The quality and performance of natural rubber (NR) are closely related to Hevea brasiliensis (rubber tree) varieties, tapping systems, seasonal variation and phenology etc. In order to uncover the annual change rules from April to December of NR qualities among different rubber tree varieties, we investigated the NR qualities from five clones including PR 107, RRIM 600, Reyan 917, Reyan 73397 and Reyan 879 cultivated in Danzhon of Hainan, China, and analysed the vulcanization characteristics and the mechanical properties of the vulcanized NR prepared from the latex harvested in May. The results showed that the mooney viscosity, protein percentage, volatile percentage, Wallace plasticity (P₀) and plasticity retention index (PRI) presented a downward or upward trend in an annual tapping cycle from April to December, which indicates that the NR quality parameters are affected by both genotypes and environmental factors such as weather and sunshine etc. The protein percentage in NR from the latex of the four rubber tree clones was more than 3.0% in December. The cure characteristics of NR from Reyan 917 were totally different from those of the other four rubber trees. Under the same tapping system of S/2 d/3, the tensile strength and the elongation at break of the vulcanized rubber from Reyan 879 was the smallest compared with the other four clones. The results would contribute to instructing the new variety breeding and rubber production on the one hand, and to providing scientific supports for high-performance NR manufacturing on the other hand.

KOH was used as the activator combined with ultrasonic treatment to treat rubber seed shell to prepare activated carbon, and the best preparation conditions were optimized. The surface structure of the chemical carbon was regulated by controlling the preparation and processing conditions. The physical and chemical properties of the active carbon were characterized by specific surface area voidness analyzer, FT-IR, SEM, element analyzer, and TGA. The adsorption capacity of methylene blue and iodine was investigated. The optimal preparation conditions were reagent∶material ratio 1∶1, ultrasonic action for 60 minutes, activation time for 60 minutes, and activation temperature of 700 ℃. Activation temperature had the greatest impact on the adsorption capacity of activated carbon, followed by the reagent to material ratio and ultrasonic time, with the activation time having the smallest impact. The absorption of methylene blue was 400 mg/g, and iodine was 1340.2 mg/g, respectively. The yield was 25.9%, the specific surface area was 1034.5009 m²/g, and the total pore volume was 0.9511 cm³/g with ultrasonic pretreatment (UAC). The adsorption value of methylene blue was 300 mg/g, iodine adsorption value was 894.0 mg/g, yield was 20.8%, specific surface area was 690.2461 m²/g, total pore volume was 0.6830 cm³/g without ultrasoni pretreatment (NAC). Both contained hydroxyl, alcohol hydroxyl and carbonyl functional groups. This is conducive to the enhancement of adsorption performance, and the characteristics of cellulose, hemicellulose and lignin were obvious. The nitrogen adsorption isotherm of the rubber seed shell activated carbon was type Ⅰ. Activated carbon contained a large number of microporous structures with uniform distribution. There was no pore structure on the surface of the rubber seed shell, and there were a large number of pore structures on the activated carbon surface after KOH activation. The surface of UAC activated carbon was smooth and flat, with many rich and regular pore structures. In contrast, the pore surface of NAC had many small pores, and the surface was rough. The carbon (C) content in the rubber seed shells was rich. After KOH activation, the C content of the activated carbon prepared by ultrasonic treatment and activated carbon prepared without ultrasonic treatment increased from 56.81% to 75.97% and 64.89%, respectively. However, the content of hydrogen (H) and nitrogen (N) decreased, making it an excellent raw material for activated carbon. The TGA results indicate that the sample activated by KOH was more stable than the rubber seed shell, and the total weight of UAC and NAC samples tended to stabilize after losing 62% and 68%, respectively. In conclusion, the better performance of the samples prepared by ultrasonic pretreatment indicates that the cavitation effect of ultrasonic wave acts on the structural surface of the activated carbon, causing it to undergo structural changes, thus, the adsorption capability of the active carbon, the specific surface area, etc. are enhanced.

The antioxidant activity, total polyphenol and total flavonoid content differences of local Hainan specialty teas (Moringa Tea, Kuding Tea, Wuzhishan Green Tea, Baisha Green Tea, Wuzhishan Black Tea, Languiren and Partridge Tea) were evaluated. Results revealed significant variations in antioxidant activity among the teas. The antioxidant activity of the tea extract exhibited a dose-dependent relationship with sample concentration and demonstrated excellent thermal stability. The total polyphenol and total flavonoid content of the teas was ranged from 9.80% to 22.84% and 0.90% to 4.67%, respectively, and the total polyphenol content of Wuzhishan Green Tea was the highest, which was 2.33 times that of Moringa Tea. The difference in total polyphenol content of Kuding Tea, Wuzhishan Black Tea, Languiren, and Partridge Tea was not significant, while the total flavonoid content of Wuzhishan Green Tea was the highest, and the total flavonoid content of Wuzhishan Green Tea was 5.18 times that of Moringa Tea. The difference in total flavonoid content of Wuzhishan Black Tea, Languiren, and Partridge Tea was not significant, and the total polyphenol and total flavonoid content of Wuzhishan Green Tea were the highest among the teas. The seven tea extracts had antioxidant reduction ability, and the tea polyphenol content and total flavonoid content showed a good quantitative relationship with the scavenging ability of free radicals. Moringa Tea had the strongest ability to scavenge ABTS, Wuzhishan Black Tea had the strongest ability to scavenge superoxide radicals, and Baisha Green Tea had the best antioxidant effect overall, with the reduction ability, DPPH scavenging ability, hydroxyl radical scavenging ability were the strongest. The antioxidant properties of the seven tea extracts did not change significantly when incubated at different temperature conditions and boiling water, indicating that the seven tea extracts had better thermal stability. This study shows that Hainan specialty teas are rich in total polyphenols and total flavonoids and exhibit strong antioxidant abilities, providing a theoretical foundation for further development and utilization of Hainan specialty teas.

The aim of this study was to explore the protective effect of arecoline on the cell model of H₂O₂-induced oxidative stress damaged model in SH-SY5Y cells and elucidate its mechanism. Cell viability was detected by CCK-8 assay. Spectrophotometry was used to detect LDH release, MDA, SOD, and CAT contents. Flow cytometry was used to detect cell apoptosis and mitochondrial membrane potential. Western blot was used to detect the expressions of Nrf2, HO-1, Keap1, Bcl-2, Bax and Caspase-3. Arecoline could reduce cell apoptosis and significantly increase mitochondrial membrane potential. The level of SOD elucidateand CAT increased while the level of MDA decreased. Arecoline 140 μmol/L group could significantly up-regulate the protein expression of Nrf2, HO-1 and Bcl-2 (P<0.001, P<0.0001), and down-regulate the protein expression of Keap1, Bax and Caspase-3 (P<0.001, P<0.0001). Conclusions: arecoline can effectively improve H₂O₂-induced oxidative stress injury in SH-SY5Y cell by activating the Nrf2/HO-1 signaling pathway, enhancing the activities of antioxidant enzymes and regulating the oxidation reduction system of cells, as well as regulating the Bcl-2/Bax/Caspase-3 signaling pathway and inhibiting cell apoptosis.

Biochar was modified with different concentrations of hydrogen peroxide, and the differences in its structural characteristics were analyzed to study the modification effect of hydrogen peroxide on biochar obtained from banana stem and the effect of modified biochar on Cr absorption of maize under Cr stress. The effects of modified biochar on the growth, Cr uptake and accumulation of maize under Cr stress were studied. With the increase of hydrogen peroxide concentration, the number of oxygen-containing functional groups on the surface of biochar increased, while the aromatics decreased and the polarity increased. After the modification, the surface of biochar was smooth, the pore diameter increased, and the specific surface area and pore volume decreased with the increase of hydrogen peroxide concentration. Modified biochar by 20% and 30% hydrogen peroxide mainly fixed heavy metals through the adsorption of functional groups, reduced its biological activity, and reduced the Cr absorption and accumulation by corn. The study showed that 20% and 30% hydrogen peroxide significantly changed the surface structure of biochar, which was conducive to alleviating the toxicity of heavy metal Cr to corn plants. 30% hydrogen peroxide modified biochar promoted the growth of corn under Cr stress.

The present work was conducted to identify the pathogen causing anthracnose of Liberica coffee (Coffea liberica) plants and to screen fungicides against the disease pathogen. The leaves of C. liberica with anthracnose symptoms were sampled from fields for fungal isolation and purification. Four pure fungal isolates were obtained and only KFTJ01 was verified pathogenic to the coffee leaves by tests following Koch’s Postulates. The rDNA-ITS sequence (554 bp), beta-tubulin gene (tub2) and calmodulin gene (CAL) were successfully amplified via PCR from genomic DNA of KFTJ01 and sequenced. Blastn analysis of the the three DNA sequences showed that KFTJ01 was identical to the strain WZ-135 (99.62%, MN856281), CREADC-ER2212 (100%, MT409131) and YMTJ4 (100%, MK569149) of Colletotrichum kahawae. KFTJ01 was also clustered with C. kahawae WZ-135 strain on the same end-branch of the phylogenic tree (bootstrap confidence is 98%). Therefore, the pathogen of Liberica coffee was identified as C. kahawae which is a quarantine species and has never been recorded in China. Fungicide selection experiments showed that among the 10 chemicals, methionine-acetazolyl and methyl thiobacillam almost completely (100%) suppressed the colony growth of KFTJ01. The median effective concentration calculated from the functions was 0.0607 mg/mL and 0.0809 mg/mL, respectively, indicating that both the chemicals were very effective against the anthracnose pathogen. The results are important references for the field diagnosis of the coffee plant anthracnose and for controlling the disease epidemics.

Hypothenemus hampei is a new invasive pest in China. It is a main coffee pest and poses a great threat to the coffee industry. The purpose of this study is to clarify the biological characteristics and field occurrence rules of the insect, and to provide a theoretical basis for later monitoring and forecasting and comprehensive management of the insect. In this study, the morphological characteristics, developmental duration and fecundity of various developmental stages of H. hampei were observed at each stage in the indoor feeding conditions. The annual life cycle of H. hampei was observed in the field. The population dynamics and spatial distribution patterns of H. hampei in Wanning city, Hainan province were measured through systematic field investigation from 2021 to 2022 to clarify the biological characteristics and field occurrence of H. hampei, and provide a theoretical basis for the subsequent integrated pest management of H. hampei. The results showed that the developmental duration of egg, larval, pupal and adult stage of H. hampei was (6.75±0.65) d, (17.41±1.63) d, (6.45±1.15) d, (42.74±9.55) d, respectively. The average generation duration was (73.35±11.26) d. The main morphological characteristics of each stage were as follows: egg, elliptic, milky white, with smooth and shiny surface; larval, usually “C” shaped, milky white, slightly transparent, with brown head and no feet; pupal, milky white at the initial stage, and later turn brown, the head hidden under the pronotum; adult body, cylindrical, dark brown to black, shiny; male smaller than the female. Female adults usually laid eggs under dark conditions, the number of eggs laid by a single female was 11.85±1.69, and the ratio of male to female was 10.25∶0.95. The results of indoor and field observations showed that H. hampei had seven generations a year in Hainan, and there was no phenomenon of overwintering. The results of the field survey in 2021—2022 showed that the population of H. hampei began to increase slowly from January, and the incidence of H. hampei increased sharply from April to May, reached a maximum of 60.15% and peak in May, and then declined rapidly. In October, it remained at a relatively stable level. The population increased again in November, with another small peak, reaching 19.87%. In December, it decreased, but it showed a slow increase until March of the following year related to the number of fruits. The survey results on space and orientation showed that during the fruit development period, H. hampei preferred the middle layer (0.5-1.0 m) fruit spatially, and preferred the east and north directions in orientation, which may be related to light and temperature. The results of the four aggregation parameters showed that H. hampei belonged to the aggregation distribution in both horizontal and vertical directions.

Potted bitter melon was treated with Bacillus velezensis N46 to explore the mechanism of preventing powdery mildew of bitter melon. The prevention mechanism of N46 was studied by detecting the spore germination rate of powdery mildew pathogen (Podosphaera xanthii), changes in leaf defense enzyme activity, accumulation of reactive oxygen species, cell allergic necrosis, lignin accumulation, changes in the expression of disease-resistance related genes and disease-resistance pathways. The control effect of high concentration (6×10⁸ CFU/mL) of B. velezensis N46 on powdery mildew of bitter melon reached 59.05%. In the N46 treatment group, the range and peak value of the activity of defense enzymes POD, CAT and SOD increased significantly, the accumulation of reactive oxygen species (ROS) increased significantly, the rate of anaphylactic necrosis increased significantly, and the rate of lignin accumulation in cell wall was significantly enhanced. N46 had a significant inhibitory effect on the conidial germination of pathogen powdery mildew. The expression levels of JA reactive marker lipoxygenase gene (LOC111018837), SA reactive marker gene (LOC111017362) and peroxidase gene (LOC111021192) associated with allergic reaction and cell wall strengthening were detected in the N46 treated bitter melon. Compared with the control group, the expression levels of the genes increased significantly when bitter melon was infected with the powdery mildew bacteria, and the expression levels of JA reactive marker genes in the treatment group were also higher than those in the control group when there was no contact with pathogenic bacteria. The results indicated that N46 treated bitter melon maintained a certain level of “preactivation” of resistance genes when it was not exposed to pathogenic bacteria, but showed a higher expression level when it was exposed to pathogenic bacteria. Finally, the JA response pathway was inhibited by ibuprofen (IBU), and the control effect of B. velesiensis N46 on powdery mildew of bitter melon was almost disappeared, suggesting that the generation of N46 induced powdery mildew resistance of bitter melon depended on JA pathway. In conclusion, B. velezensis N46 has a good control effect on powdery mildew of bitter melon by inhibiting the conidium germination of megalomycesfoliata and inducing JA pathway dependent resistance of bitter melon. This study would provide a new method for the biological control of powdery mildew of bitter melon and a theoretical basis for the effect of B. velezensis on the control of powdery mildew of bitter melon.

Fusarium oxysporum f. sp. cubense (Foc), the causal agent of Fusarium wilt (Panama disease), is one of the most devastating diseases of banana (Musa spp.). The Foc race 4 (Foc4) is currently known as a major concern in global banana production. carS is involved in the biosynthesis of Fusarium carotenoid by regulating downstream car structural genes. In this study, Foc4carS (FOIG_05085) was cloned and identified. Foc4carS had a typical RING-finger protein domain. The fusion fragment of Foc4carS was obtained by using Split-marker PCR, and the pUC-fFuCas9-HTB_NLS-hph-Foc4carS gene editing vector containing the sequence of sgRNA591 of Foc4carS was constructed, the PEG- mediated protoplast transformation was used to obtain the knockout mutants, the complement mutants and the gene-editing mutants. The biological characteristics and pathogenicity of the knockout mutants and the complement mutants were analyzed. The results showed that the colony diameter, sporulation and pathogenicity of ΔFoc4carS mutants were not significantly different with wild strain Foc4, but the colony color of ΔFoc4carS mutant was dark orange, deletion of the Foc4carS gene affected the biosynthesis of the secondary metabolite carotenoid, and gene-edited ΔFoc4carS (HDR) mutants showed typical dark orange coloration in both regenerative screening plates and subcultured PDA plates. The results indicated that Foc4carS could be used as an endogenous reporter gene to perform gene plasmid CRISPR/Cas9 editing in F. oxysporum f. sp. cubense Foc4.

Oncidium is an important fresh-cut flower in the market because of its unique flower pattern and brilliant color. The petals of Oncidium are highly susceptible to flower diversity. RNA extraction and transcriptome analysis were performed on the lateral petals of O. flexuosum ‘Honey Angel’ and variants with two lateral petals converted into lips to explore the molecular mechanism regulating the labialization of Oncidium lateral petals. A total of 45 525 415 high-quality reads were obtained from the sequencing results and 52 253 unigenes were identified. The seven databases of NR, Swissprot, PFAM, GO, NT, KO and KOG were used to annotate gene functions and annotated to 31 828, 23 174, 21 369, 21 367, 20 830, 10 523, 6465 unigenes. Upon expression comparison,3120 differential genes were obtained between O. flexuosum ‘Honey Angel’ and the mutant. A total of 1537 differentially expressed genes were annotated into three functional groups: biological processes, cellular components and molecular functions. KEGG functional enrichment analysis enriched 690 differentially expressed genes into different metabolic pathways, with the most genes enriched by metabolic pathway. To date, the study of lip formation in orchids has focused more on the MADS-box gene family, not only five significantly differentially expressed MADS-box genes were screened in this transcriptome data, but also other transcription factor such as NAC, TCP, MYB and WRKY that may be related to the lip formation in Oncidium were also discovered. RT-qPCR was used to verify the expression of key genes, and the quantitative results were consistent with RNA-seq data, most of the genes were highly expressed in the lip-like lateral petals, indicating that the genes may positively regulate the development of the lip of Oncidium. In summary, this study excavated a large number of key transcription factors involved in the variation of labialization in Oncidium, which would provide a certain reference for the study of the molecular mechanism and regulatory network of lip formation of orchid.