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.

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.

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

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 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.

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.

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.

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.

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.

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.