Natural rubber latex (NRL) is susceptible to spoilage, and current high ammonia preservation systems have serious contamination problems. In this study, NRL was preserved by thione derivative LS, and the preservation effect on NRL was investigated. The volatile fatty acid value (VFA No.) and viscosity value of LS-preserved fresh latex were relatively low, and the preservation effect of LS at 0.1% was better than that of 0.25% ammonia. LS-ammonia composite preservation was used to prepare low-ammonia concentrated natural rubber latex (CNRL), and CNRL could be preserved stably for 180 days by the dosage at 0.01%~0.05%. The preserved low-ammonia CNRL had low VFA No. and good stability, and all the indexes met the requirements of production. The stability of the preserved low ammonia CNRL was outstanding, and all the indexes met the current production application requirements. The LS-ammonia composite preserved low ammonia CNRL also had excellent physicochemical and film-forming properties, and the tensile strength and tear strength of the vulcanized film were generally better than those of the current high ammonia preserved CNRL vulcanized film. By infrared absorption spectroscopy, the structure of the preservative LS-ammonia composite preserved low ammonia CNRLvulcanized film did not change significantly; thermal analysis showed that the thermal stability of the vulcanized film was basically the same as that of the high ammonia CNRL film. In addition, the safety analysis showed that the LS-ammonia composite preserved low ammonia CNRL dry rubber film did not have potential toxic effects. There was no skin irritation reaction, and the safety was better. The preservative LS has excellent preservation effect on NRL, and the composite preservation preparation of low ammonia CNRL has good performance, which can be used in the production of a variety of pure rubber products, and at the same time, the low cost has a broad application prospect.

To study the differences in the physical and chemical properties of biochar obtained from three legumes at different temperatures, and to determine the appropriate temperature range for legume biochar. Using leguminous plant peanut straw, soybean straw and stylofoam as raw materials, peanut straw biochar (Pe), soybean straw biochar (Be) and stylofoam biochar (St) were prepared at 300 ℃, 500 ℃ and 700 ℃. A Fourier infrared spectrometer was used to qualitatively analyze the functional groups on the surface of the biochar, and the surface morphology of the biochar was observed with a scanning electron microscope, and the physical and chemical properties, such as pH, C and N content, were measured. The results showed that the carbon content of biochar prepared from three kinds of raw materials increased with the increase of pyrolysis temperature at 300 ℃ to 500 ℃, and was basically stable after 500 ℃; the nitrogen content and yield of biochar decreased with the increase of temperature. Among the biomass charcoal prepared from the three materials, Be has the highest carbon content and C/N, and N content and yield are the lowest. The ash content, ash alkalinity and pH of biochar all increase with the increase of pyrolysis temperature. The same pyrolysis ash alkalinity and pH of biochar all increase with the increase of pyrolysis temperature. The same pyrolysis temperature and different materials are all expressed as Be>St>Pe. Both the pore size and specific surface area of biochar increase with increasing temperature. The three raw materials of biochar form more stable aromatic compounds with increasing temperature, and the structure is mainly C=O and C=C. In this study, the suitable pyrolysis temperature of legume biochar is 500 ℃, and the temperature rises again, which has little effect on the physical and chemical properties of biochar. In summary, the soybean biochar produced by cracking at 500 ℃ is more used in farmland soil improvement, and can also try soil remediation, carbon sequestration and emission reduction applications.

Chalcone synthase (CHS) is the first limiting enzyme in flavonoid synthesis pathway and plays an important role in flower color formation, growth and development, and abiotic stress. In order to clarify the characteristics of cassava MeCHS gene family and its expression in cassava postharvest physiological deterioration (PPD), the MeCHS gene family was analyzed using bioinformatics, including physicochemical property and subcellular location. qRT-PCR was carried out to detect the expression levels of MeCHS genes in different varieties, different tissues and PPD process. The genes with significant relative expression were selected for cloning and subcellular localization verification. A total of 5 MeCHS gene members were identified in the cassava genome. The secondary structure analysis showed that the MeCHS gene family was mainly composed of α-helices and random coils. Tissue specific expression indicated that the expression levels of MeCHS genes were higher in stems. The major expressed MeCHS genes in cassava were MeCHS1, MeCHS2 and MeCHS3; and the expression levels of these three genes were gradually increase with PPD. MeCHS1, MeCHS2 and MeCHS3 were successfully cloned; and fluorescence transient expression showed that MeCHS1, MeCHS2 and MeCHS3 were localized in the cytoplasm, which was consistent with the predicted results. This study will provide a theoretical basis for further revealing the function of MeCHS gene family and improving the PPD tolerance of cassava.

Rubber tree (Hevea brasiliensis) is the only renewable resource among the four major industrial raw materials. The rubber tree anthracnose which infected by the Colletotrichum sp. is one of the most serious foliar disease of rubber production in China. In this study, we investigated the main rubber tree varieties (strains) and monitoring the occurrence and prevalence of anthracnose in Hainan province. It was found that PR107 and RRIM600 had the largest planting area, accounting for 51.06% (102 000 hm²) and 43.39% (86 700 hm²) respectively. The anthracnose of mature rubber plantations and value-added nurseries in Yangjiang Farm was occurred all year round, with the peak period from March to April; Therefore, the rubber tree planted in Hainan province was large, and the variety (strain) was single, so it was easy to break out and spread when the anthracnose was suitable. HCkHNQZ1736 isolated from the leaves of the rubber nursery of Yangjiang Farm in Qiongzhong County, was identified as a new strain of Colletotrichum karstii, which had highly pathogenic to four main varieties of rubber tree, PR107, RRIM600, Reyan 7-33-97 and Dafeng 95. Studied on the results of carbendazim and prochloraz-manganese sensitivity test of HCkHNQZ1736 and MeCkYN1705 showed that the two strains had no resistance to prochloraz-manganese, while the EC₅₀ was 0.0784 μg/mL and 0.0775 μg/mL respectively. However, HCkHNQZ1736 showed high resistance to carbendazim, at this time, the EC₅₀ was 1107.2654 μg/mL, while MeCkYN1705 had only 0.0554 μg/mL.

Cell wall degrading enzymes are important pathogenic factors of many pathogenic fungi, among which xylanase, as the most important hemicellulase, plays an important role in the process of host cell wall degrading by filamentous fungi to achieve host infection. In this study, RT-PCR was used to clone the coding region of xylanase GpTR1774 gene of Ganoderma pseudoferreum strain HD3 and analyze its bioinformatics. The root of Hevea tissue cultured seedlings Reyan 73397 were infected with HD3, meanwhile infection and destruction process of root cells were observed by electron microscopy. The gene expression of GpTR1774 was determined by qRT-PCR. The results showed that the total length of GpTR1774 cDNA was 780 bp, encoding 259 amino acids, among which the most abundant amino acid was alanine (Ala), accounting for 15.1%. The molecular weight of GpTR1774 protein was 28.12 kDa, fat coefficient was 81.93, and the isoelectric point was 9.07. It was a hydrophilic protein with 15 phosphorylation sites, no signal and peptide transmembrane domain, and was located in the cell solute. The main components of the secondary structureα-helix and random curling are the main components of the secondary structure of GpTR1774 protein, accounting for 38.10% and 41.31% of the amino acid sequence, respectively. Phylogenetic analysis showed that GpTR1774 gene had the highest similarity with xylanase gene of Ganoderma boninense, reaching 87.5%. qRT-PCR showed that the overall gene expression trend of xylanase GpTR1774 was firstly increased and then decreased. The expression level of GPTR1774 increased significantly on the 3rd and 4th day after infection, and reached the highest level on the 4th day, about 16 times of the initial level. The results of this study indicate that the xylanase GpTR1774 gene was likely to be involved in the pathogenesis of G. psedoferreum, providing reference for the pathogenesis analysis and green prevention and control of G. psedoferreum.

Polysaccharide is a quality marker of Polygonatum odoratum, which has significant pharmacological effects in immune regulation and anti-tumor. As one of the key enzymes in polysaccharide synthesis, sucrosesynthase (SUS) has always been an important research field to reveal the synthesis of plant polysaccharides. Based on transcriptom data of Polygonatum odoratum, the SUS gene family members were identified by bioinformatics, and their expression profiling were analyzed using qPCR. The results showed that eight PoSUS gene were identified, their protein ranged from 111 to 310 amino acid residues (aa) in length, and relative molecular weight varied from 12.81 kDa to 35.43 kDa, isoelectric point (pI) in the range of 5.83 to 9.18; phylogenetic analysis indicated that eight PoSUS genes were divided into 3 subfamily, and the subfamily Ⅲ included the largest PoSUS genes family member; subcellural localization analysis showed that most of PoSUS proteins were located in chloroplast. Additionally, expression patterns analysis revealed that PoSUS1 and PoSUS6 genes were preferably expressed in rhizome, and the transcript levels of PoSUS1 and PoSUS2 were higher in high-polysaccharide cultivar HN1 than those in a low-polysaccharide cultivar AH2. In addition, the CDS of PoSUS1 gene were cloned from HN1 and AH2, there are three amino acid difference between HN1 and AH2, which located in sucrose synthase domain. Our findings can laid a basis for the further study of functional analysis of SUS genes, and provided a theoretical basis for analyzing molecular mechanism of the formation mechanism of medicinal quality of Polygonatum odoratum.

Marine actinomycetes possess great capacity in producing special metabolites due to their special environment and unique properties in physiological characters and genetic background. In this study, sponge was used as isolation material to explore the resources of symbiotic actinomycetes with antibacterial activity. Firstly, an active actinomycetes strain, ITBB-ZK-a5, was isolated and purified from the sample of Xisha sponge by plate separation method. The strain was identified as Streptomyces by analysis of the phylogenetic tree based on 16S rRNA gene sequence and colony morphological characteristics. Secondly, the inhibitory spectrum of strain ITBB-ZK-a5 against plant pathogenic fungi was studied by plate confrontation method. The results showed that ITBB-ZK-a5 had a broad antibacterial spectrum, in which the 16 tested pathogenic fungi were inhibited significantly. ITBB-ZK-a5 also showed good antibacterial activity in 14 days and 30 days. In order to explore the reason why strain ITBB-ZK-a5 can inhibit the growth of pathogenic bacteria, the antibacterial activity of asepsis agar from the ITBB-ZK-a5 edge were determined, and the results showed that the antibacterial rate were negatively correlated with colony distance. This result revealed that actinomycetes maybe can secrete active substances to inhibit the growth of pathogenic bacteria. Thirdly, the strain had a good antibacterial stability by detecting the antimicrobial activity of five continuously dynasties. Again, light stability and thermal stability of the ITBB-ZK-a5 crude extracts from the rice solid fermentation were tested through the filter method; the results show that with the increase of bath temperature and UV duration, the antibacterial activity of the strain ITBB-ZK-a5 crude extracts were decreased. Finally, the EC₅₀ value of strain ITBB-ZK-a5 against anthrax diseases of banana and papaya were determined. Plant diseases infected by fungi are the main agricultural diseases, and chemical pesticides are the most commonly used method in diseases control. However, the widespread use of chemical pesticides will not only enhance crop resistance to drugs, but also cause pollution to the ecological environment. More importantly, pesticide residues also have a certain influence on human health. Therefore, the common goal of the world is to find more green, efficient and safe control methods. Actinomycetes are found to have biological control effects. The symbiotic actinomycetes isolated from sponges have an inhibitory effect on pathogenic fungi of tropical crops, which can be applied to efficient diseases control, conforming to the concept of green environmental protection. In this paper, we isolated and identified the strain ITBB-ZK-a5, symbiotic actinomycetes from South China Sea sponge, which has the activity of inhibiting pathogenic fungi of various tropical crops, and studied its antibacterial activity, providing a research basis for the development and utilization of biocontrol strains in the future.

Cassava leaves are rich in abundant flavonols, and efficient extraction and analysis methods are crucial for the evaluation of flavonol content in the cassava leaves. This study aims to optimize the extraction and detection methods for four flavonols (myricetin, rutin, nicotiflorin, narcissoside) in cassava leaves and to analyze the influence of different cassava varieties, harvesting periods, and maturity on the content of these flavonols. The results indicated that using a 50% ethanol-water solution, a liquid-to-material ratio of 1∶50 (g/mL), an ultrasonic extraction temperature of 50 ℃, and an ultrasonic extraction time of 60 minutes could effectively extract the four flavonols in the cassava leaves. The combination of different C18 chromatographic columns in HPLC-DAD effectively separated the four flavonoids present in the cassava leaves. The results of the method validation showed that the four flavonols exhibited good linear correlations within a certain concentration range, with R² values of 0.9999, 0.9999, 0.9999 and 0.9998, respectively. The detection limits ranged from 6.0 mg/kg to 10.0 mg/kg, and the quantification limits ranged from 20.0 mg/kg to 32.0 mg/kg. The detection method demonstrates good system adaptability, with retention time and peak area relative standard deviations (RSD) being less than 1%. The samples showed good stability in terms of intra-day, inter-day, and intra-month variations, with RSD in content variations ranging from 0.44% to 3.57%. The average recovery rates of the method ranged from 92.68% to 109.14%, all with RSD values less than 6.0%. Utilizing the established extraction and analysis methods, the study analyzed the content of the four flavonols in 30 cassava germplasm resources. Rutin and nicotiflorin maked up 93.50% to 99.30% of the total flavonol content in the cassava leaves, with the levels primarily determining the total flavonol content. However, the correlation order for the total flavonol content among different varieties was rutin>narcissoside>nicotiflorin>myricetin. Analysis of flavonol content in the cassava leaves from different harvest times and maturity levels of cassava germplasm revealed that in most cases, the levels of rutin, nicotiflorin and narcissoside were higher in the leaves harvested at 270 days compared to those harvested at 180 days, with myricetin varying by variety. Except for SC09, the levels of myricetin, rutin and nicotiflorin were higher in the young leaves compared to the tender and mature leaves in different cassava germplasms. The content of narcissoside in mature leaves (except for flower leaf cassava) was higher than that in young leaves and tender leaves. The results would provide an evaluation basis for the development and utilization of cassava flavonols in the selection of raw materials and quality control, and lay a foundation for revealing the accumulation rules of cassava flavonols.

Cassava (Manihot esculenta Crantz) is the sixth-largest food crop in the world, nearly 700 million people in the world tropical regions take it as the primary food source, and it is also an important raw material for the production of starch, modified starch, fuel ethanol and other chemical products and feed in China. It plays an important role in eradicating hunger, poverty alleviation and rural revitalization in tropical areas. Cassava root is rich in starch, which can provide energy for livestock and poultry growth. Cassava stems and leaves are rich in protein, cellulose and vitamins and other nutrients, thereby becoming a high-quality protein feed resource. Energy value of cassava is similar to that of corn, thus boasting great development potential as the feed. In recent years, it has achieved good results in the breeding of livestock and poultry such as pigs, sheep and chickens. Therefore, it is of great significance of using cassava as energy feed and replacing corn and other raw materials to mitigating competition for food between human beings and livestock and improve the economic benefits of breeding. This article comprehensively analyzed the nutritional value of cassava and the research progress of its feed application, and put forward specific suggestions for further research and utilization to provide reference for the development of cassava feed industry in the future.

Cassava is an important food crop, energy crop and industrial raw material. Cassava mealybug (Phenacoccus manihoti Matile-Ferrero) is a dangerous quarantine pest in the world, the cultivation and utilization of insect-resistant cassava cultivars can effectively block its colonization. Mining insect-resistant secondary metabolites and the regulatory genes is one of the important strategies for insect-resistant breeding. Flavonoids are unique secondary metabolites for plants to resist biotic and abiotic stresses, but the function of flavonoids and the synthesis pathway genes in cassava resistance to cassava mealybug is still unclear. Based on this, this study analyzed the expression levels of flavonoid synthesis pathway-related genes (CHS, CHI, FLS, LAR, DFR, F3H, CCoAOMT, C4H, C3'H and ANR) and flavonoid content in the leaves of insect-resistant (C1115, SC9, Myanmar) and insect-susceptible (KU50, SC205 and Bread) cassava cultivars after being damaged by cassava mealybug for different time (0, 1, 4, 8 d). Although the expression of CCoAOMT, C3'H, ANR and C4H in the leaf was up-regulated after feeding, there was no significant difference compared with that before damage, and there was no significant difference in the expression level between the resistant and susceptible cassava cultivars. In contrast, the expression levels of CHS, CHI, FLS, F3H, DFR and LAR genes were significantly higher than those before damage, and in the same damage time, the expression levels of the six genes in the insect-resistant cassava cultivars were also significantly higher than those in the insect-susceptible cassava cultivars. Further correlation analysis showed that the expression levels of CHS, CHI, FLS, F3H and LAR genes were significantly positively correlated with the insect resistance of cassava cultivars. In addition, the results of total flavonoid content determination showed that the total flavonoid content increased significantly after one day of damage compared with that before damage, and the total flavonoid content of insect-resistant cassava cultivars was significantly higher than that of the insect-susceptible cassava cultivars after 4 days of damage. Correlation analysis showed that the total flavonoid content was also significantly positively correlated with the insect resistance of cassava cultivars. Therefore, it is speculated that the increase of flavonoid content and the significantly up-regulation of CHS, CHI, FLS, F3H and LAR in the insect-resistant cassava cultivars may be related to the resistance to cassava mealybug. This study would provide an important preliminary basis for the in-depth analysis of the molecular mechanism of flavonoid synthesis genes regulating the insect-resistant defense response of cassava to mealybug, as well as the molecular design and breeding of cassava insect-resistant.