我国苎麻根际寄生线虫调查和初步研究

2010-2011年,我们在重庆、四川、湖北、湖南、江西等地苎麻主产区进行根腐线虫病调查;采集苎麻根腐病病蔸和病土,并分别利用改良贝曼漏斗法和蔗糖离心浮选法从病根和土壤中分离植物病原线虫,根据形态特征对分离到的植物病原线虫进行鉴定.研究结果表明:1)苎麻根腐病病根及根际土壤中主要发现4种植物寄生线虫,根据形态特征,鉴定为:咖啡短体线虫(Pra-tylenchuscoffeae)、穿刺短体线虫(P.penetran)、长针属线虫(Paratylenchussp.)和丝尾属线虫(Filenchussp.);其中,后2种线虫均在苎麻园中首次报道;2)四种线虫中,咖啡短体线虫发生最为普遍,存在于大多数样品中(约91%);丝尾属线虫次之,存在于54.5%的样品中;穿刺短体线虫较少,存在于少数样品(18.2%)中;长针属线虫最少,仅在13.6%的样品中检测到.3)根际土壤中植物寄生线虫的数量,随麻园种植年限增加而增多;同时,土壤类型也对线虫生长繁殖有一定的影响.     

寄生台湾春兰的短体线虫种类鉴定

厦门国际邮轮港口岸检疫部门在检验1批来自台湾的春兰（Cymbidium goeringii）花苗时,发现部分花苗根部腐烂。经分离检验和组织染色,从中发现1个形态特征一致的寄生线虫种群。该线虫经进一步形态学观察和测量,鉴定为最短尾短体线虫（Pratylenchus brachyurus）。此种线虫寄主范围广、危害大,是我国对外公布的检疫性有害生物。春兰是最短尾短体线虫新纪录寄主。     

观叶植物根际3种短体线虫的记述

2006～2009年,在对深圳市的观赏植物线虫进行调查监测中,采集长势不良的观叶植物的根和根际土壤样品,用改良贝曼漏斗法分离植物寄生性线虫。其中,分别从绿宝石(Philodendron erubescens cv.Green Emerald)、袖珍椰子(Chamaedorea elegans)和夏威夷椰子(Pritchardia gaudichaudii)的根际分离到3种短体线虫,经形态鉴定确认分别为:咖啡短体线虫(Pratylenchus coffeae Filipjev&Schuurmans Stekhonven,1941)、卢斯短体线虫(P.loosi Loof,1960)和落选短体线虫[P.neglectus(Rensch,1924)Filipjev&Schuurmans Stekhoven,1941]。并对这3个种线虫的形态特征进行了描述。     

花生短体线虫病的病原鉴定与诊断

2013年对福建省3个花生产区进行调查,发现成熟的花生荚果果面上出现紫褐至黑色病斑,病斑病健交界处清晰,花生的根和胚栓也出现不同程度的变色坏死症状。同时采集病变样品,从各病组织中分离出大量的短体线虫,其中以花生外壳组织中的线虫最多。该线虫通过形态学特征观察和分子生物学特性比较,鉴定为短尾短体线虫(Pratylenchus brachyurus)。再对短尾短体线虫侵染花生引起的病害症状进行详细描述,并通过接种试验证实短尾短体线虫对中国花生的致病性。     

番石榴根部短尾短体线虫的鉴定

从福建省漳州市云霄县的番石榴变黑腐烂的根组织内分离和鉴定了短尾短体线虫（Pratylenchus brachyurus）。根据光学显微镜和扫描电镜对该线虫进行形态特征观察及形态测量的结果,其鉴别特征为：唇环2个,唇盘椭圆形;唇片6个,包括2个侧唇片和4个近圆形亚中唇片,侧器孔窄圆形、位于唇盘两侧;口针长15.3~19.9 μm,口针基部球圆形;单卵巢直伸,受精囊不明显,后阴子宫囊长度略小于阴门处体宽,阴门位于虫体长度的83％~86％;尾宽圆锥形,腹面环纹16~21条,末端光滑、宽圆。对该线虫rDNA-ITS和28S rDNA-D2D3区进行扩增、测序与比对分析,其序列大小分别为730 bp和779~780 bp,与已登录的短尾短体线虫相应序列的相似度分别为89％~93％和97％~99％,D2D3序列比ITS序列更适于P. brachyurus分子鉴定。根据对病根组织内线虫的分离和染色观察,证实了短尾短体线虫能侵染番石榴根系并引起根表皮产生褐色斑痕和变黑腐烂等症状,这是首次在中国的番石榴上发现该线虫。     

我国北方地区玉米根寄生线虫的种类鉴定研究

1992～1995年对采自辽宁、吉林、黑龙江、内蒙古、河北、山东和江苏等省的玉米根寄生线虫进行分类鉴定研究，共鉴定出14属的36种线虫。即：丝尾垫刃线虫属Filenchus1个种；短体线虫属Pratylenchus10个种；拟短体线虫属Pratylenchoides1个种；矮化线虫属TylenchorhyNchus3个种；纽带线虫属Hoplolaimus3个种；螺旋线虫属Helicolylenchus4个种；盘旋线虫属相似文献   

菠萝的线虫病

植物寄生线虫极大地影响着世界的菠萝生产。由于菠萝根系的不再生性,因此根的损害尤为严重,当根系受损后,作物产量明显地减少;宿根作也会受毁,造成了严重的减产。同时,母株所长出的初生根系健康与否,直接影响到吸芽的数量、大小与长势。 世界范围为害的重要的线虫种类有:短尾根腐线虫(Pratylenchus brachyurus)、爪哇根结线虫(Meioidogyne javanica)和肾脏线虫(Rotylenchulus reniformis)。在巴西和象牙海岸共和国,短尾根腐线虫是最重要的种类。在南非,短尾根腐线虫和爪哇根结线虫是优势种。爪哇根结线虫在澳大利亚是一个重要的种类,而在夏威夷则以爪哇根结线虫和肾脏线虫为主要。当然,人们还发现与菠萝根有联系的其他种类的线虫,但这些线虫的致病性还未被证实,且危害性不大。     

黑龙江省马铃薯种薯田植物寄生线虫种类的调查

植物寄生线虫是导致马铃薯减产和影响马铃薯品质的原因之一,但目前黑龙江省尚未开展相关研究。自2012年以来,在黑龙江省共调查了14个县（市）的马铃薯种薯田,采集土壤样品107份,初步鉴定出植物寄生线虫8个属,其中针属线虫（Paratylenchus sp.）和螺旋属线虫（Helicotylenchus sp.）为黑龙江省马铃薯种薯田植物寄生线虫的优势种群,并分析了其地理分布特点。在黑龙江省发现短体属线虫,其属于重要农业生产的植物寄生虫。     

藤本豆根结线虫病的病原鉴定及其侵染特性的研究

在福建省发现豆科新品种多年生藤本豆（Lablab sp.）发生严重的根结线虫病,根部可产生巨大根结,根结内组织内可埋生数以百计的雌虫,卵囊产于根结内。通过形态特征及rDNA-ITS区序列扩增比对,藤本豆根结线虫鉴定为南方根结线虫（Meloidogyne incognita）。多年生藤本豆受根结线虫为害为首次记述, 也是南方根结线虫新寄主。接种实验结果表明,2龄幼虫主要侵染藤本豆根尖,也可侵染根其他部位,雌虫与卵囊埋生于根结内,卵可直接孵化并在根内直接侵染发育,根结大小发展快,根结坚硬,表面组织不易腐解,雄虫只能在后期根结腐败组织处发现。在环境温度（24~36 ℃）,生活史最短为24 d。田间重要杂草空心莲子草（Alternanthera philoxeroides）根结线虫病发生普遍,形态特征鉴定为南方根结线虫,田间调查及交叉接种实验表明其可能为田间藤本豆根结线虫病的主要侵染来源。     

海南省甘蔗寄生线虫调查与鉴定

2011～2014年,调查了海南省6个县市125份甘蔗根际土样的植物线虫发生情况。结果显示,海南甘蔗地每百克土壤中平均含有植物寄生线虫57条,其中沙性土壤中线虫平均含量达到143条,高于粘性土壤的42条。所分离出的线虫分布于13个属,包括矮化线虫属(Tylenchorhynchus spp.)、根结线虫属(Meloidogyne spp.)、短体线虫属(Pratylenchus spp.)、剑线虫属(Xiphenema spp.)、长针线虫属(Longidorus spp.)、毛刺线虫属(Trichodorus spp.)、拟毛刺线虫属(Paratrichodorus spp.)、拟长针线虫属(Paralongidorus spp.)、螺旋线虫属(Helicotylenchus spp.)、肾形线虫属(Rotylenchulus spp.)、垫刃线虫属(Tylenchus spp.)、滑刃线虫属(Aphelenchus spp.)和小环线虫属(Criconemella spp.)等。根据形态学特征及测量值,初步鉴定饰环矮化线虫(Tylenchorhynchus annulatus)及玉米短体线虫(Pratylenchus zeae)为海南甘蔗上的优势种类。     

Observations on the incidence of plant parasitic nematodes in grassland in England and Wales

Soil samples taken from one- to four-year-old swards of white clover and perennial ryegrass at 34 sites, and from older clover/grass swards at 56 sites in England and Wales, were examined for plant parasitic nematodes. Stolons of white clover from 46 of these sites were examined for nematodes. Clover cyst nematode ( Heterodera trifolii ) and white clover stem nematode ( Ditylenchus dipsaci ) were found in 62% and 41% of sites respectively. The grass cyst nematode ( Punctodera punctata ) was present in 56% of 71 sites examined, and other grass cyst nematodes ( H. bifenestra and species of the H. avenae group) occurred in 13% and 17% of sites. Two root-knot nematodes were found, Meloidogyne naasi and M. hapla, in 15% and 4% of the samples examined. Migratory nematodes were extracted from 63 samples, and spiral, pin and lesion nematodes were found in more than 90%. Stunt nematodes were less frequent (65%) and criconematids (19%) were found relatively infrequently. The significance of these observations to grassland productivity is discussed.     

Nematodes as a Limiting Factor in Potato Production in Scandinavia

Plant parasitic nematodes associated with potato feed on roots and/or tubers. About 70 species, representing 24 genera, have been reported from potato. Since nematodes attack underground plant parts, there are no reliable foliar symptoms to show that nematodes may be the major cause of poor growth and reduced tuber yields. Potato roots damaged by nematodes may show lesions, abnormal proliferation of lateral roots, emerging white females and brown cysts. Nematode attacks may render plants vulnerable to other pathogens, so disease caused by microorganisms may have nematodes as an etiological component. Therefore, nematode damage may often have been attributed to other factors. In Scandinavia, potato cyst nematodes (Globodera rostochiensis and Globodera pallida) are by far the most important nematodes on potato. In Norway, the cost of compensations schemes due to imposed statutory regulations of potato cyst nematodes may some years exceed the compensation for any other pests or diseases organism in agriculture. Other important nematodes include root lesion nematodes (Pratylenchus spp.), stubby root nematodes (Trichodorus spp. and Paratrichodorus spp.), and potato rot and stem nematodes (Ditylenchus spp.). Root knot nematode Meloidogyne hapla is considered less important. Meloidogyne chitwoodi and Meloidogyne fallax are not known to be present in Nordic countries. In the control, crop rotations using non-host crops, alternating susceptible and resistant potato cultivars, are an important control measure. However, the use of resistant potato cultivars requires knowledge of the species and pathotypes present in the field.     

Root lesion nematodes in potatoes

Pratylenchus penetrans andP. crenatus were the dominant plantparasitic nematodes in potato roots and soil in Prince Edward Island. No nematodes were recovered from potato tubers. Forage legumes and grasses grown in rotation with potatoes also harbored large populations of root lesion nematodes. The amount of water moving through the stems of potato plants infected withP. penetrans in the greenhouse generally was less than in nematode-free plants;P. crenatus did not produce this effect. Telone-II, Telone-C-17, and Temik reduced the number of nematodes substantially in field plots. Yields of Superiors, Kennebecs, Sebagos and Netted Gems in nematicide-treated plots were not significantly greater than in untreated plots. There was a small but significant reduction in the specific gravity of tubers in the Telone-treated plots.     

Nematodes and fungal diseases in barley and wheat on Prince Edward Island

A total of 31 genera and 28 species of plant and soil nematodes were identified from 30 commercial fields each of barley and wheat on Prince Edward Island. Root-lesion nematodes, primarily Pratylenchus penetrans, were the dominant plant parasites, and the only endoparasitic nematodes recovered from roots. Root-lesion nematodes were the dominant genus in soil, but stunt nematodes (Tylenchorhynchus spp., primarily T. dubius, and Merlinius spp.), and pin nematodes (Paratylenchus spp.) were also recovered frequently. Common root rot, barley net blotch, and wheat leaf blotch, incited by Cochliobolus sativus, Pyrenophora teres, and Leptosphaeria nodorum, respectively, were prevalent in barley and wheat. The nematicide aldicarb reduced the numbers of root-lesion nematodes in roots and soil in experimental plots during 1984–1987, except from soil in wheat and barley in 1984 and in barley in 1986. Aldicarb treatments also increased grain yields significantly by 10% and 19% in 1984 and 1987, respectively. Aldicarb treatments did not affect the incidence of common root rot, barley net blotch, or wheat leaf blotch disease. Correlation and regression analyses of data from experimental plots did not indicate any significant relationships between population levels of root-lesion nematodes in roots or soil and severity of root or foliar diseases in barley or wheat.     

Influence of different forage grasses on nitrate capture and leaching loss from a pumice soil

Nitrogen (N) uptake and loss in leachate from a pulse of ¹⁵N-labelled synthetic cow urine applied to a pumice soil were compared in a glasshouse lysimeter experiment among the grass species, Agrostis capillaris , Dactylis glomerata , Phalaris aquatica , Lolium multiflorum , L . perenne and a L . multiflorum/A. capillaris mixture. In addition, four L. perenne treatments investigated the effect of infection by Neotyphodium lolii strains. Leachate volumes and leachate nitrate concentrations were measured. At final harvest 24 weeks after sowing, dry matter (DM) mass of shoots and roots, plant N and ¹⁵N contents, soil residual mineral N, and root diameters and lengths were measured. Endophyte had no effect on plant or nitrate variables. Lysimeters planted with L . perenne (pooled endophyte treatments) leached 48 mg of NO₃-N compared with <3 mg N for the other grasses. Recovery of ¹⁵N was highest in A. capillaris (0·99), followed by D. glomerata and P. aquatica (0·89), the L . multiflorum / A. capillaris mixture (0·87), L . multiflorum (0·60) and L . perenne (0·44). Low ¹⁵N recoveries and high leaching losses from L . perenne were associated with low plant and root masses of DM and low rooting depth. High aerial mass of DM, root systems extending below 20 cm and high root masses of DM in lysimeters with A. capillaris , P. aquatica and D. glomerata contributed to a high rate of nitrate interception by these species and low leachate losses. The L . multifloru m/ A. capillaris mixture was intermediate between the two species for most of the variables measured.     

栀子根结线虫病的病原鉴定

为明确广西贺州市栀子根结线虫病病原种类,采集根部有明显根结的栀子根系进行根结线虫分离鉴定,通过观察根结线虫2龄幼虫、雌成虫、会阴花纹特征对其进行形态学鉴定,并利用核糖体ITS区和28S rDNA D2D3区序列比对和系统发育树分析方法对其进行分子生物学鉴定。结果表明,该病原线虫2龄幼虫和雌成虫形态特征及形态测量值与象耳豆根结线虫（Meloidogyne enterolobii Yang & Eisenback, 1983）相似;该病原线虫核糖体ITS区与NCBI数据库中象耳豆根结线虫相应序列的相似度为100%,28S rDNA D2D3区与NCBI数据库中象耳豆根结线虫相应序列的相似度为99%以上;该病原线虫核糖体ITS序列以99%的支持率与象耳豆根结线虫聚为同一分支。综合形态学和分子生物学鉴定结果将广西贺州市栀子根结线虫病病原种类鉴定为象耳豆根结线虫,栀子（Gardenia jasminoides Eills）是该线虫的新寄主纪录。