Cassava (Manihot esculenta Crantz) is an important food crop in tropical and subtropical areas. SWEETs participate in a variety of plant activities, including sugar transport, reproduction and development, plant stress, and interaction with pathogens, which play an important role in plant development. In order to clarify the function of SWEET in the growth and development of cassava, sugar transporter MeSWEET18 was cloned from Cassava South China 9 (SC9) for bioinformatics analysis and verified sugar transport capacity by yeast experiment in this study. The expression trend of MeSWEET18 in cassava in different organ, different developmental stages and under abiotic stress were determined via qRT-PCR method. MeSWEET18 contained a 714 bp open reading frame (ORF) encoding a protein of 237 amino acids residues with predicted molecular mass of 25.94 kDa and theoretical isoelectric point of 6.57. Through instability index (II) analysis by ProtParam, the instability index (II) of the protein encoded by MeSWEET18 was 37.50, indicating the protein of MeSWEET18 as stable. MeSWEET18 was a typical membrane protein with a conserved domain MtN3_slv at the N-terminal and a PQ-Loop Super family conserved domain at the C-terminal and seven transmembrane domains. ProtScale predicted that MeSWEET18 was a hydrophilic protein. Phylogenetic tree analysis revealed that MeSWEET18 belonged to Clade IV. MeSWEET18 was in the same evolutionary tree as AtSWEET16 and AtSWEET17. Alignment of amino acid sequences revealed 53.23% homology between MeSWEET18 and AtSWEET16, and 56.05%homology between MeSWEET18 and AtSWEET17. Yeast functional complementarity tests showed that MeSWEET18 primarily transported fructose. qRT-PCR analysis showed that MeSWEET18 was highly expressed in tuberous roots during the expansion and decreased sharply at maturity of cassava tuberous roots, while the expression levels in leaf, petiole and stem increased with the development of cassava, and reached the maximum at the maturity stage of cassava. qRT-PCR analysis showed that MeSWEET18 was significantly affected by fructose when the hydroponic seedlings of SC9 were treated with sucrose, glucose and fructose solutions under dark conditions. The hydroponic seedlings of SC9 were subjected to abiotic stress including high salt (8 g/L NaCl) stress, drought (100 mmol/L mannitol) stress, oxidation (10% H₂O₂) stress and low temperature (15 ℃ for 24 h, then reduced to 4 ℃ for 24 h) stress. The results show that MeSWEET18 is expressed differently in leaf, petiole, stem and root under abiotic stress. It can be speculated that MeSWEET18 play an important role under abiotic stress in cassava.

Leaf color mutants are not only an ideal material for the study of rice functional genomics, but also of great significance for hybrid rice breeding. They can also be used as ornamental rice, committed to building rural leisure agricultural sightseeing spots and promoting rural revitalization. Based on a rice bright green leaf mutant bgl-2 obtained by radiation mutagenesis in the early stage of our research group, this study compared the difference in leaf color between the mutant bgl-2 and the wild-type SIPI, and showed that the mutant bgl-2 showed a bright green color different from the wild-type SIPI. The content of photosynthetic pigments in leaves was determined by 95% ethanol extraction at tillering stage. The results showed that the chlorophyll content of mutant bgl-2 was not significantly different from that of wild-type SIPI. By observing the other plant morphology of mutant bgl-2, it was found that the leaf tips of its flag leaf and the last two leaves were bent, and the flag leaf was significantly shorter than that of wild-type SIPI, and its plant height was also significantly shorter than that of wild-type SIPI. It was found that the 1000 grain weight, grain length and grain width of mutant bgl-2 was significantly smaller than those of wild-type SIPI, but its length width ratio was not significantly different from that of wild-type SIPI. The structure of flag leaf cells of wild-type SIPI and mutant bgl-2 at tillering stage was observed by the transmission electron microscope. The results showed that the cell wall of mutant bgl-2 was significantly thickened, but the thickness of outer membrane of cell membrane was significantly reduced, the inner membrane was almost degraded, and the lamellar structure of thylakoid in chloroplast ultrastructure was looser than that of wild-type SIPI. F₁ plants were obtained by hybridization with mutant bgl-2 as female parent and wild-type SIPI as male parent. The investigation found that its leaves were normal green, and the morphology of flag leaf and inverted two leaves were normal, while the F₂ population after self pollination isolated normal green leaf seedlings and bright green leaf seedlings with obvious leaf color differences. The segregation ratio of normal leaf color plants and bright green leaf plants in the population was counted, which showed that it conformed to the single gene model of 3 : 1. The above results clarify the phenotype and genetic characteristics of the mutant bgl-2, and provide a theoretical basis for the study of the molecular regulation mechanism of the mutant bgl-2 and promoting its application in rice breeding. The location cloning and functional analysis of BLG-2 gene will be carried out later.

Paphiopedilum venustum, an endangered wild resources, has high ornamental value and conservation biological value. Chloroplast genome (cpDNA), small with stable structure and high conserved in nature, has been widely used in plant phylogeny and species identification. Understanding the chloroplast genome structure of P. venustum is of great significance in revealing the phylogenetic relationship of Paphiopedilum. In this study, the whole chloroplast genome of P. venustum was sequenced by the Illumina sequencing technology, the chloroplast genome was annotated using GeSeq, BLAST and hmmer, the genome structure, gene number, repeats, codon usage bias, phylogenetic development were analyzed using the bioinformatics softwares such as MISA, codonW and Fasttree. The chloroplast genome of P. venustum had a conserved quadripartite structure, with a pair of inverted repeats (IRs) separated a large single copy (LSC) region and a small single copy (SSC) region from the small single-copy region (SSC), with a total length of 158 298 bp. The guanine and cytosine (GC) content of chloroplast protein coding genes was 35.4%, and 129 genes were annotated, including 79 protein coding genes, 38 tRNA genes, 8 rRNA genes, and 4 pseudogenes. 78 simple sequence repeat (SSR) loci were detected, most of which were mononucleotide repeats and dinucleotide repeats, accounting for 84.62% and 10.26% respectively. There were no pentanucleotide repeats, and most of the repeats were composed of A or T base. 32 high-frequency codons were identified, and 90.6% of them ended in A or U, preferred codons ending in A or U. The codon encoding leucine (Leu) had the highest frequency of use, while the codon encoding cysteine (Cys) had the lowest frequency of use. Phylogenetic tree was constructed by comparing the chloroplast genomes of 18 orchidaceae plants. It was found that the two species of Cypripedilum calceolus and C. tibeticum were separated from 16 species of Paphiopedilum and clustered into a single branch, and the genus of Paphiopedilum was divided into two groups, among which P. venustum and P. purpuratum were closely related. SSR and nucleotide polymorphisms can be used as molecular markers for germplasm identification and genetic diversity analysis of Paphiopedilum, which could provide a theoretical basis for germplasm identification and phylogeny of rare and endangered plant Paphiopedilum and its relatives, and lay a foundation for population restoration, biodiversity protection, innovative utilization and new variety breeding of Paphiopedilum.

Chinese cabbage Sclerotinia rot is caused by Sclerotinia sclerotiorum, which seriously endangers the yield and quality of Chinese cabbage. In this study, the transcription level of resistance genes to the infection of S. sclerotiorum were explored at the molecular level and provided candidate genes for further study of disease resistance mechanism. The leaves of resistant inbred line H72 and susceptible strain Y26 were inoculated for transcriptome sequencing analysis. The results show that a total of 121.77 Gb clean reads were obtained by transcriptome sequencing analysis. Filtering the raw sequencing data, the clean reads of each sample were over 6 Gb, Q₂₀ ranged from 97.21% to 97.99%, and the average percentage was 97.61%, Q₃₀ ranged from 92.59% to 93.98%%, and the average percentage was 93.20%, indicating that the sequencing quality could be used for subsequent analysis. The number of common differentially expressed genes were 13 and 11 after inoculation for 36 h and 48 h, respectively. After removing the common differentially expressed genes at each time point, we obtained 18 differentially expressed genes. Combined with gene function annotation, 11 genes involved in defense response. MYB34 transcription factor was up-regulated, while ERF003 was down-regulated, which might negatively regulate the infection of S. sclerotiorum. Gretchen hagen 3.3 (GH3.3), PR proteins (TLP1), F-box, amino acid transporter (ANT1), caffeoyl-CoA O-methyltransferase (Cco AOMT), aspartyl protease (AED3), chaperone protein (DnaJ 11) were up-regulated, which were proposed to response to Chinese cabbage pathogen. The expression of epithiospecifier protein (ESP) and calcineurin B-like protein gene (CBL1) were down-regulated, and the disease resistance function in Chinese cabbage needs further analysis and verification. A further qPCR analysis was used to verify the transcriptome, The expression trends of differentially expressed genes ERF003, CBL1, GH3.3, MYB34, ANT1, TLP1 were consistent with that of transcriptome sequencing. These results will be helpful for further research the resistance mechanism to S. sclerotiorum.

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.

The phenotypic characters of sugarcane germplasm resources native of domestic were analyzed to study the law of genetic variation, so as to provide a theoretical basis for the selection of sugarcane genetic breeding parents and the construction of core germplasm population. 160 sugarcane varieties/parents from 8 different regions native of domestic were used as materials to evaluate the phenotypic traits with reference to the specification and data standard for sugarcane germplasm resources description. Most traits showed rich genetic diversity. Among them, the diversity index of the 20 quality traits was 0.07-1.40, with a mean of 0.84, which was the highest in bud type and the lowest in stalk shape. Five quantitative traits had 8.74%-38.26% of the coefficient of variation, with a mean of 17.69%, which was the highest in millable stalks (38.26%) and the smallest in stalk lengt (8.74%). The diversity index (H′) of the five traits was 1.46-1.83, with a mean of 1.64, which was the highest in stalk lengt (1.83) and the lowest in millable stalks (1.46). The average coefficient of variation of the tested materials in different regions was 13.56%-22.33%. The coefficient of variation of the variety population from Hainan was the largest (22.33%), and the dispersion of quantitative characters was the largest. The coefficient of variation of variety population from Fujian was the lowest (13.56%). By cluster analysis,160 accessions materials were divided into seven categories based on four traits, among them class 5 accounted for 90.62% of the total germplasm resources. This group resource has the characteristics of high yield and sugar content. The results could provide an important reference for the utilization of sugarcane germplasm resources, parental selection and variety breeding.

Southwest Guizhou Autonomous Prefecture is a typical mountainous area with low latitude and high altitude and has abundant water resources. The specific climate and geographical environment of this region enables the appearance of abundant wild sugarcane germplasm resources. In order to enrich the wild germplasm resources and genetic diversity of National Germplasm Repository of Sugarcane (NGRS), and reveal the distribution of wild sugarcane germplasm resources in the region, the wild sugarcane resource investigation team of Sugarcane Research Institute of Yunnan Academy of Agricultural Sciences conducted a survey and collection for 14 days in 4 cities of the region from May 9 to May 22, 2020. Four cities, Xingyi, Xingren, Qinglong and Pu'an, were selected as the main collection areas, and a total of 92 wild sugarcane resources were collected. We collected 6 materials of Erianthus rockii, 16 of Sacchuram spontaneum, 25 of Micanthus sinensis, 13 of Erianthus arundinacius and 32 of Erianthus fulvus. The results revealed that there were abundant phenotypic variation in the species collected from this region with variation coefficient ranging from 11.4% to 78.0% and the average over 30%. Cluster analysis showed that Sacchuram spontaneum group Ⅲ (Sp-2), Micanthus sinensis Group Ⅱ (Ma-8), Erianthus arundinacius Group Ⅲ (Ea-2, Ea-9), Erianthus fulvus Group Ⅲ (Ef-10, Ef-11), Erianthus fulvus Group Ⅴ (Ef-26) and Erianthus rockii (Er-1, Er-3, Er-4) had good yield and quality characters, and were recommended to be used as sugarcane breeding materials in further research. The germplasm collections changed the situation of CNNSGR collection system without collections from southwest Guizhou Autonomous Prefecture, and some specific materials had unique excellent characters that other wild sugarcane resources did not have, which might serve as the genetic resources for sugarcane breeding.

Cymbidium eburneum and Cymbidium insigne are species endemic to Hainan exclusively and belong to the endangered species. 23 F₁ hybrid progenies from C. eburneum and C. insigne were used to accurately verify hybrids, to clarify the genetic relationships between hybrid progenies and the parents with SSR molecular markers. Eight pairs of primers were screened out from 48 pairs of primers using PCR, and 23 hybrid progenies were confirmed to be true hybrids, with the true rate of hybrid progenies100%. 23 hybrids populations identified by primers Cym45, Hub131 and Hub8 had both parental specific loci. 23 hybrid populations identified by primers Hub125 had only father specific loci, Cym9 had a new specific loci. Primer Cym25, Hub125 and Cym47 were low polymorphi [polymorphism information content (PIC)<0.25], primer Cym45, Hub131, Hub8 and Cym9 were middle-highly polymorphi (0.25<PIC<0.5). The PIC of primer Cym172 was 0.59, indicating that it was highly polymorphi, and could be used as the preferred primer for fingerprint construction of the progenies of C. eburneum × C. insigne. UPGMA cluster analysis results showed that when the genetic coefficient was 0.8111, the studied germplasms could be divided into three categories. Among which the parents constituted two categories, and the hybrid population belonged to the third. The hybrid population could be divided into three clusters, X₇ was a clade, X₆ and X₂₁ were clustered together, and the other 20 F₁ hybrid population s were the third. This study showed that SSR molecular markers could be used in hybrid identification and genetic diversity analysis of orchids species endemic to Hainan, which could provide an effective foundation and data base for orchid breeding and new species selection in Hainan. At the same time, the PIC of SSR molecular markers was an important indicator reflecting the ability of molecular markers. The middle-highly polymorphic primers and highly polymorphic primers developed in this study could lay a foundation for the construction of Hainan wild orchid gene atlas and the establishment and development of Hainan wild orchid germplasm bank.

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.

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.

Vertical greening is a technology that uses a new substrate to plant plants on the structure facade and vertical surface, which has been widely used in various urban scenarios. The performance of vertical greening substrate has fundamental research significance for three-dimensional greening cultivation. The effect of water and fertilizer maintenance effect of the substrate is the key factor to determine whether the vertical greening planting plants can survive and grow well. Curing soilless matrix is a cultivation material processed by artificial waste. It has the advantages of clean hygiene, stable nature and good cultivation performance. It is an ideal material for vertical greening cultivation. Retention effect of water and fertilizer is the key factor to determine whether survival and growth of plants in vertical greening, this study was based on the three types of solidified soil-free substrates, which are currently commonly used in vertical greening, including the soilless substrate 'Lei Tu', the Japan solid soilless substrate 'Pafcal' and the domestic solid soilless substrate 'Tan Mian'. Peat soil was selected as the control. The physical and chemical properties, retention of water and fertility were compared, and the potted experiment was executed to verify the effect on cuttage and griwth of plants. The 'Lei Tu' bulk density was small and the water holding capacity was strong, which had advantages over the other two substrates, but the air permeability of the three substrates was poor, so it needed to keep the plant gap in the planting process. The pH value of the 'Lei Tu' and the 'Pafcal' was more suitable for plant growth. The organic matter content and nitrogen content of the three substrates were higher than the natural soil. The concentration of nitrogen and phosphate loss of the three substrates in soluble experiments was extremely low, which would hardly cause the water body to be nutritious and affect the environment. The results of the three types of matrix solidification had reached experimental expectations, which had a significant advantage over peat, the traditional substrates. The effects of cuttings and growth of Callisia repens 'Pink Lady' of the 'Lei Tu' were the best and were the most ideal vertical greening substrate among the three tested substrates. The results would provide the theory of the cultivation of vertical greening.

The problem of heavy metal pollution of crops occurs frequently, and heavy metal pollution has become one of the important factors affecting crop quality. By applying 0.75, 1.50 and 3.00 g/kg potassium sulfate into soil under cadmium (Cd) stress, the effects of potassium fertilizer on the physical and chemical properties of rhizosphere soil and cadmium accumulation in plants of Ilex asprella were studied. This study is expected to lay a foundation for the development of cadmium excess reduction technology in Ilex asprella. The result shows that, the application of high amount of potassium sulfate fertilizer could reduce the soil pH by 1.72% to 8.09%. Cadmium stress can reduce the content of soil organic matter, and the application of medium (1.50 g/kg) and high (3.00 g/kg) amount of potassium sulfate can increase the content of soil organic matter, total potassium and available potassium. In addition, the application of potassium sulfate generally increased the content of biologically available cadmium in the soil, only on the 30th day after the application of low concentration of potassium sulfate (0.75 g/kg), the content of bioavailable cadmium in the soil decreased by 1.94% compared with the Cd treatment group. Under cadmium stress, the application of potassium sulfate could increase the SOD activity in leaves of Ilex asprella, and then enhance the tolerance to cadmium stress. Low could increase the SOD activity in leaves of Ilex asprella, and then enhance the tolerance to cadmium stress. Low concentration of potassium sulfate (0.75 g/kg) inhibited the transport of cadmium from rhizome to leaf and effectively reduce the accumulation of cadmium in the root and stem of Ilex asprella. To sum up, the application of high amount of potassium fertilizer decreased the soil pH, and the application of medium (1.50 g/kg) and high (3.00 g/kg) amount of potassium sulfate could increase the content of soil organic matter, total potassium and available potassium, thus improved soil fertility. The results also showed that low concentration of potassium sulfate could reduce the content of bioavailable cadmium in soil, inhibit the transport of cadmium from roots and stems to leaves, and reduce the accumulation of cadmium in roots and stems of Ilex asprella.

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.

In order to select urban greening plants with excellent dust retaining capability, seven species of shrubs, including Allamanda cathartica, Duranta erecta 'Golden Leaves', Ficus microcarpa 'Golden Leaves', Hibiscus rosa-sinensis, Ixora chinensis, Pittosporum pentandrum var. formosanum and Heptapleurum arboricola, growing in the road green belt of University Road in Nanning, were studied to observe the leaf morphology and the ultrastructure characteristics of leaf epidermis, and collected and measured the dust retaining capability per unit leaf area at the same time. The results revealed that the plant leaves had more dust retaining in winter than in summer in this section of the road studied, and that dust particles greater than PM₁₀ were accumulated more than PM₁₀ or PM_2.5. Among the species studied, D. erecta GL had the most outstanding ability of dust retaining, I. chinensis and H. rosa-sinensis were more dust retaining capability with particle diameters more than PM₁₀, while F. microcarpa GL and P. pentandrum var. formosanum had more clear advantage in dust retaining with fine particles such as PM₁₀ and PM_2.5. According quantified principal component analysis, the five characteristic including: whether the leaf blade was hairy or not, leaf margin type, the number of primary lateral veins, the netting status of the terminal lateral veins and the distribution status of the leaf veins on the leaf surface contained most of the information on the relationship between leaf morphological traits and dust retaining capability. Among the ultrastructure features of the leaf epidermis, projecting anticlinal wall of the upper epidermal cell and granular ornamentation of waxy layer contributed to stronger dust retaining than flocculent ornamentation of waxy layer. Striped ornamentation of cuticle that was too thick or too thin and neatly arranged were not benefit to dust retaining. And the cuticle of the outer edge of stomatal outer arch of the lower epidermis of the leaf had a multilayered ring structure which facilitating the adhesion of more dust particles. The findings of this study could help to provide a reference for the selection of plants for greening and air purification in different types of atmospheric pollution environments and give us a theoretical basis for the study of plant dust retaining. In the strategy of dust retaining, seven plants showed some differences in the macro-morphological characteristics of leaves and ultrastructure of epidermis. D. erecta GL had the largest dust retaining capability, various leaf colors and outstanding landscape effects, so it is worth popularizing. In the dust environment dominated by large particulate matter, I. chinensis and H. rosa-sinensis are recommended, while in the environment with fine dust particles, F. microcarpa GL and P. pentandrum var. formosanum can be planted more.