As an important component of terrestrial soil carbon reservoirs, the agricultural soil organic carbon pool is greatly influenced by cultivation patterns. Coffee, one of the major economic crops in tropical regions of the world, a minor changes of its cultivation pattern can significantly affect the carbon balance of terrestrial ecosystems. Mulching cultivation is one of the traditional cultivation models for coffee, but its impact on the organic carbon composition of coffee plantation soil is still unclear. Therefore, based on the previous research of our team using coffee peel and leaf litter as substitutes for traditional mulch to cultivate coffee, four mulching treatments were set up in this study: uncovered coffee waste (CK), coffee leaf litter mulch (L), coffee peel mulch (P), and both coffee peel and litter mulch (PL). Soil micro-environment, microbial community diversity and biomass, organic carbon fractions, and other indicators were monitored in the coffee plantation, and the intrinsic relationships between soil micro-environment, microbial community structure, and organic carbon fractions were analyzed to investigate the effects of coffee waste cover on soil components and the key driving factors. The results showed that coffee waste cover did not affect the content of soil organic carbon (SOC), heavy fraction organic carbon (HFOC), and dissolved organic carbon (DOC), while coffee peel and litter mulch significantly increased the content of soil light fraction organic carbon (LFOC) by 13.31% and 14.12%, respectively. Coffee waste mulch did not affect soil micro-environment indicators or microbial diversity. Coffee peel cover significantly increased soil microbial biomass by 14.05%, and increased the relative abundance of Proteobacteria and Firmicutes by 18.60% and 80.77%, respectively, while reducing the abundance of Cyanobacteria by 70.14%, but had little impact on soil fungal community. Coffee litter mulch significantly increased the relative abundance of Proteobacteria and Firmicutes by 14.43% and 57.63%, respectively, while reduced the abundance of Cyanobacteria by 73.43%, and significantly increased the relative abundance of dominant fungi Ascomycota by 14.79%. The reason why coffee waste mulch did not affect the soil organic carbon content is mainly attributable to the insensitivity response of HFOC content to coffee waste mulching. The increase of microbial biomass and the increase relative abundance of Firmicutes are the main reasons to enhance the excitation effect caused by external organic carbon input, thus significantly increasing the content of soil LFOC content. The short-term mulch of coffee waste significantly increased the content of soil LFOC content, which is contribute to improve the soil carbon storage of coffee plantations and optimize the green and low-carbon production mode of coffee.

Passion fruit (Passiflora edulis) is a characteristic and advantageous fruit in Guizhou, which is of great significance in poverty relief consolidation and the rural revitalization. However, in recent years, the viral diseases of passion fruit have become increasingly severe, leading to a sharp decline in yield and quality, which thereby seriously constrain industry development of passion fruit. In order to determine the virus species, distribution and compound infestation in the main plantation areas of passion fruit in Guizhou province, a total of 153 samples suspectedly infected by virus were collected from five main plantation orchards of passion fruit in five counties, i.e. Luodian, Congjiang, Rongjiang, Zhenning and Zhenfeng, and the virus detection was carried out by RT-PCR. The results showed that seven viruses were detected from the tested samples, namely East Asian Passiflora virus (EAPV), Telosma mosaic virus (TeMV), Cucumber mosaic virus (CMV), Turnip mosaic virus (TuMV), Passiflora mottle virus (PaMV), Passiflora latene carlavirus (PLV), and Potato virus Y (PVY), among which PVY infection was firstly reported from passion fruit. EAPV was the most prevalent one with infection rate as high as 96.08%, followed consecutively by TeMV (81.70%), CMV (78.43%), TuMV (44.44%), PaMV (26.80%), PVY (24.84%) and PLV (15.03%). In the present case, the distribution of passion fruit viruses in Guizhou province and the diversity of virus sequences were analyzed. Seven viruses were detected in Zhenning, six in Zhenfeng, five in Rongjiang and Congjiang, and three in Luodian. There’s a close identity between the nucleic acid of the seven detected viruses and the corresponding reference sequences (above 95%). Phylogenetic analysis revealed that EAPV, TeMV, PaMV, PLV and TuMV somewhat geographical clustered with passion fruit virus isolated from other provinces in China. CMV and PVY were most closely related to Cucumis melo CMV isolated from Spain and Capsicum annuum PVY isolated from Rwanda respectively, suggesting that the virus sequences diversely varies among the origins in China. A total of 24 types of mixed infection were detected in the main growing areas of passion fruit in Guizhou, and the complex infection rate was as high as 94.77%. The complex infection with 3-5 types predominated in the tested samples, and the combination of EAPV+TeMV+CMV was most frequent among the complex infections among which, EAPV, TeMV and CMV detected ranged from 78.43% to 96.08% in the five counties, somehow reflecting that they were the major viruses to prevent in passion fruit industry of Guizhou province. In addition, a multiplex PCR assay system for EAPV, TeMV and CMV was established in this study, which provides technical support for the rapid detection of related viruses.

Rubber tree is important in global rubber production. In order to reveal the effects of microelement fertilizer combined with absorption enhancer on the growth of rubber tree seedlings, and lay a foundation for the innovation of microelement fertilizer application technology of rubber tree. In this study, the single application of microelement (W), the combination of absorption enhancer formula 1 and microelement fertilizer (C₁+W), and the combination of absorption enhancer formula 1 and microelement fertilizer (C₂+W) were treated with ultra-pure water as the control to investigate the effects of compound microelement fertilizer application alone or combined with absorption enhancer on the growth, dry matter accumulation, photosynthesis, root development and nitrogen distribution of rubber tree seedlings and their mechanisms. The results showed that micronutrient fertilizer could increase the dry matter accumulation of roots, stems, and leaves in rubber seedlings, thereby increasing the individual fresh weight, dry weight, and dry to fresh ratio. Among them, C₂+W increased the fresh and dry weight of plants by 4.18 and 5.89 times, which is much greater than those of C₁+W and W. The accumulation of dry matter in rubber seedlings by microelements fertilizers was positively correlated with root length, root surface area, and root volume, and with chlorophyll content, transpiration rate, and net photosynthetic rate of rubber seedlings. The root development and photosynthesis were positively correlated with nitrogen accumulation in various organs of crops, soluble protein content, nitrate reductase activity (NR), glutamine synthase activity (GS), and glutamate dehydrogenase activity (GDH) in leaves. Notably, the single application of microelements fertilizer had no significant effect on NR activity, indicating that W had a weak effect on nitrogen assimilation in the reduction of nitric acid to nitrite. Significantly, the single application of microelements fertilizer (W) had no significant effect on NR activity, indicating that microelements fertilizer had a weak effect on nitrogen assimilation in the reduction of nitric acid to nitrite. In summary, microelements fertilizers and absorption enhancer enhance the connection between C assimilation and N metabolism processes in rubber seedlings, promote the growth and development of rubber seedlings. Considering the wide and thick leaves of rubber, tight cells, and thick stratum corneum, subsequent research should continue to screen more suitable absorption enhancer and optimize the combination with microelements.

The variation of volatile aroma compounds and squalene-related enzyme activities of the tissue cultivation of Pandanus amaryllifolius Roxb. leaves (PAL) treated with different concentrations of Zn and La was studied. The volatile aroma compounds were analyzed by GC-MS, and the key enzyme activities of squalene metabolism were detected and analyzed. The results showed that there were differences in the number and content of volatile compounds in the tissue cultivation of PAL treated with different concentrations of trace elements. Compared with the untreated groud, 4 mg/L Zn treatment and 1 mg/L, 2 mg/L, 4 mg/L La treatment had more volatile compounds. Zn and La treatment increased the content of alcohols and decreased the content of olefins. Zn and La treatment significantly reduced the content of squalene. The treatment of 2 mg/L Zn increased the content of β-sitosterol, stigmasterol, ethyl palmitate, 3-methyl-2-(5H)-furanone, 2,3-dihydro-3,5-dihydroxy-6-methyl-4(h)-pyran-4-one, and decreased the content of squalene and phytol. The content of phytol in the leaves of 8 mg/L La treatment was the highest. The activities of squalene metabolism-related enzymes were changed in the process of tissue culture. Lanosterol synthase (LSS) activity and squalene epoxidase (SE) activity were stronger in the mixture, and squalene synthase (SQS) activity was stronger in adventitious roots. Different concentrations of trace elements had a certain effect on the activity of squalene-related enzymes. The content of squalene was positively correlated with LSS enzyme activity, SE enzyme activity and SQS enzyme activity in the PAL treated with different concentrations of Zn. The content of squalene in the tissue cultivation PAL treated with La was negatively correlated with LSS enzyme activity and SQS enzyme activity, and positively correlated with SE enzyme activity. The results would enrich the relevant theoretical research on the regulation of trace elements on the volatile aroma compounds of PAL, and provided theoretical basis for improving the aroma quality of PAL.

To elucidate the differences in inter-root bacterial communities of Aquilaria sinensis, and to explore the correlation with soil physicochemical properties, we used the high-throughput sequencing technology and bioinformatics-related tools to analyze the composition and multi-characteristics of the inter-root soil bacterial community of A. sinensis. In three cultivation sites in Hainan province (Wenshan village, Haikou city, Dongguang farm, Lingao, and Baolun farm, Ledong), and combined with redundancy analysis to correlate the inter-root soil physicochemical proper-ties with the bacterial community. The results showed that a total of 7 944 402 sequences belonging to 51 phyla,151 orders, 380 families, 637 families, 1296 genera and 2649 species were obtained among the sites; the variability of bacterial community and diversity of A. sinensis in the sample sites was not significant, and there were significant differences among the sample sites. The richness and diversity of inter-root soil bacteria in the sites were as follows: LDJX>LDWJ>LGWJ>LGJX>WSWJ>WSJX. In terms of community structure, the Ledong sample site differed significantly from the Wenshan and Lingao sample sites in terms of community structure.at the phylum level, the dominant bacterial phyla in Ledong were Planctomycetota, Chloroflexi, and Verrucomicrobiota; the dominant populations in Wenshan and Lingao were Firmicutes, Bacteroidota, and Proteobacteria. At the genus level, the dominant genera in Wenshan and Lingao were Bacteroides, uncultured_bacterium_f Muribaculaceae, and Faecalibacterium; the dominant genera in Ledong were the unidentified genus (g_uncultured_f__Gemmataceae) genus, Candidatus_Udaeobacter, and Bacteroides. The RDA analysis revealed that the inter-rhizosphere soil bacterial community of A. sinensis was affected by soil physicochemical factors with some differences among different sites. Total phosphorus was significantly and negatively correlated with bacterial population differences and diversity, and pH was significantly and positively correlated with bacterial population differences and diversity. The results are valuable for studying the interactions of inter-root microorganisms of A. sinensis, and have certain guiding significance for the development of Hainan incense industry.

The plant species in eight coastal parks in Xiamen island were investigated by the sample line method and a total of 288 species of plants in eight coastal parks on Xiamen island were obtained, among which 127 were introduced plants, accounting for 44.10% of the total. 80 species of exotic garden plants with invasive potential were obtained. The risk assessment system of invasive ornamental introduced plants in Xiamen island coastal parks was constructed by the literature collation method and expert consultation, and the evaluation index weights were determined by the hierarchical analysis method. The evaluation system includes one target level, five primary indicators and twenty secondary indicators. 80 exotic landscape plants with invasive potential were substituted into the risk assessment system of introduced landscape plants in Xiamen island Coastal Park to obtain the corresponding scores. 13 species with scores between 38.00 and 58.85 were considered high-risk plants. 18 species with scores between 23.00 and 38.00 were medium-risk plants. Nine species with scores between 9.30 and 23.00 were low-risk plants. Four high-risk plants that are not listed in the Chinese Invasive Alien Plant Register should be detected early and controlled with effective management measures. Medium-risk plants should be phased out and replaced with native plants, and low-risk plants should be monitored and managed. Most of the ornamental introduced plants in the eight coastal parks in Xiamen island are low-risk plants. Among them, Wutong Lighthouse Park, Bay Park and Niu Tou Mountain Park are among the top three in the number of applied introduced plant species, and it is recommended that no more ornamental introduced plants be introduced in the future. Music Square had the least number of introduced plants, and it is recommended to introduce low-risk plants to increase the vegetation diversity of the park. This study sorts out the introduced plant species in Xiamen island coastal parks and proposes relevant control suggestions for introduced plants, protects the ecological security of Xiamen island coastal parks, further enriches the invasion risk evaluation studies in small-scale areas and provides a reference for the introduction of introduced plants in coastal parks in other areas.

Both friable embryogenic callus and suspension cells are ideal materials for genetic and cell engineering. However, the induction of friable embryogenic callus of Hevea brasiliensis is low frequency and time-consuming, and its embryogenic competence usually decreases gradually or even completely loses with the increase of subculture times. Therefore, to quickly obtain friable embryogenic callus, establish embryogenic cell suspensions with high efficiency of somatic embryogenesis, and maintain the embryogenic competence as long as possible, are important research contents for genetic and cell engineering of H. brasiliensis. In this study, the immature anthers of H. brasiliensis clone Reken 525 was used as the explants to induce callus and establish embryogenic cell suspensions, and the effects of two long-term subculture methods-solid and liquid on the maintenance of embryogenic competence were compared and analyzed. The results showed that the yellow and compact primary callus tissue induced from anther explants on callus induction medium had a low ability for somatic embryogenesis, and was not suitable for suspension culture due to poor dispersion. After 70-80 d of culture on the medium for embryogenic callus induction, the formation of embryogenic structures and early somatic embryogenesis were observed, and bright yellow small granular friable embryogenic calli grew around them. The type Ⅰ embryogenic suspension cell line established through routine methods possessed typical characteristics of embryogenic cells, and the frequency of somatic embryogenesis was significantly higher than that of embryogenic callus tissue, but proned to callus formation during somatic embryogenesis; the type Ⅱ embryogenic suspension cell line established by screening specific embryogenic tissue and initiating with low density suspension culture was in an orderly embryonic structure observed by microscope, and its frequency of somatic embryogenesis could reach up to 100%. After two years of continuous subculture in liquid culture medium containing 2 mg/L 2,4-D, the cells were obviously aging with lower proliferation coefficient, and the ability for somatic embryogenesis was almost lost. However, the ability for somatic embryogenesis still remained at a high level after two years of continuous subculture on solid culture medium without 2,4-D but supplemented with abscisic acid (0.1 mg/L) and hydrolyzed casein (0.5 g/L). The type Ⅱ embryogenic suspension cell line could provide high-quality, sufficient and relatively stable material sources for genetic transformation and protoplast culture of Hevea brasiliensis in the long term.

Phalaenopsis-hybrid Dendrobium is an important ornamental plant in tropical area and has high market values, with beautiful flower appearance and abundant flower colors. In this study, the protocorms and young seedling’s stem segments of commercial varieties, Den. Yaya Victoria, Den. Swirl and Den. Sonia Hiasakul, were used as the explants. The effects of different phytohormone combination on embryogenic callus induction, adventitious bud differentiation and plantlet regeneration were investigated. During the embryogenic callus (EC) induction stage, the best induction explants were protocorms and 2-month-old seedling stem segments and EC could be obtained after 30 days culture in dark condition. The best medium for EC induction of was MSD (MS+30 g/L glucose+1 g/L Hyponex+8 g/L agar) as the basic medium with 0.5 mg/L KT and 0.2-0.5 mg/L 2,4-D. The highest average induction rate of EC was 31.11%, 22.78%, and 50% for Den. Yaya Victoria, Den. Swirl and Den. Sonia Hiasakul, and the induction time for Den. Yaya Victoria was only 15 days from explants to EC. The best proliferation medium was MSD+0.5 mg/L IBA+0.5 mg/L KT, which maintaining EC in good condition without differentiation and the multiplication rate was 0.9. The best medium for differentiation was 1/2 MS+0.5 mg/L IBA+0.15 mg/L KT under light condition of 16 h one day, EC quickly differentiating and forming 2-3 leaf adventitious buds within 30 days, and finally regenerating into plantlet after 60 days in the same medium. The best rooting medium was 1/2 MS+30 g/L sugar+0.5 mg/L NAA+8 g/L agar, with rooting rate 100% and five roots in length 1.3 cm per plantlet. In this research, the EC induction, proliferation and differentiation media have a wide-spectrum and the EC regeneration pathway could lay a solid foundation for further molecular breeding of Phalaenopsis-hybrid Dendrobium.

Natural rubber is an important strategic material and industrial raw material in China, which mainly originates from rubber tree. The growth cycle of rubber tree is long, and the quality of rubber seedling directly affects the development of rubber industry. The somatic embryo plantlet of rubber tree shows good consistency in the previous studies, and has the advantages of rapid growth and high yield. Hainan Innovation Base for production of Natural Rubber New Planting Material is the base of the current large-scale production of rubber tree somatic embryo plantlets of Reyan 73397 and Reyan 917. In this paper, in order to clarify the large-scale production of the somatic embryo plantlets of rubber tree, the plant height, stem diameter, leaves number and taproot length of Reyan 73397 somatic embryo plantlets from 2018 to 2020 were studied, the differences in each index of the two varieties in 2020 were, compared, and the classification of different varieties in different years were done. The proportions of plant height, stem diameter, leaf number and taproot length of Reyan 73397 were similar in each region from 2018 to 2020. There were no significant differences in plant height, leaf number and taproot length in three years. There were significant differences in stem diameter between 2018 and 2019, and the mean value of the three years was above 2.00 mm, and the difference between the maximum and minimum value was only 0.09 mm. The plant height of Reyan 73397 and Reyan 917 was the same, and the mean value of plant height of both varieties was 8.0 cm. The plant height of the two varieties was mainly 5.0-10.0 cm, accounting for 66.13% and 66.91%, respectively. The stem diameter range of Reyan 73397 and Reyan 917 was 0.80-4.23 mm and 1.13-3.73 mm, respectively. The mean value of the two varieties was 2.11 mm and 2.18 mm, respectively. The stem diameter of the two varieties was highly concentrated between 1.50-3.00 mm, 85.94% and 83.82%, respectively. The leaf number of Reyan 73397 and Reyan 917 was ranged from 0 to 6 and 1 to 4, respectively. The number of leaves of the two varieties was mostly 1 to 3, accounting for 88.82% and 96.32%, respectively. The rate of 2 leaves in Reyan 917 was as high as 52.94%. The average taproot length of Reyan 73397 was 9.5 cm, while that of Reyan 917 was 9.1 cm. The taproot length of both varieties concentrated in the range of 8.0-12.0 cm, accounting for 74.12% and 79.41%, respectively. There were no significant differences in plant height, stem diameter and leaves number between the two varieties in 2020, while there was significant differences in taproot length (P<0.05). The proportion of first-grade plantlets and second-grade plantlets of different varieties in different years (2018—2020) was 19%-22% and 56%-62%. It is concluded that the mass production of rubber tree somatic embryo plantlet is stable, which could provide reference for the popularization of the production technology of rubber tree somatic embryo plantlet.

Grey mold is a common disease in tomato production caused by Botrytis cinerea, a necrotrophic pathogen, which often leads to dramatic reduction of tomato yield. Sucrose catabolism plays an important role in plant defense against pathogen infection by providing carbon skeleton and energy for plant defense responses and/or regulating the expression of defense-related genes through signaling pathway. Previous studies have shown that cell wall invertase (CWIN), a kind of sucrose-degrading enzyme, can enhance plant resistance to several necrotrophic pathogens. However, no research has been conducted to study the role of CWIN in tomato resistance to B. cinerea. In this study, wild type tomato (W) and its transgenic line (R) with elevated CWIN activity were used as materials to study the effect of CWIN on tomato resistance to B. cinerea (Bc) via in vitro inoculation. In addition, inoculated leaves were sampled 12 h and 60 h post inoculation (hpi) for RNA-Seq to elucidate possible molecular mechanisms underlying the regulation of CWIN to tomato resistance against B. cinerea. The results are as follows: (1) Elevated CWIN activity enhanced tomato resistance to B. cinerea; (2) KEGG annotation showed that DEGs (W-Bc-12 h-vs-R-Bc-12 h) from 12 hpi were significantly enriched in five pathways, including biosynthesis of secondary metabolites, metabolic pathways, DNA replication, starch and sucrose metabolism, and steroid biosynthesis; No significant enrichment pathway was found for DEGs (W-Bc-60 h-vs-R-Bc-60 h) from 60 hpi. (3) By mapping DEGs to plant-pathogen interaction pathway, it was revealed that the LRR-receptor serine/threonine-like kinase gene FLS2 and heat shock protein gene HSP90 involved in hypersensitive response and defense-related gene induction were up-regulated in RNAi leaves after inoculation, indicating the two genes may participate in the regulation of CWIN to tomato resistance to B. cinerea. (4) The analysis of plant hormone signal transduction pathways and MapMan mapping showed that the signal pathway of jasmonic acid (JA) and ethylene (ET) was enhanced in RNAi leaves after inoculation, while the signal pathway of salicylic acid (SA) was weakened, indicating that the hormones might work together to improve the resistance of RNAi tomato to B. cinerea. In addition, the signal transduction of growth-promoting hormone auxin (IAA) and cytokinin (CTK) was also enhanced in RNAi leaves after inoculation, but that of senescence-promoting hormone abscisic acid (ABA) was weakened. The changes in signal pathways of IAA, CTK and ABA could inhibit the cell death in host during bacterial infection, thus preventing the necrotrophic pathogen B. cinerea from obtaining necessary nutrients from the dead host cells for its infection. In addition, MapMan mapping also revealed that cell wall thickening, proteolysis, reactive oxygen species (redox state and peroxidases) and secondary metabolites were also greatly enhanced in RNAi leaves after inoculation, which all contribute to improving the disease resistance of tomato. In conclusion, this study showed that elevated CWIN activity enhanced tomato resistance to B. cinerea. Transcriptome analysis not only verified the existing molecular mechanisms underlying the regulation of CWIN to plant resistance to microbial pathogens, such as cell wall thickening, accumulation of reactive oxygen species (ROS) and hypersensitive response (HR), accumulation of resistance hormones (SA and JA/ET), biosynthesis of pathogenesis-related protein (e.g. PR and HSP proteins) and secondary metabolites (such as phytotoxins and phenolics), but also revealed several possible new mechanisms including the signal transduction of growth-promoting hormone (IAA and CTK) and senescence-promoting hormone (ABA) and proteolysis. This study can provide theoretical guidance for the improvement of tomato resistance to B. cinerea by using modern biotechnologies such as genetic engineering and molecular breeding.