植物乳杆菌培养上清对不同血清型沙门氏菌的抑制效果及作用机理

【目的】探究植物乳杆菌培养上清(Lactobacillus plantarum culture supernatant,LPC)对3种血清型沙门氏菌猪霍乱(Salmonella cholerae,SC)、肠炎(Salmonella enteritidis,SE)和鸡白痢(Salmonella pullorum, SP)的生长和致病性的抑制作用效果及机理。【方法】将2%LPC与3种沙门氏菌分别共培养后,采用比浊法及牛津杯抑菌圈试验检测沙门氏菌生长情况及LPC中的主要抑菌物质,使用实时荧光定量PCR (quantitative real-time polymerase chain reaction, qRT-PCR)探究沙门氏菌致病性相关基因表达水平,最后通过结晶紫染色法检测沙门氏菌的生物被膜。【结果】2%LPC能够显著抑制3种沙门氏菌的生长,其作用效果与庆大霉素(gentamicin, GM)相近且对SE的生长抑制效果优于GM,其主要抑菌物质为有机酸;2%LPC对3株沙门氏菌SPI-1编码的主要毒力基因(InvA、InvF、SopE、SopB、SipB、HilA和SipA)、SPI-2毒...     

南极乔治王岛冰锥洞微生物培养探索

【目的】南极洲具备独特的环境和相对的生物地理隔离,南极洲各类生境中蕴藏了大量尚未培养和难培养的微生物,也是新颖微生物物种的重要来源之一。本研究以南极冰锥洞这类特殊生境为研究对象,通过培养条件的多样化提升南极微生物的培养率和多样性,揭示南极冰锥洞可培养微生物类群多样性,为该环境可培养微生物功能研究奠定基础,也为南极极端环境未培养微生物的培养方法提供借鉴。【方法】通过采用不同培养基添加复苏促进因子(resuscitation promoting factor, Rpf)的方式,提高南极柯林斯冰盖冰锥洞生境中微生物的可培养率,探究该生境中微生物的多样性。采用4种不同营养水平的培养基,平行添加Rpf进行菌株培养,经分离纯化与16S rRNA基因鉴定,分析冰锥洞可培养微生物的多样性及培养条件对多样性的影响。【结果】本研究共分离培养细菌407株,涵盖5个门、18个科、29个属,其中：放线菌门(Actinomycetota)为优势门,占72.73%;微杆菌科(Microbacteriaceae)为优势科,占69.78%;Lacisediminihabitans属为优势属,占45.70%。从培养基效果...     

高耐酸酒酒球菌常压室温等离子体诱变选育及其苹果酸-乳酸发酵研究

【目的】为选育出高度耐酸性酒酒球菌（Oenococcus oeni）突变菌株,研究其胁迫耐受性能及苹果酸-乳酸发酵（malolactic fermentation,MLF）能力。【方法】以酒酒球菌SD-2a为出发菌株,通过常压室温等离子体（atmospheric and room temperature plasma,ARTP）诱变技术,筛选高耐酸性酒酒球菌突变菌株,并探究其乙醇耐受性及在模拟酒和葡萄酒条件下的MLF能力。【结果】经过ARTP诱变处理后,利用pH 3.0的胁迫传代培养和分离纯化等,获得了5株β-葡萄糖苷酶活性较好的耐酸突变菌株,且在高乙醇浓度下表现出了较好的耐乙醇性。其中突变菌株ARTP-2在模拟酒中的β-葡萄糖苷酶活性和l-苹果酸累积降解量最高,且其在葡萄酒中l-苹果酸降解速率快于出发菌株,在第18天完成MLF,发酵后的葡萄酒香气成分的含量显著高于接种SD-2a的酒样。【结论】突变菌株ARTP-2具有良好的胁迫耐受性和MLF能力,对葡萄酒的香气起到积极的作用,为进一步开发优质的MLF商业发酵剂奠定基础。     

Phytopathogenic bacteria utilize host glucose as a signal to stimulate virulence through LuxR homologues

Chemical signal-mediated biological communication is common within bacteria and between bacteria and their hosts. Many plant-associated bacteria respond to unknown plant compounds to regulate bacterial gene expression. However, the nature of the plant compounds that mediate such interkingdom communication and the underlying mechanisms remain poorly characterized. Xanthomonas campestris pv. campestris (Xcc) causes black rot disease on brassica vegetables. Xcc contains an orphan LuxR regulator (XccR) which senses a plant signal that was validated to be glucose by HPLC-MS. The glucose concentration increases in apoplast fluid after Xcc infection, which is caused by the enhanced activity of plant sugar transporters translocating sugar and cell-wall invertases releasing glucose from sucrose. XccR recruits glucose, but not fructose, sucrose, glucose 6-phosphate, and UDP-glucose, to activate pip expression. Deletion of the bacterial glucose transporter gene sglT impaired pathogen virulence and pip expression. Structural prediction showed that the N-terminal domain of XccR forms an alternative pocket neighbouring the AHL-binding pocket for glucose docking. Substitution of three residues affecting structural stability abolished the ability of XccR to bind to the luxXc box in the pip promoter. Several other XccR homologues from plant-associated bacteria can also form stable complexes with glucose, indicating that glucose may function as a common signal molecule for pathogen–plant interactions. The conservation of a glucose/XccR/pip-like system in plant-associated bacteria suggests that some phytopathogens have evolved the ability to utilize host compounds as virulence signals, indicating that LuxRs mediate an interkingdom signalling circuit.     

Calcineurin B-like interacting protein kinase 31 confers resistance to sheath blight via modulation of ROS homeostasis in rice

Sheath blight (ShB) severely threatens rice cultivation and production; however, the molecular mechanism of rice defence against ShB remains unclear. Screening of transposon Ds insertion mutants identified that Calcineurin B-like protein-interacting protein kinase 31 (CIPK31) mutants were more susceptible to ShB, while CIPK31 overexpressors (OX) were less susceptible. Sequence analysis indicated two haplotypes of CIPK31: Hap_1, with significantly higher CIPK31 expression, was less sensitive to ShB than the Hap_2 lines. Further analyses showed that the NAF domain of CIPK31 interacted with the EF-hand motif of respiratory burst oxidase homologue (RBOHA) to inhibit RBOHA-induced H₂O₂ production, and RBOHA RNAi plants were more susceptible to ShB. These data suggested that the CIPK31-mediated increase in resistance is not associated with RBOHA. Interestingly, the study also found that CIPK31 interacted with catalase C (CatC); cipk31 mutants accumulated less H₂O₂ while CIPK31 OX accumulated more H₂O₂ compared to the wild-type control. Further analysis showed the interaction of the catalase domain of CatC with the NAF domain of CIPK31 by which CIPK31 inhibits CatC activity to accumulate more H₂O₂.     

The complex genome and adaptive evolution of polyploid Chinese pepper (Zanthoxylum armatum and Zanthoxylum bungeanum)

Zanthoxylum armatum and Zanthoxylum bungeanum, known as ‘Chinese pepper’, are distinguished by their extraordinary complex genomes, phenotypic innovation of adaptive evolution and species-special metabolites. Here, we report reference-grade genomes of Z. armatum and Z. bungeanum. Using high coverage sequence data and comprehensive assembly strategies, we derived 66 pseudochromosomes comprising 33 homologous phased groups of two subgenomes, including autotetraploid Z. armatum. The genomic rearrangements and two whole-genome duplications created large (~4.5 Gb) complex genomes with a high ratio of repetitive sequences (>82%) and high chromosome number (2n = 4x = 132). Further analysis of the high-quality genomes shed lights on the genomic basis of involutional reproduction, allomones biosynthesis and adaptive evolution in Chinese pepper, revealing a high consistent relationship between genomic evolution, environmental factors and phenotypic innovation. Our study provides genomic resources and new insights for investigating diversification and phenotypic innovation in Chinese pepper, with broader implications for the protection of plants under severe environmental changes.     

High-temperature stress in crops: male sterility,yield loss and potential remedy approaches

Global food security is one of the utmost essential challenges in the 21st century in providing enough food for the growing population while coping with the already stressed environment. High temperature (HT) is one of the main factors affecting plant growth, development and reproduction and causes male sterility in plants. In male reproductive tissues, metabolic changes induced by HT involve carbohydrates, lipids, hormones, epigenetics and reactive oxygen species, leading to male sterility and ultimately reducing yield. Understanding the mechanism and genes involved in these pathways during the HT stress response will provide a new path to improve crops by using molecular breeding and biotechnological approaches. Moreover, this review provides insight into male sterility and integrates this with suggested strategies to enhance crop tolerance under HT stress conditions at the reproductive stage.     

Artificial nanovesicles for dsRNA delivery in spray-induced gene silencing for crop protection

Spray-induced gene silencing (SIGS) is an innovative and eco-friendly technology where topical application of pathogen gene-targeting RNAs to plant material can enable disease control. SIGS applications remain limited because of the instability of RNA, which can be rapidly degraded when exposed to various environmental conditions. Inspired by the natural mechanism of cross-kingdom RNAi through extracellular vesicle trafficking, we describe herein the use of artificial nanovesicles (AVs) for RNA encapsulation and control against the fungal pathogen, Botrytis cinerea. AVs were synthesized using three different cationic lipid formulations, DOTAP + PEG, DOTAP and DODMA, and examined for their ability to protect and deliver double stranded RNA (dsRNA). All three formulations enabled dsRNA delivery and uptake by B. cinerea. Further, encapsulating dsRNA in AVs provided strong protection from nuclease degradation and from removal by leaf washing. This improved stability led to prolonged RNAi-mediated protection against B. cinerea both on pre- and post-harvest plant material using AVs. Specifically, the AVs extended the protection duration conferred by dsRNA to 10 days on tomato and grape fruits and to 21 days on grape leaves. The results of this work demonstrate how AVs can be used as a new nanocarrier to overcome RNA instability in SIGS for crop protection.     

Eu3+-activated red phosphor Ca3YAl3B4O15 with low thermal quenching behaviour

This paper reports a sequence of a Ca₃YAl₃B₄O₁₅:xEu³⁺ red phosphor prepared using a high-temperature solid-state reaction. At the excitation of 396 nm, the samples emitted intense red emission centred at ~623 nm, which could be attributed to the ⁵D₀→⁷F₂ transition of the Eu³⁺ ion. The results showed that the optimum Eu³⁺ doping concentration of Ca₃YAl₃B₄O₁₅:Eu³⁺ phosphor was x = 80 mol%, and the concentration quenching mechanism of Ca₃YAl₃B₄O₁₅:Eu³⁺ red phosphor belonged to the exchange coupling between Eu³⁺ ions. The Commission Internationale de l'éclairage (CIE) coordinates and colour purity of Ca₃Y_0.2Al₃B₄O₁₅:0.8Eu³⁺ were calculated as (0.6375, 0.3476) and 95.5%, respectively. Moreover, the red emission of the obtained phosphor Ca₃YAl₃B₄O₁₅:0.8Eu³⁺ exhibited a low thermal quenching behaviour with an intensity retention rate of 92.85% at 150°C. The above results manifest that the Eu³⁺-activated Ca₃YAl₃B₄O₁₅ phosphor is predicted to be a promising red luminescent component for white light-emitting diodes.     

Multistimuli-responsive fluorescence behaviours of aggregation-induced emission small-molecule and electrospun nanofibre films for acid–base vapour sensing

Multistimuli-responsive fluorescent materials have garnered great research interest benefited from their practical applications. Two twisted-structure compounds containing tetraphenylethylene (TPE) as the aggregation-induced emission (AIE) group and a pyridine unit as the acid reaction site to obtain new multistimuli-responsive fluorescent compounds (namely, TPECNPy: TPECNPy-2 and TPECNPy-3) were successfully synthesized through a one-step Knoevenagel condensation reaction. The multiple-stimuli response process of TPECNPy was investigated by means of photoluminescence (PL) spectra and emission colour. The results showed that both TPECNPy compounds with excellent AIE abilities displayed reversible emission wavelength and colour changes in response to multiple external stimuli, including grinding–fuming by CH₂Cl₂ or annealing and HCl-NH₃ vapour fuming. More importantly, fluorescent nanofibre films were prepared by electrospinning a solution of TPECNPy mixed with cellulose acetate (CA), and these exhibited reversible acid-induced discolouration, even with only 1 wt% TPECNPy. The results of this study may inspire strategies for designing multistimuli-responsive materials and preparing fluorescent sensing nanofibre films.