4-coumaric acid:CoA ligase (4CL) gene regulates the biosynthesis of lignin and flavonoids, playing an important role in plant organ color formation, disease resistance, and stress resistance. In order to understand the molecular characteristics and biological functions of the pineapple 4CL gene family, this study used bioinformatics technologies and tools to identify and analyze members of the 4CL gene family in the pineapple genome, followed by experimental validation. A total of 30 4CL genes were identified from the pineapple genome, and the physicochemical properties such as amino acid number, molecular weight, and isoelectric point were variant. Members of the Ac4CL gene family were unevenly distributed on 13 out of 25 chromosomes in pineapple. There were 5 pairs of genes exhibiting intraspecific collinearity, and 6 pairs of genes exhibiting collinearity between pineapple and Arabidopsis. There were significant differences in the expression of Ac4CL in pineapple at 60, 90 and 120 days after flowering. Among them, Ac4CL2 showed increasingly significant differences in expression after flowering. Furthermore, the gene also showed significant differences in expression among four different pineapple varieties, namely Jinzuan, Milk, Watermelon, and Bali, and it is inferred that they are closely related to the accumulation of anthocyanins during fruit ripening. This study would provide a theoretical basis for further exploring the function of the pineapple 4CL gene family.
Members of the RLK gene family are widely involved in responses to adversities such as drought and low temperature. Erianthus fulvus is a wild sugarcane species with excellent stress resistance traits. Cloning and analyzing LRK10L family member genes from E. fulvus holds significant reference value for mining stress resistance genes in sugarcane and for sugarcane stress resistance breeding. In this study, an LRK10L-type receptor-like kinase gene, EfLRK10L-2-8, was cloned from E. fulvus. Sequence analysis revealed it contained a complete coding sequence (CDS) of 1998 bp, encoding 665 amino acids. The predicted molecular weight of the protein was approximately 74.91 kDa, with an isoelectric point of 6.03. Domain analysis indicated that the protein contained a cysteine-rich extracellular domain, a transmembrane domain, and an intracellular serine/threonine kinase domain, consistent with the typical structural features of LRK10L-type receptor-like kinases (LRK10L-RLKs). Phylogenetic analysis showed that EfLRK10L-2-8 was most closely related to ZmL RK10L-1 from maize and OsLRK10L-3 from rice, suggesting it may have conserved functions in graminaceous crops. Subcellular localization results demonstrated that the EfLRK10L-2-8 protein was primarily localized to the cell membrane in tobacco leaf cells. qRT-PCR analysis showed that this gene was highly expressed in the roots, stems, and leaves of E. fulvus; its expression level was significantly induced and upregulated under drought and low-temperature stress treatments, suggesting it may positively participate in related stress signaling responses. The results indicate that EfLRK10L-2-8 plays an important role in the response of E. fulvus to drought and low-temperature stress, providing an important candidate gene resource for elucidating the stress resistance molecular mechanisms of E. fulvus and for sugarcane stress resistance breeding.
The NAM gene family play an important regulatory role in plant growth and development, organogenesis and abiotic stress responses. In order to study the regulatory function of NAM gene family members during fruit development, bioinformatics was used to identify the NAM gene family of pepper, and its protein physicochemical properties, phylogenetic relationships, chromosomal localization, conserved motif distribution, gene structure, species collinearity and gene expression were analyzed in detail. The results showed that there were 31 NAM gene family members distributed on 11 chromosomes, and there was a phenomenon of uneven distribution. Through phylogenetic analysis, the NAM gene family members of pepper were divided into five subfamilies. Gene structure analysis showed that most CaNAM genes contained 5 exons. Collinearity analysis showed that the gene collinearity between pepper and tomato was closer than that between pepper and Arabidopsis, and there were two additional collinearity segments between pepper and tomato, indicating that their evolutionary relationship was closer. The gene expression profile showed that the expression of the six CaNAM genes showed high expression levels in the four stages of the color transition process of pepper fruits, especially the expression of CaNAM3 gene was the highest when the color change reached 50%, which was consistent with the transcriptome data. Notably, the CaNAM28 gene showed a specific and significant upregulation during the red ripening stage, indicating that it may be a potential candidate gene involved in the regulation of fruit ripening. Through the preliminary identification and functional analysis of NAM gene family members in pepper, it would provide a research basis for further exploring the regulatory function of NAM gene family members in the development and fruit color transition of pepper.
Pigeon pea (Cajanus cajan) is an important legume crop worldwide, and its wild relative C. scarabaeoides harbors abundant genetic resources associated with stress tolerance and favorable agronomic traits, making it a valuable material for genetic improvement and functional gene identification in pigeon pea. However, molecular breeding in the genus Cajanus has long been constrained by inefficient transgenic systems, complex procedures and limited applicability. Here, we present the systematic establishment and validation of a simplified one-step hairy root transformation method for the genus Cajanus. Seven-day-old seedlings were used as explants; the primary roots were excised, the cut surfaces were inoculated with Agrobacterium rhizogenes, and the seedlings were directly transplanted into sterilized, moist vermiculite to allow simultaneous hairy root induction and seedling growth. This approach simplified the operational procedure, shortened the transformation period, and reduced the risk of contamination. Four C. cajan accessions (Cc224, Cc225, Cc226 and Cc227) and two C. scarabaeoides accessions (Cs040 and Cs046) were used to systematically compare the positive induction efficiency of hairy roots among three A. rhizogenes strains (Ar1193, ArQual and K599) across different genotypes. Transgenic hairy root formation and exogenous gene integration were validated by enhanced green fluorescent protein (eGFP) fluorescence observation and PCR-based molecular identification. The results demonstrated that the one-step method was simple and broadly applicable, with an overall transformation cycle of approximately 21 days, outperforming the conventional two-step method. Significant strain-genotype interaction effects were observed. Among the tested strains, K599 exhibited consistently high induction efficiency in all C. cajan accessions, with positive induction rates exceeding 70% and reaching 77% in Cc224. In C. scarabaeoides, K599 achieved a 100% induction rate in Cs046. In conclusion, this study established an efficient, stable and user-friendly one-step hairy root transgenic method for the genus Cajanus, providing a reliable technical platform for functional gene analysis and molecular breeding in pigeon pea and its wild relatives.
Arecanut (Areca catechu L.) is an important tropical specialty economic crop in Hainan Province. It is listed as the first of the four south China medicinal plants and holds a significant position in Hainan's agricultural production. Uncovering molecular markers associated with arecanut agronomic and quality traits has great significance for breeding new high-quality varieties with desirable traits, and molecular marker-assisted breeding. In the research, 50 pairs of InDel markers were utilized to genotyping 149 arecanut germplasm resources, and the genetic diversity and population structure analysis were also conducted. The association analysis was performed using both the GLM and MLM association analysis models to identify the molecular markers associated with phenotypic traits. The results showed a total of 123 allele loci were detected in the population. The average observed heterozygosity (Ho) and expected heterozygosity (He) was 0.36 and 0.43 respectively. The average Shannon’s information index (I) was 1.1548, and the polymorphism information content (PIC) of the primers was ranged from 0.15 to 0.52, with an average of 0.35. 88.00% of the primers exhibited moderate to high polymorphism, which indicating that the InDel primers in this study had high polymorphism. The population structure analysis suggested that 149 arecanut divided into three subgroups, which consisting of 118, 24 and 7 materials respectively. Using the GLM and MLM association analysis models, 58 and 40 associated loci were detected, with phenotypic variation explanation rates ranging from 4.36% to 13.39% and 4.35% to 9.29% respectively. All associated loci detected by the MLM model were also detected by the GLM model. The markers AC1505 and AC1519 were detected to be associated with fruit shape and quality-related traits in both methods, exhibiting a significant “pleiotropic effects” phenomenon. The findings would provide a theoretical basis for gene mining related to arecanut traits and breeding for quality characteristics.
Avocado, a fruit of significant economic and nutritional value, still faces technical challenges in tissue culture, with explant maturity being a key factor influencing cultivation success. This study utilized new shoot segments from mature avocado trees as explants. By establishing culture experiments with different subculture times, the effect of subculturing on shoot rejuvenation was investigated, aiming to provide a technical basis for improving avocado micropropagation efficiency. Growth indicators of new shoots (including length, stem diameter, leaf number, and leaf area) were systematically measured, and changes in the relative expression levels of miRNA156 and miRNA172 were analyzed to assess the correlation with the rejuvenation state. Results showed that with increasing subculture frequency, new shoot length, stem diameter, leaf number, and leaf area all increased significantly, indicating that a higher subculture number promotes shoot morphogenesis and leaf expansion. At the molecular level, after the second subculture, the ratio of miRNA156/miRNA172 relative expression in new shoots reached its highest value (2.32), marking the peak of rejuvenation. Subsequently, the relative expression of miRNA156 gradually declined, suggesting a transition of the shoots towards maturity. By the sixth subculture, the expression level of miRNA172 exceeded that of miRNA156, further indicating the shoots entered a mature state. Morphological and anatomical observations revealed that from the fifth subculture onward, lignification of the stem segments intensified, and xylem structure became more complete. Simultaneously, starting from the fifth subculture, pale yellow granular callus gradually appeared at the basal cut ends of stem segments. The amount and volume of this callus increased noticeably with further subculturing (up to the seventh subculture). Although root induction was not successful in any treatment, the observed morphological changes suggest that the rooting potential of the material may be gradually enhanced with increased subculture frequency. In conclusion, continuous subculturing can effectively promote the rejuvenation of mature avocado rootstock material, leading to obvious juvenile characteristics. Based on growth indicators, miRNA expression patterns, and morphological observations, it is recommended to control the number of subcultures within five for optimal rejuvenation effects. These findings provide experimental evidence and a reference for rejuvenation techniques in the tissue culture of mature avocado plants.
The selection of raw material varieties is a critical in determining the quality and market competitiveness of canned lychee. To address the lack of systematic and multidimensional comprehensive evaluation standards for the selection of lychee varieties suitable for canning, this study prepared canned lychee using eight main cultivated varieties as raw materials and systematically measured 16 key quality indicators, including chromaticity, sugar-acid components and texture characteristics. Principal component analysis (PCA) was employed to construct a comprehensive evaluation model for the suitability evaluation of lychee for canning. The results showed significant differences in quality indicators among different varieties. PCA extracted three principal components, with a cumulative variance contribution rate of 83.180%. Based on the comprehensive scores from the principal components, the ranking of varieties from best to worst was Ziniangxi>Xiantaoli>Jumeiren>Baitangying>Huaizhi>Heiye>Feizixiao>Baila. The Pearson correlation analysis further indicated that chewiness was extremely significantly positively correlated with elasticity and cohesiveness, while the sugar-acid ratio showed a significant positive correlation with the L* value. Cluster analysis categorized the eight varieties into three characteristic groups, with significant differences in texture, color and sugar-acid composition among the groups, providing a basis for the classification and utilization of varieties. The study systematically elucidates the canned quality characteristics of different lychee varieties. The established PCA evaluation model would enable rapid and objective screening of varieties. The varieties Ziniangxi, Xiantaoli and Jumeiren were identified as high-quality varieties specifically suited for canning, with large fruit characteristics, excellent texture properties, and balanced sugar-acid ratios forming an ideal quality combination. The findings would provide a solid theoretical basis and technical support for the directional selection of raw materials, precise quality control, and the breeding of specialized varieties in the lychee canning industry.
Natural rubber is a strategic national resource. With the development of the economy and national defense construction, China’s demand for natural rubber has shifted from a focus solely on yield to an emphasis on both quantity and quality. Molecular weight is one of the most critical determinants of the quality of natural rubber. Consequently, deciphering the biosynthetic mechanisms of natural rubber, elucidating the regulatory pathways that govern its molecular weight and cultivating new high-performance rubber-producing plant varieties have become key research priorities. Technological advances and innovative research methodologies have recently yielded substantial progress in studies concerning the biosynthesis and quality regulation of natural rubber. This paper provides a systematic review of the research progress on the biosynthesis of natural rubber inrubber-producing plants, as well as the factors that affect rubber molecular weight. The aim is to provide a reference for optimising the quality of natural rubber and facilitating the breeding of high-performance rubber-producing plants.
This study aimed to clarify the long-term effects of biochar after the first application and the application effects of biochar in pineapple production in tropical regions and their aftereffects. The pineapple variety Tainong 17 was used as the experimental material, and two types of biochar, peanut shell and rice husk biochar, each at four application rates: 10, 20, 40, and 60 t/hm2 (designated as T1, T2, T3 and T4, respectively), with a control (CK) receiving no biochar. The effects of biochar application on the physicochemical properties of pineapple field soil, as well as on pineapple growth and development, nutrient accumulation, and yield and quality, were investigated four years after application. Both biochar types showed a gradual increase in soil ammonium nitrogen, nitrate nitrogen, available phosphorus, available potassium, and organic carbon content in the 0-40 cm soil layer with increasing biochar application rates. The T4 treatment was significantly higher than CK and the T1 treatment. Furthermore, at fruit maturity, total leaf number and both the total leaf number and dry matter weight of pineapples increased gradually with increasing biochar application rate, with the highest values in the T4 treatment and significantly higher than those in the CK and T1 treatments. Leaf area index and chlorophyll content were significantly higher in the T4 treatment compared to the CK treatment. Similarly, nitrogen, phosphorus, and potassium accumulation, utilization rates, and yield all increased with increasing biochar application rates, peaking at T4 and significantly exceeding other treatments. The yield increase ranged from 11.2% to 62.3% compared to other treatments. Yield under rice husk biochar was marginally higher than under peanut husk biochar, although the difference was not significant. Under the T4 treatment, fruit shape index, vitamin C content, soluble protein, and sugar-acid ratio were significantly higher than in the CK, T1 and T2 treatments. Correlation analysis revealed that yield was positively correlated with soil available phosphorus, available potassium, ammonium nitrogen, nitrate nitrogen, pH, organic carbon content, total leaf number, chlorophyll content, dry matter weight, N, P and K accumulation and utilization rates, fruit shape index, vitamin C, soluble protein, and sugar-acid ratio, and was negatively correlated with soluble solids, soluble sugars, and titratable acidity. In summary, applying 60 t/hm2 of biochar continued to improve soil properties, promoted pineapple growth and nutrient accumulation, and enhanced yield and quality even after four years.
Acidic soils in Hainan are generally deficient in magnesium, and magnesium fertilizer application is necessary for achieving high crop yield and quality. In this study, a field plot experiment were conducted in the pepper planting area of Tunchang. Based on conventional fertilization of farmers, dolomite and magnesium sulfate were applied at different rates to investigate their effects on yield, magnesium uptake and accumulation of pepper, aiming to provide a theoretical basis for the rational application of magnesium fertilizers. The results showed that compared with the control (CK) without magnesium fertilizer, both dolomite and magnesium sulfate treatments significantly increased pepper biomass, vitamin C content, magnesium content, and magnesium accumulation, as well as soil exchangeable magnesium content. However, magnesium sulfate application reduced soil pH by 0.08-0.25 units, whereas dolomite increased it by 0.19-0.70 units. The yield of pepper treated with dolomite was significantly higher than that with magnesium sulfate. Dolomite could simultaneously supplement magnesium and calcium elements in the soil. The total biomass of pepper increased significantly with the increase of the application rate of magnesium fertilizer (15-60 kg/hm2), and the yield of pepper and the content of vitamin C were the highest at the application rate of 60 kg/hm2. Considering the effect of magnesium fertilizers on both yield improvement and soil acidity amelioration, dolomite is superior to magnesium sulfate. Therefore, when cultivating pepper on magnesium-deficient acidic granite latosol in Hainan, dolomite is recommended as the preferred magnesium fertilizer, with an appropriate application rate of 60 kg/hm2 (calculated as MgO).
Using the melon cultivar Zhongbao No. 1, we investigated the effect of exogenous γ-aminobutyric acid (GABA) on enhancing salt-alkali tolerance in melon seedlings. The physiological responses and growth of melon seedlings under mixed salt-alkali stress (150 mmol/L) were studied by root application of GABA at five different concentrations (25, 50, 100, 150 and 200 mmol/L). The results showed that exogenous GABA at concentrations of 100 and 150 mmol/L significantly promoted the growth of plant height, stem diameter, leaf length, leaf width, and leaf area in melon seedlings under salt-alkali stress. Among these, the treatment with 100 mmol/L GABA exhibited the most pronounced effect. Moreover, compared with saline-alkali treatment, the content of chlorophyll, carotenoid, soluble sugar, proline and AsA in leaves of melon seedlings treated with 100 mmol/L exogenous GABA increased by 11.7%, 14.5%, 37.1%, 36.1% and 7.5%, respectively, and the increases in soluble sugar and proline content were significant. The activity of SOD, POD, CAT, APX, PAL and GR increased by 5.4%, 106.2%, 30.5%, 34.0%, 1.3% and 73.8%, respectively, and the increases in POD, CAT and GR activity were significant. The content of malondialdehyde (MDA) and the production rate of superoxide anion (O2-) decreased by 6.1% and 11.6%, respectively. A TOPSIS comprehensive evaluation of different exogenous GABA treatments showed that the SG100 treatment ranked the highest. Therefore, the application of 100 mmol/L exogenous GABA had the best effect on alleviating the saline-alkali stress of melon seedlings, This study could provide a theoretical basis for improving the saline-alkali tolerance of greenhouse melon.
In order to screen effective agents for controlling three bacterial diseases of mango in Hainan, this study evaluated the in vitro toxicity of 13 tested agents (including 11 chemical agents and 2 biocontrol agents) against Xanthomonas citri pv. mangiferaeindicae (bacterial black spot), Dickeya fangzhongdai (bacterial dieback) and Pantoea dispersa (bacterial necrosis) using the agar diffusion method. Preliminary screening indicated that five agents, benziothiazolinone, ethylicin, kasugamycin, tetracycline and zhongshengmycin, exhibited inhibitory activity against the three pathogens, with varying efficacy observed among the agents against the different bacteria. Pleuromutilin, benziothiazolinone and ethylicin had the strongest inhibitory effect against X. citri pv. mangiferaeindicae, with EC50 values of 34.900‒39.151, 69.498‒110.430, 218.083‒399.371 μg/mL, respectively. D. fangzhongdai and P. dispersa demonstrated stronger resistance to the agents. Among them, ethylicin and benziothiazolinone were the most effective against D. fangzhongdai, with EC50 value of 678.652‒949.482 μg/mL and 722.494‒1228.298 μg/mL, respectively. For P. dispersa, ethylicin and pleuromutilin showed the best inhibitory effect, with EC50 value of 788.478‒1257.375 μg/mL and 922.843‒1302.518 μg/mL, respectively. This study systematically evaluated effective antibacterial agents for the three bacterial diseases in Hainan, identifying ethylicin and benziothiazolinone as the relatively effective agents against the newly reported disease (bacterial dieback). The findings would provide a basis for emergency control and scientific field application of pesticides targeting the diseases.
Coffee berry borer (Hypothenemus hampei) is one of the most destructive pests in the global coffee industry, severely affecting both yield and quality. To address the lack of effective biological control agents in China, a native entomopathogenic fungus was isolated from naturally infected coffee berry borers collected in Qionghai, Hainan province. Morphological observations showed that the fungal colonies on PDA medium were floccose to powdery, white in early growth and pale yellow in later stages. The conidia were spherical to subspherical, consistent with the morphological characteristics of Beauveria bassiana. Phylogenetic analyses based on ITS, TEF-1α and Tub2 gene sequences identified the isolate as B. bassiana Bb-QJC2. Sequence similarity comparisons with reference strains in the NCBI database B. bassiana BebaHA22A02 (OM373021.1), ARSEF5987 (KJ500423.1) and ZXYBb2 (ON994422.1) was 99.63%, 99.19% and 100.00%, respectively. Growth assays revealed that the daily radial growth rate of Bb-QJC2 on PDA medium [(4.39±0.03)mm/d] was significantly higher than that on PSA medium [(3.62±0.04)mm/d]. Pathogenicity tests demonstrated that Bb-QJC2 exhibited strong virulence against adult coffee berry borers; virulence increased with longer exposure time and higher conidial concentrations. Under the immersion-insect method, cumulative corrected mortality after 10 days was 96%, 62% and 38% at conidial concentration of 1×108, 1×107, 1×106 conidia/mL, with LT50 values of 5.343, 8.013, 16.910 days, respectively, and a LC50 of 2.34×106 conidia/mL. Under the immersion-fruit method, cumulative corrected mortality reached 100%, 80% and 58% for the conidial concentration of 1×108, 1×107, 1×106 conidia/mL, with LT50 values of 4.304, 6.317, 10.399 days respectively, and a LC50 of 7.44×105 conidia/mL. Overall, the results indicated that B. bassiana strain Bb-QJC2 exhibited strong pathogenicity against adults of the coffee berry borer, providing a valuable native biocontrol resource for the development of green pest control technologies targeting this fruit-boring pest.
Analyzing the differences in the rhizosphere soil fungal community of black pepper under different incidence levels of Fusarium wilt is crucial for developing precise and efficient control strategies. Rhizosphere soil samples were collected from healthy (CK), mildly (T1), moderately (T2) and severely (T3) diseased plants. High-throughput sequencing was employed to analyze the fungal community structure, diversity, molecular ecological networks, and functional profiles. T1 had the highest number of unique OTUs. The dominant fungal genera were Metarhizium, Thermoascus, Mortierella, Apiotrichum, Fusarium, Rasamsonia, Paracremonium, Debaryomyces and Talaromyces. The relative abundance of pathogenic fungi was significantly the highest in T3 (24.13%), followed by T1 (20.89%), with CK (14.84%) and T2 (15.39%) being lower. Fungal richness indices showed an initial increase followed by a decrease, while diversity indices exhibited an increase-decrease-increase trend. Principal coordinate analysis (PCoA) revealed distinct differences in fungal communities. Redundancy analysis (RDA) indicated that salinity, ammonium nitrogen, available potassium, available phosphorus, and organic matter were the main drivers of fungal community divergence. Linear discriminant analysis effect size (LEfSe) identified 2, 2, 3 and 2 unique biomarker species at the order level for CK, T1, T2 and T3, respectively. Correlation network analysis showed that Fusarium was positively correlated with Paracremonium and Lasiodiplodia, but negatively correlated with Rasamsonia and Thermoascus. Molecular ecological network analysis revealed a decrease-increase-decrease trend in the number of nodes and edges for the total fungal network, with modularity showing an increase-decrease-increase pattern. The subnetwork of potential pathogenic fungi also exhibited a decrease-increase-decrease trend in node and edge numbers, but its modularity only showed an increase-decrease trend. Functional prediction using FUNGuild indicated that the abundance of pathotrophic fungi followed an increase-decrease trend, whereas saprotrophic and symbiotrophic fungi both demonstrated a decrease-increase dynamic. The occurrence and spread of pepper Fusarium wilt were closely associated with the collapse of the rhizosphere soil fungal network structure and functional decline. Therefore, rhizosphere microecological regulation for wilt control should focus on maintaining the balance of dominant fungal groups.
Rice orange leaf disease is caused by rice orange leaf phytoplasma (ROLP) infection, primarily transmitted by leafhoppers. It is characterized by rapid spread and a wide range of damage, posing a serious threat to rice production in southern China. There is an urgent need to establish rapid and efficient detection methods for effective disease control. Based on recombinase-aided isothermal amplification coupled with lateral flow dipstick technology (RAA-LFD), this study designed specific primers and probes targeting conserved gene sequences of ROLP and established a rapid detection technique suitable for field conditions. Optimization results showed that the method could complete amplification and detection at 35 ℃ within 20 minutes, requiring minimal instrumentation. Sensitivity tests demonstrated a detection limit of 1×10-4 ng/μL for ROLP recombinant plasmids. Specificity tests revealed that the method produced specific bands only for ROLP samples, with no positive reactions for other rice disease samples or healthy samples. Application tests indicated that the method could detect ROLP-infected rice leaves and vector insects, specifically the leafhopper Recilia dorsalis. A total of 85 suspected rice samples and 112 leafhopper samples were collected from five regions in Guangxi, and the results showed good consistency with conventional PCR, with a consistency rate of 100.0% for rice samples and 98.2% for leafhopper samples. The RAA-LFD method established in this study is rapid, sensitive, specific, easy to operate, and cost-effective, requiring no thermal cycler and reducing detection time by more than 70% compared to conventional PCR. It would provide an efficient technical tool for early diagnosis of ROLP, detection of virus-carrying rates in vector insects, and large-scale field surveys, and is expected to be widely applied in rice orange leaf disease monitoring.
It was found that a better growth vitality was sustained in some of the tomato plants with a fungus growing on the stem epidermis after infected by plant virus. It was aimed to separate and identify the virus which infected tomato, and the fungus growing on the same tomato plant to deeply explore the symbiosis of virus and fungus, and their interactions with tomato plants and to analyze the ultrastructure and distribution characteristics of virus and fungus. In this study, the methods of microbial isolated cultivation, light microscopic observation, observation using scanning electron microscope and similarity analysis of conservative genes were used to identify the fungus. The methods of RT-PCR testing and virion observation by transmission electron microscope united negative staining were used to identify the virus. The transmission electron microscope united tissue ultra-thin section was used to investigate the distribution characteristics of virion in the cells of stem cortex in tomato plant. The results showed that the virus which infected tomato plant was Tomato brown rugose fruit virus (ToBRFV), and the fungus epibiontically growing on the necrotic epidermis of plant stem was Alternaria tenuissima (AT), which belongs to epiphyte. This study revealed the baculiform particles of ToBRFV existed in the form of viral aggregations in the cortex cells of tomato stem, and the densities of virion in the cells of stem cortex of tomato plant with AT growing were lower than those in the same cells of plant with no AT growing. This study proved that AT only obviously grew on the necrotic epidermis of stem of the diseased tomato plants infected by ToBRFV; the distribution characteristics of ToBRFV in the cortical cells of the stem of AT-attached and AT-free attached plants are significantly different. The results would provide theory foundation for the subsequent explorations of the mechanism of AT affecting the proliferation and distribution of ToBRFV.
Strict seed quarantine is crucial for preventing the long-distance spread of seed-borne diseases in Solanaceae crops and ensuring agricultural biosafety. Crops like tomato and pepper hold high economic value and extensive industrial influence. However, devastating quarantine pathogens, including Clavibacter michiganensis subsp. michiganensis, Tomato leaf curl New Delhi virus, Tomato spotted wilt virus and Tomato brown rugose fruit virus, pose a severe threat to industry security. Current molecular detection techniques for the mixed bacterial and viral infections often suffer from complex procedures, reliance on specialized laboratories and personnel, and difficulties in achieving rapid, integrated on-site testing. To address the challenges, this study developed a fully automated, rapid on-site detection system based on microfluidic chip and real-time quantitative PCR technology. The system integrates modules for co-extraction of nucleic acids, coordinated multi-target amplification and visual interpretation of results. It achieves multiplex detection of the aforementioned four pathogens within a total process time of only 36 minutes. The constructed P1000F integrated detection system demonstrated limits of detection of 4.50×104 CFU/mL for the bacterial pathogen and 1.00×101 copies/μL for each of the three viral pathogens. Testing with actual samples confirmed its good applicability and reliability. Compared with current standard methods(EPPO standards and national standards), the detection sensitivity of this system was generally equivalent. In conclusion, the P1000F integrated detection method established in this study is efficient and accurate. It eliminates dependence on traditional laboratory environments and specialized technical personnel, providing reliable technical support for the rapid on-site screening and port quarantine of tomato seed-borne diseases.
This study aimed to efficiently extract polysaccharides from coffee peel and investigate their biological activities. We employed Deep Eutectic Solvent (DES) combined with orthogonal method to optimize the extraction conditions of polysaccharides from Yunnan small-grain coffee peel, and evaluated their in vitro antioxidant, hypoglycemic, and hypouricemic activities. The optimal DES for coffee peel polysaccharides was choline chloride-glycerol, with the optimal extraction parameter combination: extraction time 30 min, water content 40%, solid-liquid ratio of 1∶50 (g/mL), reaction temperature 50 ℃, and molar ratio 4∶1. Under these conditions, the extraction yield of coffee peel polysaccharides reached 35.58%. In vitro experiments indicated that coffee peel polysaccharides exhibited significant scavenging effects on ·OH and DPPH, and inhibitory effects on α-amylase, α-glucosidase and xanthine oxidase, demonstrating favorable antioxidant, hypoglycemic, and hypouricemic activities. The study not only opens new avenues for the high-value utilization of coffee peel, a byproduct of coffee processing, but also provides scientific support for the development of natural health products with functions in regulating blood glucose and uric acid metabolism.
To develop environmentally friendly packaging materials with excellent preservation performance, this study used polyvinyl alcohol (PVA) as thefilm-forming matrix, introduced fumed silica (FS) as the nanoreinforcing phase, melatonin (MT) as the interfacial dispersant and active component, and different concentrations of eugenol (EG) as the core functional additive to prepare a series of PVA/FS/MT/EG composite films. Their physicochemical properties, including mechanical properties, water vapor barrier property, antioxidant activity, and antibacterial activity, were evaluated. The composite films were applied to preserve rambutan fruits at room temperature, and their effects on fruit storability were examined. The results showed that the addition of MT effectively improved the dispersion of FS in the PVA matrix, synergistically enhanced the antioxidant activity of the film, and reduced the water vapor permeability. With increasing EG concentration, the water vapor barrier property of the film was progressively improved, and the inhibitory activity against Escherichia coli and Staphylococcus aureus was significantly enhanced. When the EG concentration reached 10%, the DPPH radical scavenging rate peaked. The rambutan preservation experiments revealed that the PVA/FS/MT/EG composite films with different EG concentrations differentially maintainedfruit color, delayed weight loss, browning, and the decrease in soluble solids content during storage, with the composite film containing 5% EG exhibiting the optimalpreservation effect. This study provides a potential solution for developing alternative packaging materials to traditional plastic films, demonstrating good application prospects in the preservation of tropical fruits.
Intercropping cash crops in natural rubber plantations is generally recognized as an effective measure to improve soil quality and enhance ecosystem stability. However, there is a paucity of research on more intercropping plants that possess both potential ecological and economic values. In this study, biochemical analysis and metagenomic sequencing techniques were employed to systematically compare the changes in microbial community composition, diversity, and soil physicochemical properties across four rubber-based agroforestry systems, rubber monoculture (RM), rubber-Amomum villosum Lour. (RAS1), rubber-Aspidistra elatior ‘Variegata’ (RAS2) and rubber-Curculigo orchiodes Gaerth. (RAS3). The aim was to provide scientific basis and technical support for the sustainable development of rubber plantations. Compared with RM, RAS1 and RAS2 significantly reduced soil organic matter and total nutrients, while RAS3 significantly decreased soil bulk density but markedly increased soil water content and available nutrients. pH and ammonium nitrogen decreased significantly across all three intercropping patterns. Intercropping significantly increased the bacterial Ace, Chao1 and Shannon indices, and significantly decreased the Simpson index, but had no significant effect on fungal α-diversity indices. Intercropping significantly increased the relative abundances of dominant bacterial phyla such as Actinomycetota and Acidobacteriota, while significantly reducing that of Pseudomonadota. It also significantly enhanced the relative abundances of dominant fungal phyla including Mucoromycota and Ascomycota, and significantly decreased that of Basidiomycota. Correlation analysis revealed that bacterial richness indices (Ace and Chao1) were significantly positively correlated with soil pH, SOM, TP, TK, AK and NH4+-N content. Bacterial diversity index (Shannon) was significantly positively correlated with BD, but significantly negatively correlated with pH and SOM content. No significant correlations were observed between fungal α-diversity indices and any soil physicochemical factors. Redundancy analysis (RDA) indicated that soil pH and SWC were the primary environmental factors affecting bacterial community composition, while fungal community composition was mainly significantly influenced by soil pH and AK content. In conclusion, RAS3 could effectively improve the soil quality of rubber plantations and should be proposed among the three intercropping patterns.
Passiflora edulis Sims is an important tropical economic crop in southern China. Its growth and development process is closely related to temperature conditions, showing high sensitivity to low-temperature environment. Low-temperature and freezing damage has become a core bottleneck restricting the large-scale development, stable yield, and quality improvement of the industry in southern China. Especially in high-quality P. edulis Sims producing areas such as Zhangzhou, the industry is significantly constrained by low-temperature and freezing damage in winter and spring. However, current research on P. edulis Sims freezing damage mostly relies on single factors, which is difficult to meet the needs of accurate early warning. Therefore, this study aims to construct a scientific and efficient multi-factor coupling evaluation system for P. edulis Sims low-temperature and freezing damage by integrating multi-source data and conducting comprehensive analysis, so as to provide technical support for the sustainable development of the industry. Focusing on Zhangzhou P. edulis Sims as the key research object, the study was carried out based on field experiments, climate simulation tests, and historical meteorological disaster data. Comparative analysis was used to determine the critical temperature, correlation analysis to screen key disaster-causing factors, principal component analysis to construct the evaluation model, and K-means clustering combined with percentile method to complete dynamic grading. The daily minimum temperature of 2.5 ℃ was determined as the critical temperature for P. edulis Sims low-temperature and freezing damage. Four key disaster-causing factors were screened out, among which the extreme minimum temperature was extremely significantly negatively correlated with the freezing damage grade, while the harmful accumulated cold during the process, low-temperature duration, and cooling range were extremely significantly positively correlated with the freezing damage grade. A multi-factor coupling evaluation model for P. edulis Sims low-temperature and freezing damage was constructed, I=0.083X1+0.992X2-0.082X3+0.043X4. P. edulis Sims freezing damage was divided into 5 grades, including none, mild, moderate, severe, and extremely severe. Typical freezing damage events in 4 different regions in 2021 were selected for verification, and the results showed that the consistency between the grading and the actual disaster situation reached 98.7%. This study innovatively breaks through the limitations of traditional single-factor evaluation, clarifies the critical temperature and disaster-causing mechanism of P. edulis Sims freezing damage. Its grading system has high reliability after verification, and the research results can effectively improve the accuracy of freezing damage early warning, provide data basis for the government to formulate disaster prevention decisions and farmers to take protective measures, and practically consolidate technical support for the sustainable development of the P. edulis Sims industry.
The spatiotemporal variations of DOM content and optical characteristics in Wenchang Zhuxi River Basin (Hainan, China) were systematically investigated using multi-spectroscopic techniques and statistical analyses. The sources of DOM in the river basin were identified based on optical indices. DOC concentrations of water samples in Wenchang Zhuxi River Basin ranged from 0.32 mg/L to 85.77 mg/L. There was no significant differences of DOC concentration between wet season and dry season, whereas DOC concentration in the upstream was significantly higher than that in the downstream during the dry season (P<0.05). Optical analyses revealed that DOM in Wenchang Zhuxi River Basin consisted of two natural humic-like components (C1 and C2) and one anthropogenic humic-like component (C3). Contribution of C3 in wet season was higher than that in dry season, and exhibiting a decreasing trend from upstream to downstream in both seasons. DOM in wet season presented lower molecular weight, weaker aromaticity, lower humification degree, and higher autochthonous contributions than that of DOM in dry season. In spatial distribution, molecular weight and aromaticity of DOM remained relatively stable across the river basin; autochthonous index increased from upstream to downstream; humification degree exhibited the lowest value in midstream. Source identification suggested that soil, manure, and domestic sewage were the main DOM inputs of Wenchang Zhuxi River Basin, with algal contribution detected in the wet season. In spatial distribution, soil-derived DOM dominated upstream, whereas human-induced inputs (domestic sewage and manure) increased markedly from midstream to downstream with the increase of human activity. The findings highlighted pronounced seasonal and spatial heterogeneity of DOM in tropical monsoon rivers, and would provide scientific basis for DOM biogeochemical processes and water-quality management of the river basin.
Addressing the lack of clarity regarding the spatial distribution of plastic-mulched farmland in southern tropical agricultural regions, the paper used the entire area of Haikou city, Hainan, China as the study sample. Utilizing the Google Earth Engine (GEE) cloud platform, Sentinel-1 synthetic aperture radar data, and Sentinel-2 optical remote sensing imagery, key feature parameters for identifying plastic-mulched farmland in the study area were screened through feature importance analysis. The Random forest algorithm was employed to extract the plastic-mulched farmland information, with accuracy assessed via a confusion matrix. Results indicated that the Random Forest model integrating spectral, index, and texture features performed effectively, achieving an overall accuracy of 0.967 and a Kappa coefficient of 0.956. Based on the optimal feature combination scheme, the area of mulched farmland was 2279.25 hm2, accounting for 4.43% of the total cultivated land area in the main farming regions of Haikou. The distribution showed a pattern of higher density in the east and lower density in the west. Mulched farmland was concentrated in the agricultural areas of the Nandu River alluvial plain from the eastern to central parts and the southwestern suburbs of Haikou city, with relative concentrations in Meilan district and Qiongshan district. The distribution across the four districts was as follows, Meilan district, 1034.37 hm2 (45.38%), Qiongshan district, 807.63 hm2 (35.43%), Xiuying district, 307.17 hm2 (13.48%), and Longhua district, 130.07 hm2 (5.71%). The area of black film was larger at 1739.25 hm2, accounting for 76.31% of all mulched farmland, while the area of white film mulched farmland was 539.99 hm2, accounting for 23.69%. This study achieved precise identification of mulched farmland in the suburban areas of a tropical coastal city, and would provide a basis for the protection and sustainable utilization of cultivated land resources in tropical agricultural regions.
