Artocarpus heterophyllus is popular for its sweet fruit and has a very promising market, but conventional seed propagation makes it difficult to maintain its excellent traits and the grafting method has a very low survival rate. The technique of tissue culture and rapid propagation has been widely used in the propagation of many rare and valuable plants, but there are no reports of its application in the production of A. heterophyllus. In the process of tissue culture, it was found that the stem tip of A. heterophyllus was severely browned, which led to the difficulty of establishing asexual reproduction system. In order to effectively investigate the measures to overcome the browning, this experiment took the stem tips of A. heterophyllus 'Haida 2' as the explants and inoculated them into different concentrations of PVP medium after low-temperature pretreatment at different lengths for primary culture, the browning rate and germination rate were calculated after 15 d, and PPO activity, total phenol and total flavonoid content were determined to explore the inhibition of different concentrations of PVP on browning in stem the tip tissue culture of A. heterophyllus after low-temperature pretreatment. The results showed that the browning rate of A. heterophyllus explants was the lowest and the germination rate was the highest after 12-24 h low-temperature treatment of stem tip and then in 1/2MS medium supplemented with 2.0 g/L PVP. The experimental results showed that this method was beneficial to the proliferation of A. heterophyllus explants. The purpose of this experiment is to promote the establishment of technique of tissue culture and rapid propagation for A. heterophyllus, with a view to providing a theoretical basis for the construction of the A. heterophyllus seedling breeding technology system and its industrial production demonstration.

Gynostemma pentaphyllum is an important medicine-food homology plant. It enjoys the reputation of 'Southern ginseng' as it contains compounds of ginsenosides. As wild resources of G. pentaphyllum depleted gradually, artificial introduction and cultivation of G. pentaphyllum has become an inevitable trend. However, due to soil irrigation, fertilization, and pesticide use, problems such as unstable quality of medicinal materials and excessive heavy metal content in G. pentaphyllum occur from time to time, which seriously affects its standardized cultivation and the quality and safety of medicinal materials. Hydroponic production has the advantages of short cycle, high yield, no continuous cropping obstacles, and can effectively avoid heavy metal pollution, so it is widely used in the production of various Chinese medicinal materials. In this study, G. pentaphyllum seedlings were treated with different nutrient solution, temperature, light intensity and photoperiod. After that, growth characteristics and accumulation of total saponins of G. pentaphyllum were examined to obtain the most suitable hydroponics conditions, and thus provide reference and technical support for the large-scale production and organic cultivation of G. pentaphyllum. The results showed that Japanese Yamzaki formula with pH value 6.0 was the best nutrient solution for hydroponics of G. pentaphyllum. Correlation analysis showed that under different nutrient solution conditions, the total saponin content of single plant was highly positively correlated with plant height, leaf length, leaf width, number of leaves, fresh weight per plant and dry weight per plant, indicating that the cultivation of high-biomass plants was the key of the cultivation of high-quality plants of G. pentaphyllum. Under variable temperature of 20 to 30 ℃, photoperiod of 10 to 14 hours of light per day, and light intensity of 100 μmol/(m²·s), seedlings of G. pentaphyllum grew well and the total saponin content of the dry samples exceeded 3%, which was higher than the existing standards. This study would provide a scientific basis for the realization of double precise control of production and quality of G. pentaphyllum, and lay the foundation for the future research on large-scale production and quality standards of it.

To select suitable slow-release fertilizers for sugarcane productions the endophytic bacterial community structure in the stems of sugarcane under different slow-release fertilizer applications were analyzed. Based on high-throughput sequencing techniques, the endophytic bacterial community structure in the stems of sugarcanes among conventional fertilization (CK) and different slow-release fertilizers (A-F treatments) were analyzed. In comparison with CK, the diversity of the endophytic bacteria in the stems of sugarcanes was significantly increased by adding long- acting agent (235 g/t) and synergist (3 g/t and 18 g/t), but the richness of the endophytic bacteria in the stems of sugarcanes was not significantly improved by slow-release fertilizer applications except adding long-acting agent (235 g/t) treatment C. Meanwhile, Herbaspirillum was the specific endophytic dominant bacterial genus in CK. Sporocytophaga and Cellvibrio were the unique endophytic dominant bacterial genera in the slow-release fertilizer adding long-acting agent (125 g/t) treatment A. However, no specific endophytic dominant bacterial genera could be found in the slow-release fertilizer adding long-acting agent (150 g/t) treatment B. Norank_f__SC-I-84, norank_f__Neisseriaceae, norank_f__JG30-KF-AS9 and Massilia were the specific endophytic dominant bacterial genera in the slow-release fertilizer adding long-acting agent (235 g/t) treatment C. Brevundimonas, Enterobacter, Staphylococcus were the unique endophytic dominant bacterial genera in the slow-release fertilizer adding synergist (3 g/t) treatment D. Cloacibacterium was the specific endophytic dominant bacterial genus in the slow-release fertilizer adding synergist (8 g/t) treatment E. And unclassified_f__Burkholderiaceae, Paenibacillus, Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, Corynebacterium_1, Chryseobacterium were the specific endophytic dominant bacterial genera in the slow-release fertilizer of adding synergist (18 g/t) treatment F. Furthermore, the functions of the endophytic bacteria in the stems of sugarcanes did not show significantly different between CK and applications of slow-release fertilizer treatments. In comparison with CK, the diversity of the endophytic bacteria in the stems of sugarcanes was significantly increased by adding longacting agent (235 g/t) and synergist (3 g/t and 18 g/t), but the richness only could be significantly improved by application with slow-release fertilizer adding with long-acting agent (235 g/t) treatment C. Except of slow-release fertilizers +long-term agent (150 g/t) treatment B, specific endophytic bacterial genera in the stems of sugarcanes all could be detected under slow-release fertilizer applications. Although the whole functions of the endophytic bacteria in the stems of sugarcanes were not significantly altered by slow-release fertilizer applications, higher stress resistant abilities could be concluded in sugarcanes under most of slow-release fertilizer applications (B-F treatments). Among them, the highest promotion and stress resistant effect on sugarcanes growth was the slow-release fertilizer + 235 g/t long-acting agent treatment (C) according to the composition and function of endophytic bacteria in stems of sugarcanes.

Thielaviopsis paradoxa is harmful to almost all palm plants, among which stem bleeding of coconut is the most serious, and no effective and safe control method is available. Among the biocontrol bacteria screened in the early stage of this study, Pseudomonas aeruginosa wrj-2-5 and Alcaligenes faecalis brj-21 were proved to have biocontrol potential against T. paradoxa. In order to determine the specific inhibitory effect of P. aeruginosa and A. faecalis on T. paradoxa, T. paradoxa was used as the target strain to determine the bacteriostatic effect, indoor control effect and fermentation conditions of the biocontrol strains wrj-2-5 and brj-21. The results showed that wrj-2-5 and brj-21 both had a bacteriostatic rate of more than 70% against T. paradoxa. In vitro experiment found that the two bacteria still had good bacteriostasis. The lesion area of the treatment group was significantly smaller than that of the control group. Earlier inoculation would lead to better effect. In addition, the strains had strong inhibitory effect on other pathogenic bacteria of coconut leaf spot, fruit rot, gray spot and heart rot. The optimal fermentation condition of wrj-2-5 was rotation speed 180 r/min, temperature 28 ℃, culture time 36 h, initial pH value 6.0-8.0, and inoculum amount 8%. The optimal fermentation condition of strain brj-21 was inoculum amount 8%, the initial pH value 6.0-8.0, rotation speed 180 r/min, temperature 28-32 ℃, and incubation time 24 h. In conclusion, wrj-2-5 and brj-21 have good control effects on the stem bleeding of coconut and fruit rot of coconut caused by T. paradoxa. They also have a certain inhibitory effect on the pathogens of other coconut diseases, which would provide an important reference for the green and biological control of T. paradoxa.

Internal browning (IB) seriously restricts the development of pineapple industry. Its occurrence is mainly from excessive reactive oxygen species (ROS) causing membrane damage, which breaks the original compartmentalization between plastid polyphenol oxidase (PPO) and phenolic substrates in vacuoles. It polymerizes into quinones after contact with oxidation. The antioxidant clearance system is able to remove excess ROS and maintain the dynamic balance of ROS in the body. In early time, our laboratory used ascorbic acid (AsA) which can effectively delay the deterioration of IB of 'Pairs' pieapple. But the reaction mechanism of AsA is not clear. Ascorbate peroxidases (APX, EC1.1.11.1) are heme-binding enzymes that reduce hydrogen peroxide (H₂O₂) to water using AsA as an electron donor. It is involved in various developmental physiological processes and stress responses in plants. In this study, we selected six APX genes with AsA as the substrate in pineapple to analyze the occurrence process and the ascorbate transcript level changes after the AsA treatment. AcAPX1 was significantly upregulated at 9 d and 12 d after AsA treatment and was significantly different from the control group. It showed that AsA significantly enhanced the AcAPX1 expression. Correlation analysis showed that the incidence index of black heart disease was significantly positively correlated with the AcAPX1 expression level. It is speculated that this gene may play an important role in AsA delaying IB with pineapple. To further explore the mechanism of action, AcAPX1 was cloned from the pineapple pulp. The physicochemical properties and protein domain were analyzed by bioinformatics analysis. The results showed that the open reading frame length was 753 bp, encoding 250 amino acids. The predicted molecular weight of the protein was 27.410 87 kDa, and the theoretical isoelectric point was 5.52. There was no transmembrane helix region, which was a stable hydrophilic protein. Amino acid sequence alignment analysis showed that AcAPX1 of pineapple shared more than 85% homology with papaya, banana, coconut and oil palm. The functional domain analysis of AcAPX1 showed that it had heme binding sites, K⁺ binding sites and substrate binding sites (superfamily: cl00196), belonging to the members of the plant peroxidase superfamily. Cloning of AcAPX1 is of great significance for studying the molecular mechanism of its antioxidant capacity in pineapple and the control of internal browning. This study would lay a foundation for further exploring the molecular mechanism of pineapple AcAPX1 involved in AsA clearing ROS and delaying the deterioration of internal browning.

To gain insight into the genetic diversity and relationship of the tropic bioenergy plant physic nut (Jatropha curcas L.) in Yunnan, China, joint analysis of agronomic and molecular characters was performed in the present study, using different accessions collected from nine sources/geographical provenances in Yunnan. To investigate the population polymorphism, eight pairs of SSR molecular markers were developed by MISA program, and four of them with higher polymorphism were selected for PCR amplification using 95 DNA samples collected from nine populations. The results indicated that JC01 exhibited the best polymorphism (0.711). UPGMA clustering analysis suggested that Baoshan and Xishuangbanna might serve as the parents or origins of physic nut in Yunnan, which was partially related to the geographical origin of populations. Comprehensive investigations revealed among all examined biological traits of seeds or seedlings, the underground fresh weight (UFW) exhibited the highest coefficient of variation, with obvious separation among populations. Two individual seedlings with extreme variance in UFW (BNMH and CXYM) were selected for RAD-based genomic sequencing, while 2783 and 3033 contigs were assembled. Analysis of genome assembly data using GenomeScope revealed that both materials were diploid, and a total 22 756 valid SNPs were detected at the whole genome level using genome-wide association study (GWAS). High frequency-SNPs associated with UFW preferably located on LG9, and three candidate proteins were linked to the UFW trait. The results indicated that the physic nut germplasm collected from different regions of Yunnan exhibited a high level of genetic diversity and uniqueness, which should facilitate further studies on its molecular breeding.

Low-ammonia concentrated natural rubber latex (CNRL) can alleviate the ammonia contamination problem caused by high-ammonia CNRL to a certain extent, and is gaining wider and wider application in a variety of CNRL products. In this study, four CNRL preservatives, BCT-2, HY, HM and LS, were used to prepare low ammonia CNRL, and the differences between the performances of low ammonia CNRL in different preserved systems were investigated by comparison with high ammonia CNRL. The results showed that the four preservation systems had good effect on the preservation of low ammonia CNRL, and all of them could meet the requirements of GB/T 8289—2016 national standard. Among them, the low ammonia CNRL preserved by BCT-2 had the lowest volatile fatty acid value (VFA No.), but the viscosity value was the highest, the lowest mechanical stability (MST); in addition, the average particle size of rubber particles was higher; the thermal stability and zinc oxide mechanical stability (ZST) were lower; the dry rubber film strength was higher. The low ammonia CNRL preserved by HY had the lowest VFA No., the lowest viscosity, highest MST and thermal stability; the fastest pre-cure speed; pre-cure latex with the lowest viscosity, highest MST and thermal stability; higher strength of vulcanized rubber film. HM preserved low ammonia CNRL with lower viscosity; higher MST and good stability; the lowest dry rubber film strength; the slowest pre-cure speed. LS preserved low ammonia CNRL with higher VFA No. and higher viscosity value; lower MST and poor stability; the smallest rubber particle size; the highest concentrated latex dry rubber film and vulcanized rubber film strength; the best dry rubber film thermal stability. Contrast analysis showed that HY and LS saved better overall performance of low ammonia CNRL, where HY low ammonia CNRL was suitable for the production of foam products, adhesives, etc., while LS low ammonia CNRL was suitable for the production of gloves, balloons and other pure rubber impregnated products.

Eucalyptus urophylla × E. grandis is a hybrid of Eucalyptus grandis (♂) and Eucalyptus urophylla (♀). It has the advantages of rapid growth, straight trunk, high yield, short rotation period, easy to germinate, strong adaptability and so on. So it has become the main cultivated tree species in the key forest areas, important commercial timber forest bases and forest products industrial bases of Yunnan Province. Due to its endogenous plant growth inhibitors, the disposal of wood processing residues has not yet been effectively solved. In this study, urea, manure from chicken and sheep, EM bacteria and enzyme bacteria were added to Eucalyptus bark for decomposing fermentation to promote the degradation of its endogenous inhibitors, making it an organic substrate with similar physical and chemical properties to peat. In order to reveal the effects of three levels of decomposed Eucalyptus bark (raw/40-day/60-day) compounding with three volume ratios (10%, 20% and 30%) of perlite on the enzymatic activity at plant seedling stage, four crops (Lycopersicon esculentum, Brassica oleracea, Lactuca sativa and Moringa oleifera) were cultivated in a greenhouse using the two-factor and three-level experimental design. After 6-8 weeks of growth, the activity of six enzymes associated with carbon and nitrogen metabolism (SS, SPS, Rubisco, GS, GOGAT, NR) in the leaves was determined. The results showed that the decomposition level and the proportion of perlite had the extremely significant interaction on the SPS activities of L. esculentum, B. oleracea and L. sativa (P<0.01). On the whole, the activity of enzymes related to nitrogen metabolism was more affected by the decomposition level than those related to carbon metabolism. The enzymatic activity of the three vegetables in 60-day-decomposed Eucalyptus bark were significantly higher than those in the control peat, raw Eucalyptus bark and 40-day-decomposed Eucalyptus bark (P<0.05). Among them, the enzyme activity of L. sativa in compound 30% perlite was significantly higher (P<0.05). In addition, the enzymatic activity of the three vegetables in 40-day-decomposed Eucalyptus bark compounding with 20% perlite were significantly higher than those in peat (P<0.05). The enzymatic activity of M. oleifera in peat was significantly higher than that in Eucalyptus bark substrate (P<0.05), and that in raw Eucalyptus bark was significantly higher than that in decomposed Eucalyptus bark. Besides, the mechanism of endogenous compounds in Eucalyptus bark influence on the activity of enzymes related to carbon and nitrogen metabolism during plant growth needs to be further studied.

Sugarcane is an important sugar crop and energy crop. Evaluating the nutritional quality of sugarcane germplasm resources can systematically understand the nutritional value of sugarcane germplasm resources, and provide scientific basis for the development and utilization of sugarcane germplasm resources and breeding of new varieties. We carried out a study using 100 sugarcane germplasms, analyzed 14 nutritional indexes such as sucrose, reducing sugar, total free amino acid, polyphenol, mineral and protein in sugarcane juice, SPSS software was used for Principal Component Analysis (PCA) and Systematic Cluster Analysis (SCA) of nutritional quality traits. Results showed that there were differences in nutritional components among the 100 sugarcane germplasms and some nutrients had a significant correlation with each other. Sucrose content was negatively correlated with reducing sugar, protein, total free amino acid, fructose and glucose content, while protein content was positively correlated with total free amino acid and total polyphenol content. The content of fructose, glucose and sucrose was positively correlated with the content of P. Among mineral elements, Ca content and Fe content, Fe content and Cu content were positively correlated. The main factors affecting the nutritional quality of sugarcane germplasm were reducing sugar factor, protein factor, sucrose factor, Ca content factor and K content factor. The cumulative variance contribution rate of the common factors to comprehensive evaluation of sugarcane nutritional quality was 69.62%. SCA showed that the nutritional quality of the 100 sugarcane germplasms could be divided into 5 groups (European distance D=18.5). Group Ⅰcontained 77 resources, which had the highest sucrose content. Group Ⅱ contained 6 resources with higher Ca and Fe content. Group Ⅲ contained 2 resources, the average content of reducing sugar, protein, total free amino acid, total polyphenol, fructose, glucose, P, Na was high, and the average sucrose content and Fe content were low. Group Ⅳ contained 4 resources, which had the highest average total free amino acid content, higher average protein and total polyphenol content. Group Ⅴcontained 11 resources, with the highest average K content. The comprehensive evaluation of nutritional quality of the 100 sugarcane germplasms showed that the top 5 sugarcane varieties were 'Hetang 1', 'Dezhe 0978', 'Funong 40-95', 'Zhongzhe 45' and 'Yunzhe 06-193'.

Sugarcane is an important sugar crop in the world, but the main sugarcane producing areas in China are hilly and dry slopes, and seasonal droughts occur frequently due to the uneven distribution of rainfall. Droughts do great harm to yield and quality and the sustainable development of sugarcane industry in China. The plant hormone abscisic acid (ABA) not only regulates plant growth and development, but also plays an important role in the physiological and biochemical responses of plants environmental stresses. In this study, we used sugarcane (Saccharum officinarum L.) variety 'Guitang 42' as the material to investigate the effects of exogenous ABA on leaf physiological characteristics and gene expressions under water stress condition in treatments control (normal irrigation), control+ABA, drought (stop irrigation), drought+ABA. The foliar application of 15 μmol/L ABA was sprayed twice in two days before drought stress given. The results showed that the changes of main physiological and biochemical parameters and gene expression in control+ABA treatment were not significantly different from those of the control. The leaf relative water content (RWC) was gradually decreased by drought treatment but it could maintain higher in drought+ABA treatment. The drought treatment could result in an increase in malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) content, but the plants applied with ABA were found to resist the excessive accumulation of MDA. Drought stress significantly reduced the leaf chlorophyll content in sugarcane, but the exogenous ABA application decreased the degradation of chlorophyll, counteracted, at least in part, the decrease in quantum efficiency of PSII (ΦPSII). The expression of gene encoding 9-cis-epoxycarotenoid dioxygenase (NCED) for ABA biosynthesis, the genes encoding Δ1-pyrroline-5-carboxylate synthase (P5CS) for proline biosynthesis, and the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase (POD) encoding genes was significantly increased in the leaf under water stress condition, following the significantly higher endogenous ABA content, proline content and CAT, SOD, APX and POD activities in water stress treatment as compared to the control. But exogenous ABA application under water stress could further enhance the expression of the genes, hence further improved the ABA content, proline content and related antioxidant enzyme activity. The results clearly suggests that the foliar ABA application could triggering the over expression of antioxidative defense system, and improve drought tolerance of sugarcane under water stress condition.