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.