) treatment and SVM model can achieve the highest prediction accuracy (100%). This study shows that NIR-HSI technique has great potential in the genus Liriodendron identification and is suitable for classifying highly similar woods.

Near infrared hyperspectral imaging (NIR-HSI) spectroscopy can be a rapid, precise, low-cost and non-destructive way for wood identification. In this study, samples of five Guiboutia species were analyzed by means of NIR-HSI. Partial least squares discriminant analysis (PLS-DA) and support vector machine (SVM) were used after different data treatment in order to improve the performance of models. Transverse, radial, and tangential section were analyzed separately to select the best sample section for wood identification. The results obtained demonstrated that NIR-HSI combined with successive projections algorithm (SPA) and SVM can achieve high prediction accuracy and low computing cost. Pre-processing methods of SNV and Normalize can increase the prediction accuracy slightly, however, high modelling accuracy can still be achieved by raw pre-processing. Both models for the classification of G. conjugate, G. ehie and G. demeusei perform nearly 100% accuracy. Prediction for G. coleosperma and G. tessmannii were more difficult when using PLS-DA model. It is evidently clear from the findings that the transverse section of wood is more suitable for wood identification. NIR-HSI spectroscopy technique has great potential for Guiboutia species analysis.

An amendment to this paper has been published and can be accessed via the original article.

Background Clematis species are attractive ornamental plants with a variety of flower colors and patterns. Heat stress is one of the main factors restricting the growth, development, and ornamental value of Clematis. Clematis lanuginosa and Clematis crassifolia are large-flowered and evergreen Clematis species, respectively, that show different tolerance to heat stress. We compared and analyzed the transcriptome of C. lanuginose and C. crassifolia under heat stress to determine the regulatory mechanism(s) of resistance. Results A total of 1720 and 6178 differentially expressed genes were identified from C. lanuginose and C. crassifolia, respectively. The photosynthesis and oxidation–reduction processes of C. crassifolia were more sensitive than C. lanuginose under heat stress. Glycine/serine/threonine metabolism, glyoxylic metabolism, and thiamine metabolism were important pathways in response to heat stress in C. lanuginose, and flavonoid biosynthesis, phenylalanine metabolism, and arginine/proline metabolism were the key pathways in C. crassifolia. Six sHSPs (c176964_g1, c200771_g1, c204924_g1, c199407_g2, c201522_g2, c192936_g1), POD1 (c200317_g1), POD3 (c210145_g2), DREB2 (c182557_g1), and HSFA2 (c206233_g2) may be key genes in the response to heat stress in C. lanuginose and C. crassifolia. Conclusions We compared important metabolic pathways and differentially expressed genes in response to heat stress between C. lanuginose and C. crassifolia. The results increase our understanding of the response mechanism and candidate genes of Clematis under heat stress. These data may contribute to the development of new Clematis varieties with greater heat tolerance.

Background Elevated temperature and drought stress have substantial impacts on fruit quality, especially in terms of sugar metabolism and content. β-Amylase (BAM) plays a critical role in regulating jujube fruit sugar levels and abiotic stress response. Nevertheless, little is known about the regulatory functions of the BAM genes in jujube fruit. Results Nine jujube BAM genes were identified, clustered into four groups, and characterized to elucidate their structure, function, and distribution. Multiple sequence alignment and gene structure analysis showed that all ZjBAM genes contain Glu-186 and Glu-380 residues and are highly conserved. Phylogenetic and synteny analysis further indicated that the ZjBAM gene family is evolutionarily conserved and formed collinear pairs with the BAM genes of peach, apple, poplar, Arabidopsis thaliana, and cucumber. A single tandem gene pair was found within the ZjBAM gene family and is indicative of putative gene duplication events. We also explored the physicochemical properties, conserved motifs, and chromosomal and subcellular localization of ZjBAM genes as well as the interaction networks and 3D structures of ZjBAM proteins. A promoter cis-acting element analysis suggested that ZjBAM promoters comprise elements related to growth, development, phytohormones, and stress response. Furthermore, a metabolic pathways annotation analysis showed that ZjBAMs are significantly upregulated in the starch and sucrose metabolism, thereby controlling starch-maltose interconversion and hydrolyzing starch to maltose. Transcriptome and qRT-PCR analyses revealed that ZjBAMs respond positively to elevated temperature and drought stress. Specifically, ZjBAM1, ZjBAM2, ZjBAM5, and ZjBAM6 are significantly upregulated in response to severe drought. Bimolecular fluorescence complementation analysis demonstrated ZjBAM1-ZjAMY3, ZjBAM8-ZjDPE1, and ZjBAM7-ZjDPE1 protein interactions that were mainly present in the plasma membrane and nucleus. Conclusion The jujube BAM gene family exhibits high evolutionary conservation. The various expression patterns of ZjBAM gene family members indicate that they play key roles in jujube growth, development, and abiotic stress response. Additionally, ZjBAMs interact with α-amylase and glucanotransferase. Collectively, the present study provides novel insights into the structure, evolution, and functions of the jujube BAM gene family, thus laying a foundation for further exploration of ZjBAM functional mechanisms in response to elevated temperature and drought stress, while opening up avenues for the development of economic forests in arid areas.

Root growth potential (RGP) is a popular physiological indicator used to evaluate seedling vigor. However, the time scale used in the RGP test is the order of days, which leads to poor performance of the RGP method. We propose an optical interference method, called statistical interferometry, to measure minute root elongation at a sub-nanometer scale, which can decrease the time used in measuring RGP. The time scale of this method is also 104 times less than that of the RGP method. Because we can measure the length of root elongation continuously, we can compute the root elongation rate (RER), which is the variety of the length of root elongation per second. Continuous monitoring can help determine the quality of Masson pine seedling as soon as possible. To show the effectiveness of our proposed method, we designed an experiment, in which we applied different water stresses to our collected Masson pine seedlings and acquired two groups of pines, representing two different qualities: one stressed by water and one not. After measuring the RER of the groups in our experiments, we found that RER is interrelated with the quality of seedlings.Author summaryLi Wang have worked in Nanjing Forest University. His interesting includes machine learning, computer vision and plant phenotype.

In order to learn dormancy mechanism of Taxtts chinensis var. mairei seed, effects of stratification and hormone treatments on physiological and biochemical indexes of the seeds after stratifying for eight months were researched. The content of amylase activity and soluble sugar gradually increased at first stratification, and then to the maximum for the end of after-ripening period. With the dormancy of seed relieving, some soluble sugar of endosperm was used or consumed by respiration and that led to their content decreased. Seed soluble protein was gradually accumulated at the beginning of stratification and then the initial raw material of protein synthesis of embryo during development had been used or in part converted into carbohydrates for energy consumption, so that the soluble protein content decreased. The fat and starch content slowly decreased during stratification, which showed that the storage of material had continually carrying out catabolism and conversion, which might provide energy sources for seed germination in the stratification process. The peroxidase activity of Taxus seeds increased gradually at the beginning of stratification, and then reached maximum point during stratification for 4 months in A1 and A2. The G-6-PDH and 6-PGDH joint activity was rapidly increased to reach the maximum during stratification for 4 months in A1, which showed the pentose phosphate pathway was activated at this time. The peroxidase activity rapidly increased might also be related to respiratory metabolic pathway during stratification. In plants, acid phosphatase hydrolyze PAM metabolites, namely phosphate material was related to energy metabolism, especially to high-energy phosphate, and phosphate enzyme activity changes affected the energy metabolism. The acid phosphatase activity of Taxus seeds in different treatments has no significant changes during stratification process, but there were two maximums. Energy metabolism might get benefit from the increase of acid phosphatase activity. There were significant differences in amylase activity, peroxidase activity, soluble sugar and soluble protein content with different treatments. Effect of promoting seed germination soaked by GA before stratification was obvious, but the concentration of GA should not be too high. The high concentration of GA caused seed to rot and reduce the seed germination rate. In this study, the highest germination rate of seed was 71.8% and soaked in 200 mg·L-1 gibberellin.

We measured physiological parameters including water uptake, in-vitro embryo germination ratio, and seed coat structure observed by scanning electron microscopy (SEM) to explore the influence of seed coat on the germination of seeds of tallow tree (Sapium sebiferum (Linn) Roxb.). Tallow tree seeds had good water permeability. We found that germination of cabbage seeds was inhibited when cabbage seeds were soaked in extracted solutions from tallow tree seed coat. Seed coat structure at the side of the radicle appeared to be a barrier to seed germination. We tested methods to break tallow tree seed dormancy. Dormancy of tallow tree seeds was overcome by soaking the seeds in 500 mg·L−1 or 1000 mg·L−1 GA3, followed by 100 days of cold stratification.

In higher plant genomes, most sequences are unexpression sequence, the proportion of a genome that encodes for genes may be very small. Understanding gene distribution in the genome is a very important aspect for invastigating the genome structure. Funded by the U.S. Department of Energy, a clonal Populus trichocarpa genome sequencing has been completed and released to the public. The accomplishment of poplar genome offers us a unique opportunity to survey the gene distribution in the genome of a forest tree. In this paper, based on Poisson calculator, we investigated the gene density of various chromosomes in poplar genome. As a result, we found that gene density is significantly different among chromosomes in poplar genome. Modern poplar genome arose from an ancient whole genome duplication event, known as “salicoid duplication”. Thus poplar genome shared large duplication segments among different chromosome members. However, our results demonstrated that gene abundance pattern was different from the chromosomal duplication pattern of poplar genome. This implied the duplicated genes lost at different rates on the duplicated chromosomes following the salicoid duplication. Meanwhile, based on alignment with about 90 thousands ESTsi¼Œwe found that only 16.8% of the predicted gene models in poplar genome had EST proofs. Although, EST sequencing is an attractive alternative to whole genome sequencing for gene identification, the power of small scale EST sequencing study should be properly evaluated since with limited number of EST sequences, genes captured by ESTs are fairly limited.