China is currently the largest sweet potato producer globally. The postharvest starch and soluble sugar (glucose, fructose, and sucrose) contents in storage roots not only influence sweet potato utilization and commercial value (including taste, nutritional quality, and food processing properties), but also affect sprouting, weight loss, and decay during storage and transportation. Studies on tubers/roots such as potato and carrot have demonstrated that vacuolar invertase (VIN) serves as the primary sucrose-cleaving enzyme determining postharvest sugar composition and content. However, the key sucrose-cleaving enzyme regulating postharvest sugar metabolism in sweet potato storage roots remains unclear. This study systematically investigated sugar metabolism characteristics in storage roots of ‘Kokei 14’, a major sweet potato cultivar in Hainan Province, under room temperature storage (25 ℃) and low-temperature storage (15 ℃), aiming to identify the principal sucrose-cleaving enzymes affecting postharvest sugar composition and content. Low-temperature storage enhanced preservation quality by reducing dry matter loss and sprouting rate through suppression of hexokinase (HK) activity and respiratory intensity. Compared with room temperature storage, low-temperature treatment induced greater increases in soluble sugar (glucose, fructose, and sucrose) content and more pronounced starch degradation, accompanied by significantly higher β-amylase activity, indicating that low-temperature storage promotes starch hydrolysis into soluble sugars. During room temperature storage, cell wall invertase (CWIN) and sucrose synthase (Sus) activities generally declined, while VIN activity initially increased before returning to baseline levels. Notably, cytoplasmic invertase (CIN) activity exhibited a continuous upward trend, suggesting CIN as the key sucrose-cleaving enzyme responsible for hexose accumulation under ambient conditions. Conversely, low-temperature storage induced continuous declines in all three invertase activities but progressively increased Sus activity, indicating Sus as the predominant enzyme mediating hexose accumulation under cold storage. Transcriptional analysis identified IbCIN4 as the key gene family members regulating CIN activity elevation at room temperature, while IbSus6 was determined as the primary regulator of Sus activity enhancement under low-temperature conditions. This study reveals that different postharvest storage temperature induces shifts in the predominant sucrose-cleaving enzymes governing hexose accumulation in sweetpotato storage roots. Notably, our findings contrast with previous reports on potato tubers under cold storage, demonstrating that Sus rather than VIN serves as the key enzyme regulating hexose content in sweetpotato roots under low-temperature conditions. The results would establish a theoretical foundation for future genetic engineering approaches to improve postharvest quality of sweetpotato storage roots.

The study was aimed to explore the physiological response and gene expression differences of cassava seedlings under waterlogging stress and to provide theoretical basis for disaster prevention and reduction of cassava northward migration cultivation in Hunan Province. Seedlings of cassava NZ199 were used, and two waterlogging levels of moderate (W1) and severe (W2) were set. The normal water supply (CK) was used as the control. The photosynthetic characteristics and antioxidant enzyme activities of the seedlings were measured after 14 days of stress and after rewatering, and transcriptome sequencing analysis was performed on the leaves after 14 days of stress. The results showed that with the aggravation of stress, the net photosynthetic rate decreased, and the stomatal conductance, intercellular CO₂ concentration and transpiration rate showed an overall upward trend. The activities of superoxide dismutase, catalase and peroxidase were significantly higher than those of CK under waterlogging stress, the content of malondialdehyde increased, and the degree of accumulation was positively correlated with the degree of stress, indicating that the plant initiated the antioxidant mechanism when suffering from waterlogging, but still suffered a certain degree of oxidative damage. After rewatering treatment, the photosynthetic index decreased significantly compared with that before stress. Antioxidant enzyme activity and malondialdehyde content also decreased, indicating that although the plant had a certain recovery ability, it did not fully recover to the normal level before stress. The results of transcriptome sequencing showed that 900, 1542 and 575 differentially expressed genes were identified in the three comparison groups of W1 vs CK, W2 vs CK and W2 vs W1, respectively, of which 1594 were up-regulated and 1423 were down-regulated. The pathways significantly enriched by KEGG included flavonoid biosynthesis, starch and sucrose metabolism, plant hormone signal transduction, etc. In summary, cassava seedlings have certain waterlogging resistance, but the waterlogging resistance has a threshold value. Timely drainage after waterlogging helps to reduce plant damage. In this study, the physiological and gene expression changes of cassava under different degrees of waterlogging stress in Hunan were systematically analyzed, and several differentially expressed genes and pathways related to waterlogging resistance were identified, which would lay a theoretical foundation for screening candidate genes of cassava in response to waterlogging stress, and also provide a new direction for further research on the molecular mechanism of cassava waterlogging resistance and the cultivation of waterlogging resistant varieties.

Sri Lankan cassava mosaic disease, caused by Sri Lankan cassava mosaic virus (SLCMV), is a recently emerging dangerous disease in China. Existing detection methods of SLCMV are constrained by low sensitivity and poor efficiency, impeding related research and applications. Primers and probes were designed according to the gene sequences of the SLCMV, and a positive plasmid standard was prepared. The TaqMan fluorescence quantitative detection technology for SLCMV was established, and its application effect was verified. The method only generated specific fluorescence signals for SLCMV DNA samples, and the minimum detectable amount of the positive plasmid standard was 4.5×10¹ copies/μL. The standard curve showed that there was a good linear relationship between the C_t value and the logarithm of the copy number. The slope of the curve was –3.1312, the correlation coefficient R² was 0.9969, the amplification efficiency (E) was 97.9%, and the equation of the standard curve was y=–3.1312x+34.599. Using this technology to detect the tested samples from two cassava plantations in Guangxi and Fujian, the positive detection rate of leaves was 95.45% and 78.57%, respectively, and the minimum detectable copy number was 1.45×10⁵ copies/g. The virus-carrying rate of Bemisia tabaci in the field was 86%, and the minimum virus-carrying amount was 9.42×10⁴ copies/B. tabaci. This technology has good sensitivity, specificity, and repeatability, and could provide effective technical support for the monitoring and control work such as field identification, early diagnosis, and evaluation of virus-free stem cuttings of the disease.

The MYB family constitutes one of the largest transcription factor families in plants, involving in plant growth and development, signal transduction, and secondary metabolism. Based on our previous 2+3 transcriptome data of Ocimum basilicum var. pilosum, we systematically identified the O. basilicum var. pilosum MYB (ObMYB) family through bioinformatics approaches and explored members associated with essential oil accumulation. Firstly, ObMYB members were screened by homologous alignment of MYB conserved domains, and then their complete open reading frames were predicted and the basic physicochemical properties of these encoded proteins were analyzed. Phylogenetic relationship was reconstructed by neighbor-joining method of MEGA 7.0, while conserved motifs and domains were annotated using MEME and Batch CD-Search. Subsequently, incorporating the previous miRNA data of O. basilicum var. pilosum, the targeted miRNA complementing the ObMYB were predicted by TargetFinder. Lastly, differential expression analysis and visualization analysis of heat maps were conducted by TBtools. Based on the essential oil data from different developmental stages of stems and leaves, the correlation analysis between differential gene expression levels and essential oil content was conducted using SPSS 25 to identify the potential ObMYB members involving in the accumulation of essential oil. The protein-protein interaction (PPI) network was constructed by STRING database for analyzing potential metabolic pathways involved. Research results revealed that a total of 77 ObMYB members were characterized, named as ObMYB-1 to ObMYB-77. Phylogenetic analysis divided them into eight subfamilies (classⅠ-Ⅷ), each comprising 6–14 members. These ObMYB proteins exhibited hydrophilic properties and structural stability, average isoelectric point=7.11 and average hydrophobicity=–0.69. Five miRNAs were found to target and regulate four ObMYB genes. Among these 43 differentially expressed ObMYB genes, ObMYB-4, -9, -27, -34, -42, -46 and -69 displayed strong correlations with essential oil accumulation. Moreover, PPI network analysis indicated the potential involvement of ObMYB-4, -9, -34, -36, -46 and -69 in flavonoid biosynthesis and secondary metabolite regulation. This study systematically identified the ObMYB family members and analyzed their relationship with essential oil accumulation, revealing multiple ObMYB genes significantly associated with the synthesis and accumulation of essential oils. These findings provide a significant theoretical basis for an in-depth understanding of the metabolic regulation mechanisms of O. basilicum var. pilosum essential oil, and to offer new targets and insights for research on plant secondary metabolism and the improvement of aromatic plant quality.

Miniature inverted-repeat transposable elements (MITEs), as active mobile elements in eukaryotic genomes, provide novel molecular markers for germplasm genetic diversity analysis through the insertion polymorphisms. This study systematically identified hAT family MITE transposons in pitaya using bioinformatics approaches based on the whole-genome data of the Guanhua Bai cultivar. A total of 2350 candidate elements with complete terminal inverted repeats (TIRs) and target site duplications (TSDs) were screened, with an average of 213 elements per chromosome pair. Through sequence specificity and polymorphism analysis, 110 highly divergent loci (10 per chromosome pair) were selected for primer design, ultimately yielding 41 stable polymorphic hAT-MITE markers after PCR validation. Genome-wide scanning of 48 pitaya germplasms using the 41 primer pairs detected 81 polymorphic loci (polymorphism rate: 97.59%) via agarose gel electrophoresis. UPGMA cluster analysis revealed substantial genetic variation and diversity among the 48 accessions, with genetic similarity coefficients ranging from 0.57 to 0.91. At a genetic similarity threshold of 0.63, the germplasm resources were categorized into four genetically distinct groups. A digital fingerprinting system covering all germplasm resources was constructed using four core primer pairs (HU-MIT-02/06/26/75) based on the primer-band pattern combination method, achieving 100% cultivar identification accuracy. This study established the first hAT-MITE molecular marker system for pitaya, providing an efficient toolkit including a marker library and standardized identification protocols for precise germplasm classification, cultivar identification and varieties property protection of pitaya. The advancements is of significant application value for intellectual property protection in the pitaya seed industry.

In this study, three pitaya varieties, Spineless Yellow Dragon, Fuguihong, and Jindu No. 1, were selected as rootstocks. Through systematic observation and analysis of key indicators such as the growth potential of cuttings, grafting survival rate, fruit traits and quality, the most suitable rootstock variety was determined. Combined with the environmental conditions in Hainan, corresponding cultivation and management suggestions were put forward, aiming to provide solid technical support for the development of the pitahaya industry. Rootstock Fuguihong performed the best in the comprehensive survival rate of cuttings and grafting. The promoting effect of growth potential on pitahaya was significantly better than that of other rootstocks. Therefore, Fuguihong was determined as the optimal rootstock. Meanwhile, different rootstocks had a significant impact on the fruit traits of pitahaya (including 10 traits such as single fruit weight, peel weight, pulp weight, soluble solids, and total sugar). During the cultivation and management process, the suitable cultivation conditions for pitahaya in Hainan were summarized. Before cultivation, the field should be prepared and ridged first. 17 tons/667 m² of decomposed sheep manure and earthworm manure in a ratio of 3∶1 were spread over the whole garden. After rotary tillage and deep plowing, ridges with a width of 1m, a height of 25–30 cm, a row spacing of 2 m, and a ditch depth of 30 cm were built. Appropriate branches were selected as rootstocks. After treatment, they were planted at a density of 7 plants per meter in early September. In the first and second ten days of October, the “two-bud side flat grafting method” was used for grafting, and paper bags were put on. At the same time, a “丰” -shaped scaffold was built. Field management included soil covering or planting white clover and laying ground cloth, adjusting water and fertilizer according to the growth status, bending branches and leaving buds when the main branches exceeded the scaffold by 1 m, and closely monitoring common diseases such as sooty mold to ensure the orderly progress of all work, thus promoting the growth and development of pitahaya. This study would lay an important technical foundation for the vigorous development of the pitahaya industry in Hainan, effectively promote the progress of the domestic pitahaya cultivation industry, and significantly enhance its market competitiveness.

Areca palm leaf yellowing virus disease, caused by Areca palm velarivirus 1 (APV1), is a fatal disease for which no effective control measures currently exist. Breeding resistant or tolerant varieties is the key approach to addressing this issue, while the collection of superior germplasm resources is an essential foundation for breeding efforts. This study focused on three major affected areas in Hainan Province (Tunchang, Qionghai, and Wanning) and systematically conducted research activities including germplasm collection, phenotypic observation, pathogen detection, and long-term monitoring. The results revealed that among the 200 areca palm germplasm materials collected, 84 out of 100 resistant/susceptible materials did not show the presence of APV1, while 92 out of 100 susceptible materials tested positive for APV1. This finding confirmed a close association between APV1 infection and plant yellowing symptoms, and demonstrated that the screened resistant/tolerant materials are representative. Through continuous observation and correlation analysis, a significant negative correlation was found between tree age and resistance/tolerance to the disease. This study successfully identified a group of betel palm germplasm resources with resistance/tolerance traits, laying a crucial foundation for the development of disease-resistant varieties in future breeding programs.

A comprehensive evaluation of agronomic traits of 70 varieties of fresh food tomato germplasms was conducted. Genetic diversity analysis of 28 morphological traits of the germplasms was carried out using methods such as variance analysis, principal component analysis, cluster analysis and calculation of comprehensive evaluation scores. The analysis results of genetic variability of 13 quantitative traits indicated that the variation degree of the germplasms was relatively high and the variation was rich. The variation range was 21.68%‒99.08%, and the genetic diversity index was relatively high, suggesting that the phenotypic diversity of germplasms was relatively rich and there was a significant degree of variation among the traits, indicating excellent selection potential. Among these, the traits such as single fruit weight, number of chambers, sugar-acid ratio, and transverse diameter exhibit relatively high genetic variation. The correlation analysis results showed that the traits significantly corelated with fruit firmness were the greateast in number, and fruit firmness were extremely significantly positively correlated with fruit surface ridges, fleshiness, single fruit weight, number of chambers, flesh thickness, and acidity. Sugar content was significantly negatively correlated with fruit color before maturity, and it was extremely significantly negatively correlated with fruit surface ridges, single fruit weight, number of chambers, and flesh thickness, and significantly positively correlated with plant height, and extremely significantly positively correlated with fruit shape index and soluble solids content. Single fruit weight was significantly positively correlated with leaf type, significantly negatively correlated with fruit peel color, extremely significantly positively correlated with flower sequence type and fruit surface ridges, and extremely significantly negatively correlated with fruit top shape and fruit shape. The principal component analysis results indicated that the 28 phenotypic traits could be classified into nine factors. The eigenvalues were all above 1.0, and the cumulative contribution rate reached 78.143%, which could reflect most of the information of all indicators and highlight the basic characteristics of the germplasms. Cluster analysis further divided the germplasms into five groups. The first and fourth groups had smaller tomato fruits and stronger edible properties, which could be important materials for cultivating cherry tomato varieties with good taste and high quality. The fifth group had higher hardness and larger fruits, and could be used to cultivate economic tomato varieties suitable for long-distance transportation. The comprehensive evaluation results showed that the top five germplasms were XH20-48, XH20-35, XH20-37, XH20-34 and XH20-30. In conclusion, this research achievement is dedicated to discovering and exploring the excellent tomato germplasm resources retained by the research group, laying a foundation for the next step of creating core parents and breeding new high-quality tomato varieties with characteristics unique to Xinjiang.

Plant rhizosphere bacteria play a crucial role in plant nutrient uptake and utilization, and the active functional microbial communities in the rhizosphere are closely associated with high yield of crops. This study aimed to isolate, screen and identify functional bacteria from the rhizosphere soil of super high-yield rubber trees to identify beneficial strains that could potentially enhance rubber tree productivity. Using gradient dilution plating and selective medium, 60 strains of functional bacteria were isolated from the rhizosphere soil of super high yield rubber trees in Mengla Farm, Yunnan province. The isolated strains were characterized for the abilities to solubilize phosphate and potassium, fix nitrogen, and for the plant growth-promoting traits, including the production of indole-3-acetic acid (IAA), siderophores, ACC deaminase, and acetoin (3-hydroxy-2-butanone). 16S rDNA sequence analysis showed that the isolates could be classified into 12 genera, including Burkholderia, Paraburkholderia, Caballeronia, Cupriavidus, Dyella, Pseudomonas, Silvania, Enterobacter, Escherichia, Raoultella, Pantoea and Bacillus. Among these, Burkholderia was the dominant genus, comprising 40 strains (66.67%). Pot experiments with rubber seedlings demonstrated that the strain Enterobacter sp. SYK24 exhibited significant growth-promoting effects, with increases in whole plant fresh weight, aboveground dry weight, belowground dry weight and root length by 12.89%, 23.24%, 22.81% and 28.30%, respectively, compared to the control. The SYK24 treatment showed 5.01% and 18.98% reductions in total phosphorus and available potassium, respectively, compared to the control, while no statistically significant differences were observed in other soil nutrient contents. The strain Burkholderia sp. SYN37 did not promote biomass growth in rubber seedlings during the experimental period. SYN37 inoculation substantially depleted soil nutrients, resulting in reductions of soil organic matter by 31.39%, total nitrogen by 22.73%, and available potassium by 13.03% compared to the control. This study preliminarily established a small-scale functional bacterial strain library from the rhizosphere of super high-yield rubber trees, validated the growth-promoting effects of two functional strains through pot experiments, and would provide a scientific basis for the further development and application of microbial inoculants specifically tailored for rubber trees.

Cryopreservation can reduce the risk of genetic variation in the long-term subculture of rubber tree anther callus tissue, and is an effective method for long-term preservation of callus tissues. To evaluate the effects of dehydration duration on physiological parameters during cryopreservation, rubber tree anther calli were treated with plant vitrification solution PVS2 for 0, 10, 20 and 40 min and then cryopreserved for 24 h in this study. Physiological parameters related to stress resistance were analyzed, including soluble protein content, malondialdehyde (MDA) content, and activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) during cryopreservation. Dehydration duration had a significant effect on soluble protein content, MDA content, SOD and POD activities in callus tissues after cryopreservation, while showing no significant impact on CAT activity. All physiological parameters (except MDA) exhibited higher values after cryopreservation compared to pre-preservation levels across all dehydration durations. After 40 min of dehydration and cryopreservation, the soluble protein content, CAT, SOD and POD activities of anther callus reached the maximum value, which was 129.63 μg/mL, 627.30 U/g, 290.38 U/g and 25 643.33 U/g, with the lowest MDA content of 41.31 nmol/g. The findings indicate that dehydration for 40 min significantly enhances water retention capacity and antioxidant level in cryopreserved callus cells. Post-thawing viability tests revealed that 40 min dehydrated callus maintained over 70% survival rate and could induce fragile embryogenic callus formation with an average induction rate of 13.33%. This study establishes a physiological foundation for the regeneration of cryopreserved rubber tree anther callus.

The fruits of Qiongdong No. 9 Camellia oleifera at five developmental stages were taken as the experimental materials to ascertain the basic characteristics of the growth and development in Hainan and the changes in the content of antioxidant active substances. The morphological characteristics were observed, the crude fat and six main active ingredient contents of the seeds at different developmental stages were measured, and four antioxidant activity indicators of the seeds at different developmental stages were detected. The results demonstrated that the growth changes of each part of the fruit generally followed a logistic curve, presenting a slow increase in the initial stage, a rapid growth in the middle stage, and eventual stabilization. During the whole growth period, changes in crude fat content continued to accumulate, with S₃-S₅ being the period of rapid oil accumulation; the changing trends of the contents of flavonoids, total polysaccharides, vitamin E, ABTS radical scavenging ability and total antioxidant activity (FRAP) in seed kernels were consistent, experiencing a process of rapid decrease-significant increase-slow decrease. The content of carotenoids and the ability to scavenge hydroxyl radicals showed a significant increasing trend at all stages. The content of total phenols, total saponins, and total antioxidant activity (DPPH) showed a gradually decreasing trend. Through Pearson correlation analysis, the content of six active ingredients was significantly correlated with four antioxidant capacity indicators to varying degrees, and each ingredient had a different degree of response to different antioxidant capacities. S₁–S₃ were the rapid swelling stages of the fruit, accompanied by significant fluctuations in the content of active ingredients. S₃–S₄ were the key stages of substance transformation, and S₄–S₅ were the steady-state accumulation stages of contents; In the early stages of fruit development (S₁–S₃), water-soluble antioxidant components such as phenols, saponins, and polysaccharides dominated, while in the middle and late stages (S₃–S₅), they shifted towards lipid soluble components (carotenoids) and lipids. This competitive process was an important reason for the decrease in the content of the main active components. This research revealed the growth and development characteristics of C. oleifera fruits in tropical areas, which would have theoretical reference value for formulating corresponding cultivation and management measures for quality breeding purposes.

Areca palm velarivirus 1 (APV1) is identified as a causative agent of yellow leaf disease (YLD), which emerges as a prominent threat to betel palm plantation. Developing methods for rapid detection of APV1 is necessary for preventing and controlling YLD in betel palm cultivation. In this work, APV1 virions were extracted from APV1-infected Nicotiana benthamiana by using polyethylene glycol (PEG) precipitation, ultracentrifugation, sucrose density gradient centrifugation, and affinity magnetic beads. The purified APV1 virions were identified by transmission electron microscopy (TEM), SDS-PAGE and Western blotting. The purified APV1 virions were used to immunize BALB/c mice to produce polyclonal antiserum for detection of APV1. APV1 virions were precipitated from N. benthamiana homogenates by applying 5% PEG6000 and 0.6% NaCl. After resuspension and ultracentrifugation with 55% sucrose cushion, APV1 virions were distributed in the lower part of the sucrose layer or precipitated at the bottom of the centrifuge tube. APV1 was purified by 30%, 40%, 50%, 60% and 70% discontinuous sucrose density gradient centrifugation at 140 000×g for 2 h, and the results showed that APV1 was enriched in 60% and 70% sucrose layers. Affinity magnetic beads could efficiently purify APV1 virions. The purified virions were elongated, about 650–2200 nm in length and 10–13 nm in diameter. BALB/c mice were immunized with the extracted APV1 virions to obtain antiserum with high specificity for APV1 and titer of 1∶25 600. The results would provide a new idea for the separation and purification of APV1, and an important technical support for rapid detection of APV1.

Lignin serves a crucial defensive function in cassava's resistance to harmful organisms. Among the genes involved in lignin biosynthesis, shikimate hydroxycinnamoyl transferase (HCT) and caffeoyl coenzyme A-O-methyltransferase (CCoAOMT) are of particular importance. Yet, their specific roles in cassava's resistance to the insect pest P. marginatus remain to be fully elucidated. To elucidate the anti-insect defense mechanisms of cassava against P. marginatus, we conducted comparative studies using insect-resistant cultivar C1115 and susceptible cultivar KU50. Life table analysis revealed significant cultivar-dependent effects on pest developmental biology. Specifically, C1115-fed females exhibited significantly prolonged developmental duration (38.50 days in C1115 vs. 28.86 days in KU50), significantly reduced fecundity (221 eggs in C1115 female vs. 331 eggs in KU50 female), and significantly shortened adult longevity (4.30 days in C1115 vs. 8.83 days in KU50). Notably, population growth parameters demonstrated significant comprehensive suppression in C1115 cohorts: net reproductive rate (R₀=224.13 in C1115 vs. 330.67 in KU50), intrinsic growth rate (r_m=0.10 d^‒1 in C1115 vs. 0.12 d^‒1 in KU50), and finite growth rate (λ=1.11 d^‒1 in C1115 vs. 1.12 d^‒1 in KU50). Furthermore, extended generation time (T=50.25 in C1115 vs. 49.98 days in KU50) and doubling time (Dt=6.44 in C1115 vs. 5.97 days in KU50) were observed, indicating multilevel inhibition of pest population dynamics by C1115. Molecular characterization showed progressive downregulation of lignin biosynthesis genes HCT and CCoAOMT post-infestation in C1115. Although both cultivars exhibited suppression patterns, C1115 maintained significantly lower expression levels (52.99%, 66.81% of KU50) and enzymatic activities (74.42%, 73.91% of KU50) across timepoints. Using Spearman correlation analysis, it was found that both HCT and CCoAOMT gene expression levels and the activity of their encoded enzymes were negatively correlated with cassava resistance to P. marginatus. This suggests that the downregulation of these two genes may affect lignin accumulation in cassava leaves and the level of insect resistance defense responses. This study has laid a solid preliminary work foundation for in-depth analysis of the molecular mechanisms by which lignin regulates cassava's defense responses against P. marginatus

Anthracnose caused by Colletotrichum gloeosporioides occurs extensively during the post-harvest storage of papaya (Carica papaya L.), significantly affecting fruit quality and yield. In this study, the excellent antagonistic bacteria J-11 agaist C. gloeosporioides were screened from the rhizosphere soil of papaya, and the antagonistic characteristics and biological control ability were explored. The size of biocontrol bacterium J-11 was about 1.5 μm×3.3 μm (growing for 3 d), Gram-positive (G⁺), rod-shaped or oval, common single arrangement, and its morphological characteristics were consistent with Bacillus velezensis. The sequences of 16S rRNA, gyrA and gyrB genes of strain J-11 were 99.28%, 97.57% and 98.79% consistent with those of B. velezensis model strain OOT-47, respectively. Phylogenetic tree analysis showed that the tested strain J-11 and Bacillus velezensis LB4 were clustered into one branch. According to the results of morphological, molecular biological and physicochemical analysis, it was confirmed that the microbial antagonistic pathogen of papaya C. gloeosporioides in Zhanjiang area of Guangdong was B. velezensis. Strain J-11 demonstrated a broad-spectrum antifungal ability, inhibiting the growth of three pathogenic fungi of C. gloeosporioides, C. siamense and Botryosphaeria dothidea, with antagonism indices of 0.48, 0.41 and 0.40, respectively. The control testing showed that the inhibition rate of strain J-11 against the C. gloeosporioides on papaya leaves was 89.96%, and the inhibition rate of strain J-11 against the C. gloeosporioides on papaya fruits in vitro was 84.92%. Strain J-11 screened in this study has a certain control effect on papaya anthracnose, which could provide a theoretical basis for in-depth study of the antibacterial mechanism of plant biocontrol bacteria and will lay a foundation for its development and utilization.

Guangdong and Guangxi are the major production regions of pitaya and the common area for pitaya canker. Understanding the genetic diversity of Neoscytalidium dimidiatum is of great significance for the disease prevention and control. This research focused on four geographical population of N. dimidiatum mainly collected from Guangxi and Guangdong. To obtain the genetic fingerprints of N. dimidiatum, the isolates were amplified using ISSR genetic molecular markers and further analyzed the genetic diversity. The tested N. dimidiatum isolates were amplified with eight ISSR primers, resulting in 203 bands and the percentage of polymorphic sites was 31.7%, with the genetic similarity coefficient for any two germplasm resources ranged from 0.7619-1.0000. When the genetic similarity coefficient was 0.90 on the UPGMA cluster, all isolates could be divided into three groups, but the genetic groups were not closely related to the geographical distribution. The results of principal component analysis indicated considerable overlap between the four geographical groups and there were no relatively independent geographical poputation. This study proved that there existed lower level of genetic polymorphism in the isolates and there was frequent exchange of inoculum source between different places. The study would provide the scientific basis for researching the genetic architecture and pathogen surveillance of pitaya canker pathogen N. dimidiatum.

Cucumber green mottle mosaic virus (CGMMV) is one of the important plant viruses that harm melon crops, and its movement protein (MP) plays a key role in virus transmission and pathogenicity. This study cloned the MP gene of CGMMV through RT-PCR, constructed the prokaryotic expression vector pET-32a-MP, and successfully induced the expression of a recombinant MP fusion protein with a molecular weight of approximately 48 kDa in Escherichia coli BL21 (DE3). Purification of high purity protein (purity degree≥80%) using nickel column affinity chromatography was used to prepare polyclonal antibodies against the New Southwest White Rabbit. Western blot and ELISA analysis showed that the titer of the anti serum reached 409 600, and it could specifically recognize the MP protein in CGMMV infected leaves, without cross reactivity with other viruses such as Tobacco mosaic virus (TMV) and Watermelon mosaic virus (WMV). The study would provide important tools for rapid virus detection, immunohistochemistry, and protein function research, which is of great significance for ensuring the safe production of melon crops.

Rubber plantations represent one of the most widespread planted forest ecosystems in tropical regions, playing a significant role in regional carbon cycles. Global climate change has led to increasingly frequent Compound Drought-hot Events (CDHEs), posing severe challenges to rubber plantation ecosystem functions. This study focuses on rubber plantations in Hainan Island, China. Utilizing standardized soil moisture and land surface temperature indices, we constructed a Compound Drought-Hot Index (CDHI) based on Copula functions to analyze the spatiotemporal dynamics of CDHEs from 2001 to 2020, validated against historical typical drought and hot events in Hainan. Using Gross Primary Productivity (GPP) as an evaluation metric, Copula-based conditional probabilities were applied to quantitatively assess GPP loss risks under different drought-hot scenarios and evaluate compound effects. Key findings include: (1) The developed CDHI accurately identified severe CDHEs during 2001—2020, with 2005 and 2020 being the most extreme years. (2) Across all intensity levels (mild, moderate, severe), CDHEs caused significantly higher probabilities of GPP loss in rubber plantations compared to isolated drought or hot events (P<0.001), confirming the synergistic amplification effect of compound events. (3) GPP loss risks exhibited distinct spatial heterogeneity influenced by regional topography-climate interactions, with northwestern rubber plantation areas showing consistently higher vulnerability across all scenarios. (4) CDHE impacts demonstrated marked seasonal differences, being substantially greater during the dry season (particularly April—May) than the rainy season, coinciding with critical phenological stages of rubber trees and forming sensitive windows of environmental stress. This study reveals the spatiotemporal differentiation of CDHE impacts on rubber plantation GPP, providing scientific foundations for regional climate-resilient management strategies and sustainable rubber plantation practices. It also offers methodological references for studying extreme climate responses in other tropical planted forest ecosystems.

The study was aimed to develop organic fertilizers replacing chemical fertilizers and reveal the effect mechanism of fertilization on plant health, endophytic bacterial community structures in tomato roots. Five fertilization treatments were set up, no fertilization (CK), application with chemical fertilizer (T₁), peanut cake fertilizer (T₂), soybean cake fertilizer (T₃) and tea cake fertilizer (T₄) at the identical nitrogen level. Meanwhile, based on high-throughput sequencing technology, the endophytic bacterial community structure in tomato roots was analyzed. The numbers of endophytic bacterial communities in tomato roots at different taxonomic categories were all improved over CK. Meanwhile, except T₄ treatment, the diversity and richness of endophytic bacteria community in tomato roots under T₂ and T₃ were all higher than those of T₁. At the phylum or genus level, the endophytic bacterial composition and the percentage in tomato roots were all altered by different fertilizer treatments. Among them, not only the numbers of dominant endophytic bacterial were improved, but also the endophytic bacterial community structures were reshaped. Particularly, some beneficial bacterial genera, such as Rhizobium, Bacillus, Microbacterium, Castellaniella, with the function of growth promotion, plant resistance and quality improvement enriched in tomato roots under T₂ treatment. Compared with CK, the diversity and richness of endophytic bacterial community in tomato roots were improved, and the endophytic bacterial composition in tomato roots could be reshaped by different fertilization. The highest diversity and richness of endophytic bacterial communities could be found in tomato roots under T₂ treatment, followed by T₃ treatment. The beneficial endophytic bacterial genera, such as Rhizobium, Bacillus, Microbacterium and Castellaniella enriched in tomato roots under T₂ treatment only. It indicated that the effect of peanut cake fertilizer on plant health was better than those of chemical fertilizer, soybean and tea cake fertilizers under the identical nitrogen levels.

It is necessary to establish a sensitive, selective, efficient and accurate method for the simultaneous detection of multiple antibiotic residues in soil. In this study, the method of solid phase extraction-high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of 20 antibiotics simultaneously in soil was established by optimizing the extraction conditions (extractant type, extraction method, shading and overnight) and the purification conditions (cartridge type). Under the optimized analysis conditions, the target antibiotics showed good linearity in the linear range of 0.10-100.00 μg/kg, with R² ranging from 0.9951-0.9999. The recovery ratio ranged from 62%-116%, the relative standard deviation was 0.9%-16.8%, the limit of detection was 0.01-0.50 μg/kg, and the limit of quantification was 0.04-2.00 μg/kg. The method was applied for the detection of antibiotic residues in soil samples collected from greenhouse vegetable bases in Wuqing district, Tianjin, China. It showed that 4 classes of antibiotics were detected in the soil, and up to 16 of target antibiotics could be detected simultaneously. The total residual concentration of antibiotics in the soil varied from 2.52-142.00 μg/kg. The highest concentration of individual antibiotic was 105.00 μg/kg (oxytetracycline). The method established in the study is aim to provide reference for the formulation of the standard for the simultaneous detection of multiple antibiotic residues in soil and provide methodological basis for the prevention and control of emerging contaminants.

The study of methane (CH₄) emission flux from paddy fields is an important part and hot topic in the current study of carbon cycle in terrestrial ecosystems. The multi-time scale characteristics of CH₄ emission flux and its influencing factors [gross primary productivity (GPP), latent heat flux (LE), air temperature (TA), soil temperature (TS)] in paddy fields were analyzed based on wavelet analysis and eddy covariance flux observation data. The CH₄ emission flux and its influencing factors of paddy field ecosystems had obvious seasonal variation characteristics. The CH₄ emission flux from paddy fields in the rice growing season showed obvious single-peak diurnal variation characteristics, while the CH₄ emission flux from paddy fields in the non-rice growing season was low, and the diurnal variation characteristics were not obvious. GPP, LE, TA and TS showed obvious single-peak diurnal variation patterns. Based on continuous wavelet transform and wavelet variance curve analysis, CH₄ flux, GPP, LE, TA and TS had an obvious 1-day cycle during the rice growing season (July—November), while GPP, LE, TA and TS also had a half-day cycle, and TA and TS also had a long-term cycle of 4 days. From the cross wavelet transform and wavelet coherence spectrum analysis, the resonance period between CH₄ flux and GPP, LE, TA and TS was about 1 day. There was a significant resonance relationship in this frequency domain, and oscillation cohesion and coherence were the strongest. However, in the high-frequency band area, there was also a secondary resonance period of about 0.5 days between CH₄ flux and GPP, LE, TA and TS. In addition, in other frequency bands, the resonance energy of CH₄ flux and GPP, LE, TA and TS was low, but in the resonance period of 4 days and 7-10 days, CH₄ flux had good coherence with TA and TS from mid-August to mid-October. This study analyzed the multi-time scale characteristics of CH₄ flux and its influencing factors from paddy fields and would provide a scientific reference for studying the quantitative relationship between CH₄ flux and its driving factors at different time scales.

The study prepared slow-release fertilizers with different ratios of zeolite and nano-zeolite and compared them with conventional urea fertilizers to study the effect of zeolite and nano-zeolite as urea carriers on soil nutrient leaching, including nutrient release patterns, leaching characteristics, and impacts on soil nutrient content. A soil column leaching experiment was conducted with seven treatments, conventional urea (CK) and slow-release fertilizers with different ratios of zeolite (ZU₁, ZU₂, ZU₃) and nano-zeolite (nZU₁, nZU₂, nZU₃). The study analyzed the dynamic changes and cumulative leaching amounts of ammonium nitrogen, nitrate nitrogen, total nitrogen, and total phosphorus in the leachate and measured the soil nutrient content after leaching. Zeolite and nano-zeolite-based slow-release fertilizers significantly prolonged fertilizer effectiveness and reduced the concentration of ammonium nitrogen, nitrate nitrogen, total nitrogen, and total phosphorus in the leachate (P<0.05). Treatments with 50% zeolite (ZU₃) and 50% nano-zeolite (nZU₃) were the most effective in reducing nutrient leaching. Specifically, ZU3 reduced ammonium nitrogen, nitrate nitrogen, total nitrogen, and total phosphorus in the leachate by 7.19%, 6.54%, 14.51% and 9.72%, respectively, while nZU₃ reduced them by 7.20%, 6.91%, 12.84% and 6.36%, respectively. The slow-release fertilizers also significantly increased soil nitrogen content, with total nitrogen in ZU₃ and nZU₃-treated soils increasing by 14.88% and 19.83% compared to the control. From the perspective of nutrient release patterns, it was observed that zeolite and nano-zeolite slow-release fertilizers exhibited a lower release rate in the early stages of the experiment. This is attributed to the strong adsorption properties of zeolite and nano-zeolite, which can effectively slow down the release of urea. The release peak of the fertilizers was delayed to 6–8 days, and the release became more steady in the later stages of leaching. This pattern suggests that the application of zeolite and nano-zeolite can effectively reduce the risk of nutrient loss due to leaching, thereby improving the utilization efficiency of fertilizers. Furthermore, the comparison between zeolite-based and nano-zeolite-based slow-release fertilizers revealed that the differences in reducing the leaching of ammonium nitrogen, total nitrogen, and total phosphorus were not obvious, but both of them had significantly better performance than conventional urea in terms of reducing nutrient leaching (P<0.05). In summary, the use of zeolite and nano-zeolite as urea carriers in slow-release fertilizers showed to be an effective strategy for delaying nutrient release, reducing nitrogen and phosphorus leaching, and enhancing soil nutrient content. The optimal results were achieved with a 50% zeolite and 50% nano-zeolite ratio, indicating a promising application potential in agricultural practices. This approach not only contributes to the sustainable management of soil fertility but also offers a potential solution for reducing the environmental impact associated with excessive fertilizer use.

This study aimed to identify the key factors influencing vegetation changes on Hainan Island under Typhoon Yagi, determine the disaster thresholds, and provide scientific support for typhoon disaster prediction, assessment, and mitigation. Using the GEE platform, Sentinel-2 NDVI data from August 19 to September 18, 2024, covering the period before and after Typhoon Yagi landfall, were analyzed in conjunction with topographic and meteorological variables (such as typhoon path, maximum wind speed, minimum pressure, and precipitation). An XGBoost model was applied to predict post-typhoon NDVI changes, and SHAP analysis was used to explore the nonlinear effects of meteorological factors. The XGBoost model yielded a coefficient of determination (R²) of 0.75 and a root mean square error (RMSE) of 0.12, indicating a high prediction accuracy for post-typhoon NDVI changes. Feature importance analysis within the XGBoost model revealed that pre-typhoon NDVI, typhoon distance, and maximum wind speed were the primary influencing factors, while slope and aspect had a weaker effect. Further SHAP analysis confirmed that typhoon distance and maximum wind speed were the key meteorological factors driving NDVI changes. When the typhoon distance was less than 76.4 km, NDVI showed a significant decline, while NDVI changes intensified when the maximum wind speed exceeded 29.3 m/s, highlighting the crucial role of strong winds in vegetation damage. Regions within 76.4 km (approximately within the 11th wind radius) of the typhoon's path and with maximum wind speeds greater than 29.3 m/s experienced severe vegetation damage. It is recommended that the high-risk areas be prioritized in typhoon warnings and pre-disaster defense measures.

Tropical agriculture is critical to global food security and rural revitalization. However, its modernization is constrained by complex terrain, climatic variability and frequent disasters. Remote sensing, with its capacity for large-scale, real-time information acquisition, has emerged as a key enabler for smart and precision agriculture in tropical regions. This study established a framework for remote sensing research in China's tropical agriculture, proposing an integrated “space-air-ground” observation strategy and explaining the resolution-to-application matching mechanism, in which low-, medium-, and high-resolution observations are respectively suited for regional resource surveys, farmland growth monitoring, and field-scale phenotypic diagnostics. It reviewed progress in natural resource surveys, crop monitoring yield estimation, disaster assessment and ecological evaluation, analyzed challenges such as insufficient ground-truth data, limited model transferability, poor regional adaptability and low transformation efficiency; and proposes key innovation paths including coordinated sensing, multi-modal data fusion, intelligent modeling and digital twin-based forecasting. Finally, it outlined future directions focusing on system integration, intelligent perception, and global collaboration. The findings would provide theoretical and technical support for enhancing remote sensing applications in tropical agriculture.

The yield of tropical crops is highly sensitive to climate conditions, and accurately modeling the meteorological-driven mechanisms is crucial for improving tropical agricultural productivity and climate adaptability. This study systematically compared the prediction performance of six machine learning models, including LGBM, RF, XGBoost, AdaBoost, SVM and MLR based on natural rubber, mango, pineapple and banana in Hainan. The SHAP method was used to quantify the contribution and non-linear response characteristics of meteorological factors. The LGBM model demonstrated the best prediction performance, with an average R² of 0.945 for the test set (the R² of rubber, mango, pineapple and banana were 0.942, 0.902, 0.954 and 0.983, respectively), and average RMSE and MAE of 1.436 t/hm² and 1.150 t/hm², significantly outperforming the other models (the R² of RF, XGBoost, AdaBoost, SVM, MLR were 0.773, 0.563, 0.589, 0.368 and 0.508, respectively). The meteorological-driven mechanisms exhibited significant crop-specific differences. Rubber yield was mainly driven by solar radiation (the contribution was 14.7%) and temperature factors (the contribution of monthly minimum temperature and monthly maximum temperature were 14.4% and 11.7%, respectively). Mango yield was highly sensitive to monthly maximum temperature (the contribution was 19.0%) and vapor pressure deficit (the contribution was 18.5%). Pineapple and banana yield were dominated by soil moisture (the contribution was 18.9%) and relative humidity (the contribution was 23.6%), respectively. Based on the findings, differentiated agronomic management recommendations for each crop type were proposed. This study demonstrates that machine learning, combined with explainability methods, can effectively elucidate the climate response mechanisms of tropical crops, providing theoretical support for regional agricultural precision management.