Anthracnose is a common disease of coffee, which causes serious loss to the yield and quality of coffee fruit. The research on pathogenicity and biological characteristics of the pathogenic bacteria causing coffee anthracnose and screening of effective antagonists would provide reference for the biological control of coffee anthracnose. Four coffee anthracnose pathogens Wyq1 (Colletotrichum siamense), Yyq1 (C. fructicola), Xbd1 (C. gloeosporioides) and Hb1 (C. theobromicola) were isolated and tested for pathogenicity by spore suspension, and the most virulent strains were selected for further experiments. The biological characteristics of the pathogenic bacteria were studied by the plate culture method. Screening of antagonistic bacteria was done by the plate confrontation method. Xbd1 strain could infect healthy coffee leaves, and its virulence was the strongest among the four strains. The most suitable medium for the vegetative growth was PDA. The optimal nitrogen source was tryptone. The most suitable carbon source was glucose. The optimum temperature was 28 ℃. The optimal pH was 7. The difference of vegetative growth was not significant under different light conditions. Bacillus subtilis MC4-2, B. tequilensis D5-8, B. velezensis MC2-1 and B. flexus ZLSY3 and B. amyloliticus GJ7 showed good antagonistic effect in indoor screening. B. subtilis MC4-2 had the best antagonistic effect, with an inhibitory rate of 57.8%. The study would lay the foundation for the control of anthrax and the development of biocontrol agents.

Gypsophila paniculata L. is one of the most popular and bestselling cut flowers in the world. Stem rot is among the common disease of G. paniculata L. causing plant withering and death in serious cases, affecting the ornamental and utilization value of the flowers and causing certain economic losses. In March 2021, a severe wilt due to stem rot was observed on G. paniculata L. in Haikou town, Kunming, Yunnan, China. The disease mainly affected the stem base which was manifested by rot on stem base and wilting. In order to identify the pathogenic microorganism, we isolated and identified the pathogen associated with the stem of G. paniculata L.. Koch’s postulates proved that the isolate caused similar symptom on tissue culture and potted seedlings of G. paniculata L., and the isolate had similar morphology with initially isolated from with the naturally infected seedlings in the field. Through morphological identification, the isolate produced a large number of dense aerial hyphae with color ranging from white to light orange or yellow with dark red pigment deposition on the back of the colony. The conidia of the isolate was sickle-shaped with flat ventral side, the dorsal side was arched, with three to six septation. The macroconidia was in the range (21.1-57.9)µm×(2.7-5.1)µm (n=100), no microconidia were observed. The morphology was similar to that of Fusarium pathogenic fungi. Through the identification of ITS gene sequence and morphology, the isolate was initially identified as F. graminearum species complex (FGSC). In order to further identify the subspecies, the TEF-1α sequence was used for sequencing. It was found that the isolate was 100% homologous with F. meridionale. Therefore, combined with morphological and molecular biological characteristics, the pathogen of the stem rot of G. paniculata L. was identified as F. meridionale. This is the first report on the stem rot of G. paniculata L. in China, which would provide an important basis for the prevention and control of the disease.

The adsorption and desorption rates of nine cationic exchange resins on ergothioneine (EGT) were investigated to screen out the ion exchange resin suitable for the separation and purification of EGT from natural rubber serum (NRS) and determine the optimum process parameters. The results showed that the SA-2 cation exchange resin was the most suitable for the separation and purification of EGT from NRS, and the optimum parameters were as follows: pH of sample loading 3.0-4.0, sample loading flow rate 2 BV/h, and eluted with 0.5% ammonium hydroxide at the flow rate of 1 BV/h. Furthermore, a higher sample loading concentration was more conducive to the adsorption capacity of resin. Under the conditions, the EGT elution rate could reach 97.83%. This research indicated that the SA-2 cation exchange resin is an ideal medium for the separation and purification of EGT from NRS, which would lay a theoretical foundation for the industrial production of EGT.

The main taste components of six different coffee beans from various regions in Hainan, including Xinglong coffee beans (XL), Fushan coffee beans (FS), Qionghai coffee beans (QH), YSL coffee beans from Baisha Yushiling (YSL), MS1 coffee beans from Mushan No.1 (MS1), and MS2 coffee beans from Mushan No.2 (MS2) were studied. Differences in taste composition and component content of the roasted coffee beans from different regions were compared. Based on the chemical characterization of the beans using the fingerprinting of the main taste components, the influence of the origin on the taste characteristics components of coffee beans was investigated and the roasted beans were distinguished. The levels of eight chlorogenic acids, caffeine, trigonelline and eight organic acids in the roasted beans were measured using ultra-high performance liquid chromatography (UPLC), while the composition and content of monosaccharides in the coffee samples were determined using pulsed amperometry by ion exchange chromatography (HPAEC-PAD) and the composition and content of amino acids were determined using an automatic amino acid analyser. The results showed significant differences in the content of taste components among the roasted beans, with the highest content of caffeine and trigonelline found in MS2 beans and the lowest in MS1 beans. The highest content of amino acids was found in QH beans, while the lowest content of chlorogenic acids and monosaccharides was found in QH beans. The content of chlorogenic acids in the roasted beans was as follows: caffeoylquinic acids (CQAs)>feruloylquinic acids (FQAs)>dicaffeoylquinic acids (diCQAs). Only eight monosaccharide components were detected in the six varieties, with the highest content of galactose. Based on principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), the six coffees beans were successfully discriminated, with high similarity between the XL coffee beans, YSL and MS2 coffees beans, indicating that the major chemical taste components can be used to distinguish coffee beans from different regions of Hainan. The results show that the fingerprinting of key taste components can effectively distinguish coffee beans from different regions. This study would provide information on the chemical composition and quality characteristics of coffee beans from different regions and provide a theoretical basis for improving coffee flavour quality, which is important for the screening and differentiation of high-quality coffee samples.

Coconut is an important economic crop in tropics. The area of coconut palm in Hainan Island accounts for 90% of the total production area in China. Up-to-date maps of coconut palm are essential for the industrial planning of tropical agriculture. In this study, an object-oriented image analysis method was used for mapping coconut palms based on high spatial resolution imagery of Gaofen-2. Dongjiao town in Wenchang was selected as the study area. An optimal segmentation scale of Gaofen-2 imagery was obtained using the fractal evolution approach. Then, a combined layer of four original bands, five vegetation indices and 32 gray-level co-occurrence (GLCM) texture indices were used as input features. Four different sets of features (including only original bands, original bands and textures indices, original bands and vegetation indices, and all features) were applied in object-based classification. The overall accuracy (OA) and user’s accuracy (UA) of pixel-based method achieved 87.05% and 85.21%, respectively. Compared with the pixel-based method, the object-based approaches significantly increased overall accuracy (OA) between 5.51%-8.72%. The OA and user’s accuracy (UA) reached 95.77% and 97.15% respectively, which was the optimal classification result, when the combination of original bands and textural features were used in coconut palms classifying. In addition, the combination of original bands and vegetation indexes achieved a satisfactory accuracy (OA=94.88% and UA=94.42%). While the combination of original bands, vegetation indexes and textural indexes performed a lower accuracy (OA=94.67% and UA=94.17%) in comparison with that of above two combination. Generally, our researches indicate that Gaofen-2 imagery has a good potential for coconut palms classification in complex tropical regions, and the textural indexes are very useful for identifying coconut palms at object-based level. The results would provide a reference framework for tropical agriculture decision management.

Rhododendron hainanense Merr. has high ornamental and ecological value. It is of great significance for the protection and application of this plant through the study of ecological requirement and applicable range. In this paper, MaxEnt model and ArcGIS were used to simulate the potential geographical distribution of R. hainanense in China, based on the existing geographic distribution information, climate factors of this plant. And the key environmental factors, affecting the potential distribution of R. hainanense and suitable thresholds are analyzed. The results showed that under the contemporary climate scenario (1970—2000), the maximum entropy model (MaxEnt) can predict the suitable area of R. hainanense with high accuracy. The temperature and precipitation have a great influence on R. hainanense. The main factors affecting the potential distribution of R. hainanense are precipitation of warmest quarter (bio18) and mean diurnal range (bio2). When the precipitation of warmest quarter (bio18) is between 610-3990 mm and the mean diurnal range (bio2) is 5-7 ℃, the climate environment is suitable for the growth of R. hainanense. In a certain range, the probability of presence of R. hainanense will increase with the increase of precipitation. In China, the suitable habitat area of R. hainanense is mainly distributed in Hainan, Guangxi, Guangdong, Taiwan, eastern Sichuan, Chongqing and Guizhou. The total suitable habitat area of R. hainanense under contemporary climate scenarios is 132.36×10⁴ km². The purpose of this paper is to provide a scientific basis for the protection and application for the species.

To develop sustainable sugarcane production and scientific use of nitrogen fertilizer, the effect of long-term application of nitrogen fertilizer on the soil and endophytic fungal compositions in the rhizosphere and roots were explored. The soil and endophytic fungal compositions in the rhizospheres and roots of sugarcanes under long-term application of nitrogen fertilizers were analyzed. 0, 96, 482, 964 kg/hm² nitrogen fertilizer application (CK, L, M, H) were set in the same sugarcanes field, and based on the high-throughput sequencing techniques, the soil and endophytic fungal compositions in the rhizospheres and roots of sugarcanes were analyzed. In comparison with CK, although the richness of soil fungi in the rhizospheres of sugarcanes was significantly increased by different nitrogen application levels (P<0.05), particularly, L, M and H treatments increased by 39.58%, 24.04% and 35.33%, respectively; the diversity was not significantly different. Meanwhile, there were not significantly different in the diversity and richness of the endophytic fungi in the sugarcane roots under different nitrogen application treatments. Moreover, the soil fungi in the rhizospheres of sugarcanes, the relative abundances of Saitozyma, Trichoderma, unclassified_p__Ascomycota and Fusarium increased under nitrogen application. On the contrary, the relative abundances of Talaromyces, unclassified_f__Herpotrichiellaceae, Coniosporium, Penicillium, Chaetosphaeria, Chaetomium, unclassified_o__Hypocreales decressed under nitrogen application. In addition, the endophytic fungi in sugarcane roots, unclassified_k__Fungi and unclassified_p__Ascomycota increased, and Talaromyces, Chaetomium, unclassified_f__Strophariaceae decreased under different nitrogen application treatments. The results showed that the enrichment of single soil fungal communities in the rhizospheres or roots, and the potential risk of decreasing cane resistance could be induced by long-term nitrogen fertilizer application only. Meanwhile, in view of maintaining the soil health in the rhizospheres of sugarcanes, the optimal nitrogen application rate for sugarcane was 96 kg/hm².

Anthocyanins, also called anthocyans, are a group of plant secondary metabolites of flavonoid derivatives. Anthocyanins play an important role in mediating plant stress responses. However, whether anthocyanins are also involved in regulating phyllosphere bacterial communities remains unknown. To evaluate the differences of phyllosphere bacterial communities in plants with different anthocyanin contents, this study analyzed the phyllosphere bacterial communities of two cultivars of elephant grass with contrasting anthocyanins content, Pennisetum purpureum cv. Purple (Purple) with a high amount of anthocyanins and P. purpureum cv. Mott (Mott) with relatively low anthocyanins. The anthocyanins content determination results showed that the anthocyanins content in Purple leaves was nearly 20 times of that in Mott leaves. High throughput sequencing of 16S rRNA and analysis of the microbiome community indicated that though alpha diversity was not significantly changed, the bacterial communities of Purple was significantly different from that of Mott. In Purple, the relative abundance of endopphytic Proteobacteria and Bacteroidetes, and epiphytic Deinococus-Thermus were significantly increased, whereas epiphytic Bacteroidetes and Firmicutes were significantly decreased. The composition of microbiomes (ANCOM) at the OTU level, the relative abundance analysis at the genus level and correlation analysis between epiphytes and anthocyanins showed that the relative abundance of Methylobacterium, Unclassified Methylobacteriaceae and Deinococcus, which showed a significant positive correlation with anthocyanins content, were significantly increased in the episphere of Purple. In summary, the phyllosphere bacterial communities were significantly different between Purple and Mott. The findings from this work would provide new insights into the understanding of the superior forage value of P. purpureum cv. Purple, and lay a foundation to further investigate the mechanism of how plant secondary metabolism products regulate phylloshpere microorganisms.

In this experiment, we analyzed the rhizosphere fungal populations of Aquilaria sinensis (Lour.) Spreng. in different planting areas, and understood the change pattern of the rhizosphere microorganisms before and after agarwood induction, providing a reference basis for the formulation of reasonable cultivation measures for A. sinensis. High-throughput sequencing and bioinformatics methods were used to analyze the diversity and community structure of the rhizosphere soil and fungi of A. sinensis in three sample sites of Hainan province (Wenshan in Haikou, Dongguang in Lingao, and Baolun in Ledong) before and after agarwood induction, the correlation between soil physicochemical properties and fungal communities before and after agarwood induction was also clarified by redundancy analysis. The results indicated that a total of 3 697 288 ITS sequences belonging to 1 kingdom, 2 Phylum, 12 classes, 9 orders, 24 families, 55 genera, 62 species were obtained from the three planting areas. There was little variability in the fungal communities and diversity before and after agarwood induction in the sample plot, but there was significant differences in the abundance of dominant population. The Shannon diversity index of the rhizosphere soil fungi of A. sinensis before and after agarwood induction ranged from high to low: LDWJX>LDJX>LGJX>LGWJX>WSWJX>WSJX. The fungal species composition of the rhizosphere soil samples of A. sinensis was rich. There were differences in the soil fungal community composition, the relative abundance of taxonomic units and the dominant taxonomic units in the rhizosphere of A. sinensis before and after Agarwood induction in different planting areas. In terms of community structure, there were differences in the dominant populations among the three planting areas; at the Phylum level, the common dominant Phyla in the three cultivation areas were Ascomycota and Basidiomycota; at the Class level, the dominant Class in Wenshan was Dothideomycetes, In Lingao the dominant Class was Sordariomycete, In Ledong the dominant Class was Ascomycetes; at the genus level, the dominant genus in Wenshan was p__Ascomycota, in Lingao was Myrothecium, and in Ledong was c__Dothideomycetes. By correlating the physicochemical properties of the inter-rhizosphere soil with the major genera of inter-rhizosphere fungi of A. sinensis in three growing areas, it was found that soil pH, organic matter, alkaline nitrogen, total nitrogen, total phosphorus, effective phosphorus had significant effects on most of the major fungi in the inter-rhizosphere soil of A. sinensis. The results of this study are of guiding significance for the improvement of soil at the fungal level and the evaluation of soil quality of A. sinensis, and also provide a reference basis for the future fertilization strategies of A. sinensis planting areas in Hainan province.

The effects of water management and foliar spraying of exogenous plant hormone ethylene (ETH) on the accumulation of rhizosphere iron membrane, cadmium (Cd) and health risk index of rice were studied. Through the potting test, two concentrations (50 μmol/L and 100 μmol/L) ethylene (ETH) were sprayed three times at the jointing stage, the flowering stage and the grouting stage, and the water management modes of continuous flooding (CF) and interval flooding (IF) were adopted. Compared with the IF water management mode, the storage morphology of Cd in the soil was changed in the CF water management mode, and the soluble Cd was reduced from 36% to 30%, and the reducing state Cd was increased from 30% to 40%. Compared with the IF water management mode, the Fe and Cd content in the rice root surface iron film were significantly increased in the CF water management mode, and the exogenous spraying of ETH also significantly increased the Fe and Cd content in the iron film under the two water management modes, up to 50.59% and 58.06%. Compared with the IF water management mode, the Cd content in rice roots, leaves, brown rice and polished rice decreased significantly under the CF water management mode. The external spraying of ETH was also conducive to reducing the cadmium content of rice under the two water management modes, among which the Cd content in polished rice under CF+50ETH treatment was the lowest, and the Cd content in polished rice decreased from 0.68 mg/kg to 0.45 mg/kg, a decrease of 33.82% compared with CF treatment. Exogenous spraying of ETH significantly reduced the transport coefficients of Cd from rhizome and stem-grain under the two water management modes, and the transport coefficients were the lowest under CF+50ETH treatment, which was reduced by 55.17% and 23.81% respectively compared with CF treatment. CF water management mode and spray ETH treatment have a good effect on reducing the health risk index of rice Cd. It can be seen that CF water management mode and exogenous spraying of ETH have certain application prospects for reducing the accumulation of Cd in rice.