The oxalate transporters of the rubber tree (Hevea brasiliensis) exhibit structures and functions comparable to the homologs in Arabidopsis thaliana. Previous studies have demonstrated that A. thaliana oxalate transporter proteins interact with both family members and aquaporins. In rubber trees, HbOT1 and HbOT2 are oxalate transporters, while HbPIP2;3 is an aquaporin. However, the synergistic roles of the three proteins in rubber trees remain uncharacterized. In this study, the CDD database, MEME online tool, and TMHMM-2.0 platform were employed to analyze the functional domains, conserved motifs, and transmembrane structures of HbOT1 and HbOT2. Subcellular localization of HbOT1 and HbOT2 was determined using a transient expression system in tobacco leaf epidermal cells. Protein-protein interaction sites between HbOT1 and HbOT2, and between the proteins and HbPIP2;3, were predicted using AlphaFold 3. Additionally, bimolecular fluorescence complementation (BiFC) assays were performed to validate the interactions in living plant cells, providing both theoretical and experimental support for elucidating the physiological functions and mechanisms of oxalate transporters in rubber trees. Sequence analysis revealed that both HbOT1 and HbOT2 possessed the SNARE_assoc (VMP1/TMEM41/DedA) domain, were transmembrane proteins, and localized to the plasma membrane. Protein interaction predictions indicated that HbOT1 shared nine interaction sites with HbOT2, two interaction site with HbPIP2;3, and HbOT2 shared four interaction sites with HbPIP2;3. BiFC assays confirmed that HbOT1 and HbOT2, HbOT2 and HbPIP2;3, colocalized at the plasma membrane and specifically interact. The findings suggest that HbOT2 can bind both HbOT1 and HbPIP2;3 to form plasma membrane protein complexes, indicating that oxalate transporters and aquaporins in rubber trees may couple via physical interactions to collaboratively regulate physiological processes such as water homeostasis and stress responses.
Utilizing natural triploids to breed new varieties is an important approach in plant breeding. Clarifying the genetic origin of natural triploids and the mechanisms underlying the formation of 2n gametes is of great significance for evaluating the breeding potential. In this study, using the hybrid population of rubber tree clones Reshi 2-9-1× Reyan879 as material, three triploid individuals were identified from 40 progeny through flow cytometry and chromosome squash counting, yielding a triploid rate of 7.5%. Using selected SSR markers, it was confirmed that the triploids originated from the fusion of 2n female gametes produced by the maternal parent and normal n male gametes. Further analysis with high-and low-recombination-frequency SSR markers revealed that the three triploid individuals inherited 62.50%, 50.00% and 68.75% of the maternal heterozygosity, respectively. The values exceed the expected heterozygosity transmission level of traditional SDR-type gametes (30%-40%) but fall below the typical range for FDR-type gametes (70%-80%). Moreover, markers in low-recombination regions confirmed that the mechanism of 2n female gamete formation was Second Division Restitution (SDR). This study enriches the germplasm resources of natural triploids in rubber trees, validates the accuracy and efficiency of low-recombination-frequency SSR markers in identifying the origin and formation mechanisms of polyploids, and demonstrates that SDR-type 2n female gametes in rubber trees can transmit a relatively high proportion of parental heterozygosity under specific genetic backgrounds. The findings would provide a theoretical foundation for utilizing natural triploids in polyploid breeding of rubber trees.
Organic acid accumulation is a fundamental determinant of the flavor quality and overall sensory profile of mango fruits. Among various germplasms, mango variety San Nian (Mangifera indica cv. San Nian) has emerged as an ideal genetic resource for flavor improvement because its organic acid content is significantly higher than that of common commercial cultivars. Despite the critical importance of the PH gene family as a regulatory unit for the vacuolar accumulation of organic acids, a systematic investigation of this family within the mango genome has remained a significant research gap. San Nian was used as the primary research material, leveraging its whole-genome sequencing data in combination with advanced bioinformatics and qRT-PCR technologies to systematically identify members of the MiPH gene family for the first time. The research aimed to explore the correlation between the genes and organic acid accumulation, thereby providing essential gene targets and a theoretical foundation for deciphering the molecular mechanisms of organic acid transport and conducting targeted flavor modification in mango production. Through Hidden Markov Model (HMM) searches and comprehensive phylogenetic analysis, a total of 15 MiPH family members were identified in San Nian genome. The encoded proteins primarily consisted of 519 to 521 amino acids and exhibited highly conserved physicochemical properties. The proteins were characterized as hydrophobic stable proteins specifically localized to the cell membrane, a structural foundation that supporting the suspected transmembrane transport functions. Phylogenetic analysis clearly categorized the members into the PH subfamily, featuring multi-exon-intron structures and 10 types of highly conserved motifs, which indicating a high degree of evolutionary conservation. The 15 genes were non-uniformly distributed across eight chromosomes, featuring six pairs of intra-species collinear genes and 15 pairs of inter-species collinear genes with Anacardium occidentale (cashew). The findings offer crucial molecular evidence for understanding the origin and evolutionary trajectory of the gene family. Analysis of promoter sequences revealed that the regulatory regions of the genes were enriched with various cis-acting elements, including those responsive to light, methyl jasmonate (MeJA), and abscisic acid (ABA), alongside several stress-response elements. This suggests that MiPH gene expression is dual-regulated by both internal developmental programs and external environmental stimuli. Transcriptome data and qRT-PCR validation demonstrated that while MiPH2, MiPH4, MiPH5, MiPH7 and MiPH10 were effectively expressed in mango fruits, the expression patterns of MiPH4, MiPH5 and MiPH10 in Keitt mangoes aligned closely with the characteristic reduction in acidity observed during ripening. Conversely, during the post-harvest storage of San Nian, the transcription levels of MiPH4 and MiPH5 were significantly and continuously up-regulated over time, matching the process of vacuolar organic acid accumulation with high precision. Ultimately, this research would provide the first comprehensive genome-wide characterization of the MiPH gene family in San Nian and confirm MiPH4 and MiPH5 as the primary candidate genes. The findings would fill an existing research void and provide a vital theoretical basis for molecular breeding aimed at resolving the industrial challenge of sugar-acid imbalance in commercial mango varieties.
White pepper is an essential condiment and side dish in South China. Fruit color at the mature-green stage is a critical quality trait influencing commercial value and consumer preference. In this study, two inbred lines of chili pepper (Capsicum annuum L.) with white (ZW13, ♀) and green (ZG14-1, ♂) fruits were hybridized to construct an F2 segregating population. Genetic analysis was performed, and GradedPool-seq was employed for pooled resequencing of three fruit-color subgroups. Indel molecular markers were developed within the primary mapping interval to construct a local genetic map via inclusive composite interval mapping (ICIM). Combined with colorimeter-based identification, major-effect QTL mapping and candidate gene screening for mature-green fruit color were successfully completed. The results revealed a segregation ratio of 12∶3∶1 (green∶yellow-green∶white) among 426 F2 plants, indicating that mature-green color was controlled by two pairs of independently inherited genes, with the green gene exhibiting dominant epistasis over the yellow gene. Using GradedPool-seq and a local genetic map constructed via inclusive composite interval mapping (ICIM), two major QTLs were co-localized on chromosomes 1 and 10. The locus qFC01 on chromosome 1 was mapped to a ~0.13 Mb interval between MU0106 and MM0102 (contribution rate: 10.09%; LOD: 4.40). The locus qFC10 on chromosome 10 was mapped to a ~0.93 Mb interval between MM1028 and MM1035, showing a maximum contribution rate of 45.79% and an LOD of 25.04. Six genes within the qFC10 interval harbored non-synonymous mutations in the coding regions of the parents. Through qRT-PCR expression pattern validation in the mature-green fruits of both parents and F1 hybrids, combined with bioinformatic analysis, Capana10g000333 (CaGLK2) was identified as the key candidate gene. This study would provide a foundation for dissecting the molecular mechanism of pepper fruit color and offer molecular markers for breeding high-quality white pepper varieties.
Low potassium tolerant cassava germplasms were screened out to provide theoretical basis for the breeding of new varieties of low potassium tolerant cassava and to explore the low potassium tolerance of different cassava germplasms at seedling stage. 16 cassava germplasms were subjected to hydroponic experiments in this study. Two treatments of low potassium (0.6 mmol/L) and appropriate potassium (6.0 mmol/L) were set up. After 14 days of treatment, 13 indexes including plant height, stem diameter, shoot fresh weight and shoot potassium accumulation of cassava seedlings were measured. The low-potassium tolerance of the tested materials was comprehensively evaluated using multivariate statistical methods, including principal component analysis, membership function analysis, and cluster analysis. The indexes of cassava seedling stage had great variation under low potassium and suitable potassium treatment. Principal component analysis transformed 13 single indicators into 4 independent comprehensive indicators. The comprehensive evaluation value (D) of low potassium tolerance of each material was calculated by membership function value, ranging from 0.14 to 0.69. The 16 cassava germplasms were further divided into three categories by cluster analysis, with 2 low potassium tolerant materials, 6 low potassium tolerant materials and 8 low potassium sensitive materials. In this study, the evaluation system of low potassium tolerance of cassava at seedling stage was preliminarily established. It was considered that stem diameter, potassium concentrations in aboveground and underground parts, plant dry mass could be used as key indicators for rapid identification of low potassium tolerance of cassava at seedling stage. YB201 and GR8 were identified as low potassium tolerant germplasms, which could provide basic materials for the study of low potassium tolerance mechanism and new variety breeding of cassava.
The study aimed to explore the differences of the fruit traits in pomelo (Citrus maxima (Burm.) Merr) germplasm resources and screen excellent germplasm materials to provide theoretical basis for efficient exploration and utilization of pomelo germplasm resources as well as parent selection for breeding new variety. 26 pomelo germplasm resources of native and foreign origin were used as research materials. Twelve fruit traits indexes were measured, then difference, coefficient of variation, correlation analysis were performed among the indexes. The subordination function method and cluster analysis were used to evaluate overall fruit quality and screen excellent germplasms. Significant differences were observed in the fruit traits among different pomelo germplasm resources. The maximum single fruit weight was from Thailand pomelo with 1692.80 g. The longitudinal diameter and fruit shape index of Shanghang pomelo were the highest, while the total soluble solid (TSS) content Pengzhou pomelo. The fruit rind thickness of Shanghang pomelo and Africa pomelo was 19.57 mm and 21.37 mm, respectively, which were significantly higher than those of the other fruits. The highest total acid (TA) content was found in Africa pomelo (1.24%), and the highest vitamin C content was found in Shaxian pomelo (5.24 mg/100 mL). The TSS/TA ratio ranged from 8.90 to 22.34, with the highest value in Vietnam Green pomelo (22.34), followed by the Shaxian pomelo (22.21), which were significantly higher than those of the other fruits. The coefficient of variation of fruit quality traits ranged from 8.70% to 44.51%, and the diversity index ranged from 3.1794 to 3.2543, among the investigated pomelo germplasm resources. Correlation analysis revealed that single fruit mass, fruit transverse diameter, fruit longitudinal diameter, and fruit rind thickness were significantly positively correlated with each other. The fruit shape index was significantly positively correlated with fruit transverse diameter and fruit rind thickness. The edible rate was significantly negatively correlated with fruit transverse diameter, fruit longitudinal diameter, fruit rind thickness, and total acid content, while it was significantly positively correlated with juice extraction rate, TSS/TA and soluble sugar content. Through the comprehensive evaluation of membership function method, the highest comprehensive score was from Vietnam Green pomelo (78.63), followed by Shaxian pomelo (78.10). Based on comprehensive evaluation and differential analysis, seven superior or distinctive resources were identified. Vietnam Green pomelo, Dongfeng pomelo, and Taxiti pomelo were selected with outstanding comprehensive quality. Early-maturing Shatian pomelo and Shaxian pomelo exhibited high sugar content. Hongbaoshi pomelo was characterized by thin peel and thick pulp. Africa pomelo was noted for its high acidity.
Amomum tsao-ko is a perennial herbaceous plant of the genus Amomum in the Zingiberaceae family, used for both medicinal and culinary purposes, and possesses significant medicinal and edible value. A. tsao-ko exhibits a unique mechanism of dichogamy flowering. This study characterized 138 A. tsao-ko accessions for seven phenotypic traits and analysed dichogamy InDel markers. Phenotypic analysis revealed extensive genetic variation in the 138 samples across all seven traits. The correlation analysis shows that plant height was found to be significantly positively correlated with multiple phenotypic traits. Principal component analysis (PCA) reduced the multiple traits to three independent dimensions. Cluster analysis grouped the samples into three categories, providing an scientific reference and breeding strategies for the selection and development of new A. tsao-ko varieties. From the 28 pairs of InDel marker primers that have been developed, one pair with good stability and specificity was screened and confirmed as an InDel marker for distinguishing the dichogamy types of A. tsao-ko, named PGA5. A fingerprint profile of A. tsao-ko germplasm resources was also successfully constructed, clarifying the unique fingerprint codes for each resource. The fingerprint code for protogyny homozygous individuals was 20, heterozygote individuals with protogyny was 21, and homozygous individuals with protandry was 01. Using this primer pair, the germplasm were subjected to preliminary identification, and 1 protogyny homozygous, 91 heterozygote individuals with protogyny, and 46 homozygous individuals with protandry were grouped. By combining molecular identification results with phenotypic characteristics and germplasm origin information, 51 valid resources were screened and identified from the 138 A. tsao-ko samples. This study would provide an important resource base and data support for the identification, evaluation, genetic breeding, and selection of superior varieties of A. tsao-ko.
Zhanjiang is located at the southernmost tip of the Chinese mainland, at the junction of Guangdong, Hainan, and Guangxi, and possesses an extensive coastline. Using a combination of field investigations and literature review, this study systematically documented the current status of coastal plants in Zhanjiang, including species composition, life forms, invasive plants, and floristic geographical characteristics, and compared the generic geographical components with those of other regions. A total of 547 coastal plant species, belonging to 103 families and 372 genera, were recorded in Zhanjiang. Species distribution was uneven. 17 families were dominant or relatively large families, mainly including Fabaceae, Poaceae, Asteraceae, Cyperaceae, and Malvaceae, while 86 families were oligotypic and monotypic families. Life forms were dominated by herbs (333 species), followed by shrubs (116 species), trees (62 species), and lianas (36 species). The flora exhibited a pronounced tropical nature. Tropical elements accounted for 64 families (62.14%) and 324 genera (87.10%), among which pantropic distribution was predominant, with 47 families (45.63%) and 163 genera (43.82%). Temperate elements were relatively few, comprising 7 families (6.80%) and 20 genera (5.38%). At the species level, tropical elements were also overwhelmingly dominant, with 496 species (90.68%), whereas temperate elements accounted for only 29 species (5.30%). Comparisons of similarity coefficients and R/T ratios between Zhanjiang and other regions showed that the floristic similarities between Zhanjiang and Hainan Island (47.9) and Guangxi (47.1) were the highest. Meanwhile, Zhanjiang had the highest R/T ratio (16.21), higher than that of Hainan Island (13.74), which may be related to differences in survey scope, Area, and geographical isolation of islands. The proportion of tropical distribution gradually decreased with increasing latitude, while that of temperate distribution increased, which may result from variations in heat and water conditions along latitudinal gradients in coastal zones. Zhanjiang is rich in coastal plant resources with high application value, which have not been industrialized due to technical limitations. Coastal ecological restoration is urgently needed. Under the guideline of “ecology first, technology priority”, germplasm utilization can be promoted through ecological restoration, so as to achieve coordinated development between ecological conservation and high value-added industries.
Elephant grass (Pennisetum purpureum) is a high-quality forage crop widely cultivated in the tropical and subtropical regions of southern China. To date, research on establishing a genetic transformation system for elephant grass remains insufficient. This study aims to establish and optimize an efficient Agrobacterium tumefaciens-mediated genetic transformation method for elephant grass. The mature seeds of the genome-sequenced elephant grass genotype (CIAT6263) were used as explants. Hormones were supplemented into the culture medium to induce embryogenic callus from elephant grass. An overexpression vector pCXSN-eGFP, containing the visible marker eGFP and the hygromycin selection marker, was constructed and introduced into Agrobacterium. The embryogenic callus was used as the recipient material for infection and transformation. Following transformation, the callus was transferred to a selection medium containing 50 mg/L hygromycin to screen for resistant callus. The green fluorescent marker eGFP was used for preliminary identification of positive callus. Subsequently, the resistant callus was transferred to differentiation and rooting media for shoot regeneration and root formation. Putative transgenic plants were verified by PCR amplification using vector-specific primers and by observing green fluorescence. Throughout this process, key parameters including different hormone combinations for callus induction and differentiation, concentration of bacteriostatic agent, and factors affecting Agrobacterium-mediated transformation (such as Agrobacterium strain, infection concentration, infection duration, and co-cultivation time) were compared. The optimal technical parameters were determined as follows: the hormone combination for primary callus induction 2 mg/L 2,4-D and 0.01 mg/L 6-BA, for embryogenic callus induction, 1.5 mg/L 2,4-D and 1.0 mg/L 6-BA, for callus differentiation, 0.4 mg/L 6-BA and 0.1 mg/L TDZ, the optimal concentration of the bacteriostatic agent carbenicillin 300 mg/L, the optimal conditions for Agrobacterium-mediated transformation strain EHA105 at an OD600 of 0.3 for an 8-minute infection period, followed by a 24-hour co-cultivation period in darkness. This study successfully established and optimized an Agrobacterium-mediated genetic transformation method for elephant grass, providing an effective technical approach and theoretical foundation for the genetic improvement of elephant grass.
The response mechanisms of non-structural carbohydrates (NSC) in plants under drought stress, and the changes in NSC reserves in rubber trees induced by tapping, have been relatively well understood. However, the allocation pattern and response strategy of NSC in rubber trees under the combined stress of drought and tapping remain unclear. To address the above questions, this study investigated NSC component contents and the dynamic trends in leaves, bark, wood, and roots of rubber trees under two water treatments (drought control, i.e., conventional management without irrigation, and irrigated treatment) across four time points, four weeks before tapping, four weeks after tapping, three weeks before tapping rest, and two weeks after tapping rest. The results showed that the NSC response triggered by tapping differed between the two water treatment. At four weeks after tapping, under the irrigated treatment, starch reserves in the wood and roots increased by 133.24% and 72.44%, respectively, whereas under the drought control, starch reserves in the wood and roots decreased by 38.06% and 79.75%, respectively. At the same time point, the total NSC content in leaves of tapped trees under the irrigated treatment decreased by 13.20% compared with that under the drought control, indicating that increased water supply accelerated the translocation of leaf NSC to other organs. Irrigation increased latex yield by 157.71%, confirming the yield improvement potential of supplemental irrigation in arid regions, although it did not significantly affect the girth growth of rubber tree trunks. This study revealed the unique response and allocation mechanisms of NSC in rubber trees under the dual pressures of drought and tapping, enrich the understanding of carbon trade-off strategies in woody plants under multiple stresses, and provide a scientific basis for production management and irrigation practices in rubber plantations in arid regions.
The level of mechanization in the natural rubber tapping process directly affects production efficiency and the economic lifespan of rubber trees. Using manual tapping as the control (CK), comparative experiments were conducted with three machine tapping technologies: fixed tapping machine (F), electric tapping knife (E), and minimally invasive tapping (M). The effects of these machine tapping technologies on rubber tree metabolism, latex quality, and tapping quality were systematically compared. The results showed that: compared with CK, the minimally invasive tapping treatment achieved the highest yield per tree and total solids content, with no significant difference in dry rubber content; there was no significant difference in initial latex flow rate among all treatments; the tapping depth of the electric tapping knife treatment showed no significant difference, while CK had the lowest bark consumption per cut (1.32 mm); the fixed tapping machine treatment exhibited the highest wound rate (46.7%). The correlation heatmap analysis of physiological parameters and processing performance indicated that most of the 20 indices reached significant or highly significant correlations with each other. This study provides a basis for research on the effects of machine tapping on rubber tree metabolism, latex quality and tapping quality.
This study investigated the effects of cassava and soybean grown in monoculture or intercropping on crop yield and soil physicochemical properties of degraded paddy soil, aiming to provide a theoretical basis and technical support for improving cultivated land fertility and crop productivity. A degraded alluvial sandy soil in eastern Hunan previously used for turf planting was selected. Four treatments were established, cassava monoculture, soybean monoculture, cassava- double-season soybean intercropping, and cassava-double-season soybean intercropping+fertilization. Crop growth, yield, and soil quality indicators at 0‒30 cm depth were monitored during the growing season to analyze the dynamics and differences. Intercropping with spring soybean inhibited cassava growth and yield. The average cassava yield in intercropping treatment was 40%‒50% lower than that in monoculture, whereas fertilization significantly increased spring soybean yield by approximately 1.5 times (P<0.05). In the cassava-double-season soybean intercropping+fertilization treatment, the average plant height and basal stem diameter of spring soybean was 25%‒48% and 52%‒96% higher, respectively, than in soybean monoculture (P<0.05). Soil compaction at 15 cm and 30 cm depth in intercropping treatment was 16%-36% lower than that in soybean monoculture, while average soil respiration was 1.1‒1.6 times higher than that in monoculture treatments (P<0.05). Compared with cassava-double-season soybean intercropping, the cassava-double-season soybean intercropping+fertilization treatment increased the average content of readily oxidizable organic carbon in topsoil by 21% (P<0.05). Although cassava intercropped with double-season soybean in degraded alluvial sandy soil reduced cassava yield, fertilization substantially promoted spring soybean production, improved soil structure and compaction, and enhanced soil biological activity. Cassava-soybean intercropping with fertilization is recommended for rapid soil improvement during the early reclamation of severely degraded paddy fields where short-term yield reduction is acceptable. In subsequent implementation, the comprehensive benefits of this model should be further enhanced by adjusting intercropping configurations and optimizing fertilization strategies.
The effects of different concentrations of chelated calcium and magnesium single application and combined application on the growth and development, nutrient accumulation, yield and quality of pineapple were explored, aiming to screen out the optimal calcium and magnesium coupling spraying scheme suitable for pineapple. Variety Tainong 17 was used as the test material, and the two-factor randomized block test was used for spraying, including three chelating calcium (EC) concentrations (0%, 1.0%, 1.5%), three chelating magnesium (EM) concentrations (0%, 1.0%, 1.5%) and their couplings, a total of 9 treatments. When only magnesium was sprayed, 1.0% treatment could significantly increase leaf area index, dry matter accumulation and nitrogen and phosphorus accumulation compared with 0% and 1.5% treatments, and then significantly increase yield. When only calcium was applied, the dry matter accumulation, nitrogen and potassium accumulation and yield of 1.5% treatment were the best, and the pedicel cracking rate and fruit cracking rate decreased. In the coupling spraying of calcium and magnesium, the leaf number and leaf area index of 1.5% EM+1.0% EC treatment were significantly higher than those of other treatments. The dry matter accumulation, nitrogen, phosphorus and potassium accumulation were also significantly higher than other treatments, thereby increasing yield (58.71 t/hm2). The pedicel cracking rate and fruit cracking rate were significantly reduced compared with the non-spraying treatment, and the single fruit mass, fruit hardness were significantly increased, and the titratable acid content was reduced. Correlation analysis showed that the yield of pineapple was significantly positively correlated with leaf number, leaf area index, dry matter accumulation, chlorophyll content and accumulation of nitrogen, phosphorus, but negatively correlated with pedicel cracking rate and fruit cracking rate. In summary, 1.5% EM+1.0% EC treatment can synergistically promote the growth and nutrient accumulation of pineapple, increase yield, improve quality, and reduce the risk of fruit cracking and pedicel cracking, which can be used as the optimal calcium and magnesium foliar spraying mode for pineapple in tropical areas.
By analyzing the differences in the content and composition of sugar components in fruits of different coffee varieties, this study can provide a theoretical reference for the germplasm innovation and breeding of high-sugar coffee varieties. Using mature fruits of 17 coffee varieties as test materials, the contents of fructose, glucose and sucrose in the peels and green beans of coffee fruits were determined. The results showed significant differences in sugar content between the pulp and green beans among the 17 coffee varieties. Among them, the total sugar content in the pericarp of YC01 was significantly higher than that of the other varieties, YC10 had the highest total sugar content in green beans, and YC16 exhibited the highest average total sugar content in both pericarp and green beans. Differences in sugar content were also observed across different structural parts of the fruit. In the pericarp, fructose content was the highest, reaching 172.40 mg/g, while in green beans, sucrose content was the highest, at 74.09 mg/g. Furthermore, the contents of fructose, glucose, reducing sugars, total sugars, and sweetness value in the pericarp were significantly higher than those in green beans, whereas sucrose content in green beans was higher than that in the pericarp. The sugar component structure of different coffee varieties was generally consistent, but there were certain differences in the proportions. Fructose was the predominant soluble sugar component in the pericarp, accounting for 62.94% to 77.29% of the total across varieties. Sucrose was the predominant soluble sugar component in green beans, accounting for 79.18% to 84.37%. Correlation analysis revealed that the total sugar content in the pericarp was most strongly correlated with fructose content, while the total sugar content in green beans was most strongly correlated with sucrose content (P<0.001). The total sugar content and sweetness value of green beans showed an extremely significant positive correlation with glucose content in the pericarp (P<0.01) and an extremely significant negative correlation with fructose, reducing sugars, total sugars, and sweetness value in the pericarp (P<0.01). Cluster analysis classified the 17 coffee varieties into three major groups based on sugar components and content. Based on sugar components and the contents, high-sucrose germplasms (YC06, YC09, YC10, YC11, YC12) and high-total sugar and high-sweetness germplasms (YC16, YC17) were identified. The results would provide a theoretical basis and genetic resources for the breeding of high-sugar coffee varieties.
To optimize the fruit thinning technique for loquat cultivated under the net house, the suitable fruit retention per cluster for Guifei (white-fleshed) and Donghuzao (red-fleshed) loquat was determined. 10a top-grafted trees were used as experimental materials, and five treatments with fruit retention per cluster of (3, 4, 5, 6, 7) fruits were set up. The fruit appearance, internal quality, texture, skin color, commercial grade, incidence of pests and diseases, and shoot growth were systematically measured, and a comprehensive evaluation was conducted using principal component analysis. Under net house cultivation, the fruit longitudinal diameter, transverse diameter, and single fruit weight of both varieties significantly decreased with increasing fruit retention per cluster. The decrease in single fruit weight of Donghuzao (23.81%) was significantly greater than that of Guifei (17.67%). Fruit retention per cluster had no significant effect on the internal quality (soluble solids, titratable acidity, etc.), most texture parameters, or skin color of either variety, but significantly regulated fruit commercial grade, pest and disease incidence, and leaf-to-fruit ratio. Fruit retention per cluster was negatively correlated with marketable fruit rate and positively correlated with cluster weight. High load (6-7 fruits per cluster) significantly increased the incidence of fruit rot, purple spot fruit, and the risk of fruit drop. Principal component comprehensive evaluation indicated that for Guifei loquat, retaining 5 fruits per cluster achieved the best comprehensive performance in fruit quality, yield, and tree growth; for Donghuzao loquat, retaining 4 fruits per cluster gave the best comprehensive performance. In conclusion, under net house cultivation conditions, the suitable fruit retention per cluster for 10a Guifei and Donghuzao loquat is 5 and 4 fruits, respectively. The targets achieve a dynamic balance among fruit quality, yield, and tree growth, providing a scientific basis for standardized fruit thinning of net-house-cultivated loquat.
This study addresses the persistent challenges of acidic pH, poor structure, and low fertility in red soils of southern China, which severely constrain agricultural productivity. Although conservation tillage combined with straw mulching is recognized as an ecologically sustainable practice for soil improvement, the quantitative impacts of varying mulch application rates on the spatiotemporal dynamics of soil water, heat, and salt transport, as well as on maize growth, remain poorly understood. To fill this knowledge gap, a two-season field experiment was conducted in a representative red soil region of China, establishing five mulch application treatments: 0 kg/hm2(CK), 6300 kg/hm2(T1), 8300 kg/hm2(T2), 10 300 kg/hm2(T3), and 12 300 kg/hm2(T4). Soil moisture, temperature, electrical conductivity (EC), and total salt content were systematically monitored across soil profiles, alongside key maize growth parameters and final yield. Results demonstrated that mulching significantly enhanced soil water content and temperature, with effects intensifying with increasing application rates. During the seedling stage, the average soil water content in the 0-60 cm soil layer under treatments T1 to T4 increased by 13.37%, 20.35%, 21.45%, and 23.72%, respectively, compared with CK, and the water-retention effect was most pronounced in the 0-20 cm soil layer. However, mulching also induced surface accumulation of salts. EC and total salt content in the 0-20 cm layer significantly increased in a dose-dependent manner, with T4 causing a 177.17% increase in total salt content in the 0-10 cm layer relative to CK. The response of maize growth and yield to mulching amount exhibited a nonlinear relationship: medium and low mulching amounts (T1, T2) significantly promoted the growth of plant height, stem diameter, and leaf area index, synergistically improved yield components such as row number per ear and 1000-kernel weight, with an average yield increase of over 73%; in contrast, although high mulching amounts (T3, T4) showed certain benefits, their yield-increasing effect (31.06% for T3) and growth-promoting effect were significantly lower than those of medium and low mulching treatments, due to the aggravated surface salt stress that hindered root nutrient uptake. Considering both water-retention efficiency and salt control risk comprehensively, under no-tillage conditions in southern red soil regions, the mulching amount of 6300-8300 kg/hm2 is identified as the optimal threshold that balances soil improvement and high maize yield. This study would provide critical quantitative evidence to guide precision conservation tillage management in the red soil regions of southern China.
Clinacanthus nutans (Burm. f.) Lindau is rich in polyphenolic components and has significant medicinal value. Moderate drought stress can regulate the secondary metabolic pathways of plants, thereby promoting the accumulation of bioactive components. To investigate the effect of drought on polyphenol metabolism in C. nutans, plants were subjected to drought stress simulated by polyethylene glycol (PEG) at concentrations of 5%, 10% and 15% for 1, 4, 7 and 10 days. The total phenol and flavonoid contents were quantified by spectrophotometry. For the simultaneous quantification of isovitexin, orientin, isoorientin and schaftoside in the leaves, a high-performance liquid chromatography (HPLC) method was established, and method validation was conducted. The radical-scavenging capacities of the polyphenolic fraction against 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) free radicals and hydroxyl radicals were subsequently assessed. The results indicated that drought stress significantly suppressed the total phenol content relative to the control, but it showed an upward trend as the stress duration increased; total flavonoid content in the 15% PEG treatment group was significantly higher than that in the control on days 1 and 7, and further increased with prolonged stress duration. The highest content in the leaves of C. nutans was schaftoside, followed by isoorientin, isovitexin and orientin. Under 5% PEG treatment, the contents of all four polyphenols increased with prolonged stress duration, with schaftoside, isovitexin and orientin reaching the peak levels on day 10. Isoorientin showed a significant increase compared to the control only on day 10 (5% PEG) and day 1 (10% PEG). Under drought stress, the decline in the in vitro antioxidant capacity of C. nutans leaves correlated with the variation in polyphenol content. Although drought stress decreased overall polyphenol content, it selectively promoted the accumulation of schaftoside, isovitexin and orientin in C. nutans, providing novel metabolic insights for its stress physiology and quality-oriented cultivation.
Coffee is one of the most important beverage crops in the world and plays a significant role in tropical agricultural production systems. However, in recent years, the widespread adoption of large-scale contiguous monoculture farming has led to a yearly increase in the incidence of coffee root rot, severely affecting the development of the industry. To identify the differences in bacterial community structure in the rhizosphere soil between root rot-diseased and healthy coffee plants, and to explore the impact of microbial community changes on disease occurrence, rhizosphere soil samples were collected from a coffee orchard in Lujiang town, Longyang district, Baoshan city, Yunnan province. Five diseased and five healthy coffee plants were randomly selected for sampling. The V3-V4 region of the bacterial 16S rRNA gene was amplified and sequenced using high-throughput sequencing technology. Alpha diversity, beta diversity, and community composition were analyzed. The LEfSe method was applied to identify significantly different biomarkers between groups, and functional prediction was performed. There was no significant difference in alpha diversity of rhizosphere soil bacteria between diseased and healthy plants, but beta diversity differed significantly. The dominant phyla were Pseudomonadota and Actinomycetota, the relative abundance of Bacillota increased in diseased plants, while Pseudomonadota and Actinomycetota were more abundant in healthy plants. At the genus level, Neobacillus was significantly enriched in the rhizosphere soil of diseased plants, whereas beneficial bacteria such as Pseudarthrobacter were dominant in healthy plants. Significant differences were observed in the functional composition of the bacterial communities between the two sample groups, while the core functions remained largely conserved. This suggests that disease occurrence is more likely influenced by shifts in community structure rather than alterations in core functions. The occurrence of coffee root rot is closely associated with changes in the bacterial community structure of the rhizosphere soil, where the enrichment of potential pathogens and the decline of beneficial bacteria may accelerate disease progression.
This study aimed to clarify the spatial distribution characteristics and theoretical sampling techniques of Xylotrechus quadripes Chevrolat in mountainous coffee plantations in Simao district, Pu’er city, Yunnan province, to provide a scientific basis for field sampling surveys, accurate prediction and efficient management of this pest. In 2025, three sample plots were selected in Nandaohe village, Simao district for the experiment. The distribution patterns of X. quadripes larvae, the boreholes and adult emergence holes were investigated through field observation and trunk dissection. The spatial distribution patterns of larvae and emergence holes were analyzed using aggregation indices, Taylor’s power law and Iwao’s m*-m regression analysis, and the aggregation causes were explored by calculating the population aggregation mean. Meanwhile, the theoretical sampling models and sequential sampling models were constructed based on Iwao’s corresponding formulas. X. quadripes larvae were mainly concentrated in the 20–80 cm trunk section of coffee trees. Within the 0–80 cm trunk range, there was no significant difference in the number of boreholes among different sections. The number of emergence holes in the 40–100 cm trunk section was significantly higher than those in the sections below 40 cm and above 120 cm. The diameter at breast height (DBH) of coffee trees presented a weak positive correlation with larval abundance, but an extremely weak correlation with the number of emergence holes. Both larvae and emergence holes of X. quadripes followed an aggregated distribution pattern in the coffee plantations of Simao district, and the aggregation degree was density-dependent. The larval population was distributed in the form of individual colonies with mutual attraction among individuals, while the emergence holes showed mutual repulsion among individuals. The aggregation behavior of X. quadripes was mainly driven by its inherent aggregation habit and environmental factors. The established theoretical sampling models for larvae and emergence holes were N=(t/D)2×(1.102/m+5.944) and N=(t/D)2×(0.200/m+6.829), respectively. The sequential sampling models were $T_{n}=n \pm 1.96 \sqrt{1.102 n+5.944}$ and $T_{n}=n \pm 1.96 \sqrt{0.200 n+6.829}$. This study would enrich the basic data on the spatial distribution of X. quadripes and provide a theoretical reference for the precise field control of this important coffee pest.
Gaodaocao (× Sorghoryza), an emerging forage hybrid characterized by rapid growth, high tillering capacity, and broad cultivation adaptability with significant economic potential, served as the host in this study. We isolated and identified the causal agent of leaf spot disease from infected samples collected in Kunming through tissue culture isolation. The isolate exhibited morphological traits typical of Nigrospora spp., including dense white aerial mycelia and opaque black ellipsoidal conidia measuring (11.81-14.45)μm×(12.17-14.77)μm. Multilocus phylogenetic analysis (ITS, TUB2, EF-1α) confirmed the pathogen as Nigrospora oryzae. Biological characterization revealed optimal growth at 25 ℃ and pH 5.0 under 12 h photoperiod, with glucose and yeast extract as the preferred carbon and nitrogen sources, respectively. The inhibitory effect of the control agent demonstrated significant mycelial growth inhibition by four fungicides, of which prochloraz 450 g/L EW exhibited the highest efficacy with an EC50 value of 0.0205 μg/mL. The findings would provide critical scientific basis for diagnosing and managing leaf spot disease in Gaodaocao.
In order to understand the susceptibility of different rice stem borer species in Guangxi to commonly used insecticides, the rice seedling dipping method was employed to determine the susceptibility of newly hatched larvae of Chilo suppressalis (Walker), Tryporyza incertulas (Walker), Sesamia inferens (Walker) and Chilo auricilius (Dudgeno) to six insecticides in different rice-growing regions of Guangxi. Differences in susceptibility among the same borer species across different regions and among different borer populations within the same region were compared. The results showed that all six tested insecticides exhibited certain insecticidal activity against the four stem borer species, though the toxicities varied interspecifically. In general, spinetoram and emamectin benzoate demonstrated the highest toxicity to all types of stem borers, followed by abamectin and cyantraniliprole, while chlorantraniliprole and indoxacarb showed relatively lower toxicity. Regional comparisons revealed that in Bobai, the susceptibility of T. incertulas to abamectin, chlorantraniliprole, and cyantraniliprole was significantly higher than that of S. inferens. In Yizhou, the susceptibility of T. incertulas to cyantraniliprole was significantly higher than that of C. suppressalis. In Binyang, no significant differences were observed in the susceptibility of C. suppressalis and T. incertulas to all tested insecticides. Additionally, in most rice-growing regions, the susceptibility of different stem borer populations to emamectin benzoate, spinetoram, and indoxacarb showed no significant differences. The results indicate that there are interspecific and regional differences in the susceptibility of rice stem borers to the six insecticides across different rice-growing areas of Guangxi. In practical control, based on the local dominant borer species and historical pesticide use, priority should be given to insecticides with high toxicity and low interspecific variation, and attention should be paid to the rotational use of insecticides with different modes of action.
Continuous cropping obstacle is one of the significant factors restricting the development of the bitter gourd industry. Paddy-upland rotation is an effective measure to mitigate continuous cropping obstacles. Therefore, it is of great importance to conduct research on the impact of paddy-upland rotation on the microbial community structure of the rhizosphere soil of bitter gourd. The rhizosphere soil of bitter gourd was taken as the research object in this study, bitter gourd continuous cropping (CK), bitter gourd-rice rotation with straw removal (SH), and bitter gourd-rice rotation with straw return (SHJG) were established. The incidence of bitter gourd Fusarium wilt and the physical and chemical properties of the soil were investigated during the peak fruiting period. The Illumina Miseq high-throughput sequencing platform was used to detect the changes of the rhizosphere soil microbial community and analyze its relationship with the soil environment factors, and the total yield of bitter gourd in the community was statistically calculated. Compared with CK, the average yield of bitter gourd under the SH and SHJG treatments increased by 16.17% and 20.96% respectively, and the incidence of Fusarium wilt decreased from 17.22% to 3.30% and 2.78%, respectively. Both treatments significantly increased the concentrations of soil organic matter, alkali-hydrolyzable nitrogen, available phosphorus, available potassium, and significantly enhanced the diversity and richness of soil microbial communities. Proteobacteria, Acidobacteriota, Chloroflexi, Gemmatimonadota, Actinobacteriota were the dominant bacterial phyla, Ascomycota, Mortierellomycota, Basidiomycota were the dominant fungal phyla. Both treatments increased the relative abundance of Acidobacteriota, Chloroflexi, Basidiomycota, while reduced the relative abundance of Mortierellomycota, Proteobacteria, Actinobacteriota, Ascomycota. Redundancy analysis indicated that bacterial communities were primarily influenced by disease incidence, available potassium, and pH, while fungal communities were mainly affected by soil organic matter, available potassium, and available phosphorus, the SH and SHJG treatments reduced the incidence of Fusarium wilt and increased the yield by regulating soil pH, enhancing soil nutrients and improving the diversity and richness of soil microbial communities. This study would provide a theoretical basis for clarifying the response mechanism of the rhizosphere soil microbial community of bitter gourd under paddy-upland rotation.
A non-destructive prediction method for the sugar-acid ratio of pineapple fruit was developed to provide a technical basis for the rapid evaluation of internal quality in thick-skinned fruits. Reflectance spectra of pineapple fruit were acquired using a visible/near-infrared hyperspectral imaging system, and the raw spectra were preprocessed by first-order derivative (dA), second-order derivative (ddA), and logarithmic transformation (lgA). Characteristic wavelengths were extracted using Peak-Valley, competitive adaptive reweighted sampling (CARS), and the successive projections algorithm (SPA). Four linear regression models, namely partial least squares regression (PLSR), Ridge, Lasso, and Elastic Net, were then employed to establish prediction models for the sugar-acid ratio of pineapple, and the performances of full-band modeling and feature-selection modeling were compared. Among the full-band models, the lgA-PLSR model achieved the best performance, with a test-set R2 of 0.7774. Based on lgA preprocessing, feature-selection modeling was further conducted. The Peak-Valley method selected 17 characteristic wavelengths, and when combined with Elastic Net and Ridge, the resulting models achieved test-set R2 values of 0.7639 and 0.7634, respectively. The SPA method selected 18 characteristic wavelengths, and the corresponding models exhibited the smallest cross-validation standard deviation (0.078-0.082), indicating good stability. Feature wavelength selection reduced the number of model variables by more than 95% and lowered model complexity while maintaining prediction accuracy. Comprehensive comparison showed that the lgA-Peak-Valley-Elastic Net model exhibited superior overall performance. The results demonstrate that hyperspectral information can be used for effective prediction of the sugar-acid ratio of pineapple.
Pitaya (Hylocereus undatus Britt.) is prone to postharvest deterioration, and low-temperature storage readily induces chilling injury. Current preservation technologies are costly and primarily focused on the postharvest phase. Preharvest cultivation management is critical for regulating postharvest fruit behavior. Traditional preharvest treatments are often characterized by a single mode of action and carry risks of pesticide residue. Carbon dots (CDs), as emerging carbon nanomaterials, possess antibacterial, antioxidant, and plant growth-regulating functions. Nevertheless, the sustained effects throughout the entire “growth-storage” continuum in fruit crops remain unclear. In this study, Taiwan No. 6 pitaya plants were treated during the growing season with different concentrations of biogenic carbon dots (0.01, 0.05, 0.10 mg/L) alone or in combination with compound fertilizer. The effects on fruit quality at harvest and on nutritional quality, antioxidant capacity, and structural integrity during cold storage [(8±2)℃, 21 d] were systematically evaluated. CDs exerted a concentration-dependent effect on the accumulation of primary metabolites in pitaya, characterized by promotion at low concentrations and inhibition at high concentrations. Treatment with 0.05 mg/L CDs significantly increased fruit protein content (33.76 mg/g) and soluble sugar content (9.33%) at harvest, while decreasing titratable acidity thus optimizing the sugar-to-acid ratio to 68.23. In contrast, 0.10 mg/L CDs significantly enhanced the initial total antioxidant capacity (3.28 μmol/g). During storage, the 0.05 mg/L CDs treatment effectively delayed the degradation of protein and soluble sugars, maintained higher total antioxidant capacity, slowed down the reduction in peel thickness, and minimized the reduction in edible rate, demonstrating a significant positive cross-period regulatory effect. Correlation analysis showed that soluble sugar at harvest had an extremely significant negative correlation with crude fiber and a significant negative correlation with pericarp thickness, whereas titratable acid was significantly positively correlated with total antioxidant capacity. After storage, total protein content exhibited a significant positive correlation with total antioxidant capacity. In conclusion, preharvest application of biogenic carbon dots at an optimal concentration can modulate fruit metabolism during development and activate the antioxidant system, thereby sustaining fruit quality and redox homeostasis throughout the storage period. This approach represents a green and efficient strategy that integrates growth regulation and postharvest preservation. This study would provide both a theoretical basis and technical reference for the preharvest quality regulation of tropical fruits and the agricultural application of carbon dots.
