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.

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.

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.

Cowpea wilt is a soil-borne fungal disease caused by Fusarium oxysporum f.sp. tracheiphilum (FOT), and is one of the most important diseases of cowpea. In our study, several biocontrol bacteria were isolated and evaluated. One of the bacteria which were found the best antagonistic effect to FOT was identified and studied on its antagonistic mechanism and growth promoting function, while it was evaluated by the control and growth-promoting effects. This study established the foundation for the research and development of excellent biocontrol agents for cowpea Fusarium wilt. 93 strains of bacteria were isolated by plate dilution method, and 11 biocontrol strains, which exhibited good inhibitory effect on the pathogenic bacteria of cowpea wilt, were screened by plate confrontation method, and the antagonistic strain SD13 had the best inhibition rate (the inhibition rate reached 82.0%). SD13 was identified as Bacillus velezensis based on Morphology and 16S rDNA sequence. Liquid medium co-culture method showed that SD13 could break down the cell wall of the hyphae, spores, and germinated spores of the FOT. Assay medium test results indicated that SD13 could secrete cellulase, protease and β-1,3-glucanase, and had the function related to the production of siderophore, nitrogen fixation and solubilise inorganic phosphorus. Plate confrontation method showed that SD13 had antagonistic activity against a wide spectrum of pathogenic fungi, with inhibition rate ranging from 66.7% to 82.3%. Pot experiments indicated that in four treatments in concentration of 10⁴, 10⁶, 10⁸, 10⁹ CFU/mL, there were the best control effect of SD13 in concentration of 10⁶ CFU/mL, reaching 62.0%, and the growth promotion effect was the second, lower than that of the concentration of 10⁸ CFU/mL. This study shows that SD13 has good biocontrol and growth-promoting effects, and is preliminarily clarified the antagonistic mechanism and functions related to growth-promoting ability, which has potential application value for the prevention and control of Fusarium wilt.

In this study, four stabilizers including potassium hydroxide (KOH), ammonia, sodium dodecyl sulfate (SDS) and potassium laurate were added to concentrated natural rubber latex (CNRL). The performance of the CNRL film was most affected by the amount of KOH. With the increase of KOH content, the Mooney viscosity of the film increased and the shrinkage rate decreased. The tensile strength, tensile stress, elongation at break, tear strength and hardness all decreased rapidly. With the increase dosage of potassium laurate, the Mooney viscosity and the shrinkage rate of the raw rubber film decreased to a certain extent. The tensile strength had a tendency to increase first and then decrease. With the increase of ammonia consumption, there was also a trend of first rising and then falling. More dosage of sodium dodecyl sulfate (SDS) would lead to lower tear strength of the raw rubber film. The performance of the vulcanizate film was also most affected by the amount of KOH. With the increase of KOH dosage, the M_L and M_H of the vulcanizate film would increase. The t₁₀, t₅₀ and t₉₀ would be shortened, and the film shrinkage was reduced. In addition, the tensile strength and elongation at break of the rubber film decreased. The tensile stress and tear strength had a trend of increasing first and then decreasing. As the amount of ammonia increased, the t₉₀ of the vulcanizate film would increase. The shrinkage rate of the film increasesd, and the tensile stress first increased and then decreased. With the increase of the amount of SDS, the t₉₀ of the vulcanizate film would be prolonged and the film shrinkage was reduced. With the increase of potassium laurate dosage, the M_L and M_H of the vulcanizate film would increase, the film shrinkage was reduced, and the tear strength showed a trend of increasing first and then decreasing. It could be seen from the hardness change that the film would become soft after adding KOH and the hardness would be greatly reduced. The Mooney viscosity of the film was greatly improved. After the addition of potassium laurate, the Mooney viscosity of the film decreased significantly, but the hardness of the film did not change much. From the perspective of vulcanization, after adding KOH, the vulcanization degree of the rubber film increased, and the vulcanization time decreased. KOH had a certain promotion and promotion effect on the vulcanization degree of the film. However, combined with the mechanical properties of the vulcanized film. The tensile stress of the film increased after adding KOH, but the tensile strength, tear strength and elongation were significantly reduced. However, the film strength changed little when the other three stabilizers were added.

The constituents of the fruiting body of Fuscoporia punctata (Fr.) Cunn were isolated and purified by different column chromatography and HPLC method to study the the pharmacological basis, chemical constituents and biological activity. The structures of the compounds were identified by spectral data analysis including-NMR and MS. The inhibitory activity of α-glucosidase and protein tyrosine phosphatase 1B (PTP1B) for the compounds were evaluated by PNPG and pNPP methods, respectively. The DPPH scavenging activity of the compounds was determined by the DPPH method. The results preliminarily identified the main chemical composition types of F. punctata (Fr.) Cunn. 12 compounds, including 7 polyketides, were isolated from the EtOH extract of the fruiting body of F. punctata and were identified as inoscavin A (1), inoscavin C (2), phellibaumin A (3), phellibaumin D (4), inonotusin B (5), phellifuropyranone A (6), phelligridin D (7), protocatechualdehyde (8), catechol (9), pyrogallol (10), p-hydroxybenzoic acid (11), and 4-hydroxybenzylideneacetone (12). Compounds 4, 5 and 7 had definite PTP1B inhibitory activity with the IC₅₀ values of (60.83±2.01), (56.33±1.57), (66.89±0.96) μmol/L, respectively. Compounds 2 and 7 exhibited inhibitory activity againstα-glucosidase with the IC₅₀ values of (127.77±0.56), (122.99±1.39) μmol/L, respectively. The IC₅₀ value of compounds 4, 7, 2 and 6 scavenging DPPH radical was (6.71±0.69), (25.79±1.59), (30.45±1.67), (32.90±1.59) μmol/L, respectively. All the compounds were obtained from these fungi for the first time. Most of the polyketides had PTP1B inhibitory activity, α-glycosidase inhibitory activity and DPPH scavenging activity, which would provide theoretical basis for the further development and utilization of F. punctata (Fr.) Cunn.

The drying characteristics of Docynia delavayi at different temperatures (40, 60, 80 and 100 ℃) were investigated and a kinetic model was established to clarify the hot air drying characteristics and appropriate drying temperature for D. delavayi and to achieve its quality control in the hot air drying process. The effect of different drying temperatures on the dried product quality in terms of color, rehydration ratio (RR), the contents of active ingredients (polyphenols, flavonoids, polysaccharides) and antioxidant capacities were evaluated. The moisture ratio curve of D. delavayi decayed exponentially during the drying process, and the drying rate curve was divided into three stages, acceleration, constant rate and decreasing rate. With the increase of drying temperature, the moisture diffusion of D. delavayi intensified, and the drying rate increased obviously, the effective diffusion coefficient of water (D_eff) and activation energy (E_a) was 0.61×10^-6-1.78×10^-6 m²/s and 17.64 kJ/mol, respectively. The data analysis revealed that the Page model fitted well, with the coefficient of determination (R²) all above 0.98, and X², SSE in the range of 0.149×10^-3-0.548×10^-3 and 0.184×10^-2-0.493×10^-2, respectively, which could better reflect the variation pattern of D. delavayi according to moisture ratio with drying temperature during the hot air drying process. The quality of the D. delavayi exhibited some differences under different drying temperatures. D. delavayi dried at 40 ℃ had good rehydration that at 60 ℃ could maintain the maximum color, and possess the highest total polyphenols, total flavonoids, total polysaccharides content and better antioxidant capacities. The results of the post-drying quality analysis showed that temperature had a significant effect on the quality of D. delavayi, and 60 ℃ was better for the retention of color and active substances content. Correlation analysis showed that there was a correlation between color, rehydration ratio (RR), active substances content and antioxidant capacities of D. delavayi, while the active substances content was negatively correlated with the total color difference value (ΔE) and positively correlated with the rehydration ratio (RR) and antioxidant capacities. In addition, it also confirmed that the antioxidant capacities of D. delavayi were the combined effect results of multiple active substances. In conclusion, the quality of D. delavayi dried at the optimal temperature of 60 ℃ was more outstanding. The present study would provide an experimental basis for the further development and utilization of D. delavayi.

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.

Sugarcane plantations are mainly distributed in mountainous areas with high land fragmentation and complex cropping structure in Yunnan Province. Frequent cloud cover reduces the good observations of the land cover by using optical remote sensing. So it is difficult to extract sugarcane plantations with a high accuracy based on satellite optical remote sensing data. Xinping Country, a typical mountainous sugarcane plantation region, was chosen to explore a suitable method for the extraction of sugarcane plantations in mountainous areas. In this study, Landsat-8 and Sentinel-2 optical imagery for Xinping from October 1, 2019 to July 1, 2021 were used as the main data sources, and the DEM data and field survey data were used as the auxiliary data. The synthetic time-series images with high spatial-temporal resolution were constructed on Google Earth Engine (GEE). Firstly, we analyzed the differences among sugarcane and evergreen vegetation, water body, impervious, and other crops in spectral index characteristics, phenological characteristics, and topographic characteristics. Secondly, we determined the optimal thresholds for extracting sugarcane plantations for the four phenological parameters including rise time, fall time, above integral of season and below integral of season, as well as elevation and slope factors based on the training samples. Thirdly, we mapped the sugarcane plantations of 2020 and the mapping accuracy was verified using the validation samples in the study area. Finally, the spatial distribution of sugarcane plantations was analyzed at town scale. The results showed that synthetic time-series images based on the Landsat-8 and Sentinel-2 optical imagery could increase the number of good observations in the study area and improve the spatial resolution of the images, which could solve the problem of low quality of remote sensing images in mountainous areas and could better monitor phenological characteristics and seasonal changes of vegetation. The resultant 2020 sugarcane map had overall, user and producer accuracy of 97.07%, 88.85% and 80.57%, respectively with the Kappa coefficient of 0.83. According to the annual sugarcane map in 2020, there was a total of 7705 hm² sugarcane in Xinping, there were more sugarcane distribution in the southeast than in the northwest, as well as the southeast terrain was lower than that in the northwest. There were significant differences in the area of sugarcane plantations between townships, the township with the largest sugarcane plantation area is Mosha Town (2786 hm²) and the township with the smallest sugarcane plantation area is Gucheng district (0.87 hm²), which is consistent with the actual research. The sensitivity analysis of phenology parameters for sugarcane mapping demonstrated that the four parameters including rise time, fall time, above integral of season, and below integral of season are all important to improve the user accuracy and reduce the commission errors in the sugarcane mapping. The sugarcane plantation mapping algorithm proposed in this study could provide a reference for the extraction of sugarcane plantations in the complex landscapes of mountainous areas in the future.

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.