Thioredoxin (TRX), a redox regulatory protein, plays an important role in plant resistance to abiotic stress. In this study, HbTRXo2, a thioredoxin gene, was cloned from rubber tree (Hevea brasiliensis) using RT-PCR. HbTRXo2 contained a coding region of 594 bp encoding a protein of 197 amino acids. The predicted molecular weight and isoelectric point of HbTRXo2 was 21.90 kDa and 7.59, respectively. The conserved domain and phylogenetic analysis showed that HbTRXo2 had a conserved TRX domain and was clustered with other plant o-type thioredoxin, suggesting that HbTRXo2 belonged to o-type thioredoxin. Quantitative real-time PCR indicated that HbTRXo2 gene was expressed in root, bark, latex, mature leaf, senescent leaf, new shoot, female flower and male flower tissues of rubber tree, with significantly higher expression level in latex than in other tissues. Compared with the healthy rubber trees, the expression of HbTRXo2 in the bark and latex of tapping panel dryness trees was significantly reduced. Under cold, polyethylene glycol (PEG)-induced drought, and oxidative stress induced by hydrogen peroxide (H₂O₂) and methyl violet (MV), the expression of HbTRXo2 gene was significantly up-regulated, indicating the involvement of HbTRXo2 in response to abiotic stress in rubber tree. To explore the function of HbTRXo2 in stress resistance, its yeast expression vector was constructed and transferred into Saccharomyces cerevisiae INVSC1 to obtain the recombinant yeast INVSC1 (pYES2-HbTRXo2). The survival differences between the recombinant yeast INVSC1 (pYES2-HbTRXo2) and the control yeast INVSC1 (pYES2) transformed with pYES2 empty vector after H₂O₂, PEG, and low temperature stress treatments were compared, and the results showed that the survival rate of INVSc1 (pYES2-HbTRXo2) was significantly higher than that of INVSC1 (pYES2) after PEG and H₂O₂ treatments, while the survival rate of INVSc1 (pYES2-HbTRXo2) was significantly lower than that of INVSC1 (pYES2) after low temperature stress treatment, indicating that the recombinant yeast transformed with HbTRXo2 gene improved the resistance to drought and oxidative stresses, but decreased the resistance to low temperature stress. The results demonstrate that HbTRXo2 plays an important role in latex production and latex flow, as well as abiotic stress resistance in rubber tree. The study would provide important references for further elucidating the biological function of HbTRXo2 in rubber trees.

The CUT&Tag technology is a new method for protein-DNA interactions, which uses a novel pG-Tn5 transposase with ultra-high activity, to precisely target and cleave DNA sequences near the target protein under antibody guidance, thus enabling cDNA library construction and sequencing analysis. This technology is widely used in human and animal research, but due to the unique structure of plant cells, its application in plant research is relatively limited. In previous studies, we found histone acetylation can participate in the regulation of jasmonic acid induced secondary laticifer differentiation, but the molecular mechanism of histone acetylation modification regulating secondary laticifer differentiation has not been elucidated in rubber tree. In this article, we used the experimental system of secondary laticifer differentiation induced by cornetin (COR) in the vascular cambium by the CUT&Tag technology, and the high quality protoplasts of cambium cells were obtained by enzymolysis, and the Histone H3 acetylation modified antibody was used to identify in situ the region of histone acetylation modification during secondary laticifer differentiation. A cDNA library of cambium cells treatment by COR was successfully constructed using CUT&Tag technology in rubber tree bark. Quality inspection and sequencing analysis were conducted on the construction of cDNA libraries, and found that the quality of libraries were good. And GO and KEGG enrichment analysis of differential genes found the genes related to auxin, flavonoid metabolism, and protein ubiquitination were enriched. The results would provide an operational method for constructing cDNA libraries of plant tissues using CUT&Tag technology, and provide a theoretical basis for elucidating the molecular mechanism of histone acetylation modification regulating secondary laticifer differentiation in rubber tree.

Litchi (Litchi chinensis Sonn.) is one of the important economic crops in subtropical areas. However, it is difficult to store litchi after picking and easy to browning, which is one of the biggest problems in the preservation process. WRKY family is a common transcription factor in plants, which mainly regulates physiological processes such as plant stress response and maturation. In order to research the effect of WRKY on the ripening and senescence process of litchi fruit after harvest, this study took Feiziao litchi as the experimental object, and cloned LcWRKY47 gene. The gene length was 1077 bp. The protein contains WRKY conserved domain. The secondary structure is dominated by random curling, accounting for 65.64%, and the tertiary structure is dominated by random curling and α-helix. Through motif analysis and multiple sequence alignment, LcWRKY47 protein was found to be a class II WRKY transcription factor. Phylogenetic analysis showed that LcWRKY47 in litchi was closely related to DlWRKY47 in longan, which are all classified as Sapindaceae. Subcellular localization experiments showed that LcWRKY47 protein was localized in the nucleus. RT-qPCR analysis showed that after treatment with 2 mmol/L oxalic acid, the expression of LcWRKY47 gene in the peel and pulp of litchi showed the same trend, which increased first and then decreased, and the expression level of LcWRKY47 gene in the treatment group was significantly higher than that in the control group after storage, suggesting that this transcription factor plays a positive role in the regulation of oxalic acid in the ripening and senescence process of litchi fruit. Overexpression of LcWRKY47 gene showed that the expression level of LcWRKY47 in transgenic fruits was significantly higher than that in control fruits, and the senescence process and browning of transgenic litchi was significantly better than that in treatment group. In conclusion, LcWRKY47 transcription factor may play a regulatory role in the senescence and browning process of litchi.

Mango is a typical respiration leap fruit, with vigorous postharvest metabolism and very sensitive to ethylene.CTR1 is a negative regulator of the ethylene signaling pathway and plays a central role in the ethylene signaling pathway. In order to study the possible role of mango CTR1 expression pattern in mango postharvest storage, a CTR gene (MiCTR1) was screened from the Tainung No.1) mango transcriptome database, and its encoded gene was used using biological methods. The protein was sequenced and analyzed, and the expression pattern of MiCTR1 gene during mango ripening and under 1-MCP treatment was analyzed. The results showed that the length of the open reading frame of MiCTR1 was 1551 bp, encoding 516 amino acids, The molecular formula of the predicted protein was C₂₅₀₃H₃₉₃₂N₇₁₂O₇₉₇S₂₆, the total atomic number was 7970, and the weight of the protein was 57.58 kDa, the theoretical isoelectric point (pI) was 5.72, the fat coefficient was 70.78, and the overall average hydrophilicity was -0.596, with 111 phosphorylation sites, and the phosphorylation modification of serine was the main one, supplemented by threonine, had no transmembrane structure and no signal peptide. Subcellular prediction analysis showed that it was located in the nucleus. Protein domain prediction MiCTR1 protein contained a conserved PB1 domain located at amino acid sequence 189-285. Phylogenetic analysis showed that MiCTR1 was closely related to Prunus dulcis, Prunus persica, Prunus avium, Prunus armeniaca, Prunus mume. The results of fluorescence quantitative PCR showed that the relative expression of MiCTR1 increased during the ripening process of mango, and 1-MCP down-regulated its expression. In this study, the MiCTR1 gene was cloned in mango and its biological analysis was analyzed, and its expression pattern during postharvest storage was analyzed, which would provide a basis for the molecular mechanism of mango ripening.

Mango (Mangifera indica L.) is an important tropical fruit in Hainan province. Ethylene plays a vital role in the ripening process of mango. ERF transcription factors are key downstream components of the ethylene signaling pathway, and as one of the largest families of transcription factors, they play a role in regulating signal transduction and physiological responses. To investigate the impact of ERF transcription factors on the coloration of postharvest mango peels, this study focused on the Guifei mango as the research subject. Through PCR cloning, the MiERF3 gene was obtained, and bioinformatics methods were used to analyze its basic physicochemical characteristics, conserved domains, protein structure, and evolutionary relationships. Real-time quantitative PCR (qRT-PCR) technology was then employed to analyze the specific expression of the MiERF3 gene in different tissues of mango and during postharvest storage periods. The results indicated that MiERF3 was 717 bp in length, encoding 238 amino acids. The protein had a molecular formula of C₁₁₃₀H₁₇₆₃N₃₃₉O₃₅₅S₉, a molecular weight of 26.066 kDa, and a theoretical isoelectric point of 8.62, with 30 positively charged residues and 27 negatively charged residues. The protein exhibited hydrophilic properties and a structurally unstable nature. MiERF3 protein had no a signal peptide and transmembrane region, with threonine being the primary site for phosphorylation modification. It contained an AP2 conserved domain, and its secondary structure was primarily composed of 61.67% random curl, along with 27.75% α-helix, 3.96% β-fold, and 6.61% extended chain. The three-dimensional structural model of MiERF3 contained three β-fold and one α-helix, consistent with the characteristics of the AP2 structural domain. Multi-sequence alignment and motif analysis suggested that MiERF3 belonged to the ERF subfamily. Based on phylogenetic analysis, the protein most closely related to MiERF3 was PvERF3-like from Pistacia vera, a plant belonging to the same family as mango. Onion subcellular localization and transcriptional self-activation assays showed that MiERF3 was localized in the nucleus and had transcriptional self-activating activity. Quantitative real-time fluorescence analysis showed that the expression of MiERF3 varied among different mango tissues, with the highest expression observed in the sunny side peel of mango fruit. During storage, the expression of MiERF3 showed a clear trend of initial increase followed by decrease, suspecting that MiERF3 may play a positive regulatory role in the process of fruit ripening and color change. This study would provide a theoretical basis for revealing the regulatory role of ERF transcription factors in postharvest ripening and senescence of mango.

MinD is involved in the fine regulation of plastid division and plays a key role in maintaining plastid morphology. Previous laboratory research found that the MeMinD protein is involved in the division of cassava plastids, but the related proteins that work in conjunction with MeMinD to regulate the division of cassava plastids have not been clearly identified. This study constructed the pGBKT7-MeMinD vector and, through yeast two-hybrid library screening, a total of 8 candidate interacting proteins of MeMinD were obtained; after point-to-point verification using the yeast two-hybrid system, it was found that the nicotinate phosphoribosyltransferase 2 (MeNAPRT2) interacts with MeMinD. The results of this study would provide new information for further analysis of the mechanism of MeMinD's participation in the regulation of cassava plastid splitting.

Understanding the expression regulation mechanisms of enzymes related to starch synthesis in cassava can significantly advance the molecular breeding for high yield and high starch content. Prior research has uncovered that the auxin-responsive gene, MeSAUR1, upregulates the expression of MeAGPS1a, a gene encoding the small subunit of the key starch-synthesizing enzyme, AGPase. Yeast two-hybrid screening identified a Yippee protein family member, MeYippee1, as a candidate interacting protein with MeSAUR1. In this study, the coding region of the MeYippee1 gene from cassava variety SC8 was cloned. The gene was 321 bp in the coding region, lacking introns, encoding a protein of 106 amino acids, with four predicted phosphorylation sites. Expression analysis in different tissues and organs revealed that MeYippee1 was most highly expressed in axillary buds, followed by fibrous roots, storage roots, and mature leaves, while expression levels were lower in stems and petioles, and the lowest in apical buds and young leaves. Expression analysis during the different developmental stages of the storage root showed that MeYippee1 expression was primarily during the formation phase of the storage roots. Further point-to-point yeast two-hybrid verification indicated an interactive relationship between MeYippee1 and MeSAUR1 proteins. The results would provide new insights into the molecular mechanism underlying the positive regulation of MeAGPS1a expression by MeSAUR1.

Cytoplasmic invertase (CIN) irreversibly hydrolyzes sucrose into glucose and fructose and plays an important role in the development of roots in various model plants. Presently, there is no research on the CIN gene family in sweetpotato (Ipomoea batatas) and the role of IbCINs in the development of storage roots of sweetpotato remains to be elucidated. This study systematically identified the types and quantities of IbCIN gene family. Physicochemical properties, chromosome localization, phylogeny, gene structure and conserved motifs, promoter cis elements of IbCINs were also analyzed. Simultaneously, through the expression analysis of IbCINs in different tissues and different types of roots, and the activity analysis of CIN in different types of roots, several candidate CIN genes were identified that play an important role in the development of storage roots of sweetpotato. A total of 12 IbCIN genes (IbCIN1-12) were identified from the genome of sweetpotato, distributing on 8 chromosomes. The number of amino acids of IbCIN-encoded protein was 417-825 aa, the molecular weightwas 46.60-93.75 kDa, and the isoelectric point was 4.83-7.17. Phylogenetic analysis revealed that IbCINs could be divided into three groups, α1, α2 and β groups, comprising 1, 3 and 8 members, respectively. α1 and α2 members were very conservative in conserved motifs and gene structures, while β memberswere less conservative, which indicating that β group may have more diverse function than the other two groups, allowing β members to participate in more biological processes. In addition, phylogenetic analysis also revealed that IbCIN1, IbCIN7, IbCIN10 and IbCIN12 were closely related to CIN genes related to root development in Arabidopsis and cassava, suggesting that the four genes may play important roles in the development of non-storage root of sweetpotato. The analysis of the expression levels of IbCINs in different tissue (young leaves, mature leaves, stems, flowers, 60 d storage roots) and different types of roots (white fiber roots, red fiber roots, pencil roots and 60 d storage roots) showed that IbCIN4, IbCIN8 and IbCIN11 had the highest expression levels in storage roots, and simultaneously the CIN activity in storage roots was significantly higher than that in non-storage roots. Thus, it can be speculated that the three genes may play an important role in the development of storage roots of sweetpotato. Bioinformatics analysis further revealed that IbCIN4, IbCIN8 and IbCIN11 may jointly promote the development of storage roots via different mechanisms, including facilitating sucrose transport to and subsequent degradation in storage roots, attenuating photoperiod response and signal transduction of gibberellin. This study could lay a foundation for further research on the function of IbCIN genes through transgenic technology.

The plant resources from nine islands of Xisha Yongle Islands and Xuande Islands (including Yongxing Island, Shi Island, Zhaoshu Island, Dong Island, Zhongjian Island, Jinyin Island, Chenhang Island, Guangjin Island and Shanhu Island) were surveyed in 2021 to 2023. Through field survey, specimen collection and identification, and literature review, 11 plants belonging to 10 genera in 8 families were recorded for the first time. The voucher specimens are deposited in the herbarium of Chinese Academy of Tropical Agricultural Sciences (ATCH). This study would provide important information for the plant resources of Xisha Islands.

Yinggeling area of the National Park of Hainan Tropical Rainforest preserves the largest and most intact tropical rainforest in South China. It is extraordinarily rich in fungal species, especially the fungi of Boletales with important ecological, scientific and economic values. Nearly 300 specimens of Boletales were collected from Yinggeling area in the past 10 years. On the basis of morphology, molecular phylogenetic analyses, ecological characteristics, and geographical information, a total of 82 species of Boletales, belonging to 37 genera and 5 families, have been identified. Among them, 2 genera and 26 species were typified from Yinggeling, 2 were new to China, and 20 were new to Hainan Province. In the Boletales in Yinggeling area, the only dominant family, with more than 10 species, was Boletaceae, accounting for 91.46% of the total species. There were 6 dominant genera (Aureoboletus, Boletellus, Neoboletus, Phylloporus, Strobilomyces, and Tylopilus), with more than 5 species, haboring 48.78% of the total species of this Order. Among the Boletales species from Yinggeling area, 20, 4, and 8 are considered to be edible, medicinal and poisonous mushrooms, respectively.

The 16S rRNA high-throughput sequencing analysis was conducted on the rhizosphere soil of Cassava South China No.12 under treatment without fertilization (CK), organic fertilizer (T₁), conventional fertilization applied with organic fertilizer (T₂), and reduced chemical fertilizer applied with organic fertilizer (T₃) by using the Illumina Nova 6000 sequencing platform to study the effects of chemical fertilizer application combined with organic fertilizer on the growth of cassava and the bacterial diversity and community structure in cassava rhizospheric soil. T₃ not only significantly increased the height and stem thickness of cassava, but also improved the yield of cassava, compared to CK. Cluster analysis was performed on the sequences based on 97% similarity, the OTUs numbers of CK, T₁, T₂ and T₃ are 3603, 1688, 1276 and 3317 respectively. Different fertilization methods altered the diversity and richness of soil bacteria, with the species diversity ranked from highest to lowest as CK>T₃>T₁>T₂. Based on PCoA and cluster analysis, the community composition of CK and T₃ was similar, the community composition of T₁ and T₂ was similar. The dominant phylum in cassava rhizospheric soil under different fertilization treatments were Proteobacteria, Bacteroidetes, Acidobacteria, Firmicutes, Actinobacteria and Chloroflexi. The relative abundance of Proteobacteria, Bacteroidetes and Actinobacteria increased under T₃ treatment, while the relative abundance of Firmicutes and Chloroflexi decreased. Redundancy analysis results indicated that available potassium was the main factor affecting the bacterial community in the cassava rhizosphere soil. In summary, the study demonstrates that reduced chemical fertilizer application combined with organic fertilizer not only increases the yield of cassava, but also changes the community structure and diversity of the bacterial in the rhizosphere soil. The results would provide a solid theoretical foundation for the development of a green, efficient, and sustainable cassava industry.

Hyper-spectral remote sensing technology was used to explore the estimation method of nitrogen content in the leaves of macadamia to achieve a rapid diagnosis of nitrogen nutrition in macadamia trees. Lincang and Xishuangbanna were chosen as the research area to obtain the spectral reflectance and nitrogen content of the leaves of macadamia varieties O.C and HAES344. Firstly, multiple mathematical transformations were performed on the original spectral reflectance using logarithmic transformation, derivative transformation, and their combinations. Then, the correlation between nitrogen content of macadamia leaves and spectral data of different transformation forms was analyzed. Under the principle of larger determination coefficient, the wavelength corresponding to the peak characteristic point in the determination coefficient curve was selected as the nitrogen sensitive wavelength, thus the corresponding spectral variables of nitrogen sensitivity were obtained. Stepwise regression was used to further optimize the nitrogen sensitive spectral variables, and the methods of multiple linear regression (MLR), partial least squares regression (PLSR), and support vector regression (SVR) were used to construct the nitrogen content estimation models for macadamia leaves. Finally, the performance of the models was tested using validation and test sets, respectively. The results showed that the MLR, PLSR and SVR models all performed well in estimation, and the ratio of performance to standard deviate (RPD) of both the validation and test sets were above 2.0. Among them, the PLSR was the optimal estimation model, its RPD of the validation set and the test set was 2.099 and 2.110, respectively. The 19 nitrogen sensitive spectral variables selected from 6 types of transformation spectral data, including reflectance (R), logarithmic transformation of reflectance (LR), first derivative of reflectance (FDR), first derivative of logarithmic transformation of reflectance (FDLR), second derivative of reflectance (SDR), and second derivative of logarithmic transformation of reflectance (SDLR) had strong stability in nitrogen spectral response. Based on the selected 19 nitrogen sensitive spectral variables, the conventional regression modeling methods could achieve good estimation results and had strong regional universality. In this study, nitrogen sensitive spectral variables were selected from a variety of transform spectral data, which provided a new idea for the nitrogen content estimation of macadamia leaves.

Hainan is the main producing area of noni in China. Short-term waterlogging stress is caused by typhoons occuring frequently in summer. However, there are few studies on the physiological response of noni to short-term waterlogging stress and after stress relief, and the effect of stress on yield is still unclear. In this study, Noni seedlings growing for 6 months were used as the experimental materials, and short-term waterlogging stress was simulated by potted continuous immersion for 15 days. Dry weight, net photosynthetic rate (P_n), proline (Pro) content of leaves, root activity (TTC), root malondialdehyde (MDA), peroxidase (POD) and superoxide dismutase (SOD) were measured at 1st, 3rd, 7th, 10th and 15th days after waterlogging. The relevant indexes were measured on the 1st, 7th and 15th day after stress relief, and the yield of waterlogged and non-waterlogged plots in the main producing areas was measured for 3 consecutive years. The results showed that the physiological response of Noni after waterlogging stress was rapid. Compared with non-waterlogging control treatment, the net photosynthetic rate of leaves decreased on the 1st day of waterlogging, the content of Pro increased, the content of MDA in roots increased, the root activity decreased, and the activities of antioxidant enzymes such as POD and SOD increased. All the indexes changed significantly in the first 7 days. However, after 7 days, the changes of TTC and SOD activity of roots remained significant, but the changes of other indexes were slow, indicating that leaves and roots gradually adopted corresponding strategies to adapt to waterlogging stress. The biomass root shoot ratio of Noni remained unchanged at the initial stage of waterlogging, but decreased significantly after 3 days, which also reflected that Noni plants had responded to waterlogging stress in a short period of time. After the stress was relieved, the physiological processes gradually recovered, and at 15 days, Noni photosynthesis and root activity basically recovered, but the content of peroxides such as MDA was still significantly higher than that of the control, indicating that the toxic effect of peroxides formed under early stress was difficult to eliminate in the short term. The multi-year yield of main producing areas shows that short-term but frequent waterlogging stress can lead to a significant decrease in yield, which is 21.64%–35.21%, which may be related to peroxide toxicity caused by stress. In summary, short-term waterlogging stress not only has a great impact on the physiological process of noni during stress, but also its adverse effects persisted for a long time after the stress is lifted, thereby affecting crop growth and yield. Therefore, for planting noni, the plots with higher terrain and better drainage should be in priority. In water-prone planting areas, water should be drained within 72 hours to minimize the adverse impact.

The study was aimed to explore the resistance to Colletotrichum siamense, dominant specie of rubber tree induced by Burkholderia arboris DHR18. The enzyme activity changes on the treatments of different concentrations of DHR18 fermentation broth and co-treatments of DHR18 with C. siamense CH-1 using rubber clone GT1 were studied. Five defensive enzymes including catalase (CAT), peroxidase (POD), phenylalanin ammonialyase (PAL), and superoxide dismutase (SOD) were assayed. Results indicated that treatments with 1×10⁸ CFU/mL, 1×10⁷ CFU/mL, 1×10⁶ CFU/mL of DHR18 fermentation broth showed significant higher activities of CAT, POD, PAL, SOD and PPO in rubber leaves compared to the control group. The enzyme activities with broth concentration 1×10⁷ CFU/mL were the highest. The activity peak of the five enzymes was 1 009.14, 29 138.67, 110.24, 902.42 and 148.00 U/g, respectively, which was 2.68, 3.35, 1.88, 3.97 and 4.51 times of the control group, respectively. Under the co-treatments of B. arboris DHR18 and C. siamense CH-1, treatment group inoculated with DHR18 fermentation broth before inoculated with CH-1, the enzyme activities were higher than other co-treatment groups, and significantly higher than that of the control group. Activity peak of CAT, POD, PAL, SOD and PPO was 1 230.85, 45 504.67, 117.53, 1 342.17 and 134.40 U/g, respectively. They were 4.56, 3.10, 2.04, 3.28 and 5.98 times that of the control group, respectively; The plate inhibition rate of strain DHR18 against C. siamense was 71.56%, the preventive effect against C. siamense on rubber saplings was 81.79%, and the control effect was 44.35%. The results showed that Burkholderia arboris DHR18 could promote the activity of defense-related enzymes in rubber trees and induce systemic resistance in rubber trees. The induced resistance may be one of the reasons for the control of C. siamense by B. arboris DHR18.

A new cassava variety Gui 1289 with excellent comprehensive traits such as good plant type, high yield, high starch, and wide adaptability was bred by systematic breeding procedures using SC5 as the maternal parent and SC205 as the paternal parent. The average yield of fresh roots for this variety was 49.92 t/hm² in regional test over the years, which was 24.21% higher than that of the control NZ 199. The average yield of fresh roots was 50.76 t/hm² in production test, which was 21.26% higher than that of NZ 199. The average starch content in regional test over the years was 30.22 g/100 g, an increase of 5.42 g/100 g compared to NZ 199. The average starch content in production test over the years was 29.96 g/100 g, an increase of 5.57 g/100 g compared to NZ 199. The field test of Tetranychus cinnabarinus showed moderate resistance. It is suitable for popularization in cassava planting areas such as Guangxi, Guangdong, Hainan and Jiangxi, and so on. This study would provide a new germplasm resource for achieving high-quality production of cassava in China, which is of great significance to increase the income of the farmers and increase the efficiency of enterprises

The microbial community of fruit peel tissues helps to improve fruit quality and resistance to pathogens. There are few reports on the community structure and diversity of endophytic microbes of pitaya peel tissues. This study analyzed the composition and diversity of the endophytic microbial communities in the peel tissues of young healthy fruits and diseased fruits at the early stage of canker disease, and predicted microbial functions to understand the characteristics, through Illumina MiSeq high-throughput sequencing technology. The results showed that there was no significant difference in the diversity and structure of the endophytic bacterial and fungal communities between healthy and diseased peel tissues of pitaya young fruits. In the peel tissues of healthy fruits, Proteobacteria, Actinobacteriota, Firmicutes, Bacteroidota, Deinococcota, Desulfobacteriota and Chloroflexi were the dominant bacterial phyla, and Ascomycota, unclassified_k_Fungi, Basidiomycota and Mucoromycota were the dominant fungal phyla. In the early stage of canker disease, the bacterial phyla Proteobacteria, Actinobacteriota and Deinococcota, as well as fungal phylum Ascomycota, significantly decreased, while bacterial phylum Desulfobacteriota and fungal phylum unclassified_k_Fungi significantly increased in average relative abundance. Compared with the healthy fruits peel, with differences in the proportion of the above microbes, the expression levels of chemoheterotrophy, aerobic chemoheterotrophy, methylotrophic and methanol oxidation functions of endophytic bacteria in diseased fruits peel significantly decreased, the proportion of potentially_pathogenic groups of endophytic bacteria significantly increased, the proportion of saprotroph, pathotroph, pathotroph symbiotroph of endophytic fungi significantly decreased, and the proportion of unknown trophic fungi significantly increased. The results would provide biological information on the endophytic microbes in pitaya fruits peel, to reveal the role in the occurrence of pitaya canker disease and provide theoretical basis for utilizing the function of beneficial microorganisms.

The pathogen of pitaya stem rot in Guangxi was isolated by the tissue separation method and the microbial control of the disease was selected. According to Koch’s rule, the pathogenicity was verified by in vitro experiments, and the pathogenic species were identified by the morphological and multi-gene sequence analysis. Then, the biocontrol bacteria were screened by the plate confrontation method. The results showed that two pathogenic fungi, Lasiodiplodia pseudotheobromae and Neoscytalidium dimidiatum, were isolated from the decayed stems of pitaya, of which L. pseudotheobromae was the first reported to cause pitaya stem rot in China. Taking L. pseudotheobromae PY6 as the target pathogen, Bacillus subtilis L3-4 with the best control effect was obtained from 34 strains of pitaya endophytes screened, which could make the mycelium of PY6 entangled and broken. The sterile fermentation filtrate and the sterile fermentation broth after 100 ℃ treatment had antibacterial effect, and the prevention effect could reach 72.08% and 71.16%, respectively. But it did not produce volatile compounds that inhibited the growth of PY6 strain. In addition, strain L3-4 exhibited inhibition to Botryosphaeria dothidea, Fusarium pseudograminearum, F. oxysporum and N. dimidiatum with inhibition rate 77.65%, 73.13%, 64.07% and 62.01%, respectively. This study clarified the pathogenic pathogen responsible for pitaya stem rot in Guangxi. The screened biocontrol bacteria could be used as candidate strain for controlling pitaya stem rot. The result would provide a theoretical basis for diagnosing and biologically controlling pitaya stem rot.

Sisal hybrid variety of H.11648 is the main cultivated commercial variety in China. Despite of its ability to produce high fibre yield per unit area, this variety is highly susceptible to diseases. Sisal zebra disease, caused by Phytophthora nicotianae is among the diseases of economic importance affecting the variety. Several control measures like the adoption of good agricultural practices, the use of disease resistant variety and the use of chemical control are suggested in sisal zebra disease control. However, none of them seem to be sustainable due to the existing agricultural practices. Most of the existing measures are not only time-consuming but also costly due to labor intensification and high cost of purchasing agricultural chemicals which on another hand can pollute the environment and create resistance to the plants. Developing resistance variety will obviously take long time due to the long life cycle of sisal. It is very important to develop sustainable disease control methods which are environmental friendly to adopt the climate change agenda. The use of microorganisms to control the diseases is of great importance. In this study, an antagonistic strain PaHNHK01 was successfully isolated by using Phytophthora nicotianae as the target pathogen. PaHNHK01 was identified as Pseudomonas aeruginosa based on morphological, physiological and biochemical characteristics and gene sequence analysis. The antibacterial activity and control effect of PaHNHK01 were measured under in vitro condition. The results showed that, PaHNHK01 had the ability of organophosphorus and inorganic phosphorus, nitrogen fixation and iron production. Additionally, PAHNHK01 had the inhibition rate of 89.79% against P. nicotianae. The fungus effectively inhibited the mycelial growth of P. nicotianae, and the antagonistic pathogens showed decreased sporulation ability, mycelial enlargement deformity and increased branching. The control effect of PaHNHK01 on sisal zebra disease in vitro was 88.62%. PaHNHK01 aseptic fermentation liquid had obvious bacteriostatic effect on pathogenic bacteria, and its EC₅₀ value was 20.3679 μL/mL. When the concentration of PaHNHK01 crude extract was 80 μg/mL, the antibacterial rate was 89.36%, and the EC₅₀ value of PaHNHK01 crude extract was 11.9456 μg/mL. We further observed the antagonistic effects of the strain PaHNHK01 on 13 different plant pathogens, indicating that the strain PaHNHK01 had good biocontrol potential and could be developed as a biocontrol product. The results would provide a strong research basis for the biological control of sisal zebra disease.

Meloidogyne enterolobii is a soil-borne disease that seriously harms crop production in tropical areas, and the agricultural losses caused by it are incalculable every year. For the control of root-knot nematodes, the traditional physical and chemical control methods have some disadvantages, while biological control is environmentally friendly and safe for people and livestock, so it has gradually become a research hotspot. This study used the impregnation method to screen strains with killing activity against the second instar larvae of M. enterolobii. The fermentation conditions and treatment time of the screened highly active strains were optimized. The strains were identified using 16S rRNA sequencing as well as physiological and biochemical methods, and growth promoting characteristics were analyzed. The research results indicated that the nematicidal activity of the fermentation supernatant of BWLY1PSB-1, BWLY2X-4 and BWLY3X-11 were more than 65%. Through morphological, physiological and biochemical characteristics, and molecular biology identification, BWLY1PSB-1, BWLY2X-4 and BWLY3X-11 were identified as Staphylococcus pateuri, Bacillus methylotrophicus and Bacillus sp., respectively; The nematicidal activity of the fermentation supernatant of each strain could reach the maximum after 24 h treatment of nematodes, and the optimal fermentation medium was LB medium, and the nematicidal activity of the supernatant reached relatively high when cultured for five days. The research results on the growth promoting characteristics of thee strains indicated that BWLY1PSB-1 had the ability to produce iron carriers and IAA, while BWLY2X-4 and BWLY3X-11 had the ability to produce proteases, cellulases, iron carriers, and IAA. The preliminary screening of excellent strains that can effectively control plant root-knot nematodes and have rowth promoting characteristics would enrich the microbial resources for the biological control of plant root-knot nematodes.

Calix[4]arene, a class of host compounds, is capable of forming host-guest compounds with guest molecules through hydrogen bonding, electrostatic forces, or van der Waals forces. With the incorporation of sulfur atoms into the molecular structure of calix[4]arene, the cavity size of calix[4]arene would increase. At the same time, sulfur atoms offer strong coordination abilities to trace amounts of variable metallic ions (Mn²⁺, Cu²⁺) presented in natural rubber. The complexes prepared by sulfothiacalix[4]arene salt and metal ions can mitigate catalytic effects of variable metallic ions on the aging reactions of natural rubber, thus improving the thermal oxidative aging performance of natural rubber. Sulfothiacalix[4]arene was synthesized and the protective effect of sulfothiacalix[4]arene on the thermo-oxidative aging behavior of natural rubber was investigated by means of FTIR, DSC, TGA and so on. After the experiment, compared with the samples without the addition of sulfothiacalix[4]arene, it was found that the signals of O-H, C=O and C=C in the FTIR spectra of the samples with the addition group were weakened, the thermo-oxidative aging temperatures on the DSC curve were increased by about 18.87 ℃ and 29.90 ℃, and the epitaxial initial thermal decomposition temperatures in TGA were increased by 11.82 ℃ and 15.03 ℃, respectively. It is concluded that sulfothiacalix[4]arene could be used as a highly effective anti-aging agent in the thermo-oxidative aging of natural rubber.

Coconut meat is the main raw material for coconut products processing, which is mainly obtained by importing dehusked coconut fruits in containers, and the rate of bad fruit is high in the process of transportation and storage. In order to explore the method of rapid differentiation and identification, this study used gas chromatography-ion mobility spectrometry (GC-IMS) combined with principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) to analyze the volatile compounds in coconut meat of unstored normal dehusked fresh coconut fruits (FCM) and deteriorated dehusked coconut fruits under 25 ℃/70%, 35 ℃/80% and 45 ℃/90% (DCM-25, DCM-35 and DCM-45). The results showed that 42 volatile compounds were identified in the four coconut meat, including thirteen alcohols, five acids, eight ketones, ten esters, four aldehydes, two pyrazines and three unknown compounds. The alcohols were the most (including ethanol, butanol and propanol, etc.), followed by acids (including acetic acid and 2-methylpropionic acid, etc.), ketones (including acetone, 3-hydroxy-2-butanone and cyclopentanone, etc.), esters (including butyl caproate, ethyl acetate, butyl butyrate and ethyl butyrate, etc.), aldehydes (including 3-methylbutyraldehyde, pentalaldehyde and heptyl aldehyde, etc.) and pyrazines (2-ethyl-3-methylpyrazine). After deterioration, alcohol, acid and ketone volatile compounds increased. Thirteen characteristic volatile compounds, including 3-methylbutyral, cyclopentanone, 3-methylbutanol monomer, butanol monomer, heptaldehyde, acetone, 2-methylpropanol monomer, 2-heptanone monomer, heptanic acid, butyl butyrate monomer, ethyl acetate, ethanol dimer and 2-ethyl-3-methylpyrazine monomer, were analyzed by OPLS-DA, with variable importance in projection greater than 1. The characteristic volatile compounds in FCM were cyclopentanone and butanol monomer by differential heat map. The characteristic volatile compounds in DCM-25 were 2-heptanone monomer, butyl butyrate monomer, ethyl acetate, ethanol dimer and 2-ethyl-3-methylpyrazine monomer (mainly esters, alcohols and ketones). The characteristic volatile compounds in DCM-35 was heptanoic acid (mainly acids). The characteristic volatile compounds in DCM-45 were 3-methylbutyraldehyde, heptyl aldehyde and acetone (mainly aldehydes and ketones). This study would provide theoretical basis for the screening of deteriorated dehusked coconut fruits.

The pericarp color, browning-related enzyme activity and variations in phenolic compounds during the browning process of litchi pericarp were evaluated to investigate the alterations in ingredients caused by pericarp browning of two litchi varieties (Guiwei and Yuhebao) during storage. The indicators were comprehensively evaluated using correlation analysis and principal component analysis. The results showed that at a storage temperature of 4 ℃, the pericarp of Yuhebao was more likely to brown than that of Guiwei. After being stored for three days, the pericarp of Yuhebao exhibited noticeable browning, but Guiwei only displayed a similar phenomenon after seven days of storage. Over the period of 0-14 days of storage, both Guiwei and Yuhebao showed a decline in the total phenolic, flavonoid and proanthocyanidin levels in the pericarps due to browning. Both Guiwei and Yuhebao pericarps exhibited an increased trend in pH value, with the lower rise rate in pH value of Guiwei pericarp compared with that of Yuhebao. Additionally, the level of polyphenol oxidase (PPO) activity in the pericarps of both litchis exhibited a declining pattern, with a more pronounced decline observed in Yuhebao compared to Guiwei. The peroxidase (POD) enzyme activity in the two litchi pericarps exhibited a little decline, whereas the POD enzyme activity in the Yuhebao pericarp was approximately 1.33 times higher than that of Guiwei. Correlation analysis and principal component analysis revealed that total phenols, flavonoids, PPO and pH value were found to have a significant correlation with the browning color of the two litchi varieties. There was a noticeable correlation between the selected litchi varieties and the browning process, indicating distinct differences in the browning status of the pericarp. The findings of this study could offer fundamental data support for future research on suppressing the browning phenomena of litchi pericarp, extracting and processing phenolic active compounds from litchi pericarp.

The accurate identification of sugarcane stem nodes is of significant value for intelligent seed cutting, planting positioning, optimizing the production management process of sugarcane gardens, and improving yields and economic benefits. However, existing sugarcane stem node detection methods still have shortcomings in terms of performance, model complexity, and real-time performance. In order to effectively solve this problem, this study chose to use the advanced YOLOv8 model to visually detect sugarcane stem nodes in a structured scene. First, a field sugarcane image collection experiment was designed, the collected sugarcane images were manually labeled, and an image training set and a test set were established. Then, the YOLOv8 network was used as the sugarcane stem node detection model to determine the optimal hyperparameter combination and conduct model training. Finally, actual recognition experiments in the field are conducted to verify the effectiveness and efficiency of this method. Experimental results show that the precision, recall, mAP, single-frame inference time and model size of our method on the test set are 0.973, 0.958, 0.974,19.80 ms and 6.30 MB respectively. Compared with the Edgeyolo_S_Coco network and Edgeyolo_Tiny network, the mAP value of the YOLOv8_n network has increased by 1.70% and 1.30% respectively, the single-frame inference time has been reduced by 4.71 ms and 1.50 ms respectively, and the model size has been reduced by 33.70 MB and 17.50 MB respectively. This method has advantages in detection performance and generalization ability, and can effectively meet the requirements for algorithm accuracy and model complexity in outdoor environments, providing solid technical support for sugarcane harvesting and planting in intelligent agricultural production.

This study aims to screen the microbial strains capable of producing β-D-glucosidase from fermented vanilla pods and apply the screened strains to the fermentation process of vanilla with the goal of enhancing vanillin production and improving the quality of vanilla bean. Septenary selective medium was utilized to isolate β-D-glucosidase producing bacteria, identify the homology of each bacterial strain and measure the production of β-D-glucosidase activity of each strain on two strains with higher enzyme production. The phylogenetic tree was constructed. The two strains of bacteria with the highest enzyme production in different combinations were sprayed onto the fermented vanilla pods. The content of vanillin, vanillin glucoside, and volatile components in different treatments of β-D-glucosidase producing bacteria were determined. Nine strains were successfully screened from the vanilla pods originating in Madagascar (M), and twelve strains were isolated from the vanilla pods produced by Spice and Beverage Research Institute, Chinese Academy of Tropical Agricultural Sciences (S). The fifteen strains were detected as Bacillus. M3 and S7 had higher enzyme activities than other isolates. Vanilla pods treated with M3 obtained the highest vanillin content, which reached to 2.25% and possed the highest aroma components. The maximum decrease in vanillin glucoside content was 80.7% when sprayed with M3 and S7 in a volume ratio of 1:1. There were 34 volatile substances in the fermented pods sprayed with M3, making it the most volatile combination of spraying bacteria. In the present study, we successfully isolated β-D-glucosidase producing bacteria for improving the quality of vanilla pods fermentation.