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2024, 39(8): 879-887.
doi: 10.19303/j.issn.1008-0384.2024.08.001
Abstract:
Objective Strains of Salmonella typhimurium with yibT and/or csgD deleted were created to observe the effect on its biofilm formation for effective prevention and control of the foodborne pathogen. Method The λ-red homologous recombination technique was applied to create the gene-deleted mutants, WTΔyibTΔcsgD and WTΔcsgD, of WT S. typhimurium (CVCC541). Subsequently, the gene-complemented strains were also obtained using recombinant vector technology. Differences of the mutants in biofilm formation were determined by crystal violet staining, content of exopolysaccharide measured by phenol-sulfuric acid, mobility tested on semi-solid agar plates, and self-aggregation monitored. Under a scanning electron microscope, biofilm structure was observed. Finally, mRNA expressions of the target genes in the biofilm were identified by fluorescence quantitative PCR. Result A double-gene deleted WTΔyibTΔcsgD, a WTΔcsgD without csgD, and their respective complemented strains, WTΔcsgDΔyibT/pcsgD and WTΔcsgD/pcsgD, were successfully obtained. The double-gene deletion significantly reduced the ability in forming biofilm, the content of exopolysaccharide, and the aggregation of the genes to targets, and the mRNA expressions of invF and sdiA in WT S. typhimurium. Conclusion Deletion of yibT and csgD significantly impacted some critical biofunctions of S. typhimurium that could become a new approach for control of the foodborne disease.
2024, 39(8): 888-897.
doi: 10.19303/j.issn.1008-0384.2024.08.002
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Objective In vitro inhibitory effects of the prepared specific anti-vibrio antibody on Vibrio vulnificus, V. fluvialis, and V. cholerae were studied for the development of a bioagent to prevent and treat infections caused by the viruses. Method Trivalent inactivated vaccine against the three specific viruses were prepared to immunize hens, and eggs collected for producing the specific IgY. Potency, purity, and specificity of the IgY were determined. Antiviral effects of the antibody were tested by immunofluorescence electron microscopy, scanning electron microscopy, and an in vitro test. Result Indirect ELISA detected the specific IgY with peak titers as high as 1:51200 that sustained for 4–5 weeks when the target viruses were used as antigens. The SDS-PAGE analysis on the IgY purified by means of water dilution and salt precipitation showed a gradual rise in purity, reduction in protein impurities, and increase in visible heavy and light bands. The immunoblotting of the specific IgY showed its binding to the corresponding antigens with appearance of the protein bands. The immunofluorescence electron microscope displayed apparent agglutination on the bindings to the three viruses. And furthermore, a scanning electron microscopic image of the viruses treated with the specific IgY detailed the adhesion of the antibody to and structural disruption of the virus cells. Finally, significant in vitro, dose-dependent inhibitory effects of the specific IgY on the growth and proliferation of target vibrio strains were observed. Conclusion The prepared specific triple anti-vibrio egg yolk antibody exhibited significant in vitro inhibitory effects on V. vulnificus, V. fluvialis, and V. cholerae. It seemed plausible that the application could become an effective alternative to antibiotic treatment in preventing and controlling the diseases caused by these viruses.
2024, 39(8): 898-905.
doi: 10.19303/j.issn.1008-0384.2024.08.003
Abstract:
Objective Pathogen that caused duck liver hemorrhage in Anhui Province was identified and its genetics studied. Method A suspected virus strain was isolated from the ducks suffered from liver hemorrhage at a poultry farm in Anhui Province. Pathogenic nucleic acid and an animal regression test were employed to identify the culprit. VP1 of the confirmed duck hepatitis A virus type 3 (DHAV-3) were sequenced and analyzed using biological software. Results No bacterial pathogens were isolated from the culture of the diseased duck liver tissue. However, the specimens were tested positive for DHAV-3 but free of other viruses commonly known for duck liver hemorrhages by RT-PCR. The duck embryos inoculated with the isolate died with massive hemorrhages, and the 5th generation allantoic fluid detected presence of DHAV-3 by RT-PCR. The isolate was subsequently code-named AH230225 and determined to have the effective lethal dose 50 (ELD50) of 10−4.17/0.1 mL. In an animal regression test, the Cherry Valley ducklings had a mortality rate of 80%. The dissected lesions in the liver and kidneys of the dead ducks were similar to the typical clinical specimen. The sequenced VP1 nucleotides of AH230225 showed the greatest homology of 98.8% with the DHAV-3 of Anhui isolate, AH07. Its homologies with the 10 strains of DHAV-3 listed in GenBank were 90.4%~98.8%, with DHAV-1, 62.1%–63.0%, and with DHAV-2, 64.6%–64.9%. It appeared that the VP1 of AH230225 was genetically most closely related to that of AH07 but farther from those of SD01, G, or Korean AP-04009 and AP-03337. In other words, it was distant from DHAV-1 and DHAV-2 on the evolutionary branch. Conclusion The virus that caused the liver hemorrhage on ducks at the farm in Anhui was identified to be DHAV-3 with VP1 closely related genetically to that of AH07.
2024, 39(8): 906-913.
doi: 10.19303/j.issn.1008-0384.2024.08.004
Abstract:
Objective Genetic inheritance of crop yield and kernel sugar content relating to measurements of three leaves nearby an ear on a waxy maize plant was examined for correlation to facilitate breeding and quality prediction. Methods Six inbred waxy maize lines were cross-bred with 15 key inbred lines based on an incomplete diallel hybridization of NCII design. At harvest, yield of ears, soluble sugar content of kernels, dimensions of the three leaves closest to an ear, and 10 additional traits of the hybrids were measured 21 d after pollination. Ear yield by weight and kernel sweetness by Brix were obtained. Dimensions of the leaves located above, at, and below an ear on a plant were measured to correlate with the general combining ability (GCA) and special combining ability (SCA) on kernel yield and sweetness of the hybrids passed on from their parents. Results Correlations were found between the leaf length and the ear yield and between the leaf width and the kernel sugar content. However, the narrow heritability of leaf length and ear yield was relatively low, mostly shown by the SCA on length of lower ear-leaf and weight of corn-on-the-cob. On the other hand, that of leaf width and sugar content was significant and mainly the GCA on width of upper ear-leaf and kernel sugar. Conclusion The width of upper ear-leaf grown next to an ear significantly reflected the sweetness of the kernels born on a waxy maize plant. Thus, the measurement could potentially be used as a visual, easily assessable indicator for cultivars selection in breeding and/or quality estimation in forecasting a harvest.
2024, 39(8): 914-926.
doi: 10.19303/j.issn.1008-0384.2024.08.005
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Objective A slow-release fertilizer was applied on a cassava lot to analyze the responses of the fungal community and C, N, P, and S functional genes in the rhizosphere soil. Method A field experiment was conducted with treatments of no fertilization (T1), basal application of double-coating slow-release fertilizer C2 (T2), and C2 applied 34 d after planting (DAP) (T3). Rhizosphere and bulk soil samples were collected at 77, 104, and 134 DAP to determine fungal diversity according to ITS rRNA sequenced by a high-throughput Illumina Miseq PE300, copies of 72 functional genes of C, N, P, and S cycles (including total DNA) by the gene chip technology, and available nutrients by chemical analysis for a correlation analysis. Result (1) Significant differences on the relative abundance (RA) of Mortierellomycetes, Tremellomycetes, and Orbiliomycetes were found in the rhizosphere soils on 104 DAP showing T2＜T1, while that of Scatterocysts on 134 DAP indicating T2＞T1. Fungal class Scatterycetes under T2 on 134 DAP, Rubiaceae under T3 on 77 DAP, and Coprochetes under T3 on 104 DAP were relatively enriched in the rhizosphere than in the bulk soil. The RAs of the rhizosphere fungi also differed significantly on time of sampling and under different treatments. They were 134 DAP＜104 DAP for Mortieromycetes under T1, 134 DAP＞77 DAP for Scatterocystae and Coprochestae under T2, and 104 DAP＞77 DAP for Sphaeromycetes under T3. (2) The Sobs, ACE, and Chao1 indexes under T1 on 104 DAP, T2 on 104 DAP, and T3 on 134 DAP were significantly higher in the rhizosphere than in the bulk soil (P＜0.05 or P＜0.01). The Shannon index of rhizosphere soil was lower under T1 than under T2 or T3 on 77 DAP. Under T1, the index was 104 DAP＞77 DAP; and under T2, it was the opposite. The Simpson indexes ranked in the order of the rhizosphere soil under T1 on 77 DAP＞the bulk soil under T1 on 77 DAP＞the rhizosphere soil under T1 on 104 DAP＞the rhizosphere soil under T2 on 77 DAP＞the rhizosphere soil under T3 on 77 DAP. (3) The LEfSe analysis indicated the fertilizer applications enriched one class, one order, and two families of fungi in the rhizosphere soil, whereas the bulk soil was more abundant in two species on 77 DAP, in 3 orders, one family, and one genus on 104 DAP, and in one phylum, one order, one family, and one genus on 134 DAP. Two orders on 104 DAP and one class on 134 DAP were enriched in the rhizosphere soil. (4) On 134 DAP, the 9 functional genes, such as lig in the bulk soil under T1, had significantly more copies than in the rhizosphere soil. In the rhizosphere soil, the RAs of chiA and aclB under T1 on 77 DAP were higher than those on 104 or 134 DAP. (5) AK significantly correlated with 31 functional genes on 104 DAP. Some fungal classes, such as Tremella, Sarcoidales, Claviculaceae, and Sphaeromycetes, significantly correlated with 40, 15, 14, and 9 other functional genes, respectively. Conclusion Fertilization by ways of T2 or T3 enriched the diversity and abundance of cassava rhizosphere fungal community. Fertilizer used, application time, and rhizosphere could all significantly affect the fungal community structure and some functional genes in the soil. The correlations might lead to further studies to unveil the intricate ecosystem.
2024, 39(8): 927-937.
doi: 10.19303/j.issn.1008-0384.2024.08.006
Abstract:
Objective Regulation functions of JsMYB108 and JsMYB305 on the promoters of three terpene synthase genes (TPSs) relating to the aroma synthesis of jasmine were analyzed. Method The promoter fragments of JsTPSs were cloned by genome walking with the DNA of jasmine leaves as template to determine the sequences of the cis-acting elements in them. The fragments were constructed separately in the reporter vector pGWB433. Then, tobacco leaves were transformed with the reporter vector alone or with pK7FWG2.0-JsMYB108 and pK7FWG2.0-JsMYB305 effect vectors to detect the activation of JsMYB108 and JsMYB305 on the promoters. Binding of JsMYB108 and JsMYB305 to the promoters was verified by the yeast one-hybrid assay. Result The cloned promoter fragments of the three JsTPSs were 1 357 bp, 1 849 bp, and 1 005 bp with MYB recognition sites. The elements relating to light response, damage response, and abscisic acid induced cis-acting were predicted in different promoter sequences. The GUS staining and activity detection in tobacco leaves confirmed varying degrees of activity of the fragments by introducing JsMYB108 and JsMYB305. Comparing to control, JsMYB108 expanded the activities 1.96-fold on the promoter of JsTPS1, 6.47-fold on that of JsTPS3, and 4.15-fold on that of JsTPS4, while JsMYB305 did 1.57-fold, 15.18-fold, and 3.12-fold, respectively. The yeast one-hybrid assay further verified the bindings of JsMYB108 and JsMYB305 to JsTPS1, JsTPS3, and JsTPS4. Conclusion JsMYB108 and JsMYB305 could activate the promoters of JsTPS1, JsTPS3, andJsTPS4. These two transcription factors might play a key role in the synthesis and metabolism of aromatic terpenes in jasmine flowers.
2024, 39(8): 938-945.
doi: 10.19303/j.issn.1008-0384.2024.08.007
Abstract:
Objective Molecular mechanism of Passiflora edulis leaves in respond to cadmium (Cd) stress was analyzed for genetic improvement on resisting the heavy metal absorption of the plant. Method Transcriptome of the leaves of passion fruit plants under a moderate Cd stress of 50 μmol·L−1 for varied durations in a hydroponic experiment was sequenced. qRT-PCR was applied to verify and analyze the results. Results There were 3,465, 1,262, and 2,039 expressed genes in the samples under the Cd stress for 24, 48, and 72h, respectively. Sixty-three specific transcription factors and proteins that responded to the stress were obtained. The transcriptome sequencing was confirmed highly reliable by a qRT-PCR analysis. The GO functional enrichment and KEGG metabolic pathways analyses on the transcriptions showed the differential expression genes (DEGs) to be mainly associated with cell structure, catalytic activity, and transcriptional regulations as well as the photosynthesis and carbohydrate metabolism pathways. Conclusion The DEGs in passion fruit leaves responding to Cd stress were mainly enriched in the metabolic and biosynthesis-related pathways. The information would pave the way to studies on curtailing Cd contamination that seriously affects the quality and commercial value of the fruit.
2024, 39(8): 946-958.
doi: 10.19303/j.issn.1008-0384.2024.08.008
Abstract:
Objective Effects of ABA spray on endogenous hormones in Camellia reticulata seedlings under drought stress were studied. Methods An ABA solution in the concentration of 100 mg·L−1 was sprayed on the leaves of 2-year-old C. reticulata Zipao seedlings grown in potting soil under a simulated drought stress using PEG_6000. Osmoregulatory substances and hormone metabolome in the roots and leaves of the plants were measured under the treatment and subsequent rehydration. Results Osmotic regulation of the seedlings took place mainly in the leaves. Under drought stress, ABA, JA , SA ,IAA, and CKs accumulated in the leaves, while ABA, GA , and CKs increased but IAA decreased in the roots. Upon rehydration, ABA, GA, and CKs in the roots gradually declined, while IAA rose, meanwhile, the leaves started regulating with the stored JA, SA, IAA, and CKs. The KEGG enrichment analysis showed that the diterpene biosynthesis pathway in the roots and the hormone signal transduction and zein biosynthesis pathways in the leaves were significantly enhanced. There was a significant correlation between the osmoregulatory substances and endogenous hormones. The ABA spray boosted the contents of soluble protein, soluble sugar, ABA, GA, and CKs in the roots as well as those of free proline, ABA, and JA in the leaves improving the drought tolerance of the plant. With replenished water, CKs in the roots and JA in the leaves were reduced to encourage IAA synthesis, which in turn, aided the recovery of plant functions. Conclusion The responses of the roots and leaves of C. reticulata seedlings to the imposed drought and the subsequent rehydration were different. Application of foliar ABA spray could improve the draught resistance of the plants.
2024, 39(8): 959-967.
doi: 10.19303/j.issn.1008-0384.2024.08.009
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Objective Morphology and endogenous hormones of Bombax ceiba flower buds in differentiation were studied to aid the control of fallen debris at fruiting stage of the popular landscape plant in southern China. Methods Morphology of the flower buds of B. ceiba at differentiation phases were observed with the paraffin sections under a microscope and contents of endogenous GA3, IAA, ABA, and ZR determined. Results The flower bud development was classified in the phases of pre-differentiation, primordium differentiation, sepal primordium differentiation, petal primordium differentiation, stamen and pistil primordium differentiation, and stamen and pistil formation. The flower primordium differentiated in early October, while the sepal primordium did in mid-October, the petal primordium in late October, the female and stamen primordium in mid-early November, and the female and stamen formed in late November. During differentiation, GA3 and ABA in the buds were significantly higher than IAA and ZR. They generally decreased, but IAA declined at first, followed by an increase and another decline, whereas ZR rose initially and fell subsequently. The ratios of ZR/GA3 and (ZR+IAA)/GA3 were on an increasing trend, GA3/IAA decreasing, ZR/IAA and ABA/IAA rising at first followed by declining, ABA/GA3 rising-falling-rising, and (GA3+ZR+IAA)/ABA falling-rising-falling as the differentiation progressed. Conclusion The process of B. ceiba bud differentiation can be divided into six stages based on its morphological structure, in which the contents of ABA and GA3 are much higher than those of ZR and IAA , and the changes in the contents showed a significant negative correlation with the bud differentiation process. Consequently, applying either GA3 on the plant prior to the process begins or ABA at the petal primordial differentiation phase could deter the floral development and mitigate the nuisance of causing human allergy and traffic interference due to the massive tree falloffs.
2024, 39(8): 968-976.
doi: 10.19303/j.issn.1008-0384.2024.08.010
Abstract:
Objective Improvements on the appearance and fruit quality of Zheli No. 6 pear by bagging were studied. Method Zheli No. 6 pear s on the trees were covered once or twice with a variety of pouches at different times of the fruit development in a field experiment. Appearance and eating quality of the mature pears were monitored. Result The bagged fruits were significantly brighter and more shiny than the counterparts without covering (P＜0.05). The pears matured in the white single-layer large pouches had significantly lower fruit rust index (FRI) than control (P＜0.05) but no significant differences on the contents of soluble solids, total soluble sugar, and sweetness. Those being bagged twice were significantly lower on FRI than control or those being bagged only once. Nor did they differ significantly from control on the contents of soluble solids, total soluble sugar, titratable acid, and VC, but contained significantly more fructose and glucose than control or those were bagged a single time (P＜0.05). When the bagging was held 10d, 20d, and 30d after full bloom, equal to or more than half of the resulting fruits were yellowish green with few rusty streaks and spots having an FRI of 0.471-0.600 and low on latitudinal measurements and flesh density. Bagging 60d after full bloom produced 72.5% of the fruits with fully rusty-appearing peels. And, except for those bagged 10d after full bloom, no bagged pears significantly differed from control on the contents of soluble solids, total soluble sugar, titratable acid, and VC. Conclusion Bagging Zheli No. 6 pears on the tree with the white single-layer large pouches significantly affected the appearance of the matured fruits. Using the white small wax pouch in 10-30d after full bloom followed by the white single-layer large pouch for the bagging fostered bearing of yellowish green fruits. Whereas the non-rust-proof pouches for bagging once in 60d after full bloom encouraged formation of a fully rust, brown peel. Meanwhile, the appealing eating quality of Zheli No. 6 pears would basically be intact under the bagging treatments.
2024, 39(8): 977-983.
doi: 10.19303/j.issn.1008-0384.2024.08.011
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Objective Reproductive biology of Anagrus nilaparvatae strains (Ans) that lay eggs on different pests was studied to determine the best parasitoid/host matches for biocontrol. Method Nilaparvata lugens (Nl),Sogatella furcifera (Sf), Laodelphax striatellus (Ls), and Ishiharodelphax matsuyamensis (Im) were used in an indoor experiment as the hosts to study the reproductive behavior of Ans. Fitness of parasitoid/pest pairings as well as host preference by specific stains of An were determined based upon the size, body color, egg load, parasitism capacity, larva emergence, sex ratio, and lifespan of the wasps. Result The body lengths of different species of adult Ans varied significantly, as it was 728.03 μm for those hosted on Nl (AnNl), 715.5 μm on Sf (AnSf), 633.17 μm on Ls (AnLs), and 509.1 μm on Im(AnIm) . The color of wasp body also varied depending upon the pests they chose to lay eggs on. For instance, AnNl, AnSf, and AnLs were mostly light orange, with a few yellowish green, in color, but all AnIm had dark reddish orange bodies. Significant differences in fecundity existed among the strains as well. The egg counts per female were similar between AnNl at 32.93 and AnSf at 32.97 but 27.47 for AnLs and 11.83 for AnIm. The parasitism of these wasps ranked AnNl or AnSf＞AnLs＞AnIm. On the other hand, no significant differences were detected on the rate of larvae emerged from eggs, male/female ratio, or lifespan of them. Nor was on host selection—they simply deposited eggs randomly based on availability. The intrinsic rate of increase (rm) of AnNl was the highest at 0.1531 followed by 0.1482 of AnSf, 0.1307 of AnLs, and 0.0427 of AnIm. Conclusion The strains of An that parasited on Nl and Sf had significantly greater egg load, parasitism capability, and rm than those did on Ls or Im . Hence, they could be the better candidates to be artificially propagated for biocontrol on the pests.
2024, 39(8): 984-992.
doi: 10.19303/j.issn.1008-0384.2024.08.012
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Objective Regulatory functions of milk vetch on soil fertility and microbial communities were studied to determine the potential of incorporating the shrub plant in rotation cropping with tobacco and rice for further land use improvement. Method Soil samples were collected from a field practicing tobacco-rice-milk vetch rotation cropping for 5 years and one of tobacco-rice as control. Physicochemical analysis on the soil using spectrophotometry and metagenomic sequencing on the microbial community were conducted. Result With milk vetch added to the tobacco-rice rotation cropping, the field soil increased significantly on the available nitrogen and phosphorus, rose slightly on the organic matter, total nitrogen, and total potassium, maintained a same level of total phosphorus, and reduced significantly on the available potassium. The yield of tobacco rose 2.74% and that of rice 4.67% in 2023. And the microbial diversity became significantly enriched by 8.67% and 3.10% but declined by 11.57% over control on the dominant kingdoms of Proteobacteria, Nitrospira, and Acidobacteria, respectively. The microbes in the soil were largely associated with carbohydrate, energy, and amino acid metabolisms. Conclusion By incorporating milk vetch in the rotation cropping of tobacco and rice, aside from the increased yields on the crops, the physiochemical properties of field soil were significantly improved as well.
2024, 39(8): 993-1005.
doi: 10.19303/j.issn.1008-0384.2024.08.013
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Objective Diversity of the microbial communities in soils of cultivated and wild Paris polyphylla var. chinensis fields were compared. Method Total DNA of the microbes on cultivated land grown P. polyphylla plants or at field of the plants in the wild were sequenced using high throughput Illumina Miseq (2×300 bp). Structure and abundance of the microbial communities in soils of the fields were comparatively analyzed by LDA Effect Size. Result The microbial diversity of the wild P. polyphylla lots was richer than the cultivated land. The Chao, Ace, Shannon, and Simpson indexes of the wildP. polyphylla soil were higher than the cultivated counterparts. The communities significantly differed on the abundant phyla of Firmicutes, Nitrospirae, and Spirochaetae, and on the genera of Bacillus, Ktedonobacter, and Paenibacillus. LDA Effect Size showed Firmicutes and Nitrospirae to be the predominant phyla, while Bacillus, Paenibacillus, Tumebacillus,Mucilaginibacter, Nitrospira, Shimazuella, and Singulisphaera the dominant genera in the wild. In the cultivated soil, the Armatimonadetes phylum and the Bryobacter, Aquicella, and Ktedonobacter genera predominated the community. pH and total potassium content of soil were the critical factors affecting the diversity of a microbial community. Conclusion Cultivation and soil nutrients significantly differentiated the microbial composition at a P. polyphylla field.
