The effect of bacterial wilt on the fertility of different textures of latosol in Hainan province (sand from Wencheng town, Wenchang city; loam from Dacheng town, Danzhou city; clay from Yongfa town, Chengmai county) was investigated. After the occurrence of bacterial wilt, the disease incidence, physicochemical indicators including pH, organic matter (OM), available nitrogen (AN), available phosphorus (AP), available potassium (AK), soil porosity (SP), bulk density (BD), mass water content (MWC) as well as enzyme activity indicators including catalase (CAT), peroxidase (POD), sucrase (SC), urease (UE) and acid phosphatase (ACP) of the soil inoculated with Ralstonia solanacearum and blank control were compared to analyze the effects of bacterial wilt on various fertility indicators. Spearman correlation analysis and redundancy analysis (RDA) were used to determine the significant indicators affected by bacterial wilt in different soil textures. The results showed that the disease incidence and severity disease index in clay were the highest among the three soil textures, while those of loam were the lowest. In the inoculation treatments, pH, AP, SP and POD of the three soil textures were lower than those of the control, while AN, AK, MWC and UE of clay inoculation treatment were higher than those of the clay control. CAT, ACP, MWC and BD of loam inoculation treatment were higher than those of the loam control. Spearman correlation analysis results showed that OM content, AP content, SP and POD of the three texture soils were negatively correlated with disease incidence; ACP, pH and disease incidence in WCS were significantly negatively correlated (P<0.05) with disease incidence; CAT and UE were significantly positively correlated (P<0.05) with disease incidence. In loam, pH, OM, POD and UE was significantly negatively correlated with disease incidence (P<0.05); while CAT and ACP were significantly positively correlated with disease incidence (P<0.05); SP and POD in clay were significantly negatively correlated with disease incidence (P<0.05); however, AK content in clay was significantly positively correlated with disease incidence (P<0.05). RDA results showed that the SP, OM content and AN content in the control and inoculation treatments were highly correlated with UE, while both SP and AK content in the control and inoculation treatments were highly correlated with ACP and CAT respectively. After the occurrence of bacterial wilt, most fertility indicators of control and inoculation treatment of sand and loam were lower than those in clay. However, soil fertility level was not a sufficient condition for bacterial wilt, but most soil fertility indicators were reduced due to the outbreak of bacterial wilt. The lower disease incidence and disease index of tomato bacterial wilt in sand than in clay may be due to the higher AP content. The reason why disease incidence and disease index of tomato bacterial wilt in loam is lower is perhaps that low pH conditions are unsuitable for the survival of bacterial wilt. Clay with the most severe bacterial wilt disease situation including pH, nitrogen level and mass water content was suitable for the growth and reproduction of bacterial wilt. The relative abundance of potential beneficial microbial communities in clay may also be lower than sand and loam. Therefore, the control measures of bacterial wilt in different soil textures should be adapted to local conditions. Meanwhile, the relevant conclusions of this study would provide a theoretical basis for establishing the control system of bacterial wilt in Hainan province in the future.

Through the examination of the phenotypic traits of teak (Tectona grandis L. F.) seeds from diverse provenances and pedigrees, this study elucidated the genetic variability patterns of teak seeds and the mechanisms of response to environmental factor fluctuations, thereby fostering the conservation and genetic improvement of teak germplasm resources. Using seeds from 81 teak pedigrees representing 13 provenances across four provinces (Guangdong, Guangxi, Hainan, and Yunnan) as the experimental material, five traits, namely seed length, width, length-width ratio, length-width product, and hundred-seed weight, were quantified. Significant differences (P<0.01) existed among the five phenotypic traits of teak seeds across provenances and pedigrees, with trait variation coefficients ranging from 10.27% to 23.88% among different pedigrees and from 4.21% to 20.32% among different provenances. Substantial correlations prevailed among various phenotypic traits, with varying degrees of influence on seed traits from different environmental factors. Latitude, altitude, and annual precipitation were the primary determinants affecting teak seed traits, followed by annual average temperature, while the impact of annual average relative humidity was relatively minor. Distinct seed traits also exhibited heterogeneous responses to environmental changes, with seed length, seed width, and length-width product being particularly sensitive to annual precipitation, whereas length-width ratio and hundred-seed weight manifested heightened sensitivity to latitude. Cluster analysis categorized the 13 provenances into three classes. Teak seeds manifest prolific phenotypic variation across provenances and pedigrees, with seed traits being influenced by various factors, including maternal inheritance and geographical climate. The research would provide a theoretical foundation and scientific basis for the conservation and utilization of diverse teak.

This research aimed to identify a pathogenic fungus of the brown spot disease in the leaves of Cycas and screen for its chemical control agents, which provides a theoretical basis for the protection of Cycas. The pathogenic fungus was isolated from the lesion spots in some Cycas leaves. The pathogenicity of the fungus was confirmed by isolating and purifying the infected leaf tissues and reintroduced to the healthy leaves of Cycas diannanensis following Koch’s postulates. Morphological identification of the pathogenic fungus was conducted. To further confirm the identification, a phylogenetic tree was constructed using eight gene sequences: SSU, LSU, GAPDH, tef1, rpb2, Alt, OPA10-2 and ITS. Effective chemical control agents were screened from seven chemical agents by inhibition assay in vitro. Phylogenetic analyses showed that this pathogen was Alternaria burnsii. Among the tested chemical agents, the most effective inhibition was fluoxastrobin, which displayed 73.48% inhibition rate at a concentration of 0.67 mg/L.

Soil salinization is an ecological environment issue globally and is one of the major abiotic stress factors that cause crop loss worldwide as well as hindering crop productivity. Halotolerant plant growth-promoting rhizobacteria (PGPR) having potential to promote crop growth and increase salt tolerance in crops can be employed to counter this issue in a more effective and eco-friendly way. The recent study aimed to assess the salinity tolerance and growth-promoting capacity of Bacillus tequilenis Bt-RS isolated from the rhizosphere soil of islands in the South China Sea, for assessment, the corresponding media were used for qualitative and quantitative analysis. A pot trail was also conducted to further evaluated its bacterial consortium to promote banana seedlings growth under salinity stress. The results showed that strain Bt-RS could grow well under the condition of 0-10% NaCl content with various types of salts. The strain Bt-RS also possessed 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity along with indole acetic acid (IAA, up to 6.4 mg/L under the condition of 1%-5% NaCl). Base on the pot experiment, the banana seedlings that were inoculated with Bt-RS displayed a significant increase in height, leaf area, fresh weight of above ground and underground, as well as dry weight of above ground and underground (40.30%, 93.00%, 102.38%, 81.08%, 65.82% and 50.50%, respectively) compared to the control group under normal conditions; The 200 mmol/L NaCl-stress treatment significantly increased the growth of banana seedlings in height, leaf area, fresh and dry weight of both above ground and underground by 20.55%, 65.01%, 98.14%, 144.93%, 87.85% and 54.01% respectively, when compared with the control group. The plant height, leaf area and biomass of banana seedlings were significantly increased in both normal conditions and salt stress environment (P<0.05). There was no difference in plant height and leaf area between the experimental group under salt stress environment and the control group under normal conditions, indicating that applying Bt-RS can alleviated the adverse effects of NaCl stress and enhanced banana seedlings growth attributes. In conclusion, the strain B. tequilensis Bt-RS exhibits high salt tolerance and possess the ability to produce IAA and ACC deaminase, making it a valuable strain for improving banana seedling growth and salt tolerance, and also providing resources of strain for developing and utilizing in saline soil.

Shanlan upland rice (Oryza sativa L.) is an unique variety in Hainan, with excellent taste quality traits and rich nutrition. At the same time, it also has excellent stress resistance, such as disease resistance, drought resistance and heat resistance. However, thus far, the resistance of Shanlan upland rice to herbivores remains largely unknown. Thus, in this study, using TN1 and RHT as susceptible and resistant control varieties, respectively, the resistance of three Shanlan upland rice varieties, Shanlanchaihongmi, Shanlanjianshanlannuo and Shanlanyingmigaochan to BPH was evaluated, and their resistance mechanisms were analyzed. The results showed that at the seedling stage, the variety of Shanlanjianshannuo showed resistant to Nuaparvata lugens, brown planthopper BPH, whereas the other two varieties were susceptible to BPH. At the tillering stage, the resistance of the three rice cultivars to BPH was all significantly higher than that of TN1. The mechanism studies revealed that the thickness of the thick-walled tissue in the outer leaf sheaths and the level of cell wall components including lignin, pectin, cellulose and hemicellulose were significantly higher in the three Shanlan upland rice cultivars and the insect-resistant control cultivar RHT than the insect-susceptible control cultivar TN1. Moreover, the basal and BPH-induced levels of JA, JA-Ile, ABA and SA in the three Shanlan upland rice cultivars were significantly higher than those in TN1, and the content of ABA in Shanlanjianshanlannuo plants was the highest in all of the tested varieties. The results demonstrated that the thickness of the thick-walled tissue of the outer leaf sheaths of Shanlan upland rice and the rapid and strong responses of JA, ABA and SA signaling pathways to BPH infestation might be the major reasons why the BPH resistance is stronger in Shanlan upland rice cultivars than TN1.

MLO gene is an unique negative regulatory factor for disease resistance in plants, and the mutation in the gene can lead to broad-spectrum disease resistance in plants. In this study, a DNA and cDNA sequence of cassava MLO12 gene were cloned from the entire cassava genome and named MeMLO12. This gene has a total length of 3743 nt and a coding region (ORF) of 1728 nt, with a complete open reading frame containing 15 exons and 14 introns, encoding 586 amino acids. The protein has a molecular weight of 67.2 kDa and an isoelectric point of 8.85. MeMLO12 protein is located on the endoplasmic reticulum membrane, without signal peptides, and forms seven transmembrane domains at 23-45, 74-96, 161-183, 285-307, 312-334, 371-393, 413-435 aa. Quantitative analysis by qRT PCR revealed significant differences in the expression of MeMLO12 gene in resistant and susceptible cassava germplasms after infection with Xanthomonas axonopodis, indicating a negative regulatory effect in the interaction between cassava and Xam. Selecting the 11th exon of the gene for Snap Gene Viewer analysis, 10 455 seed sequences of sgRNA were obtained. Three target sequences of approximately23nt were selected, with a G terminus at the 3′ end of the base composition, and they were constructed onto the CRISPR-Cas9 vector. After verification, it was confirmed that the three target sequences of MeMLO12 have been successfully constructed onto the gene editing vector, named pSGR-Cas9-AT-MeMLO12 vector.

Plant phospholipase A (PLA) is a key enzyme in cell membrane phospholipid metabolism. It can catalyze the cleavage of multiple functional groups on phospholipids to generate signaling molecules, which are involved in regulating plant growth and development as well as environmental and biological stresses. PLA possesses important research value. In this study, the effects of various factors such as substrate concentration, reaction temperature, pH of buffer solution, buffer solution volume, and reaction time on catalytic activities of banana PLA for phospholipid hydrolysis were investigated, so as to optimize PLA activity assay method. According to the optimal assay conditions, the change of banana PLA activity under anthracnose stress was further studied. The results showed that the optimal conditions for the determination of banana PLA activity by acid-base titration method were as follows: pH 9, reaction temperature 55 ℃, substrate concentration 4 g/L, 15 mL substrate, 3 mL crude enzyme extract, the ratio of extraction buffer volume to peel weight (mL/g) 3, and reaction time 7 h. According to the optimal conditions, the PLA activity of banana peel tissue under anthracnose stress was determined. It was found that the degree of disease in peel tissue was positively correlated with PLA activity, indicating that PLA activity increased with the deepening of disease. This suggested that the level of PLA activity was probably related to fruit resistance. As disease degree deepened, PLA activity increased, membrane phospholipids degraded, and cell membrane integrity disrupted, leading to fruit decay. In this article, a convenient and feasible method for the determination of banana PLA activity was established, which laid a foundation for further study of the catalytic mechanism of banana phospholipase A.

In order to understand the fruit quality of different varieties of pitaya and to screen the germplasm resources with good quality, 33 pitaya germplasm resources were and 15 botanical traits and quality properties such as single fruit weight, fruit transverse and longitudinal diameters, proteins, total flavonoids, and beet pigments were measured, and fruit quality was comprehensively evaluated by using correlation analysis and principal component analysis. The 33 pitaya germplasm resources had a single fruit mass of 164.67-556.00 g, a transverse fruit diameter of 5.86-9.40 cm, a longitudinal fruit diameter of 7.29-11.94 cm, a fruit shape index of 0.99-1.39, a total sugar content of 78.80-126.05 mg/g, a total phenolic content of 0.64-2.46 mg/g, a total flavonoid content of 0.85-9.67 mg/g, hardness of 6.62-16.86 N, protein content of 0.29-1.45 mg/g, beet pigment content of 0.69-37.01 mg/100 g, and starch content of 14.12-44.60 mg/g. The total acid content ranged from 0.33 to 15.23 mg/100 g. The Pearson’s method was used to correlate the main botanical and quality traits of the pitaya germplasm resources. and quality traits were correlated. The correlation coefficients were 0.478 for total acid and soluble solids, and -0.532 for sugar-acid ratio, while the correlation coefficients were 0.749 and 0.942 for longitudinal and transverse diameters. The correlation coefficient between longitudinal diameter and fruit shape index was 0.426, and the correlation coefficient between weight and sugar-acid ratio and hardness was 0.360 and 0.351, respectively. After principal component analysis, the 15 traits were combined into 7 principal component factors, with a cumulative contribution of 82.55%. The first principal component contributed 22.45%, with single fruit weight, fruit longitudinal and transverse diameter, and sugar-acid ratio contributing more. The second principal component contributed 13.87%, with total sugar content, soluble solids content and starch content contributing more. The contribution of the third principal component was 12.28%, with soluble solids content contributing more. Among them, sugar-acid composition, single fruit weight, fruit transverse diameter, fruit longitudinal diameter, soluble solids content, starch content, amino acid content, etc. are the key indexes for evaluating the comprehensive quality of dragon fruit. After comprehensive evaluation, six excellent pitaya singles with high comprehensive scores were screened, i.e., Reyan 1 hao, Wanhuafenhong, Hongbaolong, Wucihong, Linjiahongyun and Hongjinbao, which can be used as high-quality parents for pitaya quality breeding.

As a traditional oleaginous resource on Hainan Island, the camellia species predominantly exist as evergreen trees of small to medium stature. The large-fruit camellia with white flowers is widely distributed across various regions of Hainan Island. This study conducted a survey and sampling of camellia populations aged 30 years and above across all municipalities and counties of Hainan Island. Ploidy identification was carried out using flow cytometry and chromosome squashing techniques. The research revealed that among the 23 populations surveyed, 16 were identified as decaploid and 7 as octoploid, covering 16 municipalities and counties across the island. Decaploid camellia populations were found in 12 counties and cities (Danzhou, Lingshui, Qionghai, Wuzhishan, Ding'an, Chengmai, Tunchang, Lingao, Changjiang, Ledong, Qiongzhong, Baoting), including ancient trees over 100 years old and wild camellia populations in tropical rainforests, all of which were identified as decaploid. In contrast, the octoploid populations were generally under 60 years of age and traced back to artificial cultivation, with no other ploidy camellia resources found in the surveyed populations. It is evident that the camellia resources on Hainan Island are primarily composed of decaploids and octoploids, with the decaploids being indigenous to the island and the octoploids, not exceeding 60 years of age, being introduced from regions such as Guangdong and Vietnam during the 1960s to 1970s. Both types of camellia have demonstrated good adaptability to the growth conditions. Given that decaploid camellia trees have not been found in other camellia distribution areas, the widespread distribution of decaploid camellias on Hainan Island and the discovery of decaploid wild camellia populations in tropical rainforests suggest that the decaploid camellia species are indigenous regional species of Hainan Island, evolved due to unique ecological factors such as the island’s tropical monsoon climate. The distribution range of the resources spans from 18°38′42″N to 19°49′53″N and from 108°51′0″E to 110°29′46″E, at altitudes ranging from 4.17 m to 1090 m.

Yunyan 774 is a newly bred rubber tree cultivar in Yunnan, the research on its latex composition and properties is of great significance for its popularization and application. The changes of non-rubber components and colloidal properties, molecular weight and distribution of Yunyan 774 concentrated natural latex during storage, as well as the differences of crosslinking density, physical and mechanical properties, aging properties and latex particle size and distribution after 90 days of storage were measured and analyzed. The experimental results showed that the total solid content and ash content of Yunyan 774 remained unchanged after 90 days of storage, and the dry rubber content decreased by 1.1%, which was related to the reaction of some non-adhesive substances to form substances that could not be precipitated by adding acid. The content of volatile matter decreased slightly, but the content of acetone soluble content, water soluble content and nitrogen increased in different degrees. The content of advanced fatty acids of Yunyan 774 increased with the extension of storage time, and the ammonium soap with protective effect was generated, which played a role in improving the mechanical stability in the early stage. The thermal stability decreased gradually, and the viscosity decreased first and then was basically constant. The increase of volatile fatty acid content was not conducive to the preservation of latex. The physical mechanical properties and aging properties of Yunyan 774 latex vulcanized rubber film were better than those of the mixed strain. Compared with the mixed strain, the molecular weight distribution of Yunyan 774 was wider, the molecular weight was slightly lower, and the particle size was not different.