Areca palm yellow leaf (AYL) disease caused by phytoplasma is a devastating disease of areca palm plantation. It is of great significance to clarify the genetic variation of phytoplasmas and the natural hosts in the garden of areca with yellow leaf diseases for the purpose of fully reveal the circulation path and epidemic law of the disease. In this study, the plant samples showing typical disease symptoms associated with phytoplasma were investigated and sampled from the diseased areca garden distributed in different areas of Hainan provinve, China. The target sequences of phytoplasma were amplified and sequenced with universal primers, revealing genetic variation and phylogeny of the phytoplasma. The results showed that 16S rRNA and secA gene fragments specific for phytoplasma was amplified from six plant sample of Trema tomentosa, which were all identical. The 16S rRNA gene fragment of phytoplasma was obtained from one plant sample of Chinaberry. Sequence analysis based on the 16S rRNA gene sequences indicated that the T. tomentosa witches'-broom phytoplasma (TtWB) strains identified in the study were in 100% similarity with TtWB phytoplasma reported previously. Chinaberry witches'-broom (CWB) phytoplasma strains identified in the study were in 100% similarity with CWB phytoplasma strains reported previously. Phylogenetic analysis indicated that TtWB phyto plasma strains identified in the study were clustered into one evolutionary branch with the phytoplasmas belonging to 16SrⅩⅩⅩⅡ group, CWB phytoplasma strain identified in the study were clustered into one evolutionary branch with the phytoplasmas belonging to 16SrⅠ group. 16S rDNA sequence similarity of phytoplasma was 100% among the strains of CWB and AYL. It is perfectly important for effective prevention and control of areca palm yellow leaf disease to timely clean up the natural hosts of phytoplasma such as chinaberry in areca diseased garden, eliminating the infection source and cutting off the transmission routes of the phytoplasma.

Polyploidy can be accompanied by some super character, such as enhanced stress resistance, larger organ size, and increasing biomass. Polyploidy provides an important way for cassava varieties breeding. The single-node axillary buds of cassava variety SC12 were used as the explants to observe the effect of the different colchicine concentrations on autotetraploid induction rate. The morphology, anatomy and agronomic characteristics of autotetraploid and the diploid parents were compared. The highest efficiency of inducing autotetraploid of SC12 was 7.78% at the concentration of 0.03 g/L colchicine. The ploidy of 20 plants was identified by the flow cytometry and chromosome numbers counts in root tip cells. Consequently, a total of 11 tetraploid plants as well as 5 chimeric plants were obtained. Positive autotetraploid cassava lines accounted for 55% of all the tested lines, and the variation rate was 80% of the tested lines. Significant differences in morphology and anatomy were observed between the autotetraploid and the diploid parents. In morphology, the tetraploid plants became shorter, the stem became thicker, the leaf tip became shield, the leaves changed from lanceolate to arch, the cleft leaf length/cleft width decreased significantly, and the chlorophyll content increased significantly. The length, width and chloroplast number of tetraploid guard cells was significantly increased by 2.33%, 28.99% and 117.79%, respectively, compared with that of diploid parent. Stomatal density was decreased by 40.06% compared with the control. The guard cells of tetraploid variant were oval, while those of diploid variant were cylindrical. The leaf thickness and palisade tissue thickness of tetraploids were significantly higher than those of diploids, and increased by 24.41% and 43.88% compared with the control, respectively. The palisade tissue/sponge tissues of autotetraploid plants were 1.9 times as large as the diploid line, indicating that the palisade tissue of tetraploid leaves was closely arranged, but the spongy tissue was not well developed. The results of yield detection showed that the tubers weight per plant and harvest index of polyploid line SC12-11 was 3.30 kg and 0.43, respectively, which was significantly higher than that of the control.

Secondary forests contribute to the global forest resources to a large extent and have a rich variety of types. Global resources and environment are facing a critical situation, and maintaining secondary forest resources from more damage, scientific research, rational use and effective management are important means of scientific mitigation. In this paper, different secondary forests in Wuzhishan were used as research objects, typical sample plots were set up, community plants were investigated from different levels, and the community composition, importance values and plant diversity were analyzed, the differences of soil physicochemical properties at different levels in terms of content were analyzed, and the correlation between plant diversity and soil physicochemical properties was analyzed by stepwise regression analysis. The study area was dominated by tree and shrub layers, and the herbaceous layer was dominated by dark green curly cypress. The species richness index and Shannon-Wiener diversity index of different secondary forest communities showed that tree layer>shrub layer>herbaceous layer, and the Simpson dominance index and Pielou evenness index showed that shrub layer>tree layer>herbaceous layer. The soil in the study area was acidic, the organic matter, total nitrogen, total potassium and alkaline nitrogen content of soil show a gradual decreased with increasing soil levels. While there was no significant difference in the physical properties of soil in different soil layers. The soil factors affecting the plant diversity index significantly were soil saturation water content, soil capillary void space, soil capacitance, total phosphorus and total potassium. The diverse characteristics of soil water content, soil nutrients, soil texture and their complex interaction had a synergistic effect on the change of plant diversity of secondary forest community. There was a positive correlation between vegetation diversity and soil action. By studying the physical and chemical properties of aboveground plant community and soil of different secondary forests in Wuzhishan City, the basic situation of community diversity of different secondary forests in Wuzhishan was mastered, the difference of community succession of different secondary forests was clarified, and the change of secondary forests was revealed, in order to provide theoretical basis for rational utilization and protection of forest community succession.

In this experiment, Pandanus amaryllifolius Roxb. plantlets in vitro were used as detected material. In order to investigate the most suitable fertilization formula for increasing aroma of P. amaryllifolius Roxb. plantlets in vitro. And the volatile components of P. amaryllifolius Roxb. plantlets in vitro were separated and identified by gas chromatography-mass spectrometry (GC-MS), and the results were analyzed by principal component analysis (PCA) and cluster heatmap analysis. The results showed that the volatile components were similar in seven different treatments, but their volatile contents were different greatly (P<0.05). A total of 21 volatile components were detected, including alcohols, pyrroles, esters, ketones, furans, furans, acids, olefins and phenols, and squalene, phytol. Among them 2-acetyl-1-pyrroline (2AP), neophytadiene, 3-methyl-2-(5H)-furanone, 2,3-dihydrobenzofuran were the main volatile components. The average content of the characteristic aroma component 2AP were (48.07±13.14)μg/g of P. amaryllifolius Roxb. plantlets in vitro, and the treatment 6 (zinc+fertilizer combinations) was hightest to 72.03 μg/g; however the treatment 1 (IBA+zinc+fertilizer combinations) was the lowest to 31.96 μg/g, and the treatment 6 could significantly increase the content of the characteristic aroma component 2AP. The results of principal component analysis showed significant difference between the fertilizer combinations treatment (ammonium bicarbonate + calcium superphosphate+potassium chloride) and the water treatment, and the main volatile components of the treatment 2 and the treatment 6 were phytol, 2AP, 3-methyl-2-(5H)-furanone, 2,3-dihydrobenzofuran, neophytadiene; and the main volatile components of the treatment 1 and the treatment 5 were ethyl oleate-based esters, 2,4-di-tert-butylphenol-based phenols, acetol-based ketones. The volatile components were mainly squalene in the treatment 3, treatment 4 and treatment 7. Cluster analysis showed that higher volatile component in the treatment 6 (zinc+fertilizer combinations), and the volatile component were significantly lower in the treatment 1 (IBA+zinc+fertilizer combinations). There were no obviously differences in other treated groups. The conclusion indicated that zinc sulfate immersion and ammonium bicarbonate+calcium superphosphate+potassium chloride fertilizer can improve aroma than other groups.

Dendrobium is the general name of all plants in Genus Dendrobium Sw. It is an important flower resource in orchid plants and has high ornamental and medicinal value. Crossbreeding is the main method to cultivate new varieties of Dendrobium, However, the breeding period of Dendrobium is long, and the whole breeding cycle usually takes several years. The identification of germplasm resources is the basis of breeding work. This study of the identification of the hybrid progeny lines of Dendrobium is expected to provide molecular basis for early selection of hybrid progeny and rapid identification of new varieties (lines), shorten the breeding cycle and accelerate the progress of Dendrobium breeding. As a new type of molecular marker, iPBS marker does not need to obtain the LTR sequence in advance. Compared with other molecular markers, it has the advantages of simplicity, efficiency and wide application. In the study, the authenticity of 19 hybrid F₁ lines of Dendrobium Pittero Gold 'Diamond Ring' × Dendrobium Btilliant Smile 'Hiromi' was identified by iPBS molecular marker technology, and perform genetic diversity and cluster analysis. Seven primers with clear amplification bands, high polymorphism and good repeatability were selected from 83 iPBS primers for the authenticity identification of hybrid progenies of Dendrobium. A total of 69 bands were amplified by the seven primers, of which 51 were polymorphic, and the polymorphic ratio was 73.91%. The 19 F₁ hybrid lines tested could amplify paternal characteristic bands and were identified as true hybrids. A large number of paternal characteristic bands were amplified in the offspring plants, indicating that more genetic information of Dendrobium Pittero Gold 'Diamond Ring' was introduced into the offspring individuals, showing obvious paternal inheritance. Cluster analysis showed that the vast majority of the hybrid offspring tended to be paternal first and then maternal. The results of genetic similarity coefficient analysis showed that the average genetic similarity coefficient between the hybrid offspring and the male parent was greater than that of the female parent, indicating that the tested hybrid offspring were more inclined to the male parent in heredity, which was consistent with the clustering results. The variation of genetic similarity coefficient between the two parents and the offspring was small, indicating that the genetic diversity between the offspring of the hybrid combination was not rich. This is not conducive to the emergence of heterosis varieties, in the subsequent experiments, plants with large genetic differences should be selected for hybrid breeding in order to obtain heterosis varieties. The results showed that the iPBS molecular marker technology could be used as an effective method for the screening and identification of early hybrids in Dendrobium cross breeding. The results of this study would provide a scientific basis for further revealing the genetic diversity between parents and progeny of Dendrobium population.

The fungal secretory expression vector p74HSP-EGFP constructed in a previous study can express the target gene in fungal pathogens and secrete the target protein into plants during fungal infection and colonization, thus verifying the function of the target gene. However, the promoter of toxin A gene (ToxA) driving the target gene in p74HSP-EGFP is not a endogenous promoter of Fusarium oxysporum f.sp. cubense (Foc). For more efficient expression of target genes in Foc, the promoter of secreted in xylem 1d (Six1d), which is highly expressed in Foc, was cloned using the genomic DNA of Foc race 1 (Foc1) as a template, replacing the ToxA promoter in p74HSP-EGFP, and the newly constructed fungal secretory vector was named pSix1d74HSPG. Foc tropical race 4 (Foc TR4) was transformed by p74HSP-EGFP and pSix1d74HSPG. The transformed strains were cultured in potassium salt liquid medium (KK) containing 100 μg/ml hygromycin for 5 days, respectively. The fluorescence intensity and the abundance of EGFP protein secreted outside the cell were detected. The results showed that the expression intensity of EGFP driven by Six1d promoter in pSix1d74HSPG was 1.6-1.7 times of that driven by ToxA promoter in p74HSP-EGFP, which could replace the p74HSP-EGFP vector for more efficient expression and secretion of target proteins in Foc for functional characterization. Our work provides an important experimental tool for the study of the molecular mechanism of resistance and susceptibility to banana fusarium wilt.

The above-ground biomass (AGB) is an important indicator to reflect the productivity, carbon sequestration capacity, and carbon storage of rubber tree. However, the AGB models of individual rubber tree with high estimation efficiency and accuracy are still needed to develop. In the present study, an 8-year-old forest established for rubber tree breeding trial was scanned to obtain the point cloud data by using Unmanned Aerial Vehicle-Light Detecting and Ranging (UAV-LiDAR), meanwhile, the actual AGB of every tree in this forest was measured experimentally. Four individual tree structure parameters, such as tree height, crown width, crown projected are, and crown volume, were extracted from the point cloud data, and then, used as predictors to establish the individual rubber tree AGB model. The multiple nonlinear regression and random forest regression were both applied to establish the model, and the estimation accuracy, generalization ability and reliability were evaluated by five-fold cross-validation. The tree height and crown width values extracted by special algorithms from individual tree point clouds data were highly correlated with the values manually measured on point clouds, the Pearson correlation coefficients of the two parameter wase 0.999 and 0.951 respectively, and the root mean square errors (RMSE) was 0.109 m and 0.452 m respectively. The correlations between the four structure parameters and the AGB of individual rubber tree was significant. Especially, the parameter of crown volume had the highest Pearson correlation coefficient (0.904). All four parameters had good explanations for AGB. Both established AGB models based on the four individual tree structure parameters could achieve good fitting results. However, the method of random forest regression had a better performance compared with multiple nonlinear regression. The coefficient of determination (R²) of the random forest regression model was 3.64% higher than that of the multiple nonlinear regression model, and the relative root mean square error (rRMSE) of the random forest regression model was 2.66% lower than that of the multiple nonlinear regression model. In general, there is higher goodness of fit and stronger generalization ability of the random forest regression model which can more accurately estimate the rubber tree AGB.

This paper aimed to clarify the effect of different microbial agents on pepper blight and the influence of rhizosphere soil bacterial community structure, and to provide a green prevention technical basis for reducing the occurrence of pepper blight. Six microbial agents, including Bacillus subtilis, Trichoderma harzianum, Pseudomonas fluorescens and Streptomyces enissocaesllis were selected as the main research objects to study the effects on the control of pepper blight and the bacterial community structure in rhizosphere soil under pot experiment by high-throughput sequencing. A₁ (1×10⁸ CFU/g of B. subtilis microcapsule) and A₂ (1×10⁸ CFU/g of T. harzianum water-dispersed granule) had the best control effect, and the control effect was 85.58% and 81.97%, respectively, and others the control effects of A₃ (5×10⁸ CFU/g Pseudomonas fluorescence granules). The best control effect of A₄ (4×10⁹ CFU/g S. enissocaesllis NBF715 powder), A₅ (1×10¹⁰ CFU/g B. subtilis wettable powder), A₆ (3×10⁸ CFU/g T. harzianum wettable powder) and A₇ (50% carbendazim wettable powder) was 47.17%, 49.12%, 30.60%, 39.86%, 25.83%, respectively. Based on the high-throughput sequencing analysis, the bacterial community composition of pepper rhizosphere soil at phylum level, different microbial agents increased the proportion of Proteobacteria and Bacteroidota, especially A₁ and A₂ significantly increased the richness of Proteobacteria and Bacteroidetes. At the family level, the richness of Chitinophagaceae, Steroidobacteriaceae and Micrococcaceaee were improved by microbial agent treatment, and significant difference was found between A₁ and A₂ treatments. The total number of bacterial OTUs and the number of unique bacterial OTUs in the rhizosphere soil of Capsicum treated with A₁, A₂, A₇, A₈ (treatment of inoculated P. capsici) and CK (water) were analyzed by Venn diagram. The total number of bacterial OTUs and the number of unique dominant bacteria in the rhizosphere soil of capsicum increased in the A₁ and A₂ treatments, while the richness and diversity of soil bacteria decreased in the A₇ treatment. In conclusion, the control effect of A₁ and A₂ on pepper blight was more than 80%, and the richness and diversity of unique dominant bacteria in the rhizosphere soil of pepper increased, and the ability of pepper to resist P. capsici infection was enhanced. A₁ and A₂ could be used as agents to control pepper Phytophthora blight. At the same time, the use of carbendazim reduced the richness and diversity of soil bacteria, and the pathogen could invade the root of pepper more quickly after the reduction of microbial diversity.

Two genuses and species of Orchidaceae, Taeniophyllum glandulosum Blume and Tainia dunnii Rolfe, together with other two species, Bulbophyllum henanense J. L. Lu and Goodyera yangmeishanensis T. P. Lin, were reported as new records to Hubei province. The morphological characteristics were briefly described, and color photos were provided. The new records enrich the wild orchid resources and are of great significance for further study of orchid plants and biodiversity conservation in Hubei province.

In this paper, a combination of traditional morphological features and modern molecular phylogenetic analysis was used to identify and describe a gasteroid fungus collected from Guangdong. The studied specimens is Asperosporus subterraneus Karlsen-Ayala, Gazis & M.E. Sm., a member of the new genus Asperosporus Karlsen-Ayala, Gazis & M.E. Sm. of Agaricaceae which newly reported from Florida, USA, and firstly reported from China. A. subterraneus was mainly characterized by its irregular spherical basidiomata, white to grayish white at first, then becoming brownish when mature, rapidly stain pinkish-red when cut or bruised, earthy smell, Basidiospores, 14-18 μm×11-16 μm, broadly elliptical to subglobose and thick-walled basidiospores ornamented with larger pyramidal to irregular warts, turn to orange brown in 5% KOH solution and dark brown when added to Melzer solution, and the spores were often attached with sterigma remnants. Specimens were deposited in the Fungarium of Guangdong Institute of Microbiology (GDGM).