Previously, we achieved gene editing using CRISPR/Cas9-RNP and plasmid in the PEG-mediated protoplasts transient transformation of rubber tree, and by targeting the HbPDS gene, callus with albino phenotype were obtained, but no edited plants were regenerated because the technology of embryogenesis from callus is not yet mature. In order to obtain gene edited seedlings, we used the same HbPDS target as previous in the callus editing, but used somatic embryos as the transformation receptor instead of callus. After hygromycin resistance screening, 116 positive T₀ generation embryos were selected through Cas9 gene PCR detection, following by next generation sequencing, five embryos were found to be edited at the target, accounting for 4.3% of PCR positive embryos. At last, two regenerated plants were obtained, both were chimeric because only partial albino leaves appeared in the plantlet. Sequencing of both albino and green parts revealed that gene editing had occurred in all samples, besides a homozygous biallelic mutation in one albino leaf, all other leaves exhibited chimeric mutations, with mutant sequences in albino parts accounting for 86% to 100% ratio, while green parts accounting for 66% to 69% ratio. This indicates that the mutation threshold inducing the expected phenotype in rubber tree CRISPR/Cas9 editing plants is higher than 69%, ranging from 70% to 85%, providing theoretical guidance for obtaining gene editing seedlings with expected phenotype in the future. Meanwhile, it is proven that nearly all the regenerated plantlets obtained from T₀ generation somatic embryos are chimeric, thus T₀ generation embryos are not suitable as regenerated materials, but also providing insights to improve the regeneration procedure by using T₁ embryo to get homozygous seedlings in the future. This is the first report about gene editing plants in rubber tree, although they are chimeric, it still enhances the understanding of the function of CRISPR/Cas9 in rubber tree, laying the foundation for improving and applying gene editing technology in rubber tree.

MLO gene is an unique negative regulatory factor for disease resistance in plants, and the mutation in the gene can lead to broad-spectrum disease resistance in plants. In this study, a DNA and cDNA sequence of cassava MLO12 gene were cloned from the entire cassava genome and named MeMLO12. This gene has a total length of 3743 nt and a coding region (ORF) of 1728 nt, with a complete open reading frame containing 15 exons and 14 introns, encoding 586 amino acids. The protein has a molecular weight of 67.2 kDa and an isoelectric point of 8.85. MeMLO12 protein is located on the endoplasmic reticulum membrane, without signal peptides, and forms seven transmembrane domains at 23‒45, 74‒96, 161‒183, 285‒307, 312‒334, 371‒393, 413‒435 aa. Quantitative analysis by qRT PCR revealed significant differences in the expression of MeMLO12 gene in resistant and susceptible cassava germplasms after infection with Xanthomonas axonopodis, indicating a negative regulatory effect in the interaction between cassava and Xam. Selecting the 11th exon of the gene for Snap Gene Viewer analysis, 10 455 seed sequences of sgRNA were obtained. Three target sequences of approximately23nt were selected, with a G terminus at the 3° end of the base composition, and they were constructed onto the CRISPR-Cas9 vector. After verification, it was confirmed that the three target sequences of MeMLO12 have been successfully constructed onto the gene editing vector, named pSGR-Cas9-AT-MeMLO12 vector.

Choline monooxygenase (CMO) is a key enzyme in the synthesis of betaine in higher plants and plays an important role in the physiological process of plant resistance to stress. A CMO gene was identified in banana A and B reference genomes in banana gene database, and the biological information analysis of MaCMO and MbCMO genome sequences showed that MbCMO might be formed by a gene encoding a banana O-fucosyltransferase family protein and MbCMO gene in tandem. The CMO gene coding sequences of Zhanjiang AA (ZJ; AA genotype), Baxijiao (BX; AAA genotype), Guangdong Dajiao (GD; AAB genotype) and Jinfen (JF; ABB genotype) were cloned and compared, it was found that ZJ and BX only contained CMO-A, GD and JF both contained CMO-A, CMO-B1 and CMO-B2, and JF also contained CMO-H. Codon usage characteristics showed that there were 23 common high frequency codons among the four banana CMO gene, and the codons CUU and CCG were the most biased and the weakest codons, respectively. The physicochemical properties of CMO-A protein and CMO-H protein showed that the minimum number of amino acids was 425, the maximum number of amino acids was 470, and the secondary structure of CMO-B1 protein was the most complex. The molecular weight of CMO-B2 protein was 52.02 kDa, and the molecular weight of CMO-A protein was 47.48 kDa. All the four CMO proteins were acidic proteins, which did not have a transmembrane structure and were hydrophilic proteins. Subcellular localization prediction showed that all four CMO were localized in chloroplasts. In terms of evolution, plant CMO had obvious branches in monodicotyledonous plants during evolution, and the CMO-A, CMO-H, CMO-B1 and CMO-B2 proteins of banana were more closely related to other monocotyledonous plant CMO proteins. The results of RT-qPCR showed that CMO expression was up-regulated in the four kinds of banana roots in the early stage of osmotic stress, and the expression levels of ZJ and BX CMO in homozygous A genome were higher than those of GD and JF CMO in heterozygous A and B genomes. CMO expression in the four kinds of banana leaves was down-regulated at the early stage of osmotic stress. The expression levels of homozygous ZJ and BX CMO in A genome were up-regulated at the late stage of osmotic stress, while the expression levels of heterozygous GD and JF CMO in A and B genomes peaked at 10 days and then down-regulated again at 15 days later. It was significantly lower than that of ZJ and BX CMO. This study revealed the differences of CMO genes between the A and B genomes of bananas and the expression patterns of CMO genes in different genotypes of bananas under osmotic stress, which would lay a foundation for further research on the biological functions of CMO genes in the A and B genomes of bananas, especially the relationship between CMO genes derived from different genomes and the ability of banana to resist osmotic stress. It would provide a reference for improving the stress resistance of banana by genetic engineering.

Tigernut (Cyperus esculentus L.), most likely originated from Africa and Mediterranean, represents a novel herbaceous oil crop accumulating high levels of oil in its underground tubers. Water balance is essential for tuber development and metabolism in tigernut. Tonoplast intrinsic proteins (TIPs), which include five phylogenetic groups (i.e. TIP1-5), constitute a subfamily of aquaporin facilitating the fast and passive transport of water across vacuolar membranes. Based on available genome and transcriptome data, one TIP gene named CeTIP2;1 was isolated from tigernut tubers by using the RT-PCR technique. Sequence analysis showed that the full gene length of CeTIP2;1 is 3323 bp, including two introns with a coding sequence of 747 bp; the gene was predicted to encode 248 amino acids with the theoretical molecular weight of 24.73 kDa, the isoelectric point of 5.09, the grand average of hydropathicity of 0.948, the aliphatic index of 114.60, and the instability index of 21.76, implying its stable, acidic, and hydrophobic features, which is consistent with its tonoplast-localization; presence of one conservative MIP domain was observed, which possesses six transmembrane helices, two half helices, and two typical NPA motifs. CeTIP2;1 was shown to exhibit the sequence similarity of 87.20% with AtTIP2;1, which was considerably higher than 46.23% with SoPIP2;1. Further phylogenetic analysis revealed that CeTIP2;1 belongs to the TIP2 group and is a true ortholog of AtTIP2;1. Interestingly, the phylogenetic analysis also supported that TIP2 has diverged into two subgroups sometime before monocot-eudicot divergence. Tissue-specific expression analysis showed that CeTIP2;1 was highly expressed in all tissues examined in this study, i.e., leaf, sheath, root, shoot apex, rhizome, and tuber, with most in tuber/rhizome and lowest in shoot apex. A bell-like expression pattern was observed during tuber development, peaking at the medium stage of swelling and lowest in maturation. Moreover, CeTIP2;1 was also detected in the tuber proteomes, implying its high abundance and key roles. These findings would lay a solid foundation for further uncovering the mechanism of water balance in tigernut tubers.

In order to understand the fruit quality of different varieties of pitaya and to screen the germplasm resources with good quality, 33 pitaya germplasm resources were and 15 botanical traits and quality properties such as single fruit weight, fruit transverse and longitudinal diameters, proteins, total flavonoids, and beet pigments were measured, and fruit quality was comprehensively evaluated by using correlation analysis and principal component analysis. The 33 pitaya germplasm resources had a single fruit mass of 164.67-556.00 g, a transverse fruit diameter of 5.86-9.40 cm, a longitudinal fruit diameter of 7.29-11.94 cm, a fruit shape index of 0.99-1.39, a total sugar content of 78.80- 126.05 mg/g, a total phenolic content of 0.64-2.46 mg/g, a total flavonoid content of 0.85-9.67 mg/g, hardness of 6.62- 16.86 N, protein content of 0.29-1.45 mg/g, beet pigment content of 0.69-37.01 mg/100 g, and starch content of 14.12-44.60 mg/g. The total acid content ranged from 0.33 to 15.23 mg/100 g. The Pearson’s method was used to correlate the main botanical and quality traits of the pitaya germplasm resources. and quality traits were correlated. The correlation coefficients were 0.478 for total acid and soluble solids, and -0.532 for sugar-acid ratio, while the correlation coefficients were 0.749 and 0.942 for longitudinal and transverse diameters. The correlation coefficient between longitudinal diameter and fruit shape index was 0.426, and the correlation coefficient between weight and sugar-acid ratio and hardness was 0.360 and 0.351, respectively. After principal component analysis, the 15 traits were combined into 7 principal component factors, with a cumulative contribution of 82.55%. The first principal component contributed 22.45%, with single fruit weight, fruit longitudinal and transverse diameter, and sugar-acid ratio contributing more. The second principal component contributed 13.87%, with total sugar content, soluble solids content and starch content contributing more. The contribution of the third principal component was 12.28%, with soluble solids content contributing more. Among them, sugar-acid composition, single fruit weight, fruit transverse diameter, fruit longitudinal diameter, soluble solids content, starch content, amino acid content, etc. are the key indexes for evaluating the comprehensive quality of dragon fruit. After comprehensive evaluation, six excellent pitaya singles with high comprehensive scores were screened, i.e., Reyan 1 hao, Wanhuafenhong, Hongbaolong, Wucihong, Linjiahongyun and Hongjinbao, which can be used as high-quality parents for pitaya quality breeding.

Paphiopedilum is one of the most valuable orchid groups with its unique shape, rich flower colors and long flowering period. The shape of the lip of Paphiopedilum is peculiar, and it is specialized as a pouch or helmet, it looks like a lady’s slippers, so it is also known as the slipper orchid. However, due to the low seed germination rate of Paphiopedilum, low propagation rate of traditional division propagation, immature tissue culture propagation technology, and relatively difficult to cultivate, it is difficult to meet the market demand through artificial breeding. Resulting in the serious exploitation of wild resources and the destruction of its living environment, wild resources continue to decrease, Paphiopedilum is now one of the most endangered species in the world. In this paper, the geographical distribution and habitat of Paphiopedilum in the world and China were analyzed by means of literature retrieval, with special attention to the new species published in recent years, which can provide reference for the conservation and utilization of wild Paphiopedilum germplasm resources. Understanding the geographical distribution characteristics of Paphiopedilum is of great significance for in situ and ex situ conservation of Paphiopedilum germplasm resources. At present, there are about 109 species and 26 varieties of Paphiopedilum in the world. Since the English edition of the Flora of China in 2009, 7 new species of Paphiopedilum have been discovered in China, on the basis of the original 27 species of Paphiopedilum, and 30 new species have been discovered in the world during this period. Paphiopedilum mostly distributed in tropical and subtropical transition areas, originated in southwest China and Southeast Asia, and then spread to Southeast Asian islands, Indonesia (Sulawesi, Java etc.) and China (Yunnan, Guangxi etc.) are the distribution centers of Paphiopedilum. The main factors affecting the distribution of Paphiopedilum are climate, topography, soil, symbiotic microorganisms, pollinators and so on. The distribution pattern of Paphiopedilum is influenced by both large scale (climate factor) and small scale (small habitat, such as landform, soil, etc.). Paphiopedilum may gradually spread and migrate to areas within its temperature tolerance range. In the past 50 years, the high latitude area has warmed more, and the suitable area for the growth of Paphiopedilum has expanded, resulting in its distribution range spreading or migrating to high latitudes and high altitudes. The seasonal temperature changes may cause the distribution of Paphiopedilum plants (Paph. subgenus Brachypetalum) to shift to higher or lower latitudes. The phenology, morphology and genes of Paphiopedilum plants may also undergo certain changes, and the number of species that do not adapt to environmental changes will gradually decrease until extinction, and new species will continue to emerge. The distribution of Paphiopedilum is also affected by topography, soil physical and chemical properties, soil microorganisms and other factors. Microorganisms in soil, especially fungi, can promote the germination of Paphiopedilum seeds. If fungi that are mutually beneficial to Paphiopedilum are lacking in the new habitat, the seeds of Paphiopedilum may not germinate smoothly, and the population of Paphiopedilum may be restricted to a specific area. The distribution of Paphiopedilum is also closely related to pollinators, and the species, quantity and distribution of pollinators affect the distribution pattern of the corresponding Paphiopedilum. Pollinating insects of Paphiopedilum are abundant, mainly belonging to the family of Syrphidae, and insects of Apidae, Halictidae, Colletidae and Megachilidae can also be used as pollinators for Paphiopedilum. There is usually more than one effective pollinator of each Paphiopedilum species. The study on the geographical distribution pattern of Paphiopedilum would provide reliable evidence for the species evolution between genera and within genera. The more primitive Paphiopedilum was mostly terrestrial, while the more evolved Paphiopedilum evolve into semi-epiphytic or epiphytic orchids due to environmental adaptation and competitive pressure, growing on cliffs or between rocks.

As a traditional oleaginous resource on Hainan Island, the camellia species predominantly exist as evergreen trees of small to medium stature. The large-fruit camellia with white flowers is widely distributed across various regions of Hainan Island. This study conducted a survey and sampling of camellia populations aged 30 years and above across all municipalities and counties of Hainan Island. Ploidy identification was carried out using flow cytometry and chromosome squashing techniques. The research revealed that among the 23 populations surveyed, 16 were identified as decaploid and 7 as octoploid, covering 16 municipalities and counties across the island. Decaploid camellia populations were found in 12 counties and cities (Danzhou, Lingshui, Qionghai, Wuzhishan, Ding'an, Chengmai, Tunchang, Lingao, Changjiang, Ledong, Qiongzhong, Baoting), including ancient trees over 100 years old and wild camellia populations in tropical rainforests, all of which were identified as decaploid. In contrast, the octoploid populations were generally under 60 years of age and traced back to artificial cultivation, with no other ploidy camellia resources found in the surveyed populations. It is evident that the camellia resources on Hainan Island are primarily composed of decaploids and octoploids, with the decaploids being indigenous to the island and the octoploids, not exceeding 60 years of age, being introduced from regions such as Guangdong and Vietnam during the 1960s to 1970s. Both types of camellia have demonstrated good adaptability to the growth conditions. Given that decaploid camellia trees have not been found in other camellia distribution areas, the widespread distribution of decaploid camellias on Hainan Island and the discovery of decaploid wild camellia populations in tropical rainforests suggest that the decaploid camellia species are indigenous regional species of Hainan Island, evolved due to unique ecological factors such as the island’s tropical monsoon climate. The distribution range of the resources spans from 18°38′42″N to 19°49′53″N and from 108°51′0″E to 110°29′46″E, at altitudes ranging from 4.17 m to 1090 m.

Through the examination of the phenotypic traits of teak (Tectona grandis L. F.) seeds from diverse provenances and pedigrees, this study elucidated the genetic variability patterns of teak seeds and the mechanisms of response to environmental factor fluctuations, thereby fostering the conservation and genetic improvement of teak germplasm resources. Using seeds from 81 teak pedigrees representing 13 provenances across four provinces (Guangdong, Guangxi, Hainan, and Yunnan) as the experimental material, five traits, namely seed length, width, length-width ratio, length-width product, and hundred-seed weight, were quantified. Significant differences (P<0.01) existed among the five phenotypic traits of teak seeds across provenances and pedigrees, with trait variation coefficients ranging from 10.27% to 23.88% among different pedigrees and from 4.21% to 20.32% among different provenances. Substantial correlations prevailed among various phenotypic traits, with varying degrees of influence on seed traits from different environmental factors. Latitude, altitude, and annual precipitation were the primary determinants affecting teak seed traits, followed by annual average temperature, while the impact of annual average relative humidity was relatively minor. Distinct seed traits also exhibited heterogeneous responses to environmental changes, with seed length, seed width, and length-width product being particularly sensitive to annual precipitation, whereas length-width ratio and hundred-seed weight manifested heightened sensitivity to latitude. Cluster analysis categorized the 13 provenances into three classes. Teak seeds manifest prolific phenotypic variation across provenances and pedigrees, with seed traits being influenced by various factors, including maternal inheritance and geographical climate. The research would provide a theoretical foundation and scientific basis for the conservation and utilization of diverse teak.

Three newly recorded species of China, viz. Annulohypoxylon albidiscum, A. bahnphadengense, and A. spougei, are described and illustrated based on the morphological characters and molecular phylogeny. The specimens were collected from Hainan, China. The detailed morphological features descriptions and photographs were provided for each species. Maximum likelihood analysis and Bayesian inference were used to construct phylogeny trees based on ITS sequences. The three species were supported and confirmed by molecular data. The comparisons between the three Chinese records and holotype specimens were discussed. The specimens are deposited in the Fungarium of Chinese Academy of Tropical Agricultural Sciences (FCATAS).

Soil salinization is an ecological environment issue globally and is one of the major abiotic stress factors that cause crop loss worldwide as well as hindering crop productivity. Halotolerant plant growth-promoting rhizobacteria (PGPR) having potential to promote crop growth and increase salt tolerance in crops can be employed to counter this issue in a more effective and eco-friendly way. The recent study aimed to assess the salinity tolerance and growth-promoting capacity of Bacillus tequilenis Bt-RS isolated from the rhizosphere soil of islands in the South China Sea, for assessment, the corresponding media were used for qualitative and quantitative analysis. A pot trail was also conducted to further evaluated its bacterial consortium to promote banana seedlings growth under salinity stress. The results showed that strain Bt-RS could grow well under the condition of 0-10% NaCl content with various types of salts. The strain Bt-RS also possessed 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity along with indole acetic acid (IAA, up to 6.4 mg/L under the condition of 1%-5% NaCl). Base on the pot experiment, the banana seedlings that were inoculated with Bt-RS displayed a significant increase in height, leaf area, fresh weight of above ground and underground, as well as dry weight of above ground and underground (40.30%, 93.00%, 102.38%, 81.08%, 65.82% and 50.50%, respectively) compared to the control group under normal conditions; The 200 mmol/L NaCl-stress treatment significantly increased the growth of banana seedlings in height, leaf area, fresh and dry weight of both above ground and underground by 20.55%, 65.01%, 98.14%, 144.93%, 87.85% and 54.01% respectively, when compared with the control group. The plant height, leaf area and biomass of banana seedlings were significantly increased in both normal conditions and salt stress environment (P<0.05). There was no difference in plant height and leaf area between the experimental group under salt stress environment and the control group under normal conditions, indicating that applying Bt-RS can alleviated the adverse effects of NaCl stress and enhanced banana seedlings growth attributes. In conclusion, the strain B. tequilensis Bt-RS exhibits high salt tolerance and possess the ability to produce IAA and ACC deaminase, making it a valuable strain for improving banana seedling growth and salt tolerance, and also providing resources of strain for developing and utilizing in saline soil.

In order to find out the ratio of silicon and calcium fertilizer suitable for the cultivation of passion fruit in the low-heat valley area of Guizhou, this study took passion fruit Qinmi No. 9 as the test material. The experiment was conducted with 50 g of silicon fertilizer per plant before flowering, spraying calcium fertilizer about 10 days after flowering, spraying once every 15 days, spraying three times continuously, and the concentration of calcium fertilizer was 500 times, 1000 times and 1500 times. CK was used as the control group, which received no fertilizer application. The effects of different medium and micro fertilizers, as well as dosages, on the quality and related cell wall metabolism indexes of passion fruit were explored by applying silicon fertilizer to the soil and spraying calcium fertilizer during the flowering and fruiting periods. The aim was to screen for the best specialized silicon-calcium fertilizer formula. The aim is to provide a theoretical basis and practical guidance for improving the quality of passion fruit. The results showed that compared with the control, soil application of silicon fertilizer and spraying calcium fertilizer 1000 times combined application increased the single fruit weight, fruit hardness and fruit shape index of passion fruit. Additionally, they elevated the content of soluble solids (TSS) and vitamin C (Vc), while reducing the content of titratable acidity (TA). Furthermore, there was an increase in soluble sugar (SS) and soluble protein content (SP). Peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activities were promoted. However, the activities of water-soluble pectin (WSP) content, cellulase (CX), polygalacturonase (PG), and pectin methylesterase (PME) decreased due to the increase in protopectin and cellulose in the peel, each index was significantly different from the control group. It shows that silicon-calcium fertilizer had the best effect on enhancing passion fruit quality and improving the mechanical strength, toughness and stability of peel. Compared to CK, the single fruit weight, fruit hardness, longitudinal diameter and transverse diameter increased by 11.15%, 27.18%, 6.23% and 3.29%, respectively. Moreover, the contents of TSS, Vc, SS and SP increased by 16.95%, 16.12%, 20.57% and 24.55%, respectively, while the content of TA decreased by 36.03%, and the activities of POD, SOD and CAT increased by 13.16%, 19.67% and 21.65%, respectively. The content of protopectin and cellulose in peel increased by 19.29% and 17.19%, respectively. Meanwhile, the content of WSP decreased by 10.63%, and the activities of CX, PG and PME decreased by 8.58%, 22.98% and 7.52%, respectively.

Pigeonpea is an important food and forage crop in the tropics. In order to dissect the physiological characteristics of pigeonpea under cold stress and its cold tolerance, eight seedlings of pigeonpea were tested and analyzed by 8 physiological indexes under 4 ℃ stress, and cold tolerance of pigeonpea were evaluated by subordinate function value method in this study. The results showed that with the prolongation explored to cold stress, REC, SS, MDA and Pro increased respectively, SOD and POD increased firstly and then decreased, and Chl showed a general trend of decline, and the variation of CAT activity was significant difference only in P₂ among the 8 accessions. The cold tolerance of the 8 accessions was in the order: Miandian>Danzhou>170306001>060302216>ICPL7086>Nan 02137>Guangxi>Qiongzhong. The content of Chl, SOD and POD activity were significantly correlated with cold tolerance of pigeonpea, which could be the reliable physiological indexes to evaluate the cold tolerance of pigeonpea.

Five shading levels (0, 30%, 50%, 70% and 90%) were set up to analyze the biomass distribution patterns, the differences in mineral element composition characteristics and nutrient accumulation of Ficus hirta Vahl (FH). The average plasticity index of the biomass indicators of FH was 0.81. The proportion of stem biomass was less affected by shading, while fruit biomass and its proportion were significantly affected. 90% shading level inhibited fruit production, while the 50% shading level exhibited the highest fruit biomass proportion. Shading increased nitrogen and potassium content in FH, while decreasing calcium and phosphorus. The calcium-to- phosphorus ratio ranged from 1.65 to 6.32, with lower ratios in fruits and higher ratios in leaves. Among trace elements, iron content was most affected by shading. 70% and 90% shading levels led to a more than 65% reduction in iron content compared to the control. The iron content was most affected by shading. Under shading, the crude protein content in FH leaves and fruits ranged from 13.91% to 16.82% and 12.22% to 16.46%, respectively. The average content of crude fiber in leaves and fruits was 13.73% and 17.33%, respectively. The ether extract content in FH fruit planted in the full light was the highest, at 13.30%. Shading significantly reduced the content of flavonoids in leaves, stems, and fruits of FH, but the polyphenol content in the leaves and fruits reached its highest under 30% shading rate. In conclusion, The production mainly based on seed harvesting for seedling breeding is not suitable for high shading cultivation. 50% shading level can be used to improve the fruiting rate. Shading altered the accumulation and composition ratio of nutrient in different plant parts. When used as feed material, environmental impact and nutrient ratio adjustments should be considered in FH cultivation. 30% shading rate is better for FH planting when using its leaves as materials for beverage production.

Plant phospholipase A (PLA) is a key enzyme in cell membrane phospholipid metabolism. It can catalyze the cleavage of multiple functional groups on phospholipids to generate signaling molecules, which are involved in regulating plant growth and development as well as environmental and biological stresses. PLA possesses important research value. In this study, the effects of various factors such as substrate concentration, reaction temperature, pH of buffer solution, buffer solution volume, and reaction time on catalytic activities of banana PLA for phospholipid hydrolysis were investigated, so as to optimize PLA activity assay method. According to the optimal assay conditions, the change of banana PLA activity under anthracnose stress was further studied. The results showed that the optimal conditions for the determination of banana PLA activity by acid-base titration method were as follows: pH 9, reaction temperature 55 ℃, substrate concentration 4 g/L, 15 mL substrate, 3 mL crude enzyme extract, the ratio of extraction buffer volume to peel weight (mL/g) 3, and reaction time 7 h. According to the optimal conditions, the PLA activity of banana peel tissue under anthracnose stress was determined. It was found that the degree of disease in peel tissue was positively correlated with PLA activity, indicating that PLA activity increased with the deepening of disease. This suggested that the level of PLA activity was probably related to fruit resistance. As disease degree deepened, PLA activity increased, membrane phospholipids degraded, and cell membrane integrity disrupted, leading to fruit decay. In this article, a convenient and feasible method for the determination of banana PLA activity was established, which laid a foundation for further study of the catalytic mechanism of banana phospholipase A.

Banana is an important economic crop in the subtropical region of China. The occurrence of banana Fusarium wilt has seriously hindered the development of banana industry in recent years. Biological control has attracted attention because of its green environmental protection and durable disease resistance. It’s very important to get the efficient biocontrol strains with different inhibition mechanisms on banana Fusarium wilt. In this study, four different types of biocontrol strains against banana Fusarium wilt which were obtained in the laboratory in the early stage were mutated by ultraviolet-nitrite compound mutagenesis, with the highest antimicrobial activity increased by 186.24% and the highest control effect increased by 46.54%. The disease prevention mechanism of the four mutants obtained was preliminarily investigated. The results showed that the strain Ba62v had the highest inhibition rate on the colony growth of Fusarium oxysporum f. sp. cubense (Foc), and could also induce the activity of SOD enzyme in banana seedlings. The strain Blz02v could promote the growth of banana seedlings and induce the activities of POD and SOD of banana seedlings. The strain Bc11v had the highest inhibition rate on the spore germination of Foc, and could induce the activities of PPO, CAT and SOD in banana seedlings. The strain Pt05v had the highest inhibition rate on the sporulation of Foc, and could induce the activities of POD, PPO and SOD in banana seedlings. The main action mechanisms of the four biocontrol mutants on Foc and hosts are different, and there is a potential for biocontrol of compound synergism, which would provide an important strain resource for the development and utilization of the disease-resistant compound fungicides in the future, and has a good application prospect.

Shanlan upland rice (Oryza sativa L.) is an unique variety in Hainan, with excellent taste quality traits and rich nutrition. At the same time, it also has excellent stress resistance, such as disease resistance, drought resistance and heat resistance. However, thus far, the resistance of Shanlan upland rice to herbivores remains largely unknown. Thus, in this study, using TN1 and RHT as susceptible and resistant control varieties, respectively, the resistance of three Shanlan upland rice varieties, Shanlanchaihongmi, Shanlanjianshanlannuo and Shanlanyingmigaochan to BPH was evaluated, and their resistance mechanisms were analyzed. The results showed that at the seedling stage, the variety of Shanlanjianshannuo showed resistant to Nuaparvata lugens, brown planthopper BPH, whereas the other two varieties were susceptible to BPH. At the tillering stage, the resistance of the three rice cultivars to BPH was all significantly higher than that of TN1. The mechanism studies revealed that the thickness of the thick-walled tissue in the outer leaf sheaths and the level of cell wall components including lignin, pectin, cellulose and hemicellulose were significantly higher in the three Shanlan upland rice cultivars and the insect-resistant control cultivar RHT than the insect-susceptible control cultivar TN1. Moreover, the basal and BPH-induced levels of JA, JA-Ile, ABA and SA in the three Shanlan upland rice cultivars were significantly higher than those in TN1, and the content of ABA in Shanlanjianshanlannuo plants was the highest in all of the tested varieties. The results demonstrated that the thickness of the thick-walled tissue of the outer leaf sheaths of Shanlan upland rice and the rapid and strong responses of JA, ABA and SA signaling pathways to BPH infestation might be the major reasons why the BPH resistance is stronger in Shanlan upland rice cultivars than TN1.

This research aimed to identify a pathogenic fungus of the brown spot disease in the leaves of Cycas and screen for its chemical control agents, which provides a theoretical basis for the protection of Cycas. The pathogenic fungus was isolated from the lesion spots in some Cycas leaves. The pathogenicity of the fungus was confirmed by isolating and purifying the infected leaf tissues and reintroduced to the healthy leaves of Cycas diannanensis following Koch’s postulates. Morphological identification of the pathogenic fungus was conducted. To further confirm the identification, a phylogenetic tree was constructed using eight gene sequences: SSU, LSU, GAPDH, tef1, rpb2, Alt, OPA10-2 and ITS. Effective chemical control agents were screened from seven chemical agents by inhibition assay in vitro. Phylogenetic analyses showed that this pathogen was Alternaria burnsii. Among the tested chemical agents, the most effective inhibition was fluoxastrobin, which displayed 73.48% inhibition rate at a concentration of 0.67 mg/L.

Citrus is one of the most important fruits in China, and its post-harvest occurrence of citrus green mold is a serious threat to the quality and safety of citrus, and also causes mycotoxin contamination in the fruit. A strain of Streptomyces sp. R₂A-15 with good antagonistic effect on the pathogen of citrus green mold was isolated from the root soil of red orange plants in the red orange orchard of Jiuzhoujiang, Lianjiang, Zhanjiang city, Guangdong province. The optimization of the fermentation conditions and stability analysis of the bacterial inhibition activity were studied to provide reference for the preparation and application of the biocontrol agent of citrus green mold. In this study, Penicillium digitatum was used as the target fungus, and the fermentation broth was used as the inhibitory activity according to the size of the diameter of the inhibition zone by paper diffusion method. The fermentation medium of strain R₂A-15 was optimized using one-way and cross-combination tests, and the fermentation conditions were optimized by response surface analysis to improve the inhibitory activity of the fermentation broth, and the stability of the fermentation broth was investigated under different acid-base, temperature and ultraviolet light conditions. The optimum carbon source for the fermentation medium of the strain was cornmeal and the optimum nitrogen source was acid-hydrolyzed casein in the one-way and cross-combination tests. Based on response surface analysis, it was concluded that cornmeal and fermentation time had a significant effect on the bacteriostatic activity of the fermentation broth. The optimal fermentation medium for maximum inhibitory activity of the fermentation broth, as determined by validation tests, was 12.09 g of cornmeal, 4.00 g of acid-hydrolyzed casein, 2.00 g of calcium carbonate, 2.00 g of magnesium sulfate, 2.00 g of dipotassium hydrogen phosphate, 1.00 g of sodium chloride, and 1 L of distilled water. The optimal fermentation conditions were: initial fermentation pH 7.0, fermentation time 37.50 h, fermentation temperature 34 ℃, inoculum volume 3%, and shake flask filling volume 100 mL/250 mL. The bacteriostatic activity of the fermentation broth of the strains increased by 39% after optimization. The overall bacteriostatic activity of the fermentation broth of the strain could be maintained at a relatively stable and high activity level after treatment with different temperatures and ultraviolet light conditions, but the bacteriostatic activity of the fermentation broth decreased under strong acid and alkali. The results indicate that Streptomyces sp. R₂A-15 has a good and stable inhibitory effect on the citrus green mold pathogen, and has a good prospect for practical application, which lays a foundation for the later scale fermentation as well as the development of bacterial agents.

Yunyan 774 is a newly bred rubber tree cultivar in Yunnan, the research on its latex composition and properties is of great significance for its popularization and application. The changes of non-rubber components and colloidal properties, molecular weight and distribution of Yunyan 774 concentrated natural latex during storage, as well as the differences of crosslinking density, physical and mechanical properties, aging properties and latex particle size and distribution after 90 days of storage were measured and analyzed. The experimental results showed that the total solid content and ash content of Yunyan 774 remained unchanged after 90 days of storage, and the dry rubber content decreased by 1.1%, which was related to the reaction of some non-adhesive substances to form substances that could not be precipitated by adding acid. The content of volatile matter decreased slightly, but the content of acetone soluble content, water soluble content and nitrogen increased in different degrees. The content of advanced fatty acids of Yunyan 774 increased with the extension of storage time, and the ammonium soap with protective effect was generated, which played a role in improving the mechanical stability in the early stage. The thermal stability decreased gradually, and the viscosity decreased first and then was basically constant. The increase of volatile fatty acid content was not conducive to the preservation of latex. The physical mechanical properties and aging properties of Yunyan 774 latex vulcanized rubber film were better than those of the mixed strain. Compared with the mixed strain, the molecular weight distribution of Yunyan 774 was wider, the molecular weight was slightly lower, and the particle size was not different.

In order to obtain the structural mechanical property parameters of rubber bark and solve the problem that there is no reliable reference for accurate detection of rubber depth and accurate control of skin loss thickness in the research and development of mechanized rubber picking equipment, a test device for nonlinear mechanical property measurement of rubber bark based on PLC was designed to realize automatic continuous detection and data collection of rubber bark mechanical properties with high precision and low loss measurement of bark thickness. The mechanical properties of bark of 15-, 20- and 25-year-old rubber trees of Reyan 7-33-97 and PR107 were studied, and the mathematical model of piercing force with piercing depth was established. The experimental results showed that the performance of the device was stable, and the piercing force curves of different strains and different ages were similar, showing a high-low-high trend, and were highly correlated with the layered characteristics of the bark structure. Under the same age, the piercing force of two strains of Reyan 7-33-97 and PR107 was not significantly different, and the piercing force of older trees of the same strain was greater than that of younger trees. The maximum piercing force reached 48.5 N. The test device meets the requirement of detecting structural mechanical parameters of rubber bark and provides theoretical basis for the research and development of mechanized rubber harvesting equipment.

In order to explore the application of coffee protein in food processing, non-fat green coffee powder was used as the raw material. Different ultrasonic powers (0 W, 200 W, 400 W, 600 W and 800 W) effect of synergistic interaction with deep eutectic solvent method and alkali method on composition (SDS-PAGE), structural properties (particle size distribution, Fourier transform infrared spectroscopy, circular dichroism spectrum, fluorescence spectroscopy and scanning electron microscopy) and functional properties (solubility, water absorption, oil absorption and emulsification) of coffee protein were studied. The average particle size of coffee protein (DES) extracted by deep eutectic solvent (12.30 μm) was significantly smaller than that of coffee protein (AEP) extracted by alkali method (113.67 μm). The solubility of DES was higher under acidic conditions, and the solubility of AEP was higher under alkaline conditions. DES had better water and oil absorption than AEP. After ultrasonic pretreatment, the results of coffee protein electrophoresis, Fourier infrared spectrum, circular dichroism spectrum and fluorescence spectroscopy showed that different ultrasonic power pretreatment did not cause significant changes in protein molecular weight distribution, but it affected the secondary and tertiary structure of proteins. The surface microstructure of DES showed that the surface structure was loose and porous, and the surface of AEP was tight and flat. After ultrasonic pretreatment, the microstructure of AEP became loose and porous, the texture became dispersed, and more irregular fragments were presented. The surface of DES changed slightly, and showed more small-particle porous disordered structure when treated at 400 W and 600 W for 15 min. The microstructure changes could affect the chemical and physical properties and functional properties of proteins. When the ultrasonic power was 400 W, the particle size of DES decreased significantly, and the particle size parameters D_[3,2] and D_[4,3] decreased from 10.50 μm, 30.43 μm to 7.89 μm and 11.27 μm, respectively. The solubility increased significantly, and the solubility increased from 47% and 71% to 75% and 81% respectively under acidic and alkaline conditions. In addition, ultrasonic pretreatment could improve the water absorption and emulsification activity of coffee protein, which are important functional properties of proteins in food applications. The results show that the modification of coffee protein by ultrasonic technology is effective, and this study could provide a theoretical basis for the application of coffee protein in food processing.

The purpose of this study was to provide a scientific basis for the classification, breed selection and targeted development and utilization of different germplasm of Aquilaria sinensis. The samples of agarwood from six different germplasms were studied: Aquilaria sinensis ‘Haixiang 1’, A. sinensis ‘Haixiang 2’, A. sinensis ‘Haixiang 3’, Piyou type, Big leaf type and Nangpao type. Gas chromatography-mass spectrometry (GC-MS) was used to study the composition of the agarwood samples extracted by ultrasonic ether method. The volatile components of agarwood produced by the above six germplasms were higher in sesquiterpenoids and lower in chromones, The volatile components of six germplasms were quite different, except two components in common, namely butylated hydroxytoluene and 2,2'-methylenebis[6-(1,1-dimethylethyl)-4-methyl-phenol]. The number of sesquiterpenoids (10-26 kinds) and the total relative percentage content (25.39%-87.50%) were higher, and the main component was baimuxinal, among which A. sinensis ‘Haixiang 3’ had the highest amount and content. The quantity (1-3 species) and total relative percentage content (4.66%-37.32%) of chromones were low, mainly 2-(2-phenylethyl) chromones, among which A. sinensis ‘Haixiang 1’ had the highest quantity and content, while A. sinensis ‘Haixiang 3’, Big leaf type and Nangpao type were not detected. The agarwood from A. sinensis ‘Haixiang 1’, A. sinensis ‘Haixiang 2’, A. sinensis ‘Haixiang 3’, Piyou type, had relatively rich aromatic components (baimuxinal,7α-H-9(10)-ene-11,12-epoxy-8-oxoeremophilane, karanone and so on). The agarwood produced by A. sinensis ‘Haixiang 2’, A. sinensis ‘Haixiang 3’, Piyou type and Nangpao type contained many sesquiterpenoids, such as agarospirol and (-) jinkoh-eremol. The content of benzylacetone in A. sinensis ‘Haixiang 1’, A. sinensis ‘Haixiang 2’ agarwood was high. 7α-H-9(10)-ene-11,12-epoxy-8-oxoeremophilane and 6,7-dimethoxy-2- (2-phenylethyl) chromone in the agarwood produced by A. sinensis ‘Haixiang 1’, A. sinensis ‘Haixiang 3’ and Big leaf type were high. The types and contents of volatile components of agarwood derived from the six different germplasms showed great difference, which could be developed according to the difference of active components.

Natural rubber, a crucial industrial raw material worldwide, and a significant part of the income for Laotian farmers, is influenced by alternative planting policies and fluctuations in rubber prices. Aaccurate and rapid monitoring of local artificial rubber plantation is of crucial significance for promoting the sustainable development of the rubber industry. Most research has focused on the extraction of rubber plantation information in small areas, typically utilizing single or dual-temporal image classification, which fails to capture the long-term expansion characteristics of rubber forests. To investigate the long-term, large-scale expansion features of rubber plantation, this study selected a continuous thirty-year Landsat time series imagery from 1990 to 2020. The LandTrendr algorithm was employed to extract changes in rubber plantation across Laos over the three decades. International rubber futures prices and terrain data were also utilized for spatiotemporal change analysis. The selected feature combination, after optimization, can better extract rubber forest distribution. The overall accuracy of rubber forest distribution extraction in 2020 was 89.85%, with a Kappa coefficient of 0.82, revealing Laos’ rubber plantation area to be 321 000 hectares in 2020. The overall accuracy of rubber forest expansion change monitoring using the LandTrendr algorithm and secondary classification was 92.44%, with a Kappa coefficient of 0.82. The expansion of artificial rubber forests in Laos was closely related to the rubber futures market. Through terrain factor analysis, it is deduced that rubber forests are suitable for planting in low-altitude, gently sloping, and sunny areas. This study effectively monitors changes in rubber forests at the national level over an extended period, providing valuable data support for the development of the rubber industry and policy control.

The effect of bacterial wilt on the fertility of different textures of latosol in Hainan province (sand from Wencheng town, Wenchang city; loam from Dacheng town, Danzhou city; clay from Yongfa town, Chengmai county) was investigated. After the occurrence of bacterial wilt, the disease incidence, physicochemical indicators including pH, organic matter (OM), available nitrogen (AN), available phosphorus (AP), available potassium (AK), soil porosity (SP), bulk density (BD), mass water content (MWC) as well as enzyme activity indicators including catalase (CAT), peroxidase (POD), sucrase (SC), urease (UE) and acid phosphatase (ACP) of the soil inoculated with Ralstonia solanacearum and blank control were compared to analyze the effects of bacterial wilt on various fertility indicators. Spearman correlation analysis and redundancy analysis (RDA) were used to determine the significant indicators affected by bacterial wilt in different soil textures. The results showed that the disease incidence and severity disease index in clay were the highest among the three soil textures, while those of loam were the lowest. In the inoculation treatments, pH, AP, SP and POD of the three soil textures were lower than those of the control, while AN, AK, MWC and UE of clay inoculation treatment were higher than those of the clay control. CAT, ACP, MWC and BD of loam inoculation treatment were higher than those of the loam control. Spearman correlation analysis results showed that OM content, AP content, SP and POD of the three texture soils were negatively correlated with disease incidence; ACP, pH and disease incidence in WCS were significantly negatively correlated (P<0.05) with disease incidence; CAT and UE were significantly positively correlated (P<0.05) with disease incidence. In loam, pH, OM, POD and UE was significantly negatively correlated with disease incidence (P<0.05); while CAT and ACP were significantly positively correlated with disease incidence (P<0.05); SP and POD in clay were significantly negatively correlated with disease incidence (P<0.05); however, AK content in clay was significantly positively correlated with disease incidence (P<0.05). RDA results showed that the SP, OM content and AN content in the control and inoculation treatments were highly correlated with UE, while both SP and AK content in the control and inoculation treatments were highly correlated with ACP and CAT respectively. After the occurrence of bacterial wilt, most fertility indicators of control and inoculation treatment of sand and loam were lower than those in clay. However, soil fertility level was not a sufficient condition for bacterial wilt, but most soil fertility indicators were reduced due to the outbreak of bacterial wilt. The lower disease incidence and disease index of tomato bacterial wilt in sand than in clay may be due to the higher AP content. The reason why disease incidence and disease index of tomato bacterial wilt in loam is lower is perhaps that low pH conditions are unsuitable for the survival of bacterial wilt. Clay with the most severe bacterial wilt disease situation including pH, nitrogen level and mass water content was suitable for the growth and reproduction of bacterial wilt. The relative abundance of potential beneficial microbial communities in clay may also be lower than sand and loam. Therefore, the control measures of bacterial wilt in different soil textures should be adapted to local conditions. Meanwhile, the relevant conclusions of this study would provide a theoretical basis for establishing the control system of bacterial wilt in Hainan province in the future.