植物诱抗剂研究进展

植物诱抗剂包括许多种类，如：寡糖、蛋白，糖蛋白等。这类物质作用于植物后植物后使植物细胞内发生一系列发生。诱导植物产生植保素，从而使其具有抗病性，本文综述了植物诱抗剂的种及其作用及植物后，植物细胞对于这类物质的识别及信号传导。     

昆虫P450的诱导及其与抗药性的关系

现已充分证明,昆虫体内重要的解毒酶如多功能氧化酶(MFO),谷胱甘肽S—转移酶(GST)和酯酶(Est)等都能被各种外源(xenobiotics)或内源(endogenous)化合物所诱导(in-duce)。解毒酶系的诱导高表达,显然能使昆虫对有毒物质的解毒作用增加,代谢加速,从而使昆虫产生暂时的耐药性(tolerance),以帮助昆虫渡过“危险期”。但这种由诱导产生的耐药性不具遗传性,与具有遗传性的抗药性不同,后者已有很多专著,并进行了深入的研究;前者     

植物生长调节物质的混用效果

在农业生产上,常常应用某一种植物生长调节物质就能达到应用的目的,但有时仅用一种生长调节物质,不能达到完满的要求,而添加另一种甚至两种以上的生长调节物质的混合使用时,才能达到应用的目的。这是因为植物生长发育的许多过程并非受某一种内源激素的作用,通常受多种内源激素同时或交错地相互作用的结果。另外,植物体内某一内源激素的水准,常常受温度、湿度、光照及肥水等栽培条件的影响。因此,在植物上使用某种生长调节物质时,其效果有时不够稳定,故     

植物免疫：从设想到实践

自从十九世纪晚期发现了动物免疫系统之后,人们便已认识到植物被真菌或从真菌衍生的抗生物质感染后,有可能产生一种后天免疫功能此即为系统获得抗性(systemic acquired resistance,简称SAR)。Chester已总结了对植物免疫性研究的早期历史。大部分实验是寻找凝集试验中存在抗体的证据,但由于交叉反应蛋白质的植物萃取物的扩散而没有获得实际结果,这些     

嘧肽霉素诱导烟草BY-2悬浮细胞防卫反应的研究

[目的]利用烟草BY-2悬浮细胞研究抗病毒新农药2%嘧肽霉素水剂诱导植物防卫反应的机制。[方法]用不同质量浓度的嘧肽霉素处理悬浮细胞,分光光度法测定胞外H2O2产生的动态过程及RT-q PCR方法测定防卫反应基因表达。[结果]烟草BY-2悬浮细胞经嘧肽霉素处理,产生活性氧迸发,并在处理1 h后达到高峰;嘧肽霉素能诱导细胞的FLS2、MAPKKK、PR1、NPR1和HSP70的上调表达,其中HSP70的上调效果最为显著。[结论]嘧肽霉素可通过诱导植物防卫反应相关基因的表达,达到诱导植物抗病毒病的作用。     

海藻酸钠改性高吸水树脂在遇水膨胀橡胶中的性能研究

以淀粉(ST)和丙烯酸(AA)为单体,采用微波辐照法对海藻酸钠(SA)进行接枝改性,得到了一种三元共聚高吸水树脂(SAR)。将SAR与丁腈橡胶(NBR)共混得到一种遇水膨胀橡胶(WSR)。考察了不同SAR与硫化剂(DCP)用量对WSR力学性能和吸水膨胀性能的的影响,结果表明,WSR中SAR的最佳用量为75phr,DCP最佳用量为2phr,得到的遇水膨胀橡胶兼具良好的力学性能和吸水膨胀性能。     

金黄色葡萄球菌金属磷酸酶的遗传特征分析及功能鉴定

目的对金黄色葡萄球菌(简称金葡菌)一种新型金属磷酸酶(metallophosphatase,MPP)SA1662进行遗传特征分析及生物学功能鉴定。方法从金葡菌基因组DNA中克隆SA1662基因,通过序列比对和构建进化树分析其遗传特征;构建重组表达质粒,转化大肠埃希菌BL21,IPTG诱导表达,表达的重组蛋白经Ni柱纯化后,测定酶活性。应用同源重组技术构建SA1662基因缺失株,分析SA1662基因缺失对金葡菌生长、万古霉素敏感性、细菌自溶性和细菌生物菌膜形成的影响,探讨SA1662的生物学功能。结果 SA1662蛋白具有MPP类蛋白结构域,并含有特征性金属离子结合位点,与金葡菌和施维茨葡萄球菌中相关蛋白有更近的亲缘关系。该蛋白酶活性依赖于Mg^2+和Mn^2+,特别是Mg^2+。与野生型菌株相比,SA1662基因缺失后,细菌生长速度减慢,万古霉素敏感性、TritonX-100诱导下的细菌自溶性和细菌生物菌膜形成能力均下降。结论 SA1662蛋白为一种新型的金葡菌MPP,在细菌抗逆性中起着重要作用。     

植物CDPKs响应逆境胁迫信号传导作用研究进展

钙依赖蛋白激酶(CDPKs)是由多基因族编码,在植物响应逆境胁迫信号转导通路中处于关键位置。从CDPKs结构特征、CDPKs在非生物胁迫信号转导中的作用、CDPKs在生物胁迫信号转导中的作用和CDPKs介导的信号传导途径中的交互作用这几个方面综合阐述了植物CDPKs响应逆境胁迫信号传导作用研究进展,旨在探讨CDPKs的功能及调控防御机制。     

黑龙江垦区农药安全使用问题和对策

黑龙江垦区农药使用水平较高 ,特别是化学除草技术全国领先 ,随着农业生产的发展 ,农业种植结构调整以及自然条件变化 ,在农药使用方面出现了一些问题如药效不佳 ,局部药害 ,影响了质量效益农业的发展 ,这些问题亟待解决。1　植物生长调节剂危害严重植物生长调节剂是指所有用来调节植物生命过程的内源植物生长物质。这些物质能影响植物的大小、形态特征、开花结果和产量 ,干燥、落叶以及除草 ,人们习惯上称这些物质叫植物激素 ,把植物体内产物叫内源激素 ,把人工合成的叫外源激素。目前生产应用的内源激素有益微增产菌 (Ｂａｃｉｌｌｕｓｃ…     

动态转录调控微生物代谢途径研究进展

传统的微生物代谢工程主要是通过过表达或敲除关键基因来实现产物产量最大化,但会造成代谢流失衡,生产效能降低。而对微生物代谢途径进行动态调控可维持细胞生长,平衡代谢流,提高生产效率。本文根据信号分子的来源不同,将微生物在转录水平的动态调控分为两种：一种是在光、温度、化学诱导剂的外源信号刺激下,利用响应该信号的启动子等元件调控下游代谢途径的人工诱导动态调控;另一种为在胞内代谢物水平或细胞密度改变的内源信号感应下,利用启动子、转录因子、核糖核酸开关调节关键基因的细胞自主诱导动态调控。本文同时介绍了转录水平动态调控策略在微生物代谢工程中的应用实例,以期对代谢途径的多个基因实现连续动态表达以及适配表达,有效提高目标产物的产量。     

Biosynthesis and Roles of Salicylic Acid in Balancing Stress Response and Growth in Plants

Salicylic acid (SA) is an important plant hormone with a critical role in plant defense against pathogen infection. Despite extensive research over the past 30 year or so, SA biosynthesis and its complex roles in plant defense are still not fully understood. Even though earlier biochemical studies suggested that plants synthesize SA from cinnamate produced by phenylalanine ammonia lyase (PAL), genetic analysis has indicated that in Arabidopsis, the bulk of SA is synthesized from isochorismate (IC) produced by IC synthase (ICS). Recent studies have further established the enzymes responsible for the conversion of IC to SA in Arabidopsis. However, it remains unclear whether other plants also rely on the ICS pathway for SA biosynthesis. SA induces defense genes against biotrophic pathogens, but represses genes involved in growth for balancing defense and growth to a great extent through crosstalk with the growth-promoting plant hormone auxin. Important progress has been made recently in understanding how SA attenuates plant growth by regulating the biosynthesis, transport, and signaling of auxin. In this review, we summarize recent progress in the biosynthesis and the broad roles of SA in regulating plant growth during defense responses. Further understanding of SA production and its regulation of both defense and growth will be critical for developing better knowledge to improve the disease resistance and fitness of crops.     

Small RNAs Participate in Plant–Virus Interaction and Their Application in Plant Viral Defense

Small RNAs are significant regulators of gene expression, which play multiple roles in plant development, growth, reproductive and stress response. It is generally believed that the regulation of plants’ endogenous genes by small RNAs has evolved from a cellular defense mechanism for RNA viruses and transposons. Most small RNAs have well-established roles in the defense response, such as viral response. During viral infection, plant endogenous small RNAs can direct virus resistance by regulating the gene expression in the host defense pathway, while the small RNAs derived from viruses are the core of the conserved and effective RNAi resistance mechanism. As a counter strategy, viruses evolve suppressors of the RNAi pathway to disrupt host plant silencing against viruses. Currently, several studies have been published elucidating the mechanisms by which small RNAs regulate viral defense in different crops. This paper reviews the distinct pathways of small RNAs biogenesis and the molecular mechanisms of small RNAs mediating antiviral immunity in plants, as well as summarizes the coping strategies used by viruses to override this immune response. Finally, we discuss the current development state of the new applications in virus defense based on small RNA silencing.     

The THO/TREX Complex Active in Alternative Splicing Mediates Plant Responses to Salicylic Acid and Jasmonic Acid

Salicylic acid (SA) and jasmonic acid (JA) are essential plant immune hormones, which could induce plant resistance to multiple pathogens. However, whether common components are employed by both SA and JA to induce defense is largely unknown. In this study, we found that the enhanced disease susceptibility 8 (EDS8) mutant was compromised in plant defenses to hemibiotrophic pathogen Pseudomonas syringae pv. maculicola ES4326 and necrotrophic pathogen Botrytis cinerea, and was deficient in plant responses to both SA and JA. The EDS8 was identified to be THO1, which encodes a subunit of the THO/TREX complex, by using mapping-by-sequencing. To check whether the EDS8 itself or the THO/TREX complex mediates SA and JA signaling, the mutant of another subunit of the THO/TREX complex, THO3, was tested. THO3 mutation reduced both SA and JA induced defenses, indicating that the THO/TREX complex is critical for plant responses to these two hormones. We further proved that the THO/TREX interacting protein SERRATE, a factor regulating alternative splicing (AS), was involved in plant responses to SA and JA. Thus, the AS events in the eds8 mutant after SA or JA treatment were determined, and we found that the SA and JA induced different alternative splicing events were majorly modulated by EDS8. In summary, our study proves that the THO/TREX complex active in AS is involved in both SA and JA induced plant defenses.     

Oxidative and Molecular Responses in Capsicum annuum L. after Hydrogen Peroxide,Salicylic Acid and Chitosan Foliar Applications

Hydrogen peroxide (H₂O₂) is an important ROS molecule (Reactive oxygen species) that serves as a signal of oxidative stress and activation of signaling cascades as a result of the early response of the plant to biotic stress. This response can also be generated with the application of elicitors, stable molecules that induce the activation of transduction cascades and hormonal pathways, which trigger induced resistance to environmental stress. In this work, we evaluated the endogenous H₂O₂ production caused by salicylic acid (SA), chitosan (QN), and H₂O₂ elicitors in Capsicum annuum L. Hydrogen peroxide production after elicitation, catalase (CAT) and phenylalanine ammonia lyase (PAL) activities, as well as gene expression analysis of cat1, pal, and pathogenesis-related protein 1 (pr1) were determined. Our results displayed that 6.7 and 10 mM SA concentrations, and, 14 and 18 mM H₂O₂ concentrations, induced an endogenous H₂O₂ and gene expression. QN treatments induced the same responses in lesser proportion than the other two elicitors. Endogenous H₂O₂ production monitored during several days, showed results that could be an indicator for determining application opportunity uses in agriculture for maintaining plant alert systems against a stress.     

Systemin Regulates Both Systemic and Volatile Signaling in Tomato Plants

The prevailing reaction of plants to pest attack is the activation of various defense mechanisms. In tomato, several studies indicate that an 18 amino acid (aa) peptide, called systemin, is a primary signal for the systemic induction of direct resistance against plant-chewing pests, and that the transgenic expression of the prosystemin gene (encoding the 200 aa systemin precursor) activates genes involved in the plant response to herbivores. By using a combination of behavioral, chemical, and gene expression analyses, we report that systemin enhances the production of bioactive volatile compounds, increases plant attractivity towards parasitiod wasps, and activates genes involved in volatile production. Our data imply that systemin is involved in the systemic activation of indirect defense in tomato, and we conclude that a single gene controls the systemic activation of coordinated and associated responses against pests. G. Corrado and R. Sasso contributed equally to the work     

Symptomless Endophytic Fungi Suppress Endogenous Levels of Salicylic Acid and Interact With the Jasmonate-Dependent Indirect Defense Traits of Their Host,Lima Bean (Phaseolus lunatus)

Symptomless ‘type II’ fungal endophytes colonize their plant host horizontally and exert diverse effects on its resistance phenotype. Here, we used wild Lima bean (Phaseolus lunatus) plants that were experimentally colonized with one of three strains of natural endophytes (Bartalinia pondoensis, Fusarium sp., or Cochliobolus lunatus) to investigate the effects of fungal colonization on the endogenous levels of salicylic acid (SA) and jasmonic acid (JA) and on two JA-dependent indirect defense traits. Colonization with Fusarium sp. enhanced JA levels in intact leaves, whereas B. pondoensis suppressed the induction of endogenous JA in mechanically damaged leaves. Endogenous SA levels in intact leaves were significantly decreased by all strains and B. pondoensis and Fusarium sp. decreased SA levels after mechanical damage. Colonization with Fusarium sp. or C. lunatus enhanced the number of detectable volatile organic compounds (VOCs) emitted from intact leaves, and all three strains enhanced the relative amount of several VOCs emitted from intact leaves as well as the number of detectable VOCs emitted from slightly damaged leaves. All three strains completely suppressed the induced secretion of extrafloral nectar (EFN) after the exogenous application of JA. Symptomless endophytes interact in complex and strain-specific ways with the endogenous levels of SA and JA and with the defense traits that are controlled by these hormones. These interactions can occur both upstream and downstream of the defense hormones.     

Hormonal Responses to Susceptible,Intermediate, and Resistant Interactions in the Brassica napus–Leptosphaeria maculans Pathosystem

Hormone signaling plays a pivotal role in plant–microbe interactions. There are three major phytohormones in plant defense: salicylic acid (SA), jasmonic acid (JA), and ethylene (ET). The activation and trade-off of signaling between these three hormones likely determines the strength of plant defense in response to pathogens. Here, we describe the allocation of hormonal signaling in Brassica napus against the fungal pathogen Leptosphaeria maculans. Three B. napus genotypes (Westar, Surpass400, and 01-23-2-1) were inoculated with two L. maculans isolates (H75 8-1 and H77 7-2), subsequently exhibiting three levels of resistance: susceptible, intermediate, and resistant. Quantitative analyses suggest that the early activation of some SA-responsive genes, including WRKY70 and NPR1, contribute to an effective defense against L. maculans. The co-expression among factors responding to SA/ET/JA was also observed in the late stage of infection. The results of conjugated SA measurement also support that early SA activation plays a crucial role in durable resistance. Our results demonstrate the relationship between the onset patterns of certain hormone regulators and the effectiveness of the defense of B. napus against L. maculans.