Areca palm is an important tropical economic crop in Hainan Province. Areca palm yellow leaf disease (YLD) caused by phytoplasma infection is a devastating disease in the production of areca in China. In order to establish an accurate and efficient detection method for areca palm yellow leaf phytoplasma, this study designed and synthesized specific primers AMf/AMr and AM-Prode based on the 16S rDNA gene of areca palm yellow leaf phytoplasma. The method was used to test the accuracy, sensitivity, specificity and repeatability, and to detect phytoplasma diseases in other plants. The method could accurately detect the positive samples, and the healthy samples had no amplification curve. In the sensitivity test, the method could detect the sample concentration level of 1.16×10¹ copies/μL, and the standard curve equation was y=–3.4185x+43.624, the amplification efficiency was 96.12%, and the correlation coefficient R²=0.9833. In the specificity test, the method had good specificity for the detection of YLD, and the genomes of areca, other disease pathogens and the endophytes did not interfere with the method. In the repeatability test, the method had good repeatability for the detection of YLD. The detection method could be used to detect 8 phytoplasma diseases such as chinaberry yellow leaf disease, ‘Pericampylus glaucus’ witches' broom disease and pepper yellow leaf disease and the detection of phytoplasma has certain universality. The establishment of detection method is conducive to providing reliable technical means for the accurate diagnosis of YLD, pathogen monitoring and vector insect detection.

Hevea brasiliensis is an important natural rubber-producing plant. Rubber particles (RP) in latex are important organelles for the synthesis of natural rubber, which can be divided into large rubber particles (LRP) and small rubber particles (SRP) according to the diameter. Although the specific mechanism of its regulation of natural rubber synthesis in response to exogenous ethylene stimulation has been studied. However, the specific regulatory mechanism of LRP and SRP in regulating natural rubber synthesis in response to ethylene stimulation is still unclear. In order to clarify the role of RP with different diameters in the synthesis of natural rubber, LRP and SRP stimulated by ethylene were isolated and the proteins of corresponding samples were extracted for differential protein analysis. 37 differential proteins in response to ethylene stimulation were identified in the LRP, which were involved in natural rubber biosynthesis, glycolysis/gluconeogenesis, carbon metabolism and amino acid biosynthesis, and some other metabolic pathways, including four members of the REF/SRPP family. 56 differential proteins were identified in SRP, which were involved in protein processing, endocytosis, splicing in endoplasmic reticulum, and some other metabolic pathways, including five members of the REF/SRPP family. The key differential accumulation protein REF138 had many isoforms with different isoelectric points (pI) and molecular weights (MW). REF138 isoforms below the standard pI (4.80) on LRP were down-regulated in response to ethylene stimulation, while isoforms above the standard pI were up-regulated to ethylene stimulation. Different from LRP, more isoforms of REF138 on SRP changed in response to ethylene stimulation, and isoforms with standard MW (14.7 kDa) were up-regulated in response to ethylene stimulation, while isoforms with higher than standard MW were down-regulated in response to ethylene stimulation. The function analysis of key differential proteins showed that there were interactions among the members of the REF/SRPP family. REF138, REF175, REF258, SRPP117 and SRPP204 may form protein complexes and bind to RP. In addition to the members of the REF/SRPP family, 20 proteins interacting with REF138 were mainly involved in the spliceosome and endocytic metabolic pathways, and 50 proteins interacting with REF258 were involved in the regulation of lipid metabolism and the synthesis of secondary metabolites. In conclusion, functional analysis of differential proteins and the interaction proteins responsive to ethylene stimulation on LRP and SRP might preliminarily reveal the metabolic regulatory mechanism of LRP and SRP in regulating natural rubber synthesis in response to exogenous ethylene stimulation.

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.

The germplasm resources of Amomum tsao-ko (AT) at different altitudes in Nujiang, Yunnan were used as the materials to explore the genetic diversity of the agronomic phenotypic traits of AT germplasm resources at different areas. The genetic diversity of the agronomic phenotypic traits of AT was analyzed by measuring 8 agronomic phenotypic traits, using coefficient of variation, genetic diversity index, variance analysis, correlation analysis, cluster analysis, principal component analysis and comprehensive evaluation. The results showed that there were large variations in the agronomic phenotypic traits, and the variation coefficient was 7.63%-32.51%, among which the variation coefficient of tiller number was the largest. The traits showed good diversity, H' (diversity index) was 1.933-2.355, with an average of 2.024. There were significant differences in the agronomic phenotypic traits among different germplasms. There was a significant positive correlation between fruit longitudinal diameter and fruit shape index and fruit weight. There was a significant positive correlation between fruit transverse diameter and fruit weight. There was a significant negative correlation between fruit shape index and leaf width. Cluster analysis divided the AT germplasm resources at different areas into two groups, among which the AT germplasm resources from the areas of Lushui and from Fugong were clustered into one group. Three principal components were extracted from eight agronomic phenotypic traits, and the cumulative contribution rate reached 76.940%, which could comprehensively reflect most of the information of agronomic phenotypic traits of AT. The comprehensive evaluation results showed that SD12, SD20, SD7, SD17, SD18 and SD5 were ranked in the top six, and the comprehensive performance was better. The genetic diversity of the agronomic phenotypic traits of 24 AT germplasm resources in different areas of Nujiang, Yunnan is relatively rich, and the variability of AT germplasm resources in different areas is obvious. Among them, the agronomic phenotypic traits of SD12, SD20, SD7, SD17, SD18 and SD5 AT are better, which are more suitable for breeding.

Bombax ceiba is a deciduous tree belonging to the Genus Bombax in the Malvaceae family. It holds significant importance as an ornamental plant of economic, medicinal and edible value in southern China. It is the city flower of Guangzhou and Panzhihua. The traditional propagation methods for B. ceiba are seed sowing and grafting. However, the seeds are difficult to preserve and easily deteriorate, leading to decreased germination rates. Grafting results in even lower survival rates. Therefore, this experiment aimed to study the tissue culture techniques for the rapid propagation of B. ceiba. In this study, B. ceiba seeds were used as the experimental materials, and different disinfection methods were tested to determine the most suitable method for seed disinfection, aiming to obtain sterile seedlings. Using the sterile seedlings as the explants, various basic culture media, combinations of shoot-inducing hormones, induction and proliferation media for apical and adventitious buds, as well as rooting media, were tested and optimized. Additionally, seedling acclimatization experiments were conducted to explore the optimal basic culture medium, hormone combination, induction and proliferation medium, rooting medium, and seedling acclimatization methods. The results showed that the optimal basic culture medium for B. ceiba tissue culture was MS medium supplemented with 30 g/L sucrose and 7.5 g/L agar. The best disinfection method for B. ceiba seeds was 75% ethanol treatment for 1 min, followed by five rinses with sterile water, 4-hour sterilization with a 50% H₂O₂ solution prepared from 30% H₂O₂, and another five rinses with sterile water. The optimal plant growth regulators for inducing differentiation of apical buds into young shoots were a combination of 6-benzylaminopurine (6-BA) and naphthaleneacetic acid (NAA). The best induction and proliferation medium was MS medium supplemented with 0.5 mg/L 6-BA, 0.5 mg/L indole-3-butyric acid (IBA), 30 g/L sucrose, and 7.5 g/L agar. The optimal rooting medium was half-strength MS medium supplemented with 0.5 mg/L IBA, 30 g/L sucrose, 7.5 g/L agar, and 0.2 g/L activated charcoal. The recommended substrate for seedling acclimatization was a mixture of sand, peat soil, and vermiculite in a ratio of 1∶1∶1. Through the optimization of seed disinfection methods, culture media selection, hormone combinations, and seedling acclimatization experiments, an efficient tissue culture system for B. ceiba was established. This would provide technical support for the in vitro preservation of B. ceiba seedlings, propagation of superior individuals, healthy seedling breeding, and the industrialized production of seedlings, and lay a foundation for the genetic transformation system of B. ceiba.

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.

Fenjiaren is a new Dendrobium variety bred by Sanming Academy of Agricultural Sciences for both ornamental and edible purposes. In factory seedling cultivation, it was found that Fenjiaren had slow cluster bud proliferation, low proliferation coefficient, underdeveloped root system of tissue culture seedlings and other problems, which affecting the large-scale production of this variety. To improve the efficiency of factory seedling cultivation of the variety, the sterile seedlings were used as the explants, the effects of plant growth regulators including 6-BA, NAA, and additives such as banana puree and AC on the proliferation of stem segments and the rooting of seedlings were studied using L₉(3³) orthogonal experiments. The suitable culture medium for the proliferation of stem segments of Fenjiaren was 1/2 MS+6-BA 3 mg/L, banana puree 100 g/L, white sugar 30 g/L, activated carbon AC 1 g/L, and agar powder 5.6 g/L. After 4 months of cultivation, the proliferation coefficient of the stem segment was 5.08. Range analysis indicated that the primary and secondary relationship of the factors was 6-BA>NAA>banana puree. The inter subject effect test showed that 6-BA had a significant impact on the growth rate coefficient (P<0.05). The most suitable culture medium for rooting was 1/2 MS+NAA 1 mg/L+banana puree 100 g/L+white sugar 15 g/L+agar powder 5.6 g/L. After 2 months of cultivation, the growth rate coefficient of the rooting was 12.82, the average plant height of the seedling was 12.66 cm, the average leaf length was 4.02 cm, the average number of roots was 11.80, and the average plant weight was 1.67 g. Range analysis indicated that the primary and secondary relationship of the factors was NAA>AC>banana puree. This study optimized the proliferation and rooting conditions of a new variety of Fenjiaren, which could provide technical reference for the seedling breeding of new varieties of Dendrobium and other Orchid plants.

The study was aimed to investigate the effects of litchi orchard intercropping Stylosanthes guianensis on soil physicochemical properties and soil bacterial community structure, and to provide theoretical basis for litchi orchard intercropping S. guianensis. Soil samples from litchi orchard intercropped with S. guianensis and litchi monocropping modes were used to determine soil physicochemical properties and analyzed by bacterial amplicon sequencing. After intercropping S. guianensis in litchi orchard, in the soil layer depth of 0-20 cm, nitrate nitrogen content significantly increased by 47.52%, available phosphorus content highly significantly increased by 141.53% and available potassium content highly significantly reduced by 125.59%; in the soil layer depth of 20-40 cm, nitrate nitrogen content highly significantly increased by 76.02%, available phosphorus content highly significantly increased by 48.52%, and available potassium content highly significantly reduced by 188.57%. In terms of alpha bacterial diversity, there were no significant changes in Chao1 index, AEC index, Simpson index and Shannon index in 0-20 cm soil layer and 20-40 cm soil layer after intercropping S. guianensis in litchi orchard. In terms of soil bacterial community structure, the main dominant phyla in the soil samples were all Acidobacteriota, Proteobacteria, Firmicutes, Chloroflexi, Bacteroidota, Verrucomicrobiota, Actinobacteriota, Gemmatimonadota, Myxococcota, Crenarchaeota, and Crenarchaeota were soil-specific relative abundances greater than 1% of the phyla after intercropping S. guianensis at 0-20 cm soil depth; at the genus level, in the 0-20 cm soil layer, Candidatus_Nitrosotalea was the genus with soil-specific relative abundance greater than 1% after intercropping S. guianensis, and at the 0-40 cm soil level, Nitrospira was the genus with soil-specific relative abundance greater than 1% after intercropping S. guianensis, Proteobacteria, Verrucomicrobiota, and Gemmatimonadota increased at all soil depths after intercropping S. guianensis; the results of the redundancy analysis showed that the soil bacterial community was mainly affected by effective phosphorus, nitrate nitrogen, and organic matter. In summary, intercropping litchi orchard with S. guianensis would improve the physicochemical properties and change the structure of soil bacterial community in litchi orchard soil, and play a certain role in optimizing the environmental conditions of litchi orchard soil.

The wood of most tree species of Dalbergia L. f. is well-known in the world. The research on wood anatomy mainly focus on tree species, while the research on vine or climbing plant species is rare. This paper discussed the macroscopic and microscopic wood structures of seven species of vines or climbing plants of Dalbergia L. f., and summarized systematically, and compared with the tree species of D. odorifera, so as to provide a scientific basis for wood identification, species identification, protection, breeding, development and utilization of this genus. The macrostructure showed that the difference between heartwood and sapwood was not obvious, and had little glossy, aromatic and oily when rich in gum. The growth ring was not obvious. The pores were obvious and common rich in gum, which were smaller and sparsely distributed in primary xylem, larger and densely distributed in secondary xylem. Included phloem was round. The microstructures indicated that they were all diffuse-porous wood, single pores, radial multiple pores, pores arrangement dispersed, single perforation, inter-vessel pitting alternate, vestured pitting, elliptical to nearly round, and obvious on the tangential section. Axial parenchyma was abundant and overlapped, paratubular banded, annular tubular. The wood rays were non overlapping, more fine and dense. D. odorifera was diffuse-porous wood to near semi-ring-porous wood, included phloem was absent, pith was smaller, axial parenchyma was mainly winged and polymerized-winged (paratubular banded type) or minimal banding (off tube type), low pores density. To sum up, there are many similarities in the wood anatomical structures of the seven vines or climbing plants of Dalbergia L. f., but there are also significant differences mainly in wood rays, wood rays width and pith core inclusions. Wood rays were mainly homotypic multiple columns, occasionally homotypic uniseriate of D. tsoi and D. yunnanensis. D. pinnata and D. benthamii were similar with homotypic single or multiple columns, while the former also had heterogeneous Ⅲ type rarely. D. hancei and D. peishaensis were similar with mainly heterogeneous uniseriate, occasionally heterogeneousⅠ type, while the former also had heterogeneous Ⅲ type rarely. D. candenatensis was mainly heterogeneous Ⅱ type, followed by heterogeneousⅠtype and heterogeneous uniseriate. The wood rays width of D. hanei and D. peishaensis was 1-2 cells, that of D. pinnata, D. benthamii and D. candenatensis was 1-3 cells, that of D. yunnanensis was 1-4 (mostly 2-3) cells. that of D. tsoi was 1-5 (mostly 3-4) cells. The pith core inclusions was mainly golden yellow, but that of D. tsoi was silver white, and that of D. pinnata was absent or not obvious.

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.