植物抗病毒基因工程

植物病毒病难以防治已成为植物界的"癌症",给全球农业生产造成巨大的损失。有效地防治植物病毒病,减少经济损失,满足日益增长的世界人口需求。是农业生产当务之急。病毒分子生物学,植物基因工程的迅速发展,为筛选培育抗病、优质、丰产的新植物开辟了广阔的前景。自1986年,全球范围内兴起了多种利用分子生物学及基因工程研究成果防治植物病毒病害的策略,并成功地培育筛选出多种抗病毒的工程植物。1病毒外壳蛋白介导的基因工程抗病性外壳蛋白是形成病毒颗粒的结构蛋白,它的功能是将病毒基因组核酸包被起来,保护核酸;与宿主互相识别…     

兰花抗病毒基因工程研究进展(综述)

兰花病毒病严重影响兰花产业的发展,研究和探索防治兰花病毒病的新技术、新途径已成为众多研究者普遍关注的焦点。本文综述目前抗兰花病毒研究中应用的各种抗病毒基因工程策略,包括病毒来源基因中的外壳蛋白基因和运动蛋白基因介导的抗性策略,RNA介导的抗病毒策略,植物自身的抗病毒基因介导的抗性策略,利用多基因介导的抗性策略,以及抗体基因介导的抗性策略等。最后对兰花抗病毒基因工程的发展及应用进行了展望。     

抗病毒植物基因工程的研究进展

病毒病害一直是农业生产的一大问题,分子生物学的发展,特别是基因工程的发展为防治病毒病带来了希望。就目前的情况看,有效的抗基因主要来源于病毒本身,如外壳蛋白基因、卫星RNA基因、正义RNA序列,反义RNA序列等。除此之外,一些其它的策略也被采用,如核酶(Ribozyme)策略等。人们也正在试图从植物本身分离抗病毒基因和探索新的抗病毒策略,这一切都有助于推动抗病毒植物基因工程的发展。本     

转基因植物抗病毒机制

植物病毒病给全球农业生产造成巨大的损失.有效地防治植物病毒病,减少经济损失,满足日益增长的世界人口的食品需求,是科学家的重要目标之一.随着病毒分子生物学、植物基因工程研究的迅速发展,近年来,利用分子生物学及基因工程技术培育抗病毒工程植物已成为防治植物病毒病害的有效策略,许多具有重要经济价值的转基因作物已经开始陆续进入实际应用阶段.     

植物抗病毒的基因工程

本文就利用基因工程手段防治植物病毒病的主要策略进行了综述。所涉及的方法包括病毒基因组的和非病毒的,甚至非植物基因的转基因表达。对比了不同方法的特点,针对广谱抗性策略的开发是当前研究趋向之一。     

微生物来源的抗植物病毒活性物质研究进展

近年来,研究者利用微生物及其次生代谢产物开展了大量防治植物病毒病的研究,从中发现了许多具有抗植物病毒活性的大分子物质及小分子化合物。本文对来源于不同种类微生物的抗病毒活性物质及抗病毒机理作了论述,并对微生物来源抗植物病毒物质研究进行了展望,以期为开发用于植物病毒病防治的微生物农药提供借鉴。     

抗TMV和CMV双价转基因烟草纯合系进入大田试验

植物病毒病被称为作物生长和发育的“癌症”,常造成产量降低、品质下降乃至绝产。植物抗病毒病基因工程研究采用多种抗病毒策略。通过基因转移使植物产生较明显的抗病毒病的功能,在农业生产中具有可应用的良好前景。中国科学院微生物研究所、河南省农科院植物保护研究所。中国农科院烟草研究所的科研人员共同合作,针对国内烟区产生主要危害的烟草花叶病毒(TMV)和黄瓜花叶病毒(CMV)及上述两种病毒混合感染的问题,采用双价(TMV     

植物抗病基因工程的研究进展

植物病原真菌、细菌、病毒常年危害农作物,给农业生产带来巨大损失,而防治病害的最有效措施是抗病育种。生物技术的发展给抗病育种开辟了新途径。本文简述了国内外抗病毒病害,抗细菌病害,抗真菌病害基因工程的研究现状及其发展趋势。同时指出在发展生物技术的同时,须基因工程与基础研究并重,要基因工程技术与常规农业技术有机结合以及加强基因工程与环境生态平衡的研究。     

烟草抗病毒基因工程研究进展

烟草花叶病毒病是一种危害严重的世界性病害,可大幅度降低烟草的产量和品质。研究和探索防治烟草花叶病毒病的新技术、新途径已成为众多研究者普遍关注的焦点。分子生物学的发展,特别是基因工程的发展为防治该病毒病带来了希望。综述了目前普遍采用的几种烟草抗病毒基因工程策略的研究现状及评价。     

抗病毒蛋白抑制植物病毒的应用前景

探索应用外源性抗植物病毒蛋白进行植物病毒病的防治．已经取得了一定的成效;但不同来源的抗植物病毒蛋白,它们的作用机理是不完全一样的．根据近年的研究结果,对这类蛋白的抗病毒作用的机理进行了综述,并对抗病毒蛋白的应用前景进行了展望．     

An equilibrium model for coat protein mediated resistance to viral infection in plants

Virally infected plants are resistant to secondary viral infection by similar viruses. This phenomenon has been used to confer virus resistance. Here we develop an equilibrium model of viral Coat Protein Mediated Resistance (CP-MR). This model successfully explains qualitative experimental observations. Our model also suggests an approach of developing transgenic viral infection resistant plant with minimal yield penalty.     

Plant viruses and new perspectives in cross-protection

Cross-protection in plants is the phenomenon whereby a plant preinoculated with a mild virus strain becomes resistant to subsequent inoculation by a related severe strain. It has been used on a large scale in cases where no resistant plants are available. Although several hypotheses have been proposed to explain the molecular mechanism underlying cross-protection, no single hypothesis can account for all the data obtained. Recently, a phenomenon akin to cross-protection has been achieved in transformed plants harboring the cDNA of a part of a viral RNA genome. These results obtained by genetic engineering raise new hopes for obtaining plants resistant to virus infection.     

Beet curly top virus DI DNA-mediated resistance is linked to its size

Beet curly top virus (BCTV) infection is associated with the de novo synthesis of a heterogeneous population of subgenomic viral DNAs. Nicotiana benthamiana plants transformed with a partial repeat of one such subgenomic DNA remained susceptible to infection but produced ameliorated symptoms when agroinoculated with BCTV. Symptom amelioration is associated with the mobilization of subgenomic DNA from the integrated copy. In an attempt to improve the resistance, N. benthamiana has been transformed with a partial repeat of a much smaller subgenomic DNA. However, transgenic plants showed almost no resistance although subgenomic DNA was mobilised from the host genome. To further understand the molecular basis of the interference phenomenon, we compared the ability of BCTV to replicate and accumulate in leaf discs derived from resistant and non-resistant transgenic plants. Both subgenomic DNAs were able to interfere with virus replication but only in case of resistant plants the DI DNA efficiently suppressed viral accumulation.     

Establishing RNA virus resistance in plants by harnessing CRISPR immune system

Recently, CRISPR‐Cas (clustered, regularly interspaced short palindromic repeats–CRISPR‐associated proteins) system has been used to produce plants resistant to DNA virus infections. However, there is no RNA virus control method in plants that uses CRISPR‐Cas system to target the viral genome directly. Here, we reprogrammed the CRISPR‐Cas9 system from Francisella novicida to confer molecular immunity against RNA viruses in Nicotiana benthamiana and Arabidopsis plants. Plants expressing FnCas9 and sgRNA specific for the cucumber mosaic virus (CMV) or tobacco mosaic virus (TMV) exhibited significantly attenuated virus infection symptoms and reduced viral RNA accumulation. Furthermore, in the transgenic virus‐targeting plants, the resistance was inheritable and the progenies showed significantly less virus accumulation. These data reveal that the CRISPR/Cas9 system can be used to produce plant that stable resistant to RNA viruses, thereby broadening the use of such technology for virus control in agricultural field.     

Targeting specific genes for RNA interference is crucial to the development of strong resistance to rice stripe virus

Rice stripe virus (RSV) has a serious negative effect on rice production in temperate regions of East Asia. Focusing on the putative importance of the selection of target sequences for RNA interference (RNAi), we analysed the effects of potential target sequences in each of the coding genes in the RSV genome, using transgenic rice plants that expressed a set of inverted-repeat (IR) constructs. The reactions of inoculated transgenic T(1) plants to RSV were divided subjectively into three classes, namely highly resistant, moderately resistant and lacking enhanced resistance to RSV, even though plants that harboured any constructs accumulated transgene-specific siRNAs prior to inoculation with RSV. Transgenic plants that harboured IR constructs specific for the gene for pC3, which encodes nucleocapsid protein, and for pC4, which encodes a viral movement protein, were immune to infection by RSV and were more resistant to infection than the natural resistant cultivars that have been used to control the disease in the field. By contrast, the IR construct specific for the gene for pC2, which encodes a glycoprotein of unknown function, and for p4, which encodes a major non-structural protein of unknown function, did not result in resistance. Our results indicate that not all RNAi constructs against viral RNAs are equally effective in preventing RSV infection and that it is important to identify the viral 'Achilles heel' for RNAi attack in the engineering of plants.     

Molecular and biochemical characterization of mungbean yellow mosaic India virus resistance in leguminous host <Emphasis Type="Italic">Vigna mungo</Emphasis>

Mungbean yellow mosaic India virus (MYMIV)—the causal agent of the yellow mosaic disease is responsible for severe damage of crops that are of great economic importance. In the current study, we explored the process of MYMIV infection and its natural resistance by analysing the expression of early and late viral genes at different time points in the leaves of resistant and susceptible Vigna mungo plants. Accordingly, we have periodically evaluated several biochemical parameters commonly associated with oxidative status of resistant and susceptible V. mungo plants during MYMIV infection. Our study revealed that accumulation levels of the early as well as late expressed genes of MYMIV were low and high in the resistant and susceptible plants, respectively; whereas membrane stability index (MSI) exhibited an opposite response. Moreover, a decrease in the malondialdehyde levels along with an increase in the activities/levels of different antioxidant enzymes, total phenol and H₂O₂ was noted during the early stages of infection in the resistant plants. Such observations argue in favour of strong defensive capability of the resistant plants in restricting the accumulation of viral RNA and generation of harmful free radicals within the studied tissue. Collectively, it appears that obstruction of viral invasion in plant cell wall, restriction in viral DNA replication, and early onset of antioxidant defense responses altogether might be responsible for MYMIV natural resistance. Such information is helpful in understanding the pathogenesis of MYMIV infection and its resistance in V. mungo and other economically important crops.     

Inhibition of virus DNA replication by artificial zinc finger proteins

Prevention of virus infections is a major objective in agriculture and human health. One attractive approach to the prevention is inhibition of virus replication. To demonstrate this concept in vivo, an artificial zinc finger protein (AZP) targeting the replication origin of the Beet severe curly top virus (BSCTV), a model DNA virus, was created. In vitro DNA binding assays indicated that the AZP efficiently blocked binding of the viral replication protein (Rep), which initiates virus replication, to the replication origin. All of the transgenic Arabidopsis plants expressing the AZP showed phenotypes strongly resistant to virus infection, and 84% of the transgenic plants showed no symptom. Southern blot analysis demonstrated that BSCTV replication was completely suppressed in the transgenic plants. Since the mechanism of viral DNA replication is well conserved among plants and mammals, this approach could be applied not only to agricultural crop protection but also to the prevention of virus infections in humans.     

Expression of the crucifer-infecting TMV-Cg movement protein in tobacco plants complements in trans a TMV-U1 trafficking-deficient mutant

Tobamovirus movement proteins play a determinant role in the establishment of infections in plants, allowing the local movement of viral RNA genome through plasmodesmatas. We expressed the movement protein (MP) of the crucifer- and garlic-infecting Tobacco Mosaic Virus strain Cg (TMV-Cg) in both resistant Xanthi NN and sensitive Xanthi nn Nicotiana tabacum plants. MP-Cg function was assayed by inoculating transgenic plants with a trafficking-deficient mutant of TMV strain U1. Following infection, local necrotic lesions were developed in resistant transgenic plants, and a systemic infection was produced in sensitive tobaccos. Thus, movement function of the mutant virus was complemented in trans by MP-Cg expressed in transgenic plants, causing the same symptoms as wild-type strain. We demonstrated that the function of MP-U1 could be replaced efficiently by MP-Cg, even though these proteins share only 36% of identity. Similar hydrophobic patterns of MP-Cg and MP-U1 suggests structure and function conservations of both proteins. This work is an example of how two tobamoviruses differing in their host range help to understand viral movement mechanism during the infection.