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Articles just accepted have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
Functional study and natural variation analysis of glycosyltransferase gene SlUGT75C1-like in tomato
XIANG Lijun, LAI Jun, GUO Hao, YANG Jun, WANG Shouchuang
Accepted Manuscript  doi: 10.15886/j.cnki.rdswxb.20230062
Abstract(194) FullText HTML(72)
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In order to analyze the natural variation related to luteolin glucoside content in tomato population, 426 tomato samples were used as materials to performed metabolome genome-wide association study (mGWAS) analysis, and found that there was a mutation site downstream of tomato SlUGT75C1-like gene which was closely related to the content of luteolin-7-O-glucoside. Furthermore, the nucleotide polymorphism of the whole genome was calculated in three subgroups of tomato population, and it was found that the region where SlUGT75C1-like was located was obviously different among different subgroups. Further analysis of the correlation between metabolomics and transcriptome data showed that the transcription level of SlUGT75C1-like was positively correlated with the relative content of luteolin-7-O-glucoside. Finally, the fusion protein of SlUGT75C1-like was obtained by prokaryotic expression of the protein, and the enzyme activity test in vitro showed that SlUGT75C1-like catalyzed the glycosylation of luteolin. The results indicated that the natural variation of SlUGT75C1-like gene causes the content difference of luteolin-7-O-glucoside in tomato population. mGWAS has a large advantage and great potential in identifying new plant metabolic gene clusters, and is important in providing the molecular basis for fine plant breeding.
A survey of soil fertility and number of root-knot nematodes in dragon fruit orchards in Hainan
LI Juan, GAO Xiang, CHEN Siru, WU Jiamin, GAO Wei, ZHANG Hong, RUAN Yunze
Accepted Manuscript  doi: 10.15886/j.cnki.rdswxb.20230034
Abstract(124) FullText HTML(73)
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To clarify soil fertility and damage of root-knot nematodes in dragon fruit orchards in Hainan Island, a total of 186 soil samples were collected from 62 dragon fruit orchards, and the soil contents of nutrient elements such as nitrogen, phosphorus, potassium, calcium and magnesium, and the number of root-knot nematodes in the orchards were analyzed. The comprehensive soil fertility in the orchards was evaluated by using the fuzzy comprehensive evaluation method, and the correlation between the number of root-knot nematodes and soil nutrients was analyzed. The results showed that the average soil pH was 6.4 in the dragon fruit orchards, with the soil being generally neutral or weakly acidic in the orchards. The average soil content was 19.9 g/kg for organic matter, 63.9 mg/kg for alkali-hydrolyzed nitrogen and 95.8mg /kg for available potassium content, all of which were in the state of deficiency. The soil contents of available phosphorus and exchangeable calcium were abundant or above, and the soil exchangeable magnesium content was in the medium level. The soil pH was positively correlated with the soil contents of organic matter, exchangeable calcium and magnesium, indicating that a neutral soil pH level was conducive to the accumulation of organic matter in the soil and had important significance for the availability of calcium and magnesium. The soil content of organic matter was positively correlated with the soil contents of alkali-hydrolyzed nitrogen, available phosphorus, available potassium, exchangeable calcium and magnesium, which indicated that the increase of soil organic matter would help to increase the contents of soil basic mineral nutrients. The number of root-knot nematodes in the dragon fruit orchards varied greatly. The maximum number of second-stage juveniles (J2) of root-knot nematodes in the orchards was 736 per 100 g dry soil, while the minimum number of the J2 root-knot nematodes was only 14 per 100 g dry soil. The incidence of the root-knot nematodes was different between the orchards in the north and the south of Hainan Island. On the whole, the number of the root-knot nematodes in the dragon fruit orchards was lower in the north than that in the south of Hainan Island. The soil pH and the soil contents of organic matter, available phosphorus and exchangeable calcium were positively correlated with the number of the root-knot nematodes in the soil. The findings of this survey showed that the comprehensive soil fertility index of the dragon fruit orchards in Hainan Island is at a high level. The changes of the soil pH and the contents of organic matter, available phosphorus and exchangeable calcium might have some reference for integrated management of the root knot nematodes in the dragon fruit orchards in Hainan.
Effects of different fertilizer combinations on total polyphenols contents and antioxidant activities of the cakes of Camellia vietnamensis T. C. Huang ex Hu
JI Nanhuan, HOU Yaohui, WANG Kaiji, LAI Hanggui, PANG Zhenzhen
Accepted Manuscript  doi: 10.15886/j.cnki.rdswxb.20220045
Abstract(147) FullText HTML(77)
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An attempt was made to explore the effects of different fertilizer combinations on the total polyphenol content and antioxidant activity of the cakes of Camellia vietnamensis T. C. Huang ex Hu, improve the fertilizer application methods for C. vietnamensis in Hainan, and promote the healthy development of the C. vietnamensis industry. C. vietnamensis trees with similar growth and vigor were selected and treated with different fertilizer combinations (compound fertilizer (M1), compound fertilizer with earthworm soil (M2), compound fertilizer with vermicompost and biological fertilizer (M3), compound fertilizer with slow-release medium-trace element fertilizer (M4), compound fertilizer with the special plant regulator compound fertilizer (M5)) with no fertilizer as the control (CK) in an experiment, and a randomized complete block design was arranged with 3 plots, 6 trees per plot. The contents of total polyphenols in the extracts of the cakes of C. vietnamensis were determined under different fertilizer treatments. The antioxidant activities of the extracts were determined by using FRAP test, DPPH radical scavenging, hydroxyl radical (OH·) scavenging and ABTS radical scavenging. The results showed that the total polyphenol content and antioxidant activity of the cakes were higher in the treatments M1, M3 and M4 than in the CK, and the total polyphenol content and antioxidant activity of the cakes in the treatment M4 were the highest. Moreover, the addition of slow-release medium-trace element fertilizer on the basis of compound fertilizer could further enhance the total polyphenol content and antioxidant activity of the cakes. Therefore, the quality of the cakes of C. vietnamensis can be improved by applying compound fertilizer with slow-release medium-trace element fertilizer in actual production.
Diversity of entophytic bacteria in different tissues of cassava
FENG Yating, ZHANG Yijie, LIN Nanfang, CHEN Yinhua, LUO Kai
Accepted Manuscript  doi: 10.15886/j.cnki.rdswxb.20230077
Abstract(145) FullText HTML(98)
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In order to study the diversity of endophytic bacteria in cassava (Manihot esculenta) and explore the endophytic bacteria resources, 16S rDNA sequencing technology was used to analyze the Alpha and Beta diversity of tuber, stem and leaf tissues in ‘SC8’ and ‘SC9’ cassava varieties. The structural composition of bacterial community was analyzed and the gene function of endophytic bacteria community was predicted by comparing with Kyoto Encyclopedia of Genes and Genomes (KEGG) database. The results showed that 19,087 bacterial OTUs (operational taxonomic unit) were clustered from ‘SC8’ cassava samples, and belonged to 48 phyla, 126 classes, 438 families and 805 genera, and 20,148 bacterial OTUs belonged to 46 phyla, 130 classes, 390 families and 863 genera in ‘SC9’. There were 171 common bacteria genera in all tissues of cassava, accounting for 78.44% of all endophytic bacteria species. There were 118 unique bacteria in ‘SC9’ and 100 in ‘SC8’, and endophytic bacteria in stem (phloem) had the highest diversity. The dominant bacterial groups of endophytic bacteria from cassava are Proteobacteria, Cyanobacteria, Actinobacteria, Bacteroidetes, Firmicutes and Acidobacteria. Biosynthesis of terpenoids, ketones, amino acids, vitamins and other secondary metabolites is involved in the function of cassava endophytic bacteria. These results showed that there were abundant endophytic bacteria in all cassava plant samples, and the diversity was highest in stem (phloem). Cassava contains a variety of active ingredients, and the metabolism-related pathways of these active ingredients are also reflected in the function prediction.
Effects of rice-soybean-rice rotation on soil physicochemical properties and microbial community
LI Ran, LI Jinghua, LIN Shengwei, XIE Tianjie, FAN Pingshan, WANG Qing, LI Tingyu, WANG Shuai
Accepted Manuscript  doi: 10.15886/j.cnki.rdswxb.20230036
Abstract(153) FullText HTML(43)
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Paddy rice (Oryza sativa L.) is mainly grown thrice a year in Hainan Island. However, long-term continuous cropping and excessive nutrient input will reduce soil microbial activity and soil nutrient conversion, which is not conducive to the sustainable development of agricultural production. The soil under rice-rice-rice (RRR) continuous cropping and rice-soybean-rice (RSR) rotation systems in Dong fang City, Hainan Island was determined by using conventional soil physical and chemical analysis and microbial analysis methods, and the soil physical and chemical properties, carbon components and microbial community structure under the rice continuous cropping and the rice-soybean-rice rotation were compared to analyze the effects of the RRR and RSR on the soil physical and chemical properties and microbial community structure. The results showed that soil organic matter, total nitrogen content, available phosphorus, available potassium and rice yield under the RSR treatment were all higher than those under the RRR treatment, indicating that the RSR treatment significantly increased soil total nitrogen and available potassium content and decreased soil pH value. The soil microbial analysis showed that ACE, Chao1 and Shannon indices of the soil bacteria under the RSR treatment increased by 40.2%, 40.3% and 5.7%, respectively as compared with those under the RRR treatment. The soil microbial analysis also showed that the Shannon and Simpson indices of the soil fungi under the RSR treatment increased by 20.1% and 16.5%, respectively as compared with those under the RRR treatment. The soil microbial analysis showed that the RSR rotation had a significant effect on soil microbial community composition. The soil bacterial and fungal community compositions were significantly correlated with soil organic matter, available potassium, pH, hot water extractable carbon (HWEC) and microbial biomass carbon (MBC) (P>0.01). All the results showed that the RSR rotation significantly improved the soil microbial community structure, promoted the decomposition of organic matter, improved the availability of phosphorus and available potassium, and thus improved the crop yield.
Decomposition characteristics of pineapple plant residues returned to the soil in different ditches
YANG Shuyun, CAI Jinwen, LI Shoupeng, HAN Yan, JIN Xin, HOU Guangqing, SHAO Xujie, CHENG Wenxiao, LI Changjiang
Accepted Manuscript  doi: 10.15886/j.cnki.rdswxb.20230054
Abstract(70) FullText HTML(42)
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Returning straw to soil in ditches can increase soil temperature, nutrients and organic matter content, change soil microbial community composition, and thus increase crop yield. However, this method has not been reported to use in returning pineapple plant residues to soil in the field. Five treatments for ditching and returning the pineapple plant residues to the soil in the field were designed: Ditching 10 cm deep, returning the plant residues into soil in the ditches, ridging and covering with film (DRF10); ditching 20 cm deep, returning the plant residues to the soil in the ditches, ridging and covering with film (DRF20); ditching 30 cm deep, returning the plant residues to the soil in the ditches, ridging and covering with film (DRF30); ditching 30 cm deep, returning the plant residues into the soil in the ditches and ridging (DR30); ditching 30 cm deep, returning the plant residues into the soil in the ditches and leveling (DL30). The decomposition characteristics of the pineapple plant residues buried in different ditches were observed and analyzed. The results showed that the decomposition of the pineapple plant residues mainly occurred in the first 60 days after they were returned to the soil, with a decomposition rate of more than 56%. The decomposition rate of the plant residues was the highest at 15-30 days after returning to the soil. In the DRF20 treatment, the cellulose release rate and decomposition rate were significantly higher at 15 days after returning to the field, and the lignin release rate and decomposition rate were also the highest after 30 days of returning to the soil. The decomposition and decomposition rate, release rate of cellulose and hemicellulose were significantly lower in the DRF30 treatment than in the other treatments. The lignin release rate and decomposition rate were significantly higher in the DRF30 treatment than the other treatments at 540 days after returning to the soil. Soil water content and temperature were higher in the DRF30 treatment than in the DR30 and DL30 treatments. The enzyme activities were higher in the DRF30, DR30 and DC30 treatments than in the other treatments, but not significantly. The decomposition rate of the pineapple plant residues was positively correlated with the release rate of cellulose and lignin and negatively correlated with phosphatase. In conclusion, the pineapple plant residues decomposed fast at the early stage in the DRF20 treatment but at the middle and late stages in the DRF30 treatment.
Isolation of plant protoplast and its application in transient transformation
MA Chaoyue, PENG Shiqing, GUO Dong, ZHU Jiahong, WANG Ying
Accepted Manuscript  doi: 10.15886/j.cnki.rdswxb.20230026
Abstract(234) FullText HTML(735)
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The cell wall was removed from plant cells, and the cytoplasm wrapped by a single cell membrane is called protoplast. It has been widely used in protein subcellular localization, gene expression analysis, protein-protein interaction and gene editing among others. The factors influencing plant protoplasts isolation by enzymatic method, the effects of electroporation and PEG-mediated methods on the transient transformation efficiency of protoplasts and their application in transient transformation were summarized in this review. Plant species, different PEG concentrations, transfection time, DNA concentration, and number of protoplasts were found to affect the PEG-mediated transient transformation efficiency of protoplasts. The electroporation had an optimum transformation efficiency of protoplasts only under the adequate conditions of pulse voltage, pulse duration, pulse number, cell number, and DNA concentration. This review might provide reference for establishment of more plant protoplast isolation systems and transient transformation systems for plant protoplasts.
Whole-genome analysis of the HubHLH gene family in Pitaya and its differential expression in response to supplementary light-induced flowering in winter
LI Jiaxue, DING Yi, WANG Meng, LI Tao, GUO Panyang, LUI Chengli, WEI Shuangshuang, HUANG Jiaquan, LI Hongli, HU Wenbin, TANG Hua
Accepted Manuscript  doi: 10.15886/j.cnki.rdswxb.20220108
Abstract(262) FullText HTML(121)
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In order to obtain relative complete candidate genes, the HubHLH gene expression response in Pitaya during the flowering process induced by supplementary light in winter was investigated, and the whole genome of HubHLH gene family in Pitaya was analyzed. There were 153 pitaya HubHLH genes identified, and their encoding proteins contained 176-687 amino acids with their molecular weight being 19.28 – 74.44 kDa, pI 4.81-9.88. These proteins were all hydrophilic. The prediction of subcellular localization showed that most of the proteins were localized in the nucleus. The pitaya HubHLH proteins were compared with 120 Arabidopsis AtbHLH proteins for phylogenetic analysis. Phylogenetic analysis showed that the pitaya HubHLH proteins were divided into 12 groups and 25 subfamilies. Analysis of conserved motif, gene structure and location distribution in chromosomes showed that genes of the same subfamily had similar motif composition and gene structure. Analysis of the internal replication events of the pitaya HubHLH gene family found that 78 genes were identified as fragment repeating genes, indicating that fragment replication was the main expansion force of the pitaya HubHLH gene family. In addition, based on the transcriptomic data of the four phases of supplementary light-induced flowering of Pitaya in winter, 59 HubHLH genes were differentially expressed during the process of supplementary light induced flowering in winter. GO function enrichment showed that they were enriched in response to red or far-red light, light stimulation, sexual reproduction function, and radiation. The HubHLH gene family may play a regulatory role in the flowering process of Pitaya induced by supplementary light in winter. In this study, we conducted a comprehensive genome analysis of the HubHLH gene family in Pitaya, obtained relatively complete candidate genes, and preliminarily investigated the expression response of HubHLH genes in the winter flowering process induced by supplementary light in Pitaya.
Genome-wide identification and expression analysis of GRF gene family in litchi
DONG Chen, ZHENG Xuewen, WANG Yi, QUAN Zhenxuan, LI Weicai
Accepted Manuscript  doi: 10.15886/j.cnki.rdswxb.20230099
Abstract(69) FullText HTML(36)
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In order to reveal the functions of litchi GFR gene, the whole genome of litchi growth-regulating factor (LcGRF) gene family was identified and analyzed, and its expression patterns in different tissues of litchi were studied. Based on the litchi genome database, bioinformatics software was used to conduct genome-wide identification of members of the LcGRFs family, an analysis was made of basic physical and chemical properties, chromosome localization, gene structure, evolutionary relationships, protein conserved motifs, cis-acting elements, and spatiotemporal expression for systematic analysis. A total of 12 GRF genes were obtained from litchi, which were unevenly distributed on 10 chromosomes, with 2-5 introns. The analysis of the conserved motifs of the GRF protein found that all the GRF proteins in litchi contained conservative motifs of motif 1 (WRC) and motif 2 (QLQ). According to evolutionary analysis, LcGRF was divided into five subfamilies. There were a large number of cis-acting elements related to light, plant hormones, abiotic stress responses and growth and development on the promoter of LcGRFs. The results of different transcriptome expression patterns show that LcGRFs exhibits diverse expression characteristics in various tissues, indicating that different members may play regulatory roles in different growth and development processes of litchi, participating in regulating the growth and development of litchi. The analysis shows that there are 12 members of the litchi GRF family, which are divided into 5 subfamilies.
Identification of catechols and their protecting groups usin gcolor reactions
MENG Mingmin, XU Pengshu, LI Ruwen, HU Bihuang, LIU Zhongqiang
Accepted Manuscript  doi: 10.15886/j.cnki.rdswxb.20220091
Abstract(185) FullText HTML(46)
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To explore a simple analytical method for identifying catechols and the types of their protecting groups, the colors of phenol and catechol with FeCl3 in aqueous solutions and their visible absorption spectra were compared, and over thirty phenolic substances were tested for color developments with FeCl3 on TLC silica-gel plates. Color-developing effectiveness between phenols and four metal chlorides were evaluated to establish a correlation between catechol concentrations and shades of spot colors. The kinetics of acetonide decomposition in dilute FeCl3 ethanol solution were analyzed. The experiments demonstrated that phenols with weak binding abilities did not develop colors with FeCl3 on TLC silica-gel plates while phenols with strong chelating abilities such as catechol did. The greenish/bluish black color on the spots of catechol samples arose from the mono- and bi-coordinated Fe(III) complexes, not from the tri-coordinated ones. Since FeCl3 is a strong Lewis acid and can selectively cleave phenol protections, catechols protected by various types of protecting groups showed different color changes. Catechols protected by weak-acid labile protecting groups exhibited slow color development at room temperature; those protected by strong-acid labile protecting groups displayed no color at room temperature but bluish-black after heated on the silica-gel plate at 110℃ for 5 min; those protected by strong-acid stable protecting groups showed no color change under both conditions. The results also indicated that FeCl3 was the best color-developing agent among the four metal chlorides in testing phenols, with the optimum concentration of the phenols ranging from 10 to 50 mmol·L−1.
Effect of calcium and magnesium foliar fertilizer on sugar contents and sugar metabolizing enzyme activities in 'Feizixiao' litchi pulp
PENG Junjie, DU Jingjia, MA Wuqiang, CHEN Tiantian, SHUI Xian, ZHOU Kaibing
Accepted Manuscript  doi: 10.15886/j.cnki.rdswxb.20230033
Abstract(89) FullText HTML(35)
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In order to explore the reason why the "sugar receding" problem of 'Feizixiao' litchi fruit can be solved by the foliar nutrient of calcium and magnesium, the 16-year-old 'Feizixiao' litchi trees were taken as the experimental material, sprayed 0.3% CaCl2+0.3% MgCl2 mixed water solution on the leaf surface as the treatment, and sprayed water as the control, and the sugar contents and sugar metabolism enzyme activities of the fruit were determined. The results showed that fructose, glucose and sucrose accumulated rapidly in the early and middle stages of fruit growth and development, and the contents of fructose and glucose in the control fruit remained stable in the mature stage, while the contents of sucrose and soluble sugar decreased. The contents of fructose and total sugar in the fruit of the treatment were significantly higher than that of the control at 69 days after anthesis. The treatment significantly changed the activities of sugar metabolizing enzymes. At 69 days after anthesis, the treatment significantly increased the activities of neutral invertase and net activities of sucrose metabolizing enzymes, while the activities of acid invertase, sucrose phosphate synthase, sucrose synthase synthesis direction and phosphofructokinase significantly decreased. In summary, calcium and magnesium foliar fertilizer treatment enhances the net activities of sucrose metabolizing enzymes by increasing the activity of neutral invertase, reducing the activities of sucrose phosphate synthase and sucrose synthase synthesis, promoting sucrose decomposition, and reducing the activity of phosphofructokinase to inhibit glycolysis pathways, thereby causing the accumulation of fructose and soluble sugars, solving the problem of "sugar receding" during the mature stage of 'Feizixiao' litchi.
Comparative metabolomic analysis of epidermal bladder cells in Mesembryanthemum crystallinum under salt stress
ZHU Kunyu, PAN Chengcai, JI Yiying, WANG Yu, ZHOU Yang, JIANG Xingyu
Accepted Manuscript  doi: 10.15886/j.cnki.rdswxb.20230020
Abstract(176) FullText HTML(111)
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To investigate the changes of metabolites in epidermal bladder cells of the halophytic species Mesembryanthemum crystallinum under salt stress, the metabolites in the epidermal bladder cells of M. crystallinum under control and salt stress were identified and analyzed by using the liquid chromatography tandem mass spectrometry (LC-MS/MS), and a total of 356 known metabolites were identified in the epidermal bladder cells. Analysis of differential metabolites showed that the levels of 37 metabolites in the epidermal bladder cells were significantly changed under the salt stress. Metabolic pathway enrichment analysis of the differential metabolites based on the KEGG database showed significant perturbations in six biochemical pathways defined in KEGG, such as phytohormone signaling, zeatin biosynthesis, purine metabolism, etc. These results indicate that salt treatment can cause significant changes in metabolites in epidermal bladder cells of M. crystallinum .
Soil nutrient evaluation of pitaya orchards based on factor and cluster analysis
WANG Qingxuan, RUAN Yunze, ZHAO Pengfei
Accepted Manuscript
Abstract(70) FullText HTML(21)
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In order to investigate the current soil nutrient status of pitaya orchards in Hainan Province, 184 soil samples were collected and analyzed by using 6 soil nutrient indices. Their nutrient indices were graded each and then comprehensively evaluated based on factor and cluster analyses. The results showed that soil acidification was evident in most of the pitaya fields under survey, with 72.82% of the pitaya fields at pH < 4.5 and pH 5.0-6.5. The soil ammonium nitrogen content was generally low, less than 0.01mg/kg in 100% of the total pitaya fields. The contents of available potassium, total nitrogen and organic carbon were low in some fields, 23.37%, 23.37% and 33.7%, respectively, which were at the low or below levels. The soil available phosphorus content was the highest, and the proportion of plots in medium grade and above accounted for 100%. Factor analysis showed that two common factors could be extracted from the six nutrient indexes measured, among which total nitrogen, organic carbon, available potassium, ammonium nitrogen and pH were listed in factors 1 and 2 that mainly affected the comprehensive soil nutrient status of pitaya orchards. Cluster analysis of the soil nutrient comprehensive index IFI showed that the soil IFI values of the pitaya orchards in Hainan Province ranged from −0.904 to 1.405 with an average value being −0.171, of which only 41.3% of the soil was at medium or above fertility levels. In Ledong, Dongfang, Sanya and Lingshui which were pitaya major producers, the soil IFI values were at low fertility level in 80.33% and 50% of the pitaya orchards in Dongfang and Lingshui, respectively. In Sanya, the soil IFI values were above medium fertility level in 61.9% of the pitaya orchards. Overall, the soil fertility status in most areas of the pitaya orchards in Hainan Province (except Sanya) was below the medium level.
GNAT acetyltransferase regulates the growth and virulence of Xanthomonas oryzae pv. oryzicola
CHEN Yu, CHENG Yuguo, CAI Jing, TAO Jun
Accepted Manuscript
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To investigate the function of GNAT acetyltransferases in Xanthomonas oryzae pv. oryzicola (Xoc), a pathogen of rice bacterial leaf streak, we performed domain analysis of GNAT family proteins in Xoc, and then constructed the single and multiple mutants of these GNAT genes. Finally, we compared the growth rates, extracellular enzyme activities, and virulence of these mutants and the wild type Xoc strains. The results showed that GNAT acetyltransferases regulated Xoc growth in nutrient deficiency media. All mutants except Δxoc_1598 and Δ6 grew more slowly than the wild type, and had lower ability of acetyltransferases than the wild type strain. We also found that mutation in acetyltransferases could alter motility and the activities of the extracellular protease and amylase. All the results showed that protein acetylation is an important regulatory mechanism for Xoc growth and virulence as well as the virulence-related factors′ production.
Analysis of aporphine alkaloids in Cassytha filiformis
HUANG Zibao, CHEN Mimi, ZHANG Yong, ZHANG Xiaopo, DONG Lin, ZHANG Caiyun
Accepted Manuscript
Abstract(97) FullText HTML(38)
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In order to discover aporphine alkaloids with hypoglycemic activity in Cassytha filiformis, the total alkaloids were extracted from C. filiformis by acid solubilization and alkaline precipitation, obtained by ethyl acetate extraction, separated and purified by various chromatographic methods. The structures of the compounds purified were identified by using spectrometry, and the glucose oxidase method was used to evaluate the glucose consumption activity of the resulting aporphine alkaloids on HL-7702 cells. Thirteen aporphine alkaloids were identified from the extract of C. filiformis: cassamedine ( 1 ), cassameridine ( 2 ), thalicminine ( 3 ), neolitsine ( 4 ), N-metilseconeolitsine ( 5 ), N-methyl-2, 3, 6-trimethoxymorphin-andien-7-one ( 6 ), 1, 2-methylenedioxy-3, 10, 11-trimethoxyaporphine ( 7 ), cassythidine ( 8 ), norneolitsine ( 9 ), O-methylcassythine ( 10 ), cassythine ( 11 ), filiformine ( 12 ), and 1, 2-Dimethoxy-5, 6, 6a, 7-tetrahydro-4H-benzo[de][1, 3]benzodioxolo[56-g]quinoline ( 13 ). Among them, compounds 5 and 13 were first isolated from C. filiformis. Cellular glucose consumption activity assay showed that compounds 3 and 11 significantly promoted glucose consumption in HL-7702 cells and displayed a potential value for research and development into hypoglycemic lead compounds.
Effect of supplementary feeding with Artemia sp. nauplii on the survival and growth performance of juvenile freshwater black angelfish (Pterophyllum scalare)
LI Xi, LIN Siqi, LI Jiaoni, VASQUEZ Herbert Ely, WANG Aimin, ZHENG Xing, GU Zhifeng
Accepted Manuscript  doi: 10.15886/j.cnki.rdswxb.2022.05.001
Abstract(477) FullText HTML(265)
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Nauplii of Artemia sp. are a common and important live larval feed used in fish seed production. To make clear the effect of Artemia sp. nauplii as supplementary feed on the rearing of the juveniles of freshwater black angelfish (Pterophyllum scalare), the angelfish juveniles are selected and reared for 26 days in an experiment with two treatments to observe their growth performance. The juveniles were fed with commercial pellet feed without Artemia sp. nauplii as a control group (M), and with commercial pellet feed supplemented with Artemia sp. nauplii as the other treatment group (MA). The results showed that the other treatment group improved the survival rate of the angelfish juveniles significantly due to supplementary feeding with Artemia sp. nauplii, and increased the specific growth rate, as compared with the control group. The survival rates were (95.53±3.21)% and (82.50±4.32)% for the other treatment group and the control group, respectively, and their specific growth rates were (8.50±1.47)%·d and (6.92±1.06)%·d, respectively. Supplementary feeding with the nauplii of Artemia sp. is conducive to the growth of the qualitative and morphological traits of the angelfish juveniles, and increased the body length, condition factor, and uniformity of body length and weight of the angelfish juveniles in fish population. At the end of the experiment the juveniles were 25 mm in body length, 12 mm in height, 22 in pelvic fin length, 10 mm in dorsal fin height and 5 mm in caudal fin length, and their body length and the condition factor increased by 12 mm and 3%, respectively. The uniformity of body length and the uniformity of body weight in fish population were 92% and 90%, respectively. The finding is helpful to optimize the management and improve rearing techniques for freshwater black angelfish juveniles.
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Tropical Crop
Cloning and expression analysis of sucrose non-fermenting 1-related protein kinase 2.7 (SnRK2.7) gene in Hevea brasiliensis
LIU Yunfei, LI Yan, TIAN Weimin
2024, 15(1): 1-9.   doi: 10.15886/j.cnki.rdswxb.20230004
[Abstract](145) [FullText HTML](63) [PDF 2501KB](1)
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To explore the role of sucrose non-fermentation associated protein kinase 2 (SnRK2) in the response of Hevea brasiliensis to low temperature stress, a member of the SnRK2 subfamily, named HbSnRK2.7, was cloned from the leaves of the cold-resistant clone Reyan ‘93-114’ of Hevea brasiliensis by using RT-PCR. The gene cloned contains an open reading frame of 1 095 bp that encodes a protein of 364 amino acids. HbSnRK2.7 has a conserved serine/threonine protein kinase domain with a molecular weight of 41.39 kD and an isoelectric point of 4.70. It is predicted that it can catalyze the transfer of phosphate groups from ATP to the serine/threonine residues on the protein substrate, which is also the concentrated region of phosphorylation sites. It also has domains needed for abiotic stress and ABA-dependent domains for HbSnRK2.7 activation. Quantitative PCR (qPCR) results showed that HbSnRK2.7 gene was down-regulated in response to ABA induction. When treated with ABA for 8 h, the expression was down-regulated to the lowest point. Under low temperature stress, the expression of HbSnRK2.7 decreased significantly. The expression of HbSnRK2.7 was down-regulated continuously under low temperature stress for 4 h and 8 h, and the expression of HbSnRK2.7 was down-regulated to the lowest level at 24 h under low temperature stress, which was about 1/2 of non-stress expression. Moreover, the expression of HbSnRK2.7 was significantly higher in the cold-susceptible clones than in the cold-resistant clones. These results suggest that HbSnRK2.7 may act as a negative regulatory factor to mediate the formation of low temperature stress resistance of Hevea brasiliensis dependent on ABA.
Cloning and physicochemical characterization of MePPD3 gene from cassava (Manihot esculenta)
JIA Suhang, ZHU Shousong, FU Renwen, LI Chunxia, CHEN Yinhua
2024, 15(1): 10-18.   doi: 10.15886/j.cnki.rdswxb.20230035
[Abstract](100) [FullText HTML](110) [PDF 3519KB](3)
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The subcellular localization and expression analysis of Psbp protein MePPD3 (Manihot esculenta PsbP domain-containing protein 3, Phytozome database number: Manes.05G127800) were performed to explore whether MePPD3 is involved in disease resistance of cassava. MePPD3 gene was amplified by RT-PCR. Sequence analysis showed that MePPD3 gene was 807bp in length, encoding 268 amino acids, with PsbP domain located at position 106-266 aa. Bioinformatics analysis of MePPD3 protein was conducted by NetPhos 3.1 Server, SignalP 5.0 Server, TMHMM Servervr, PSIPRED and PHYRE2 online, respectively. The results indicated that MePPD3 protein contained 32 phosphorylation sites, 5 glycosylation sites, and 1 transmembrane domain. The secondary structure of the protein was composed of 21.3% Helix (Helix), 26.5% fold (strand) and 52.2% random curl (loop). The multiple sequence alignment, phylogenetic tree analysis and conserved domain analysis indicated that PPD3 protein had a high genetic relationship among different plants. Subcellular localization showed that MePPD3 protein was localized in chloroplast. QRT-PCR results revealed that the expression level of MePPD3 gene in different cassava tissues was significantly different, and was the highest in mature leaves. In addition, the expression of this gene was induced by Xanthomonas phaseoli pv. manihotis (Xpm), indicating MePPD3 is involved in the resistance of cassava to Xpm. After MePPD3 gene was silenced by VIGS technique, the leaf lesion area of silent plants was significantly smaller than that of the control plants, which implies that MePPD3 negatively regulates cassava resistance to bacterial fusarium wilt caused by Xpm.
Effects of different nitrogen sources on seedling growth and development of four cassava varieties
ZHAO Jinling, PAN Jinlong, WU Yuyao, HAN Haoxiang, ZHANG Huaifang, CHEN Xin, ZENG Changying
2024, 15(1): 19-26.   doi: 10.15886/j.cnki.rdswxb.20230018
[Abstract](181) [FullText HTML](115) [PDF 1037KB](3)
Abstract:
In order to explore the effects of different nitrogen sources on the growth and development of different cassava varieties and their differences, three different nitrogen sources, namely -N, NO3 and NH4+, were used to treat four cassava varieties,‘CH16’, ‘SC16’, ‘SC205’ and ‘17Q’, in the experiment. The growth status, nitrogen content, root morphology, nitrogen accumulation and nitrogen use efficiency of four cassava varieties were observed and analyzed. The results showed that under the treatment of NaNO3 (3 mmol·L−1) and NH4Cl (3 mmol·L−1), the cassava varieties ‘SC205’and ‘17Q’ had a relatively higher nitrogen utilization efficiency for ammonium nitrogen, belonging to the ammonium preferred varieties, while ‘SC16’ and ‘CH16’ had no difference in nitrogen utilization efficiency and preference for nitrate nitrogen and ammonium nitrogen. Under the condition of no nitrogen, ‘17Q’ and ‘SC16’ were nitrogen efficient cultivars with relatively high resistance to low nitrogen stress, while ‘SC205’ and ‘CH16 ’were nitrogen inefficient cultivars with relatively low resistance to low nitrogen stress, among which ‘CH16’ had the lowest tolerance to low nitrogen. The study lays the foundation for genetic improvement of nitrogen use efficiency and scientific fertilization in cassava agricultural production.
Collection and evaluation of Camellia oleifera germplasm in the tropical areas of China
LI Xinyao, ZHANG Shihui, ZHAO Xin, ZHANG Jingtao, SONG Jiaming, LAI Hanggui, ZHOU Yang, HU Haiyan, LIU Jinping, WU Wenqiang
2024, 15(1): 27-35.   doi: 10.15886/j.cnki.rdswxb.20220094
[Abstract](138) [FullText HTML](41) [PDF 1273KB](3)
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A germplasm survey of Camellia oleifera was made in tropical areas of China from October to December 2021, and their geographical distribution, habitats, morphological characteristics, and correlation and variability with the economic traits were analyzed for evaluation. A total of 230 tropical Camellia oleifera germplasm resources were collected in 18 cities and counties in three provinces (Hainan, Guangxi, and Guangdong). The analysis showed that the C. oleifera germplasm resources collected in the 18 cities and counties in the three provinces had an annual average temperature of 21.2 to 24.3 ℃, an annual average precipitation of 1,304.2 to 2,684.0 mm, and an altitude of 0.56 to 1,090.00 m. A total of 33 species of companion plants for C. oleifera were found, among which 29 species were plants of angiosperms. The fruit were mainly multicolored, and mostly spheroid or citrus-like in shape, and the leaf shape index was significantly different. The variation coefficients of 11 economic traits ranged from 11.03% to 145.10%, among which the variation coefficient of the leaf shape index was relatively stable. Fruit peel thickness was the most important economic trait, and was significantly positively correlated with fruit diameter, fruit height, fresh fruit weight, fresh seed weight, fresh seed yield, number of seeds, and thousand kernel weight. There was a significant correlation between fruit peel thickness and leaf shape index.
Analysis of extraction method of arecoline from areca callus
LI Xiangning, ZHAO Jin, LI Dongdong, ZHENG Yusheng
2024, 15(1): 36-41.   doi: 10.15886/j.cnki.rdswxb.20230038
[Abstract](186) [FullText HTML](99) [PDF 974KB](6)
Abstract:
In order to establish a simple, rapid and less sample method for the determination of arecoline in Areca catechu callus, an ultrasonic extraction method was used to extract arecoline from A.catechu calli, and four factors including solid-liquid ratio, extraction time, extraction temperature and extraction times were selected. On the basis of single factor experiment an orthogonal L9(34) experiment was performed to optimize the extraction system for arecoline from A. catechu calli. The results showed that the optimum extraction system for arecoline included the solid-liquid ratio of 1∶9, extraction time of 30 min, extraction temperature of 75 ℃ and 4 extraction times.
Biodiversity and Ecological Culture
Analysis of varying patterns and driving factors of GPP in Hainan Island during the past 20 years
LEI Jizhou, CUI Wei, ZHU Jishuai, ZHANG Runqing, ZHAO Junfu, ZHANG Jie, ZHANG Xiang, SUN Zhongyi
2024, 15(1): 42-51.   doi: 10.15886/j.cnki.rdswxb.20230006
[Abstract](203) [FullText HTML](209) [PDF 2089KB](8)
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In order to explore the relative contribution of meteorological factors and human activities to the variation of gross primary production (GPP) in Hainan Island during the past 20 years, the Theil-Sen and Mann-Kendall methods were first used to obtain spatial and temporal distribution characteristics of GPP. Based on this, land Use and cover change (LUCC) was used as an indicator of human activities, air temperature (Ta), vapor pressure deficit (VPD) and photosynthetically active radiation (RAR) were used as meteorological factors. By using spatial statistics and machine learning techniques, a model attributing the variations in Hainan Island′s GPP was constructed to quantify the relative contribution of driving factors. The results showed that during the study period, GPP showed a significant increasing trend, with a rate of change of 0.44 Tg·a−1 (P=0.024) in time. Spatially, 87.8% of the island′s area showed a significant increasing trend, while a small portion region around Haikou and Sanya and other part of Hainan Island showed a decline (about 9%). Land use and cover change in Hainan Island had a total transfer of 15 528.40 km2, mainly occurring in forested areas, with a net increase of 642.88 km2 in forests, a transfer area of 4 759.28 km2 in grasslands and 4 051.23 km2 in croplands. Compared to human activities, the interannual of meteorological factors during the study period were the dominant factor influencing the variation in Hainan Island′s GPP. However, the impact of LUCC on cities and counties were more prominent in certain years.
Effects of host identity and leaf traits on foliar endophytic fungal communities in Lauraceae and Fagaceae plants of tropical montane rainforest of Hainan Island
LUO Zhuhui, WU Chunling, WANG Yanli, LI Cuiling, WAN Ling, DING Qiong
2024, 15(1): 52-59.   doi: 10.15886/j.cnki.rdswxb.20220109
[Abstract](162) [FullText HTML](71) [PDF 892KB](6)
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To investigate the effects of plant identity and leaf traits on foliar endophytic fungal community assembly, the species composition of foliar endophytic fungi in dominant plants in the tropical mountain rainforest in Jianfengling, Hainan Island were determined by using the Illumina Miseq sequencing method, based on which the effects of host identity and leaf traits on the species composition of foliar endophytic fungi were explored. A total of 1,539,567 fungal ITS2 sequences were obtained from the leaves of 8 species of Lauraceae plants and 7 species of Fagaceae plants, which were classified into 5,471 Operational Taxonomic Units (OTUs) belonging to 8 phyla, 30 classes, 108 orders, 281 families, and 892 genera. Ascomycota was the largest group of the foliar endophytic fungi, accounting for 94.5% of all the fungal sequences. The number of endophytic fungal species in the leaves of individual Lauraceae plants (805 ± 32) OTUs was significantly higher than that of Fagaceae plants (554 ± 41) OTUs. However, there was no significant difference in Shannon-Wiener and Simpson diversity indices between the endophytic fungi in the leaves of the plants of these two families. Partial redundancy analysis showed that the host plant identities of family, genus and species significantly affected the composition of endophytic fungal communities. After removing the effect of plant traits, the host plant identities of family, genus, and species could independently explain 2.9%, 15.7%, and 33.7% of the variation in endophytic fungal species composition, respectively. After removing the effect of host plant identity, leaf traits could explain 21.3% of the variation in endophytic fungal species composition (P =0.003), of which leaf calcium content, specific leaf area, leaf nitrogen content, and leaf potassium content had significant effects on the composition of endophytic fungal communities. These findings suggest that host identity and leaf traits are important factors driving the assembly of endophytic fungal communities in the tropical mountain rainforest.
Dynamic analysis of grassland leaf area index changes under different grazing strategies based on multispectral UAV
LIU Jiahui, YU Rui, WANG You, LI Xin, CHEN Ronghao
2024, 15(1): 60-72.   doi: 10.15886/j.cnki.rdswxb.20230047
[Abstract](81) [FullText HTML](66) [PDF 4690KB](4)
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Disorderly grazing in grassland on abandoned cultivated land hindered the sustainable development of the grassland in Hainan Island. Grassland grazing experiments were conducted according to different grazing methods (rotational grazing and continuous grazing) and different grazing intensities (severe, moderate, and slight). Multispectral UAVs and vegetation canopy analyzers were used to obtain daily-scale grassland leaf area index (LAI) during the grazing period, and the impact of different grazing strategies on changes in grassland leaf area index and cattle behavior were also quantitatively analyzed. Results showed that rotational grazing under moderate grazing intensity was beneficial to improving grassland LAI. Under severe grazing intensity the proportion of areas where LAI increased in rotational grazing and continuous grazing grassland accounted for 3.21% and 12.65% of the total grassland area, respectively. Under moderate grazing intensity the proportion of areas where LAI increased in rotational grazing and continuous grazing grassland accounted for 52.01% and 25.83% of the total grassland area, respectively. Under slight grazing intensity the proportion of areas where LAI increased in rotational grazing and continuous grazing grassland accounted for 61.02% and 60.37% of the total grassland area, respectively. Under severe grazing intensity the proportion of cattle's feeding time to the total behavior was always the highest. As the proportion of feeding time increased, the reduction of grassland LAI was also increased, but when the proportion of feeding time increasing to 70.88%-73.42%, the reduction of grassland LAI was gradually decreased. At this time, the leaf area index of the grassland dropped to 79.60%-79.90% of the initial leaf area index (before grazing on the first day), which meant that the number of leaves fed by the cattle was upto the limit that the LAI of the grassland could supply on the day. When this limit was exceeded, individual livestock competition would be intensified. At the same time, the proportion of time spent by cattle on gnawing behavior greatly increased. All these results will help to select the best grass and livestock management methods at the pasture scale, to provide theoretical methods and decision-making support for the sustainable development of tropical grassland livestock systems from a new perspective, and to assist the construction of the National Pilot Zone for Ecological Conservation (Hainan).
Plant Protection
Quarantine and identification of Bostrychoplites cornutus (Olivier, 1790), a pest of potential invasion risk
CAI Bo, GENG Junjie, MENG Rui, ZHANG Huajian, WAN Peidi, LIU Fuxiu, WU Shaoying
2024, 15(1): 73-78.   doi: 10.15886/j.cnki.rdswxb.20230046
[Abstract](90) [FullText HTML](70) [PDF 1898KB](4)
Abstract:
Bostrychoplites cornutus (Olivier, 1790) is distributed in Africa, Asia, Europe, North America and other regions, and it mainly infests economic plants such as Triplochiton scleroxylon, Gliricidia sepium, Nesogordonia papaverifera, etc. The pest has been intercepted many times at quarantine ports in China, which is a potential threat of invasion to China. The taxonomic status, morphological characteristics, distribution, hosts, the morphological differences between Bostrychoplites species were illustrated, so as to simplify the difficulty of quarantine and identification of this pest, and provide some reference for its identification at frontier ports.
Effects of nitrogen fertilization on reproduction and offspring sex ratio in Megalurothrips usitatus (Bagrall) (Thysanoptera: Thripidae)
ZHANG Zhong, ZOU Youxing, DAN Jianguo
2024, 15(1): 79-84.   doi: 10.15886/j.cnki.rdswxb.20230061
[Abstract](167) [FullText HTML](80) [PDF 638KB](2)
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In order to evaluate the influences of nitrogen fertilization on reproduction and sex ratio of Megalurothrips usitatus (Bagrall), an economically important pest of legumes, the 1-day-old mated females were provided daily with leaf disks cut from the first leaves of potted cowpea at the age of 13 to 15 days, which were fertilized as a single pre-plant application with three different levels of urea at rates of 0, 160, and 320 N kg·hm−2, respectively. After being checked the number of eggs, each leaf disk was transferred into a glass tube containing a section of young bean pod of cowpea, which was harvested from the field plants. Oviposition days of the focal females were recorded, and their offspring adult were sexed and counted. Sex ratios of offspring were calculated as proportion of males. The results showed that the females reared on leaf disks from plants fertilized with high N had significantly prolonged survival duration and oviposition duration, and shortened pre-oviposition period, and significantly greater oviposition rate and daily oviposition rate, compared to low N and medium N treatments. Offspring sex ratios for low N, medium N and high N treatments were 0.70, 0.59, and 0.45, respectively, which were significantly different among each other. The number of offspring females produced by the females increased as N application rate increased. The number of offspring adults for high N treatment was significantly higher than those for low N and medium N treatments. N application level had no effect on immature survival of the offspring. In conclusion, nitrogen fertilization impacts on development, reproduction, and sex ratio of M. usitatus. Nitrogen overfertilization increases offspring production of this thrips, with a female-biased sex ratio.
Identification and functional analysis of candidate effector FoSSP20 in Fusarium oxysporum f. sp. cubense
WANG Tian, FU Liying, ZHAO Yang, LIU Shuang, ZHANG Yufang, CHEN Daipeng, ZHENG Li
2024, 15(1): 85-93.   doi: 10.15886/j.cnki.rdswxb.20230045
[Abstract](435) [FullText HTML](89) [PDF 2091KB](20)
Abstract:
Fusarium wilt of banana caused by Fusarium oxysporum f. sp. cubense (Foc) is destructive to banana (Musa spp.) industry. Effector proteins play a key role in the interaction between Foc and banana. Previously researches screened the candidate effector FoSSP20 in Foc race 4 (Foc4) which could suppress BAX-triggered programmed cell death (PCD). In this study, yeast secretion system was used to verify the secretory function of signal peptide of FoSSP20. Subcellular localization assay showed that the FoSSP20 was localized in the nucleus and plasma membranes in Nicotiana. benthamiana cells. qRT-PCR assay showed that the expression levels of FoSSP20 was significantly up-regulated at the early infection phase. All the results showed that effector FoSSP20 is a classic secretory protein which may function well in the infection process of pathogens.
Discovery and description of male Atrichopogon palmatus based on DNA barcodes
HE Zehua, LI Jiahui, LIN Xiaodan
2024, 15(1): 94-99.   doi: 10.15886/j.cnki.rdswxb.20230012
[Abstract](122) [FullText HTML](33) [PDF 2340KB](2)
Abstract:
Only females of Atrichopogon palmatus Tokunaga, have been recorded since 1962, while males have never been discovered. Specimens of Atrichopogon palmatus collected in Hainan Island were identified by using DNA barcoding and morphological methods. The DNA barcodes of the specimens were used to establish a phylogenetic tree for analysis, based on which the males were successfully associated with females. The males of A. palmatus collected in Hainan were newly described and illustrated, and their CO I- barcodes were also provided.
Tropical Marine Biology and Aquaculture
Characteristics of phytoplankton community in the offshore area of Sanya Bay
HONG Peng, ZENG Ru, HE Jinman, LI Zhijie, LI Yajun, ZHANG Xiuxia, YAN Jia, DENG Xiaodong
2024, 15(1): 100-108.   doi: 10.15886/j.cnki.rdswxb.20220111
[Abstract](80) [FullText HTML](48) [PDF 1606KB](3)
Abstract:
In order to study the characteristics of phytoplankton community and water quality in Sanya Bay, Hainan Province, net sampling surveys were conducted in April 2020 and 2021, respectively. Samples of phytoplankton and seawater were collected in 4 stations, and their community characteristics and water quality and environmental status were analyzed and evaluated by using Shannon-Wiener diversity index, Pielou evenness index, dominance index and richness index. Microscopic examination results showed that 98 species in 4 phyla of phytoplankton were identified in 2020 and 65 species in 3 phyla in 2021. Diatoms were the dominant group in both surveys. The number of dominant phytoplankton species was 8 in 2020 and 9 in 2021. Cluster analysis and Kruskal-Wallis test showed that the phytoplankton community structure in 2020 was significantly different from that in 2021. The diversity index and richness index in 2020 are 3.35 and 3.72, respectively, both of which are higher than those (3.27 and 2.5, respectively) in 2021, while the evenness index is 0.59, which is lower than that (0.66) in 2021. The average phytoplankton cell density in 2021 was 41.95% lower than that in 2020. The redundancy analysis (RDA) showed that ammonia nitrogen, conductivity and total phosphorus were the main environmental factors affecting the phytoplankton community structure in Sanya Bay in 2020 and 2021. All the results showed that the sea water in Sanya Bay is generally excellent ecologically in 2020 and 2021. The phytoplankton community structure is mainly composed of diatoms. The sea water has poor nutrients, indicating no possibility of occurrence of red tides or eutrophication.
Transcriptome analysis of Streptococcus iniae from fish at different culture temperatures
JIA Xinlei, HUANG Zengchao, YANG Lindi, LYU Jing, LI Yanping, JIAN Jichang, HUANG Yucong
2024, 15(1): 109-121.   doi: 10.15886/j.cnki.rdswxb.20230027
[Abstract](107) [FullText HTML](36) [PDF 1970KB](1)
Abstract:
To identify the differences in transcription level of Streptococcus iniae at different temperatures, the growth and pathogenicity of S. iniae cultured at 25 ℃ and 35 ℃ were analyzed by using growth curve and artificial infection test, and strand-specific RNA-seq technology was used for sequencing analysis of S. iniae Tozj-1 strain cultured at 25 ℃ and 35 ℃. The differentially expressed genes (DEGs) were screened and their GO function and KEGG pathway enrichment were analyzed based on the GO (Gene Ontology) database and KEGG (Kyoto Encyclopedia of Genes and Genomes) database. The key differentially expressed virulence genes were filtrated using virulence factor database (VFDB) and verified by real-time quantitative PCR. The results showed that S. iniae grew faster with a higher virulence at 35 ℃. A total of 927 significantly differentially expressed genes were screened (P<0.05), including 820 up-regulated genes and 107 down-regulated genes. GO functional enrichment analysis showed that the DEGs were mainly enriched in metabolic process, cellular process, binding process and catalytic activity. KEGG enrichment analysis revealed that the DEGs were mainly enriched in ribosome, quorum sensing, ABC transporters and other signaling pathways. These results indicated that temperature regulated the transcription and expression of S .iniae genes and the enrichment of related pathways, which provided data support for further research in the pathogenesis of S .iniae.
Development and application of a three-loop recirculating freshwater aquaculture system
PAN Guoying, WEN Chang, HUANG Weiwei, YAO Xuemei, DONG Lili, ZHOU Meiyang, YANG Fei
2024, 15(1): 122-132.   doi: 10.15886/j.cnki.rdswxb.20230007
[Abstract](263) [FullText HTML](176) [PDF 1380KB](15)
Abstract:
In order to meet the increasing demand for high-quality fish protein and environmental protection requirements, a pilot intensive three-loop recirculating freshwater aquaculture system (RAS) was developed in Qionghai, Hainan province, China. Backwashing water from a microfilter is used as the carbon source for the denitrification process, and an operation mode is established to ensure the treatment of water quality and fish sludge to comply with the requirements for fish growth and pollution control. Tilapia (Oreochromis mossambicus) was cultured in the pilot three-loop freshwater RAS for 121 days in an aquaculture experiment, and the fish growth, water quality and microbial communities in the system were observed and analyzed. The results showed that the tilapia had a survival rate of 100%, with the stocking density and the feed conversion ratio (FCR) being 107.7 kg·m−3 and 1.74, respectively. The average concentrations of total ammonia (TAN), nitrite (NO2-N) and nitrate (NO3-N) were 0.95, 0.15 and 43.01 mg·L−1 respectively. The volume for daily water drainage was 2.66% of the total water volume in the system, and 6.67% of the water volume in the fish tank. No fish sludge was discharged throughout the experiment, and only a small amount of sludge existed in the anaerobic digestion unit by the end of the experiment. Microbial community analysis showed that a total of 21 genera of microorganism were involved in nitrogen metabolism, including Rhodobacte, Flavobacterium and Azospira. These results implicated that the recirculating aquaculture system provides a potentially sustainable and ecological aquaculture mode for freshwater fish such as tilapia.

Supervisor: Department of education of Hainan Province

Sponsor: Hainan University

ISSN 1674-7054

CN 46-1078/S

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