受玉米大斑病菌侵染后玉米抗感近等基因系SOD动态变化的研究

 以玉米抗、感大斑病菌近等基因系为材料,研究了玉米抗病系和感病系在接种玉米大斑病菌后SOD活性和SOD同工酶谱的动态变化。结果发现,在病原菌侵染初期携带显性抗病单基因的抗病系SOD活性一般呈下降趋势,明显地低于不携带任何已知抗病基因的感病近等基因系;在病原菌侵染中、后期却较大幅度上升,反而逐渐明显地高于感病近等基因系。在HZ1遗传背景中Rf值为0.25的SOD同工酶酶带,与Ht2和HtN等抗病基因的作用有关。本文认为SOD及有关活性氧代谢在玉米对大斑病菌抗性中可能具有重要的作用。     

细胞微丝骨架在玉米抗纹枯病菌Rhizoctonia solani 侵染中的作用

为探究细胞微丝骨架在玉米抗纹枯病侵染过程中的作用,采用微丝骨架解聚剂LatB预处理玉米离体叶片后接种立枯丝核菌Rhizoctonia solani AG1-IA,显微观察病原菌的侵染过程,并检测活性氧(ROS)、细胞坏死及抗病基因(PR1、ZmDREB2A)表达等抗病反应情况。结果显示,与未经LatB预处理相比,LatB预处理加快了R.solani侵染后玉米病斑的形成,并影响了侵染结构的发育;在侵染后期,LatB促进了R.solani诱导的玉米叶片中ROS积累、细胞坏死反应和PR1基因表达;溶剂DMSO预处理与未经LatB预处理的结果类似,表明DMSO对本试验的影响较小。研究表明,细胞微丝骨架不仅参与玉米抗R.solani的侵入,而且通过调控ROS、PR1基因表达,细胞死亡等抗病信号提高玉米抗病防御能力。本研究为进一步研究细胞微丝骨架在玉米对纹枯病的抗病机理中的作用提供了重要参考。     

西甜瓜果斑病菌avrRxo1同源基因激发玉米Rxo1抗性产生的研究

生物信息学分析发现西(甜)瓜果斑病菌(Acidovorax citrulli,Ac)基因组中存在水稻条斑病菌(Xanthomonas oryzae pv.oryzicola,Xoc)avrRxo1的同源基因avrRxo1_(Ac)。为了揭示avrRxo1_(Ac)是否能够激发玉米R基因Rxo1介导的过敏反应(Hypersensitive response,HR),本研究克隆了avrRxo1_(Ac)基因;氨基酸同源性分析结果显示:AvrRxo1_(Ac)与AvrRxo1的同源性为53.16%。将avrRxo1_(Ac)置于Xoc的avrRxo1突变体中,发现其不能恢复该突变体在含有Rxo1玉米上激发HR反应的能力;借助农杆菌瞬时表达体系发现AvrRxo1A,也不能在Rxo1玉米上激发HR反应。这些结果表明avrRxo1_(Ac)-Rxo1互作不表现为基因-对-基因关系,暗示Rxo1抗病基因转入西甜瓜中,将不能起到抗西(甜)瓜细菌性果斑病的作用。     

玉米种质对玉米大斑病抗性鉴定与评价

为给玉米大斑病抗病育种和生产上进行抗性基因轮换提供基础材料和科学依据。2012—2013年,用田间人工接种玉米大斑病菌混合菌种的方法,对283份国内外玉米种质进行了玉米大斑病[Exserohilum turcicum(Pass.)Leonard et Suggs]抗性鉴定与评价。在加大玉米种质对大斑病菌种群的抗性选择范围条件下,鉴定筛选出以5级中抗为主的抗病种质116份。试验结果同时表明,玉米种质对玉米大斑病的抗性表现存在差异。但总体抗病能力较低。国内玉米种质对大斑病的抗病能力强于新引进的国外玉米种质的抗病能力。具Ht1背景种质的抗性丧失较为严重,具Ht2、Ht3和Ht N背景种质的抗性相对较好。     

玉米大斑病菌CaM基因的克隆及三氟拉嗪的抑菌作用

 以玉米大斑病菌为材料,根据同源序列法分别进行了3'端和5'端的RACE扩增,获得了玉米大斑病菌钙调素基因cDNA全长。利用genomic walking技术获得了CaM基因启动子序列,该序列含有多个与转录调控有关的保守序列(如TATA-box、Spl、AP-2和TFⅡD)。Southem杂交结果表明,玉米大斑病菌CaM基因在基因组中以单拷贝形式存在。用CaM特异性抑制剂三氟拉嗪(trifluoperazine)处理玉米大斑病菌,发现其对孢子萌发和附着胞形成的抑制作用与浓度呈正相关,同一浓度下,抑制剂对附着胞形成的抑制作用大于对孢子萌发的抑制。推测CaM基因在玉米大斑病菌的致病过程中起着至关重要的作用。     

Ht2背景下玉米对大斑病菌1号小种抗性基因的表达差异研究

以玉米自交系黄早四和黄早四Ht2近等基因型系为材料,利用cDNA-AFLP差异显示方法,分析玉米抗大斑病Ht2相关基因受大斑病菌1号小种胁迫后的差异表达情况。用筛选的70对引物在黄早四Ht2中扩增出76个差异显示片段,对差异条带回收、克隆和测序,并在NCBI上进行BLAST分析,有52个在GenBank中发现相似性较高、功能已知的EST序列,按其功能分为以下8类:基础能量代谢、跨膜运输蛋白、抗逆或抗病相关蛋白、蛋白质代谢、染色体组成蛋白及DNA复制和转录中的蛋白、信号传导、生长发育调控因子和转录因子,而其中以参与基础能量代谢的基因和抗逆或抗病相关基因所占比例较大。功能已知的52个差异表达片段在玉米1～9号染色体上均有分布,且在非亲和互作前期(6h)主要是一些信号相关基因的表达,12h表达的基因多属于抗病反应初期阶段的相关基因,与防卫有关的基因主要在48～72h表达,生长发育类基因在所检测的非亲和互作的不同阶段均表现作用,在非亲和互作后期主要是蛋白质代谢基因的表达。     

玉米小斑病研究进展

玉米作为重要的粮、饲、工兼用作物, 是重要的战略资源, 在国民经济中具有举足轻重的作用。但在实际生产过程中, 玉米受多种病虫害的威胁, 其中由玉蜀黍平脐蠕孢Bipolaris maydis引起的玉米小斑病严重影响玉米产量与品质, 是制约玉米高产与稳产的重要因素之一。近些年该病害的发病频率与严重程度均呈快速增长的态势, 对我国玉米安全生产构成巨大的潜在威胁。本文综述了玉米小斑病发生概况, 包括发生时期和引起的主要症状; 概括了玉米小斑病菌的侵染过程和相关功能基因的致病机制; 总结了抗玉米抗小斑病基因的定位、克隆与功能分析方面的研究进展, 玉米小斑病的防治措施等, 并对未来研究提出了一些建议和展望, 以期为玉米小斑病可持续治理提供理论参考和研究思路。     

玉米大斑病菌ISSR反应体系的优化和遗传多样性分析

以玉米大斑病菌基因组DNA为模板,采用单因素水平优化的方法对DNA聚合酶的来源及浓度、引物浓度、dNTPs浓度、DNA模板浓度、Tm(退火温度)、PCR反应循环数等重要参数进行摸索和优化,建立了玉米大斑病菌ISSR-PCR优化反应体系,并从40条ISSR引物中筛选出9条多态性较好的ISSR引物。对来自河北、河南、辽宁等玉米主产区的44个菌株进行ISSR分析表明,ISSR标记在我国玉米大斑病菌中存在较高的多态性,多态性条带占40.3%。聚类分析显示,在阈值为0.8时菌株被分为7个类群。对ISSR揭示的玉米大斑病菌的遗传多样性与菌株交配型、地理来源之间的关系进行分析,结果显示菌株的遗传多样性与交配型间的关系密切,而与其地理来源无明显相关性。     

大麦抗条纹病基因的定位分析

为发掘大麦中抗条纹病的新基因,采用三明治法通过人工接种大麦条纹病菌Pyrenophora graminea强致病力菌株QWC对甘啤2号(免疫)与Alexis(高感)杂交F_1代及F_2代分离群体进行抗性遗传分析,利用群体分离分析法鉴定与抗病基因连锁的SSR标记,并通过QTL IciMapping软件构建遗传连锁图谱完成对抗病基因的定位。结果显示,甘啤2号与Alexis杂交F_1代对大麦条纹病菌强致病力菌株QWC表现为免疫,F_2代表现3∶1抗感分离,表明甘啤2号对菌株QWC的抗性由1个显性抗性基因控制,将该抗病基因暂命名为Rdg3;该基因位于大麦7H染色体上的SSR标记Bmag206和Bmag7之间,与二者的遗传距离分别为1.78 cM和2.86 cM。经与已定位于7H染色体上的抗病基因比较,发现Rdg3是一个新的抗条纹病基因,可作为大麦抗病育种的新种质资源。     

两个玉米自交系对纹枯病的抗病反应机制初探

玉米纹枯病是由立枯丝核菌(Rhizoctonia solani Kühn)引起的一种重要病害。具有优良性状的自交系是开展玉米抗病品种选育的重要种质资源。本试验以西南地区两个优良玉米自交系R08与18-599R为材料,采用人工接种R.solani菌丝融合群AG1-IA,对成株期玉米进行了抗性鉴定,并对病原菌诱导后苗期玉米叶片上的活性氧(ROS)、抗病相关基因(PR1、ZmDREB2A、ZmERF3和WIP1)表达及细胞坏死情况进行了动态检测。结果显示,R08对纹枯病表现为中抗,而18-599R为高感材料;受R.solani侵染后,玉米叶片ROS的积累在R08中较18-599R多;两个自交系中基因表达量及表达时间存在显著差异;R08叶片出现显著的细胞坏死反应,而18-599R相对较轻。本研究表明两个自交系对R.solani的抗性差异主要体现在相关抗病反应的时间和强度上,这为进一步研究玉米纹枯病抗病机理提供了依据。     

重视有害蚜虫研究,确保作物安全

<正>蚜虫隶属半翅目蚜虫总科,是世界上分布最广的微小昆虫之一。世界已知4 700余种,中国分布约1 100种[1-2]。蚜虫种类多、繁殖快、世代重叠,还存在孤雌生殖与两性生殖世代交替等独特生物学现象。许多蚜虫种类是非常重要的农作物害虫,其刺吸式口器可吸食植物汁液,造成植物生长不良,其唾液也对植物有毒害作用[3-4]。受蚜虫为害的植物具有多种不同症状,如生长率降低、产生叶斑、泛黄、发     

高原人体生理适应学理论在进藏旅游中的应用

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...     

稻瘟病菌对三环唑抗药性测定方法的建立

研究了稻瘟病菌对三环唑抗药性的测定方法,确定了保绿培养基的成分,建立了抗药性测定的标准化模型。4叶I心期将稻苗在三环唑系列浓度药液中浸根处理36 h,剪取稻苗叶段插于100 μg/mL苯并咪唑+0.5％水琼脂保绿培养基上,用孢子含量为10⁵个/mL的稻瘟病菌孢子悬浮液喷雾接种,保湿培养8 d后调查结果,计算EC₅₀值。该测定方法与小苗测定相比较结果更加稳定且灵敏度高,重复性好。     

白刺花(Sophoraviciifolia)适应土壤干旱的生理学机制

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。     

Heritability of Ulmus minor resistance to Dutch elm disease and its relationship to vessel size,but not to xylem vulnerability to drought

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.     

Contribution of Fimbrial and Afimbrial Adhesins of Xylella fastidiosa to Attachment to Surfaces and Virulence to Grape

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.     

A grower-friendly method to transfer predacious mites to commercial orchards

The establishment of predacious mites in commercial orchards may be accelerated by the transfer of pruned wood in winter and summer from donor orchards to release orchards. Following winter pruning, 3-year-old and older wood is collected and transported as soon as possible in bundles to a release orchard for distribution. If the release orchard is composed of dwarf trees, then one or two bundles of 5 kg each are placed vertically at the base of the trunk of every tree in the block (0.5 to 1 ha); if the trees are of standard size, then four or five bundles used. Following summer pruning, annual shoots and suckers are distributed immediately in a release orchard composed of dwarf trees by placing 12–15 branches on the foliage of fruit-bearing branches; if the release orchard is composed of standard trees, then 50 branches are used. The pruned wood should have 20–25 leaves and not less than one predator per leaf. The release orchard should have a light infestation (two or three mites per leaf) of pest tetranychids. These phytophagous mites would serve as food and help establish the predators. The release orchard grower should develop a pest management program based on the same groups of pesticides used in the donor orchard. http://www.phytoparasitica.org posting Aug. 31, 2005.     

Note to chew on: insect damage to musical instruments

Insects have a diverse range of ecologies that leaves many pre‐adapted to exploiting manufactured products as food sources, including musical instruments. To review what is known and to make recommendations for preventing and managing insect damage to musical instruments, we conducted a systematic search and a narrative review of the area. Of 339 papers, only eight peer‐reviewed publications met the inclusion criteria, and all were on xylophagous insects causing damage to wooden instruments. To supplement this material, we report a case of damage to the key pads (composed of felt enclosed in fish buoyancy bladder skin) of a clarinet by carpet beetles (Anthrenus verbasci (Dermestidae)), the first reported case of non‐woody damage and the first instance of insect damage rendering an instrument unplayable. To avoid such damage, regular inspection of instruments is recommended, and rapid treatment of any insect infestations in the immediate environment that could extend to affecting stored instruments. Instruments themselves can be extremely expensive, and if insects are still present these should only be treated by an expert; instrument cases can be more easily dealt with by heat treatment (black plastic bag in the sun) or application of a residual insecticide. © 2020 Society of Chemical Industry