植物线虫分子分类及鉴定研究新进展

 植物线虫系农作物上重要的病原生物之一,同一类群的线虫种间具有很多相似的特征;种内群体因生态条件的差异有明显的生理分化现象,存在不同的生理小种或致病型,同一种线虫因生理小种或致病型的差异对特定作物品种的危害程度差别很大,因此采取可靠的分类鉴定方法,快速、准确地鉴定和鉴别植物线虫的种、生理小种或致病型是植物线虫病害防治的基础。     

植物寄生线虫滞育机制研究进展

植物寄生线虫防治困难与其在土壤中存活时间和抗逆能力有直接关系。休眠或滞育是其度过逆境条件或缺乏寄主时的主要策略。根据植物寄生线虫休眠或滞育的特点和规律可确定防治的关键时期。本文就植物寄生线虫休眠或滞育的影响因素和不同寄生线虫的滞育特点, 以及一些植物寄生线虫休眠或滞育生理生化机制的研究进展进行综述, 以期为植物寄生线虫的综合防治提供新的思路。     

干旱胁迫下3种岩石边坡生态修复植物的抗旱性

植物的抗旱性直接影响着岩石边坡生态修复的效果。为研究不同植物在持续干旱下的抗旱机理,选择草地早熟禾、狗牙根和红三叶3种常用于岩石边坡生态修复的植物,采用盆栽控水试验和室内分析相结合的方法,研究干旱胁迫下3种植物叶片的相对含水量、相对电导率、丙二醛（MDA）含量、可溶性糖含量、脯氨酸(Pro)含量和叶绿素含量6个生理生化指标的变化情况。结果表明：所有参试植物的生理生化指标都随干旱胁迫的程度而变化,但植物之间和生理生化指标之间存在差异。运用模糊数学隶属函数分析法和灰色关联分析法,综合评价3种植物的抗旱性和各指标对干旱胁迫的敏感性。结果显示：干旱前期和中期,植物的抗旱性为：狗牙根＞红三叶＞草地早熟禾;干旱后期,植物的抗旱性为：草地早熟禾＞狗牙根＞红三叶;各生理生化指标与植物抗旱隶属度的关联度从大到小依次为0.708,0.694,0.638,0.630,0.609和0.607,可作为岩石边坡生态修复抗旱性植物筛选的评价指标,其中,以叶绿素含量和相对含水量对干旱胁迫的反应最为敏感。     

乌桕对南方根结线虫与地上不同食性昆虫互作的光合生理响应

本文通过比较乌桕对两种地上不同食性昆虫(专食性癞皮夜蛾、广食性斜纹夜蛾)与南方根结线虫互作的光合生理响应,分析不同空间植食性生物间的互作关系及植物的响应机制。结果表明:无南方根结线虫胁迫下,2种地上不同食性昆虫对乌桕的净光合速率(P_n)、气孔导度(G_s)及胞间CO_2浓度(C_i)的影响与对照组无显著差异;而南方根结线虫胁迫下,2种地上昆虫显著降低了乌桕G_s及C_i。其中,与对照组及癞皮夜蛾处理组相比,南方根结线虫与斜纹夜蛾的共同胁迫显著降低了乌桕P_n、G_s及C_i。此外,斜纹夜蛾为害增加了乌桕叶绿素含量,南方根结线虫胁迫降低了叶绿素含量。因此,南方根结线虫与斜纹夜蛾间形成一种加性效应,并对乌桕光合生理产生了拮抗效应,而这种效应在南方根结线虫与癞皮夜蛾间并不显著。由此可见,乌桕对地上-地下植食性生物胁迫形成不足补偿机制,且具体的响应机制与植食性生物的食性相关。     

植物线虫的分类现状

 植物线虫是一类重要的病原生物,其中有许多是国际公认的毁灭性有害生物如松材线虫(Bursaphelenchus xylophilus)、香蕉穿孔线虫(Radopholus similis)、马铃薯白线虫(Globodera pallida)和马铃薯金线虫(G. rostochiensis)等,全世界每年因植物线虫危害而造成的经济损失超过1 000亿美元。植物线虫对植物的危害不仅表现在掠夺寄主植物营养以及取食活动所造成的机械损伤,更为重要的是其食道腺分泌物导致寄主植物发生一系列病理变化以及传播其它病原物或刺激和促进其它病原物的继发性侵染危害,所以植物线虫的研究属于植物病理学范畴。     

植物寄生线虫及其检疫地位

寄生线虫主要危害植物的花蕾，叶，茎和根，许多种类的线虫可以使作物受到严重危害甚至杀死，有些植物因受到线虫的危害而降低的抗病能力，增加了真菌和细菌性病害的发病机率，损失极为严重，另外，已有充分资料证明，某些被列为我国的危险性病毒病可以通过线虫而传播。我们仔细分析我国危险性线虫病害的名录，发现它们对作物的危害都是毁灭性的直接危害，还未考虑线虫寄生后所造成的间接危害，本文将着重论述线虫的间接危害及其检疫     

几种最常见花卉线虫及其防治

花卉线虫是一类重要的植物病原生物,常因在种植生长过程中经常受到线虫的危害而造成严重损失。危害花卉的线虫种类较多,而且许多花卉都受到一种或多种线虫的危害,线虫可以侵染危害花卉的根、茎、叶、花、芽和种子等各个部位,并可随其扩散传播。花卉在贸易交往中携带和传播植物线虫的可能性、隐蔽性和传入后对传入国家或地区的花卉及其他农业生产带来的危害性都很大。     

壳聚糖对芒果离体叶片渗透胁迫的缓解效应

研究不同浓度壳聚糖溶液对芒果(Mangiferaindica)离体叶片在20%聚乙二醇(PEG-6000)渗透胁迫条件下生理生化的影响,结果表明,渗透胁迫下,壳聚糖可减缓叶片中水分的丧失以及叶绿素含量的下降,并能提高过氧化物酶活性和增加脯氨酸含量。因此,壳聚糖可有效缓解渗透胁迫对植物的损伤,提高植物的抗旱性。     

生姜对南方根结线虫侵染的生理生化反应

 本试验就生姜感染南方根结线虫后几种生理生化指标的变化进行了研究.结果表明,接种南方根结线虫后,生姜体内各种生理生化指标主要在初次侵染前期和二次侵染前期表现出一定的反应,其余时间则基本丧失这种反应,且生姜不同部位对南方根结线虫侵染的反应程度也有很大差异,以叶片的反应最为剧烈,根系次之,根茎反应最弱.结合南方根结线虫的生活周期,本文提出了生姜对南方根结线虫的生理生化反应主要表现在侵染初期,对再次侵染则部分丧失敏感性的论点.     

植物耐盐性研究进展

概述了盐胁迫下植物的生理生化反应机理,在此基础上阐述了渗透调节、离子区域化、大分子蛋白、基因表达的调控、保护酶相关基因利用转基因技术转化植物的研究进展,旨在为开展植物耐盐研究、选育耐盐新品种提供参考。     

Eenige waarnemingen met betrekking tot eenzijdige graanbouw

Summary In the Wieringermeerpolder reclaimed about 1930, some cases of severe damage caused by the Oats Nematode (Heterodera avenae Filipjev) have been observed since 1943. In one of the cases mentioned (I) 8×cereals have been grown in 13 years, viz. 3×oats, 3×wheat, 1×barley and 1×rye. In another case (II) 8×cereals occurred in 12 years, viz. 3×oats, 3×wheat and 2×barley. It is obvious that this crop rotation promotes the occurrence of the Oats Nematode. A crop rotation with less cereals is recommended.

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Voorlichtingsdienst in de Wieringermeer     

Note: Effect of neem and organic amendments on nematode populations in a coastal savanna tropical soil

Nematode numbers were assessed at 2-week intervals in a coastal savanna soil amended with neem leaves and animal manure for 12 weeks under fallow conditions. The number of plant-parasitic nematodes decreased significantly with the application of the neem-based amendments, whereas the number of non-parasitic nematodes increased. http://www.phytoparasitica.org posting July 14, 2005.     

Effect of plant elicitors on the reproduction of the root-knot nematode Meloidogyne chitwoodi on susceptible hosts

Sustainable strategies for plant-parasitic nematode control are required to reduce dependence on chemical nematicides. Foliar application of various compounds can induce a systemic defence response that reduces nematode infestation. The effects of benzothiadiazole (BTH), β-aminobutyric acid (BABA), jasmonates (cis-jasmone and methyl jasmonate) and salicylic acid (SA) in the development and reproduction of the root-knot nematode Meloidogyne chitwoodi in tomato plants were assessed. The effects of BTH and of the jasmonates were further tested on potato plants. Pot assays were conducted using tomato plants cv. Tiny Tim or potato cv. Désirée treated with foliar sprays and inoculated with 300 second stage juveniles. Nematode development and reproduction were assessed 21 and 45 days after inoculation. Treatment with SA had a negative effect on nematode development in tomato plants but did not affect reproduction and methyl jasmonate treatment was the most effective in reducing nematode penetration (58 %). Nematode development was significantly affected in potato plants sprayed with cis-jasmone. Nematode penetration was reduced by 90, 67 and 81 % in plants treated with BTH, cis-jasmone and methyl jasmonate respectively, although the reproduction factor (Rf) was only significantly lower in the BTH treatment (Rf?=?7.6) when compared to the control (Rf?=?18.1). Our results suggest that both the SA and JA pathways play an important role in plant defence mechanisms against root-knot nematode development and reproduction for both plants, and should be considered in the design of integrated pest management approaches.     

RNAi在植物寄生线虫功能基因组研究中的应用

最近,南方根结线虫（Meloidogyne incognita）和北方根结线虫（M. hapla）的基因组测序工作已经完成,而大豆孢囊线虫（Heterodera glycines）和马铃薯白线虫(Globodera pallida)的基因组测序工作也在进行之中。截至2008年,Nematode.net数据库中已经有近500 000个表达序列标签ESTs序列和1 200 000个来自30种线虫的基因组序列。如何从众多的序列中筛选出有实际应用价值的信息是线虫学研究面临的一大挑战。对于缺乏有效转化系统的植物寄生线虫来说,RNAi无疑是研究植物寄生线虫基因功能的有力工具。本文介绍了RNAi及其在植物寄生线虫基因功能研究中的应用。     

Characterization of populations of entomopathogenic nematodes isolated at diverse sites across Israel

Entomopathogenic nematodes (EPNs) are known as effective biological agents against soil-dwelling stages of insect pests. In the present study new EPN populations from the Steinernematidae and Heterorhabditidae families were isolated at different locations in Israel. The newly isolated populations were subjected to a series of bioassays for beneficial traits, for selection of a superior isolate for biological control of insect pests. Nematode motility was measured in sand columns, with and without the susceptible insect Galleria mellonella. Infectivity was evaluated using an invasion rate assay, as well as a dose response assay in which LD₅₀ values were calculated. Nematode tolerance to environmental stresses was examined in heat and desiccation tolerance assays. The reproductive potentials of the new isolates were assessed in cadavers of G. mellonella. All Steinernematid populations were identified as Steinernema feltiae and the Heterorhabditids as Heterorhabditis sp. Large variation between the various populations was recorded in all assays. In order to identify a superior isolate, each strain was scored as 1 if its performance did not differ significantly from the highest level recorded in the particular assay; −1 if its performance did not differ significantly from the lowest level; and 0 if its performance was between the highest and lowest levels or did not differ from either. The scores for the different traits were then summed for each population and the totals were compared. The best score (+4) was obtained for a S. feltiae population isolated in northern Israel. These results will be used for the utilization of the new population as a biological control agent.     

Enhanced ambient storage stability of an entomopathogenic nematode through anhydrobiosis

Limited shelf‐life is a major obstacle to large‐scale use of entomopathogenic nematodes in biological control. Recently, the development of a water‐dispersible granular formulation (WG) containing entomopathogenic nematodes was described. This paper reports that storage stability of Steinernema carpocapsae Weiser infective juveniles at 25 °C is enhanced from three to six months in this WG. It is also demonstrated that the enhanced stability is achieved through the induction of partial anhydrobiosis that reduces oxygen and lipid reserve utilization by infective juveniles. Nematode infectivity is unaffected during storage under partial anhydrobiosis in the WG formulation. © 2000 Society of Chemical Industry     

湖南省蔬菜根结线虫发生及种类鉴定

对湖南省蔬菜主产区的根结线虫病发生与危害程度进行了系统调查,结果显示蔬菜根结线虫病发生普遍,大棚蔬菜发病率高达80%,露地蔬菜发病率也在10%左右。对采自湖南省内10种蔬菜作物上的23个根结线虫种群进行了种类鉴定。采用2龄幼虫测量值、会阴花纹形态特征、PCR法及序列测定相结合的方法进行了鉴定,结果表明南方根结线虫是湖南省蔬菜根结线虫病的优势病原种群,占87%。     

Book reviews

Book reviews in this article:
Applied Molecular Genetics of Fungi , edited by J. F. Peberdy, C. E. Caten and J. W. Burnett.
Plant Molecular Biology 2 , edited by R. G. Herrmann and B. A. Larkins.
Biology and Management of the Soybean Cyst Nematode . edited by R. D. Riggs and J. A. Wrather.
Fundamentals of Plant Virology , by R. E. F. Matthews.
Plant Genetic Manipulation for Crop Protection , edited by A. M. R. Gatehouse, V. A. Hilder and D. Boulter.     

Cyst-forming Nematodes on Cereals in Bulgaria1

Heterodera avenae and Heterodera latipons are widespread on cereals in Bulgaria and mixed populations are encountered. H. avenae populations reach their highest point on barley after ten years cereal monoculture. The two-field crop rotation maize/cereals keeps the population at a low level. H. avenae has been found on most cultivars of wheat and barley cultivated in Bulgaria. The author had detected two previously unreported hosts: Agrostis capillaris and Cynosurus cristatus. The most appropriate conditions for infection on cereals occur in April. Nematode development starts in April and finishes in the first half of June. Nematophthora gynophila parasitizes about 20% of the cysts, while Catenaria auxiliary and Lagenidiaceous fungi do so to a lesser extent.     

Potential of combined biological control agents to cope with <Emphasis Type="Italic">Phytophthora parasitica,</Emphasis> a major pathogen of <Emphasis Type="Italic">Choisya ternata</Emphasis>

The Cook Agronomy Farm of Washington State University is a long-term precision agriculture study site. Since 2000, the farm has been in various three-year no-till rotations with winter wheat, spring wheat, and various rotation crops such as barley, canola, peas, lentils, and chickpea. The spatial distribution of root lesion nematodes (Pratylenchus spp.) and their relationships with soil and terrain variables were studied by collecting soil samples at 127 and 124 geo-referenced points in two 12-ha fields during the spring of 2010 and 2011, respectively. Pratylenchus spp. were detected in more than 85% of the sampled locations in both fields. Nematode densities spatially mapped using ArcGIS software occurred in an aggregated pattern. Previous rotation crops had no effect on the spatial distribution. Classification and regression tree analysis (CART) using soil and terrain variables, and nematode density, explained 61 and 34% of the variability associated with nematode density in 2010 and 2011, respectively. Soil edaphic factors, such as organic matter, were stronger predictors of nematode populations than rotation effects.