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番茄细菌性斑点病菌无毒基因研究进展 总被引：1，自引：0，他引：1
番茄细菌性斑点病是影响番茄产量和品质的重要病害,Pseudomonas syringaepv.tomato(Pst)为其病原菌,其与番茄的互作系统是研究植物抗感病机理的典型模式系统。Pst存在2种无毒基因:avrPto和avrPtoB,它们编码的蛋白质均能与番茄抗性基因Pto编码的Ser-Thr蛋白激酶互作,符合Flor"基因对基因"学说。AvrPto和AvrPtoB在表达Pto的抗性植物中,与Pto互作,表现无毒功能,引发植物防御反应;而在缺失Pto的感病植物中,它们具有毒性,促进细菌的生长。本文综述了番茄细菌性斑点病菌无毒基因avrPto及avrPtoB的结构特点及其功能,这有助于了解病原物与植物的互作机制,对认识植物的感病性、抗病性以及植物防御反应都具有重要意义。 相似文献
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水稻与稻瘟病菌的互作已成为研究植物与病原真菌互作的模式系统。利用RT-PCR技术检测了6个水稻品种(分别含有抗病基因Pik-s、Pita、Pit、Pi1、Pi9的近等系及回交亲本丽江新团黑谷LTH)与稻瘟病菌互作过程中多个信号相关及PR基因的表达。结果表明带有稻瘟病抗性基因Pik-s、Pita、Pit的水稻品种和LTH对稻瘟病菌#626侵染表现为亲和互作,带Pi1和Pi9的水稻品种表现为非亲和互作;稻瘟病菌接种后,亲和互作中MAPK6和MAPK12表现为上调表达,带有抗性基因Pi9的水稻品种IRBL22中BIMK2表现为上调表达。总体来看,含有不同抗病基因的水稻近等系中的PR基因对稻瘟病菌的响应较为多样,非亲和互作中在早期或早中期表现为PR基因上调表达,而亲和互作中主要在晚期上调表达,说明这些PR基因表达的时间在植物与病原互作的不同时期发挥着不同的作用。 相似文献
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QTL作图在植物数量抗病性遗传研究中的应用 总被引：6，自引：0，他引：6
本文综述了近年来在植物数量抗病性遗传研究方面的进展及发展动态。列举了利用DNA分子标记定位和估计植物数量抗性座位或基因(QRL)的18个实例,从中归纳总结了控制植物数量抗病性的QRL数目、类别、效应及其基因与基因和基因与环境、植株生育期、病菌生理小种(或致病类型)间的互作关系。展望了QTL作图对复杂的数量抗病性的标记辅助选育和数量抗性基因图位克隆的发展前景。 相似文献
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水稻-稻瘟菌(Magnaporthe grisea)相互作用的细胞生物学研究 总被引：2，自引：0，他引：2
在植物一病原菌非亲和性互作中,病菌感染后寄主细胞中会发生一系列与植物抗病性相关的事件。这些事件在时间和空间上与寄主细胞坏死和病原菌的受抑制密切相关,因而人们推测这些事件在植物抗病性中具有重要的意义。 相似文献
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十字花科黑腐病菌(Xanthomonas campestris pv.campestris,Xcc)是全球范围内能引起十字花科植物黑腐病的重要植物病原细菌,也是研究植物病原细菌与植物互作机制的模式细菌。利用自杀质粒pK18mobsacB诱变十字花科黑腐病菌Xcc 8004的XC_3605基因,获得缺失突变体D3605。表型分析发现D3605胞外多糖合成能力、游动能力及致病力显著降低,积聚形成生物被膜的能力增强。用带有全长XC_3605基因序列的pLAFRJ对D3605进行功能互补,其胞外多糖产量、游动性、致病力和生物被膜均得到恢复。研究结果表明,XC_3605基因在十字花科黑腐病菌致病过程中发挥作用。 相似文献
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基因对基因假说阐明了病原菌无毒基因(avirulence gene,Avr gene)与寄主植物抗性基因(resistance gene,Rgene)相互识别和互作的关系。禾谷类白粉菌无毒基因产物作为重要的激发子,能够与其寄主R基因产物发生特异性互作,诱导植物细胞防卫反应。为了更加深入地了解这些无毒基因的作用,作者总结了最近关于AVRa1、AVRa10、AVRa13、AVRk1、AvrPm2和AvrPm3a2/f2等已克隆无毒基因的研究进展,讨论了它们作为效应蛋白(effector)或激发子的双重功能,在毒性菌株中的变异规律,与其对应R基因之间的互作模型,以及与转座子等重复序列之间的关联等。本文还对无毒基因研究方法的改进和未来的研究方向提出了建议。 相似文献
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植物水通道蛋白PIP不仅担负细胞间或细胞内外水分子输导的基本功能,还参与植物-微生物互作与植物防卫反应,这种双重功能的调控机制目前还不清楚。水稻OsPIP1;2和拟南芥AtPIP1;4可以与水稻黄单胞III型泌出蛋白Hpa1互作,Hpa1定位于植物细胞的质外体,诱导过氧化氢在质外体产生及向原生质转运,进而影响植物防卫反应与对病原细菌的抗性。根据植物水通道蛋白拓扑结构与病原细菌Ⅲ型分泌系统工作模型,水稻OsPIP1;2与Hpa1互作的功能域是互作发生的分子基础。互作引发信号转导,调控过氧化氢信号从植物细胞的质外体向原生质转运与植物防卫反应。由于Hpa1对Ⅲ效应蛋白来说具有转位子的功能特征,OsPIP1;2-Hpa1还可能对水稻黄单胞菌Ⅲ型效应蛋白从细菌细胞向植物细胞转运发生调控作用。围绕这些设想进行研究,可以深入阐释水稻-黄单胞菌互作机制,同时为植物水通道蛋白功能调控提供新的见解。 相似文献
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高原人体生理适应学理论在进藏旅游中的应用 总被引：2，自引：0，他引：2
青藏铁路的贯通运行,带来了国内外进藏旅游热.然而,青藏高原毕竟是世界屋脊,高海拔带来的低氧及其引发的高原疾病依然威胁着游客的身体健康.健康高原旅行是当前游客进藏旅游的基本前提,通过综合国内外高原医学工作者对高原医学生理学的研究成果,提出阶梯进藏旅游的方法.旨在对越来越多的短期赴西藏高原旅行的人群以正确的健康指导,从而减... 相似文献
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白刺花(Sophoraviciifolia)适应土壤干旱的生理学机制 总被引：2，自引：1，他引：1
用盆栽的方法人工控制土壤干旱条件,研究白刺花天然实生幼苗适应土壤干旱的生理学机制。结果表明:随土壤含水量的减少,白刺花叶水势在胁迫前期下降缓慢,随胁迫时间的延长,水势大幅度下降。白刺花通过在叶片内积累大量渗透保护性物质可溶性糖和K ,增加细胞的保水力,维持细胞生长所需膨压。白刺花游离脯氨酸含量变化与水分关系不大,可溶性蛋白质含量随土壤含水量减少而下降,可能是水分胁迫下受伤害的表现。随土壤水分含量的减少,白刺花SOD的活性明显升高,POD活性不高但随胁迫时间延长其活性较稳定,CAT活性下降但幅度不大,且CAT活性变化趋势与POD活性相反,说明三个保护酶能够相互配合协同作用,降低膜脂过氧化程度,减少水分胁迫造成的伤害,提高质膜稳定性,维持细胞膜的完整性,表现出很强的抗旱适应性。 相似文献
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ABSTRACT The role of fimbrial and afimbrial adhesins of Xylella fastidiosa in biofilm formation was assessed by visualization of cell aggregates of mutant strains after incubation on glass surfaces. FimA- or FimF- fimbrial mutants adhered as solitary cells at a slightly lesser frequency to glass surfaces than the parental strain; however, cell aggregates were not formed, unlike the wild-type strain. Conversely, whereas the XadA- and HxfB- nonfimbrial mutants also exhibited a much lower frequency of adherence to glass surfaces than the wild-type strain, most of the cells retained on the surfaces were in cell aggregates of different sizes, much like that of the parental strain. Neither fimbrial or afimbrial mutants formed a mature biofilm on the sides of flasks of broth cultures, unlike the dense biofilm formed by the wild-type strain. Although FimA- and FimF- mutants did not form cell aggregates on glass surfaces when incubated as individual strains, aggregates of a FimA- or FimF- mutant were observed when co-incubated with either a XadA- mutant or HxfB- mutant, respectively. These results are consistent with a model in which the fimbrial adhesins FimA and FimF are involved preferentially in cell-to-cell aggregate formation whereas the afimbrial adhesions XadA and HxfB preferentially contribute to initial cell binding to surfaces, whereupon further cell aggregation can occur. In each of five separate experiments, FimA, FimF, XadA, and HxfB mutants of X. fastidiosa all were less virulent to grape than the corresponding wild-type strain. Fimbrial and afimbrial mutants might produce a reduced biofilm within vessels of grape and, hence, be deficient in various cell-density-dependent traits required for movement through the plant and, thus, virulence. 相似文献
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Laboratory studies were conducted to evaluate the risk of developing field resistance to zoxamide, a new Oomycete fungicide which acts on microtubules. Zoxamide, metalaxyl and dimethomorph were compared with respect to the ease with which fungicide‐resistant mutants could be isolated and their level of resistance. Attempts to generate mutants of Phytophthora capsici and P infestans with resistance to zoxamide by mycelial adaptation on fungicide‐amended medium were unsuccessful. Similarly, changes in sensitivity to zoxamide were small (resistance factors ≤2.2) in mutants of P capsici isolated by chemical mutagenesis of zoospore cysts. In parallel experiments with metalaxyl, highly resistant mutants were obtained using both adaptation (P capsici or P infestans) and chemical mutagenesis (P capsici). For dimethomorph, chemical mutagenesis (P capsici) yielded moderately resistant mutants (maximum resistance factor = 20.9), and adaptation (P capsici or P infestans) did not induce resistance. It is proposed that failure to isolate mutants resistant to zoxamide results from the diploid nature of Oomycete fungi and the likelihood that target‐site mutations would produce a recessive phenotype. Our studies suggest that the risk of a highly resistant pathogen population developing rapidly in the field is much lower for zoxamide than for metalaxyl. However, as with any site‐specific fungicide, appropriate precautions against resistance development should be taken. © 2001 Society of Chemical Industry 相似文献
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寡聚糖诱导黄瓜对白粉病抗病反应的超微结构研究 总被引：13，自引：0，他引：13
中科6号(2%氨基寡糖素)处理黄瓜植株叶片,5 d后接种白粉菌Sphaerotheca fuliginea(Schlecht.) Poll.,可诱导黄瓜Cucumis sativus产生对白粉病的抗病性,寄主细胞对病原菌的侵入产生了防卫反应结构和物质以及过敏性坏死反应。表现为寄主细胞壁加厚,染色加深,寄主细胞壁下产生多层次结构的乳突,在寄主细胞壁与质膜之间有黑色物质沉积;吸器外质膜皱褶,染色加深,吸器外基质中出现染色加深的颗粒状电子沉积物;寄主细胞质紊乱,细胞器解体,整个寄主细胞解体、坏死。 相似文献
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Dutch elm disease (DED) is a vascular wilt disease that causes the occlusion and cavitation of xylem vessels. Therefore, it is hypothesized that those elms that are less vulnerable to cavitation by drought might be more resistant to DED. To test this hypothesis, the relationship between xylem vulnerability to cavitation and susceptibility to DED was examined in progenies of crosses between susceptible and resistant individuals of Ulmus minor. Hydraulic conductivity and xylem vulnerability curves were evaluated and anatomical features such as vessel size, length and grouping were measured. Next, elms were inoculated with Ophiostoma novo‐ulmi, the cause of DED, and pre‐dawn and midday water potentials, stomatal conductance and wilting percentages were assessed. Progenies of R × R crosses showed significantly lower mean wilting percentages (30–50%) than the progeny of S × S crosses (75%). Fifty percent conductivity loss was reached at c. ?1 MPa, pointing out a high vulnerability of this species to drought‐induced cavitation. Crown wilting percentage as a result of inoculation and xylem vulnerability to cavitation by water stress did not show any significant correlation. Nevertheless, significant differences in theoretical hydraulic conductivity and vessel size parameters (diameter, length and size distributions) were found among the tested progenies. Susceptible trees had significantly wider and longer vessels. Xylem structure of resistant elms seems to restrict pathogen spread rather than prevent cavitation. 相似文献
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Sixty-four strains of Septoria which had been isolated from a range of hosts at different locations and in different years were characterized for their adaptation to wheat or barley, growth at near-maximum temperature, fluorescence, colony morphology, conidial (pycnidiospore) length and hexokinase and alkaline phosphatase isozymes. For each character except conidial length, the strains could be divided into two or three discrete groups. The variation in these six characters was strongly associated, such that 60 strains could be classified into two groups, designated W-type and B-type. W-type strains are adapted to wheat, produce large colonies at 31 C, fluoresce, produce brown-pigmented colonies, and have fast isozymes. B-type strains are adapted to barley, produce small colonies at 31 C, do not fluoresce, produce pink-pigmented colonies, and have slow isozymes. A few strains differed from these norms in one of the six characters, but only one showed an atypical host adaptation. The four unclassified strains differed from W- or B-type in two or more characters. The many differences between the W- and B-types suggest they are genetically distinct populations within Septoria nodorum. 相似文献
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S. Verdejo-Lucas M. Galeano F.J. Sorribas J.B. Forner A. Alcaide 《European journal of plant pathology / European Foundation for Plant Pathology》2003,109(5):427-433
Experiments simulating interplanting of resistant rootstocks with susceptible rootstocks that maintain high population densities of Tylenchulus semipenetrans in field soil were carried out in microplots at two locations, and in an naturally infested orchard. Selections of Cleopatra mandarin (03) × Poncirus trifoliata (01) 03.01.5 and 03.01.13, Citrus volkameriana (23) × P. trifoliata 23.01.17, Troyer citrange (02) × Cleopatra mandarin 02.03.24, Troyer citrange × Common mandarin (04) 02.04.18, King mandarin (05) × P. trifoliata 05.01.7, and Carrizo citrange were exposed to continuous high population densities of a population of the Mediterranean biotype of T. semipenetrans. The selection 23.01.17 retained its resistance in the microplots and in the field (< 1.2% females and eggs per gram fibrous root of those on Carrizo citrange). The selection 03.01.5 also retained its resistance in the microplots at Moncada (< 0.5% females and eggs per gram fibrous root of those on Carrizo citrange) but numbers of females and eggs per gram fibrous root were 27% and 22% at Amposta, and 139% and 18% in the orchard of those on Carrizo citrange, respectively. The selection 05.01.7 supported equal number of females and 43% eggs per gram fibrous root of those on Carrizo citrange in the nematode-infested orchard. The remaining selections supported high populations of T. semipenetrans. 相似文献
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Resistance to pyrethroids in insects is rare, but its recent rapid development in the field suggests that this resistance may be facilitated by previous exposure to or by resistance to insecticides of unrelated groups. To test this houseflies of strain 49r2b, originally resistant to dimethoate in the field, were selected eight times during ten generations with either pyrethrum extract or bioresmethrin with or without piperonyl butoxide or with dimethoate. Selecting with any of the pyrethroids led to resistance to these insecticides and in particular to pyrethrum/piperonyl butoxide. Selecting with pyrethrum/piperonyl butoxide resulted in strongest resistance to the pyrethroids tested, whereas selecting with bioresmethrin/piperonyl butoxide resulted in least resistance. These results show that dimethoate-resistant flies selected with pyrethroids can readily develop resistance to these insecticides, but development of resistance can be minimised by using bioresmethrin/piperonyl butoxide. The implications of these findings on the sequential use of insecticides are discussed. 相似文献