The effect of composite passivators on the in-situ Cd contaminated soil and its absorption and accumulation of Cd in cabbage were explored, which would provide a scientific basis for the treatment and restoration of medium and mild Cd contaminated farmland. Field experiments were carried out in Cd polluted farmland soil with five passivator combinations: red mud + lime + phosphate rock powder (T₁), red mud + lime + biochar (T₂), lime + humic acid + sepiolite (T₃), sepiolite + biochar + red mud (T₄), sepiolite + biochar + phosphate rock powder (T₅), in order to study the effects of the five passivating agent combinations on the content of various forms of Cd, enzyme activity, microbial carbon (MBC), microbial nitrogen (MBN) and the absorption and accumulation of Cd in various parts of Chinese cabbage in the cultivated layered soil. The five compound passivating agents could improve soil pH and reduce the availability of Cd in the soil in different degrees. Soil pH in T₃, T₄ and T₅ treatments was significantly higher than that in CK, and soil available Cd content in T₂, T₃, T₄ and T₅ treatments was significantly lower than that in CK. In each form of Cd, in T₅ treatment, the content of Cd in weak acid extraction state and reducible state was significantly higher than that in CK, while the content of Cd in residue state was significantly lower than that in CK. Compared with CK, T₁, T₃, T₄ and T₅ treatments significantly increased soil sucrase and acid phosphatase activities by 42.06%-152.46% and 15.95%-26.48%, respectively. Treatments T₁, T₂, T₃ and T₄ significantly increased urease activity by 18.43%-35.19%, treatments T₃ and T₄ significantly increased catalase activity by 18.78%-19.01%, treatments T₁, T₂ and T₃ significantly increased soil MBC content by 31.83%-53.19%. T₂, T₃ and T₄ treatments significantly increased soil MBN content by 19.14%-59.89%. Different treatments had different effects on Cd absorption and accumulation in different parts of Chinese cabbage. Compared with CK, T₄ and T₅ treatments significantly reduced Cd content in roots, T₁, T₄ and T₅ treatments significantly reduced Cd content in stems, and the five treatments significantly reduced Cd content in leaves, and the enrichment and transport capacity of Cd in leaves of Chinese cabbage was greater than that in stems and roots. In terms of comprehensive passivation effect, T₄ and T₅ treatments, namely sepiolite + biochar + red mud (3∶5∶3), sepiolite + biochar + phosphate powder (3∶5∶3), had better passivation effect in the field soil mildly polluted by Cd during in-situ passivation restoration, which could effectively reduce the absorption of heavy metal Cd in soil by plants.

Phytosulfokine (PSK) is a small peptide hormone unique to higher plants, widely involved in biological processes such as plant growth and development, division and differentiation, biotic and abiotic stress. PSK receptor (PSKR) is a direct receptor for PSK and is crucial for PSK signal transduction. In the present study, HbPSKR2 was cloned from rubber tree by RT-PCR (reverse transcription-polymerase chain reaction), and its bioinformatics, gene expression pattern, interacted proteins screening and identification were also analyzed. Results showed that the open reading frame of reading frame of HbPSKR2 had a total length of 3159 bp and encoded 1052 amino acids with molecular weight 114.84 kDa and theoretical isoelectric point 6.34. Domain analysis showed that HbPSKR2 was a typical trans-membrane protein. The first 640 amino acids were the antenna structures composed of leucine rich repeat (LRR), the 692 to 714 amino acids were transmembrane domains, and the 765 to 1052 amino acids were kinase domains. Multiple comparisons were conducted on the membrane kinase domain of HbPSKR2 and the membrane kinase domain of PSKR homologous proteins in Arabidopsis and rice. The results showed the existence of conserved sites such as ATP binding site, CaM binding site, Activation segment, GC Centre. Expression pattern analysis showed that HbPSKR2 was highly expressed in the cambium region of rubber tree. The expression level of HbPSKR2 was significantly increased at the early stage of coronatine (COR) treatment. Twelve candidate proteins interacted with HbPSKR2 were screened by yeast two hybrid technology, and the interaction between two protein kinases (HbPBL8 and HbPIX13) and HbPSKR2 was further verified by luciferase complementary imaging. The strong fluorescence signal was observed by co-transformation HbPSKR2-nLUC/HbPBL8-cLUC and HbPSKR2-nLUC/HbPIX13-cLUC into tobacco, suggesting the interaction between HbPSKR2-HbPBL8 and HbPSKR2- HbPIX13 in vivo. The cloning of HbPSKR2 and identification of HbPSKR2 interacted protein would provide new insights into the molecular mechanism of laticifer differentiation in rubber tree.

The traditional method for detecting the copy numbers of exogenous gene in transgenic plants is Southern hybridization, which is costly and time-consuming, and is difficult to meet the breeding needs of high-throughput detection of the copy numbers of exogenous gene. Therefore, this study aims to establish a fast and high-throughput method for detecting the copy numbers of exogenous gene in transgenic papayas. In this study, two single copy genes, Cpa03g018830 and Cpa03g018770, were selected from the papaya genome. Using the known exogenous gene as a single copy integrated transgenic papaya as a reference, the copy numbers were identified by digital PCR. Further, using them as reference genes, and the commonly used screening marker gene NPTII in papaya transgenic breeding as an exogenous target gene, methods for detecting the copy numbers of exogenous gene in transgenic papaya using digital PCR and fluorescence quantitative PCR were established. The results showed that Cpa03g018830 and Cpa03g018770 were both single copy genes; the established digital PCR method was accurate and reliable in detecting the copy numbers of exogenous gene in transgenic papayas, while fluorescence quantitative PCR had a higher accuracy in detecting single or low copy integration of exogenous genes in transgenic papayas, and a lower accuracy in detecting multiple copy integration of exogenous genes. Therefore, fluorescence quantitative PCR is suitable for initially screening out single or low copy integration plants from a large number of transgenic plants. The single copy Cpa03g018830 and Cpa03g018770 identified in this study can be used as reference genes for detecting the copy numbers of exogenous gene in transgenic papayas. The established methods for detecting the copy numbers of exogenous gene in transgenic papayas using digital PCR and fluorescence quantitative PCR techniques are simple, fast and suitable for batch detection, providing new methods for selecting single or low copy lines in transgenic resistance breeding of papayas.

To explore the relationship between the expression of psoralen synthase gene (PS) and psoralen synthesis, quantitative real-time PCR (qPCR) and high performance liquid chromatography (HPLC) were used to determine the expression of PS and the content of psoralen in roots, stems, leaves and fruits of Ficus hirta Vahl (FH) from Guangxi and Fujian. PS was expressed in roots, stems, leaves and fruits of Guangxi and Fujian FH, and the expression was tissue-specific. The relative expression level in roots was the highest (expression in branch roots was higher than that in principal roots), followed by leaves (expression in entire margined leaves were higher than that in incised leaves), and the expression levels in stems and fruits were extremely low. The psoralen contents of FH had some differences from the two producing areas. They were accumulated in the principal root, branch root, entire margined leaf, incised leaf, stem and fruit from Guangxi and Fujian provinc FH, and the contents were the highest in branch roots, which was 3.206 mg/g and 2.947 mg/g respectively, followed by principal root (2.136 mg/g and 0.419 mg/g). The content in incised leaves was 0.022 mg/g and 0.028 mg/g respectively, that in entire margined leaves was 0.069 mg/g and 0.035 mg/g. The psoralen content of stem (0.003 mg/g and 0.003 mg/g) and fruit (0.002 mg/g and 0.001 mg/g) was lower than other parts. The psoralen content was correlated with the expression of PS. The study would provide insights into understanding the role of PS in the psoralen metabolic in Ficus hirta Vahl.

Pepper mild mottle virus (PMMoV) is one of the most serious pathogens worldwide. Currently, five pathogenic types of PMMoV have been reported, including P₀, P₁, P_1,2, P_1,2,3 and P_1,2,3,4. The wide host range and strong pathogenicity of PMMoV seriously affect the yield and quality of pepper, and breeding for disease resistance is the most economical and effective means to control this virus. Our previous study determined that PMMoV infected with Danzhou pepper germplasm nursery in Hainan is the P_1,2 pathogenic type. In order to screen PMMoV-resistant pepper germplasm resources, 110 germplasms were tested for PMMoV resistance using the reported L³-linked molecular markers. 46 pepper germplasms containing molecular markers of resistance were inoculated with PMMoV P_1,2 pathogenic type by inoculation at seeding stage. Local symptoms were investigated 5 d after inoculation, and systemic symptoms were investigated 20 d after inoculation, and disease indices were calculated. The results showed that there were sig-nificant differences in disease resistance among different pepper germplasms, and the disease indexes of various germplasms ranged from 8.86-60.00. The germplasms showing high resistance (HR) to PMMoV P_1,2 pathogenic type were CF19-34m and 19FB6-1. The germplasms showing resistance (R) wasCCJ93-1. The germplasms showing medium-resistance (MR) included 17YB32, 17SCa28m, 15SM39-2, 14SM555×14SM1, 14SM567-2, 14SM526-1, 14SM565-1, 14SM502-1, 14SM519-1, 14SM504m, 14SM503m, 14SM519-3, 14SM518-2, 14SM519-2, CCJ52-1, etc. The presenting susceptible (S) germplasms were 14SM514m, CCJ22-1, CCJ113-2, CCJ135-1, CCJ157-1, L537-1m, L545, CCJ87-2 and CCJ133-1, and the obtained disease-resistant germplasms accounted for 80.43% of the total identified materials. The results of this study would lay the foundation for creating germplasm resources resistant to pepper mild mottle virus and breeding resistant varieties.

Cassava (Manihot esculenta Crantz) is the third largest food crop in the tropics and is the food ration of nearly 600 million people in the world. Cassava is mainly cultivated in tropical regions, where often damaged by waterlogging in rainy season, which leads to serious decline in yield and quality. Therefore, it is important for selecting cassava germplasm resources with high waterlogging-resistance. In this study, a pot experiment was carried out, and plant height increment, relative chlorophyll content (SPAD), relative conductivity, superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) of 28 cassava germplasm resources were measured under waterlogging stress treatment after 6 days. Variance, correlation analysis, principal component analysis and subordinate function analysis were used to evaluate waterlogging resistance and screen the waterlogging tolerant germplasms at the seedlings stage. The waterlogging tolerance of 28 cassava germplasms had great difference and the response mechanism of different cassava germplasms to waterlogging stress showed huge difference among the 28 germplasm resources. There were significant positive correlation between plant height increment and relative chlorophyll content (P<0.01), and the correlation coefficient was 0.253. There were negative correlation coefficient between the relative chlorophyll content with relative conductivity of 0.266 (P<0.01). Principal component analysis using 6 indexes indicated that the 4 principal components accounted for 82.85% of accumulative contribution rates among the germplasms. The main factors were CAT, plant height increment, SOD, and relative chlorophyll content, respectively. According to subordinate function analysis, waterlogging tolerance of the germplasms from high to low was Qiongzhong 1, SC6068, SC201, ME191, M-F532, GR891, C222, GR3, F2000, Luoyong 80, 46-12, GR5, KU58, H660, SC5, F03P, M-GR911, CH20, M-F671, COL713, Boss 2, JG1301, GR911, E407, F274, SC8, M-SC5, Thailand. The results of this study would provide basic materials for the breeding of new varieties of cassava with high waterlogging-tolerance and for the future research of cassava waterlogging tolerance mechanism.

Banana classification is a difficult problem, using morphological features to classify is unable to meet the needs. Molecular marker technology has been gradually applied to population identification and classification, genetic relationship analysis and genetic diversity research of banana varieties (lines). In this paper, SRAP molecular marker technology was used to analyze the genetic relationship of 89 banana germplasm resources. Using 10 pairs of positive and negative primers to form 100 pairs of primer combinations, and 13 pairs of SRAP primers with easy identification, clear band type and high polymorphism were screened out. 170 identifiable bands were amplified by the 13 pairs of primers, with an average of 13.08 bands per pair of primers, of which 140 bands showed polymorphism, with a polymorphism ratio of 79.00%. The similarity coefficient of 89 banana germplasm resources varied from 0.241 to 1.000, and the genetic diversity was very rich. The similarity coefficient of the same type of wild banana from the same place or different places was high. When the similarity coefficient was 0.49, the 89 banana resources could be divided into six groups. The first major category were AAA group Xiangyajiao, AA group Gongjiao, AAB group Longyajiao and AA group wild banana (AAA, AA, AAB). The second major category were ABB group Fenjiao, ABB group Fendajiao and BB group wild banana (ABB, BB). The third major category were Dajiao and a banana wild relative Musa itinerans. M coccinea, Musella lasiocarpa, Heliconia belonged respectively to the fourth, fifth and sixth category. The results are basically consistent with the current classical classification conclusion. Only some banana germplasm have different classification status, indicating that it is feasible to use SRAP markers to classify banana germplasm resources. At the same time, the cultivated Xiangya banana, Gongya banana and Longya banana have the same ancestry, and are close to the wild banana of AA genotype, while the wild banana of BB genotype is close to the pink banana, the pink banana and the wild banana of BB genotype, and the banana germplasm resources of different genomes are gathered together, which showing that the origin of banana germplasm resources affects the genetic relationship of offspring, and a single classification method cannot completely distinguish the banana germplasm resources. In addition, the genetic relationship between plantain and plantain is relatively close, but it is impossible to distinguish whether plantain contains A and B genomes, so the genotype and genetic background of plantain need further study.

Eight main agronomic traits were statistically analyzed using cassava germplasm resources. The result showed that the data for the eight agronomic traits were normally distributed, with the coefficients of variation ranging from 7.2% to 46.9%. The coefficient of variation for starch yield was 46.9% and the coefficient of variation for the dry matter rate was 7.2%. Correlation analysis showed that there was a degree of significant positive correlation between the different traits, with a highly significant positive correlation between weight of fresh tuberous root per plant and stem diameter. Principal component analysis combined eight traits into three main components. The cumulative contribution rates in each year amounted to 92.55% and 93.67%, respectively. The first principal components were weight of fresh tuberous root per plant, fresh tuberous root yield, starch yield and dry tuberous root yield. The second principal components were starch content and dry matter. Cluster analysis suggested that the resources could be divided into four groups in each year at the Euclidean distance of 6.0. Group Ⅱ had excellent performances in weight of fresh tuberous root per plant, fresh tuberous root yield, starch yield and dry tuberous root yield, which could be preferred as parental materials for new cassava varieties selection and breeding of high yield and good quality.

Phenotypic traits are the basis of breeding, which can reflect the genetic variation of species to a certain extent. Exploring the phenotypic diversity of Hibiscus rosa-sinensis cultivar can provide reference for the utilization of germplasm resources and the breeding of new varieties. In this study, 39 H. rosa-sinensis cultivar resources were selected as the research object. Data of 25 phenotypic traits were collected and measured, including 9 quantitative traits and 16 qualitative traits. Diversity analysis, correlation analysis, cluster analysis, principal component analysis and comprehensive evaluation were carried out. The results of diversity analysis showed that there was abundant variation in the 39 H. rosa-sinensis cultivar resources resources, and the coefficient of variation of 9 quantitative traits ranged from 9.49 to 31.05, among which, the coefficient of variation of pedicel length was the largest, and the coefficient of variation of leaf length/width was the smallest; the index of diversity was 1.7592 to 2.0299, among which the index of style length was the highest, and edicel length diversity index was the lowest. The diversity index of 16 quality traits ranged from 0.3898 to 1.3203, among which the diversity index of flower heart and eye area was the highest, and the diversity index of flower pattern was the lowest. Correlation analysis showed that there were significant positive correlations between flower diameter and petal length, outermost petal morphology and petal secondary color, leaf length and leaf width, petal length and style length, flower diameter and style length, petal length and width, and flower diameter and petal width. There was a significant negative correlation between petal width and pattern, style length and pattern, leaf width and leaf length-width ratio, and petal length and pattern. The cluster analysis showed that the 39 species could be divided into four groups at Euclidean distance of 20. The Ⅰ group contained 33 species resources, which were mainly characterized by the flower diameter between 11 cm and 17 cm, and could be further divided into two subgroups. The Ⅱ group contained two species, which were mainly characterized by double petals and small flower diameter between 10 cm and 11 cm. The Ⅲ group contained three species, which were characterized by single petals and large flower diameter, with the flower diameter between 18 cm and 20 cm. The Ⅳ group contained only one species. Principal component analysis showed that 9 principal components were extracted, the cumulative variance contribution rate of 79.85%. Through the calculation of main component of the 39 specie, the comprehensive score of Huo fenghuang was the highest, followed by Valentine's day, Moorea Hanging Garden and Fei jiangjun, while that of Yueyecaihong and Chocolate Cake was the lowest.

Spontaneous plants have strong growth adaptability, can self-multiply and form a good natural landscape, which are important materials for the construction of conservation-oriented landscape. The typical-sampling method was used to investigate the spontaneous plants in 16 city parks of Haikou, so as to comprehensively understand the diversity level of spontaneous plants and provide reference for the construction of conservation-oriented gardens. The results showed that 220 spontaneous plant species belonged to 59 families and 176 genera were recorded in this research. Among them, 154 plants were native plants (accounting for 70%) and 66 plants were exotic species (accounting for 30%), meanwhile, 48 plants were invasive alien species (accounting for 22.27%). Asteraceae, Poaceae and Fabaceae, the largest families, played a major role in the quadrats with 75 species from 64 genera, accounting for 36.36% and 34.09% of the total genera and species of Spontaneous plants. Perennial herbs and annual/biennial herbs were the main life forms, accounting for 51.36% (113 species) and 44.09% (97 species), respectively. Spontaneous plants have strong ecological adaptability and high potential for landscape application. In the future construction of urban landscape, the existing spontaneous plants in the parks should be reasonably planned and utilized, increasing the proportion of native plants and constructing the spontaneous plants landscape with regional characteristics according to different environments.