我国烟草根结线虫病发生与防治研究进展

 烟草根结线虫病是一种严重影响烟叶产量和质量的重要病害之一。近年来,随着烟叶种植布局的优化调整以及大气温室效应的影响,烟草根结线虫病在全国各烟区的危害逐年加重,因此必须加强对烟草根结线虫病的发生与防治研究。本文详细综述了我国烟草根结线虫病的发生分布、危害损失、致病机制、发病规律及防治措施等研究进展,并对烟草根结线虫的鉴定技术、协同致病、抗病育种以及新型防控技术进行了总结和展望。明确了我国烟草根结线虫病优势种为南方根结线虫,并且多种根结线虫混发的现象逐步增加。同时,发现由烟草根结线虫病诱发的多种其他根茎类病害的危害逐年加重。通过加强烟草根结线虫发生动态监测、合理布局抗病品种、应用针对性的农业防治、生态防治和生物防治等综合防治措施,可以逐步实现对烟草根结线虫病的绿色防控,从而促进烟草产业的健康发展。     

内蒙古赤峰市保护地蔬菜根结线虫种类鉴定

正根结线虫(Meloidogyne spp.)广泛分布于世界各地,是影响我国农业生产最大的一类植物病原线虫,寄主植物有3 000多种,可侵染几乎所有的蔬菜作物,其中,茄科(Solanaceae)、葫芦科(Cucurbitaceae)和十字花科(Brassicaceae)等蔬菜受害最重~([1])。常见的根结线虫种类有南方根结线虫     

根结线虫侵染寄主对莲草直胸跳甲生长发育及食物利用的影响

分别用接种南方根结线虫的空心莲子草、莲子草和未接种南方根结线虫的空心莲子草、莲子草喂养莲草直胸跳甲幼虫,比较两种寄主植物莲草直胸跳甲饲喂生长发育及食物利用情况。结果表明,植物种类和线虫侵染的交互作用对莲草直胸跳甲的化蛹率、蛹重及食物转化率存在极显著影响。在未接种线虫处理中,两种寄主植物上莲草直胸跳甲生长发育及食物利用指标均无显著差异,接种线虫后,空心莲子草饲喂的莲草直胸跳甲化蛹率和蛹重显著降低,莲子草饲喂的莲草直胸跳甲蛹重和食物转化率显著增高。由此推断,南方根结线虫侵染抑制了空心莲子草上莲草直胸跳甲的生长发育,而促进了莲子草上莲草直胸跳甲的生长发育及食物利用。     

象耳豆根结线虫对抗病番茄品种VFNT的致病性研究

 象耳豆根结线虫是近年在我国发现的一种扩散迅速、寄主广泛、致病性强的根结线虫。为探究象耳豆根结线虫的强致病性原因,本研究用象耳豆根结线虫和南方根结线虫分别接种抗线虫番茄品种VFNT和感病番茄品种Rutgers,30 d后象耳豆根结线虫对VFNT和Rutgers的累计侵入率分别为14.1%和19.2%、虫瘿率为62.5%和81.6%,而此时南方根结线虫累计侵入率为0%和18.8%、虫瘿率为0%和68.5%,象耳豆根结线虫的侵染力和致病力显著强于南方根结线虫;通过侵染抗病番茄品种VFNT的病理切片以及根尖侵染早期胼胝质、活性氧染色发现象耳豆根结线虫的侵染不会激活Mi-1基因诱导的特异性抗性,在侵染早期南方根结线虫引起的胼胝质沉积量在72 h最大,是象耳豆根结线虫的2.0倍;体外H₂O₂应激测试发现,H₂O₂浓度为10～80 μmol·L^-1象耳豆根结线虫对H₂O₂的耐受性显著强于南方根结线虫。象耳豆根结线虫具有强致病性的原因可能是:具有更强的侵染力和活性氧耐受力;侵染不会激活Mi-1基因诱导的特异性抗性且侵染引起的胼胝质的积累量较低。     

穿刺巴斯德菌活体大量繁殖体系的优化

穿刺巴斯德菌Pasteuria penetrans专性寄生于根结线虫Meloidogyne spp.,具有很好的生防潜力。为了进一步提高其产量,本研究比较了5个对南方根结线虫敏感的番茄栽培品种繁殖穿刺巴斯德菌的效率。结果表明,佳粉18和毛粉802繁殖效率最高,单株番茄上的产孢量分别为1.54×108孢子.株-1和1.47×108孢子.株-1。以佳粉18为根结线虫的寄主植物,研究线虫接种量、接种次数、线虫接入时的苗龄及接种后第1周的培养温度对穿刺巴斯德菌活体繁殖量的影响。研究表明,在番茄9片真叶时,每株番茄接种7500条线虫,分3次接入,根粉的产孢量可提高至1.86×108孢子g-1。在18～31℃温度范围内,温度越高,穿刺巴斯德菌对线虫的侵染率越高;31℃时,其孢子侵染率平均达44.57%。     

红麻根结线虫生活习性及防治研究

研究表明,我国红麻上的根结线虫有南方根结线虫(Meloidogyne incognita)1号和2号小种,爪哇根结线虫(M.javanica)和花生根结线虫(M.arenaria)2号小种,南方根结线虫是优势种。它们都不为害棉花、花生、小麦、芝麻和苎麻,对高粱和玉米为害极轻。丝瓜、西瓜、番茄和空心莲子草为其共同寄主。南方根结线虫还侵染大豆、豇豆、苦瓜、菜瓜、南瓜、茄子、辣椒、烟草、黄麻、甘薯、黄瓜、白菜、莴苣、菜豆和扁豆等作物。红麻根结线虫的二龄幼虫主要分布在0～40cm 土层内,砂壤土中的线虫密度大于黄壤土。病原线虫以卵和二龄幼虫主要在病株残体中越冬。实行轮作、清除病残和药剂处理土壤是防治本病的有效措施。     

中国南方稻田及其周边环境根结线虫种类鉴定

为了解根结线虫在中国南方稻区的分布和种类, 从15个省(直辖市/自治区)采集1 181份土样, 经生物测定发现312份土样中种植的水稻或番茄幼苗根系会产生根结, 阳性总检出率为26.42%。利用线虫特异性引物从171份阳性样品中鉴定出6种根结线虫:拟禾本科根结线虫Meloidogyne graminicola、北方根结线虫M.hapla、花生根结线虫M.arenaria、爪哇根结线虫M.javanica、象耳豆根结线虫M.enterolobii和南方根结线虫M.incognita, 分别占鉴定总样品数的88.89%、41.52%、29.82%、10.53%、4.09%和3.51%。被1、2、3、4、5、6种根结线虫混合侵染的土样比例分别为42.11%、41.52%、12.87%、2.92%、0.58%和0, 其中最常见的为拟禾本科根结线虫单独侵染(34.50%)、拟禾本科根结线虫与北方根结线虫(22.81%)或花生根结线虫(13.45%)混合侵染。本研究结果将为制定相应的传播阻断策略和防控措施提供参考。     

蔬菜根结线虫病的发生与防治

根结线虫病为蔬菜上的重要病害,一般造成蔬菜减产２０％～３０％,严重的减产５０％以上。由于根结线虫主要为害蔬菜的根部,一般药液难以直接到达植株的根部,这就给防治带来较大的难度。１　发病症状　　植株受根结线虫为害,发病轻时,地上部无明显症状。发病重时,地上部表现生长不良、矮小、黄化、萎蔫,似缺肥水或枯萎病症状。果菜类蔬菜结果小而少,且多为畸形。根结线虫病常导致枯萎病、细菌性病害的发生。因为根结线虫造成根部的伤口,有利于枯萎病菌、细菌的侵染。拨起植株,细观根部,可见有许多葫芦状根结,以侧根和须根上最多…     

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.     

成都平原水旱轮作田常见根结线虫调查

调查四川省成都平原地区水旱轮作田根结线虫发生情况及种类分布,为水旱轮作田根结线虫的防治提供依据。对成都平原15个县(市、区)28个乡(镇)共159块水旱轮作田的土样进行根结线虫普遍率调查,利用线虫ITS通用引物和8对根结线虫特异性引物对其中检出率高的地区重新采集的土样进行根结线虫种类分子鉴定。结果表明,成都平原水旱轮作田根结线虫平均检出率为40.25%。重新采集的土样共鉴定出5种根结线虫:拟禾谷根结线虫Meloidogyne graminicola、花生根结线虫M. arenaria、南方根结线虫M. incognita、北方根结线虫M. hapla和爪哇根结线虫M. javanica,各线虫的检出率分别为40.91%、34.09%、13.64%、13.64%和2.27%,其中29.55%的样品由2种以上根结线虫混合侵染。拟禾谷根结线虫和花生根结线虫为该地区优势种群。     

Local and Systemic Induced Resistance to the Root-Knot Nematode in Tomato by DL-beta-Amino-n-Butyric Acid

ABSTRACT Chemical inducers of pathogenesis-related proteins and plant resistance were applied to tomato plants, with the aim of inducing resistance to the root-knot nematode Meloidogyne javanica. Relative to control plants, foliar spray and soil-drenching with dl-beta-amino-n-butyric acid (BABA) reduced root-galling 7 days after inoculation, as well as the number of eggs 30 days after inoculation. Other chemicals (alpha- and gamma-amino-n-butyric acid, jasmonic acid, methyl jasmonate, and salicylic acid) were either phytotoxic to tomato plants or did not improve control of root-knot nematodes. Fewer second-stage juveniles invaded BABA-treated tomato roots, and root-galling indices were lower than in control tomato plants. Resistance phenomena in seedlings lasted at least 5 days after spraying with BABA. Nematodes invading the roots of BABA-treated seedlings induced small, vacuolate giant cells. Postinfection treatment of tomato plants with BABA inhibited nematode development. It is speculated that after BABA application tomato roots become less attractive to root-knot nematodes, physically harder to invade, or some substance(s) inhibiting nematode or nematode feeding-site development is produced in roots.     

Nematophagous Verticillium spp. in soils infested with Meloidogyne spp. in Cuba: Isolation and screening

Root-knot nematodes cause substantial economic loss of yield in coffee plantations and vegetable crops in Cuba. At present, methods to control the nematodes are ineffective or inappropriate and alternatives are being sought. The nematophagous fungus Verticillium chlamydosporium (Goddard) was isolated from soils collected from coffee plantations and infected root-knot nematode eggs from roots of tomato plants grown in these soils. A total of 83 isolates were collected and identified morphologically as V. chlamydosporium var. chlamydosporium, V. chlamydosporium var. catenulatum, V. psalliotae, V. suchlasporium and an isolate of V. chlamydosporium var. chlamydosporium with unusually large dictyochlamydospores. From these, 24 that represented a range of origins were selected and screened for their ability to parasitize eggs of root-knot nematodes, colonize the rhizosphere of barley roots and produce chlamydospores. None of the isolates grew at temperatures below 15°C and V. suchlasporium grew at a faster rate at lower temperatures than the other isolates. These were also screened in the glasshouse and V. chlamydosporium var. catenulatum caused the greatest reduction in nematode populations. One isolate of each subspecies of V. chlamydosporium was tested with the standard, Rothamsted isolate 10, on a range of host plants. The greatest reduction in numbers of nematodes occurred on tomato plants (cv. Pixie). The Rothamsted isolate 10 reduced numbers of nematodes toa greater extent than the other isolates, and therefore has the greatest potential as a biological control agent of root-knot nematodes.     

The role of weeds in the epidemiology of pospiviroids

Many weeds that are closely associated with horticultural activities are known as natural reservoirs of plant viruses. However, whether these weeds can also serve as hosts of pospiviroids is not well known. Pospiviroids are naked, non‐coding RNA pathogens that cause severe economic damage in many solanaceous crops. In this study, we examined the overall risk of pospiviroid spreading from weeds to economically important crops, by combining the results from previous inoculation studies with new results coming from a survey, a contact experiment and an inoculation experiment. A survey of commercial ornamental glasshouses revealed that ornamental plants mainly belonging to the Solanaceae harbour pospiviroids, in contrast to weed species sampled in the same places. No new weed hosts could be identified after testing weeds that grew in contact with Tomato apical stunt viroid (TASVd)‐infected plants of tomato (Solanum lycopersicum) and jasmine nightshade (Solanum jasminoides) in an experimental glasshouse. Finally, in mechanical inoculation experiments with TASVd, none of the six tested weed species were determined to be a host at 6 weeks after inoculation. Commonly occurring weed species therefore do not appear to play a significant role as reservoir hosts for pospiviroids. This does not rule out other potential weed hosts that have not yet been tested. Inoculation studies should include rigorous experimental protocols with a sufficient number of replicated as well as adequate positive controls. The information gained through this study may prove useful in future risk assessments for the pospiviroid group.     

真菌Sr18代谢产物对根结线虫胁迫下黄瓜叶片保护酶的影响

为探究根结线虫胁迫下丝状真菌Sr18代谢产物对黄瓜的作用机理,采用温室盆栽及人工接种试验,研究了不同浓度的Sr18代谢产物对南方根结线虫胁迫下黄瓜叶片保护酶的影响。结果表明,线虫侵染黄瓜根部以后,黄瓜叶片SOD、POD和CAT活性减弱,PPO和PAL浓度降低。施加不同浓度的Sr18代谢产物,能够使线虫胁迫下的黄瓜叶片SOD、POD和CAT活性增强,使PPO和PAL的含量增加,说明Sr18代谢产物能够提高黄瓜的保护酶活性与含量,增强黄瓜对南方根结线虫的抗性。     

Assessment of the pest status of Pratylenchus curvicauda and ultrastructural changes in roots of infected wheat and barley

Pratylenchus curvicauda, which was first described in metropolitan Perth in 1991, was recently identified in grain-growing areas in Western Australia. The biology of this root-lesion nematode, and especially its pest status, is unknown. We investigated its life cycle and interaction with host plants, because such information is essential for its management. The life cycle took 45 days to complete in a wheat cultivar maintained at 23°C. Over 10 weeks, the nematode multiplied in 26 of 61 genotypes; these host plants were all cereals and included widely grown cultivars of wheat and barley. Eighteen other cereal genotypes and 13 cultivars including canola, chickpea, ryegrass, lupin, soybean, and tomato, sustained the nematodes to different degrees without multiplication. Four cover crops were not suitable hosts. The patterns of attraction of the nematodes and penetration into roots of the host and tolerant plants were similar. The nonhosts attracted fewer nematodes, none of which penetrated the roots. Browning of infected roots was atypical—it occurred late in some roots, 55 days after inoculation, and in the presence of a fungus. The nematodes were confined to, and fed from, cortical cells. The ultrastructure of infected wheat and barley cells showed typical signs of damage caused by Pratylenchus spp. and included cell disorganization and lack of membrane integrity, disintegration of cytoplasm, hypertrophy of some nuclei, and deposition of tannin-like granules. This detailed characterization of P. curvicauda–host interaction indicates the nematode is likely to be a pest of major crops, and attention should be given to its management.     

Suitability of weed species prevailing in Spanish vineyards as hosts for root-knot nematodes

Commercial vineyards in southern Spain were surveyed and sampled during October to December 2004 to determine the extent to which common weeds present were suitable hosts of root-knot nematodes infesting soils of those vineyards. Seven weed species commonly growing in grapevine soils in southern Spain were found infected by either Meloidogyne incognita or M. javanica: Amaranthus retroflexus (redroot pigweed), Anchusa azurea (ox-tongue), Chenopodium album (goosefoot), Erodium moschatum (musk stork’s bill), Malva rotundifolia (low mallow), Sinapis alba (white mustard), and Solanum nigrum (black nightshade). The host suitability of the weeds to root-knot nematodes was evaluated on the basis of root galling severity and nematode population densities in soil and roots. Also, the host–parasite relationship in these naturally Meloidogyne-infected weeds was examined. All the weed species in the study were considered suitable hosts for M. incognita and M. javanica because: (a) high Meloidogyne spp. populations occurred in roots and surrounding soil of the weed species; (b) the severity of root galling was high, and (c) well-established permanent feeding sites were observed in the histopathological studies of infected root tissues. In addition, this study presents the first reports of S. alba and A. azurea as hosts for M. incognita, and of E. moschatum as a new host for M. javanica, thus increasing the list of reported weed hosts for Meloidogyne spp. These results indicate that noticeable population densities of M. incognita and M. javanica can be maintained or increased in these weeds, at population levels higher than those previously reported for the same nematodes infecting grapevine roots. The weeds infesting vineyards thus represent an important source of inoculum of Meloidogyne spp., and furthermore may act as reservoirs of these nematodes which can be disseminated within or among vineyards by agricultural operations.     

A high-throughput method for early screening of coffee (<Emphasis Type="Italic">Coffea</Emphasis> spp.) genotypes for resistance to root-knot nematodes (<Emphasis Type="Italic">Meloidogyne</Emphasis> spp.)

Root-knot nematodes (Meloidogyne spp.) threaten the livelihood of millions of farmers producing coffee worldwide. The use of resistant plants either as cultivars or rootstocks appears to be the single most effective method of control. A screening method was developed to evaluate large populations of plants for resistance to root-knot nematodes. Two coffee cultivars, one susceptible and the other resistant to Meloidogyne paranaensis, were grown under controlled conditions in two substrates: a commercial sieved potting compost and an inert substrate containing sand with a water-absorbent synthetic polymer. Plant growth and development and nematode multiplication were compared for two inoculation dates (2 and 8 weeks after planting) and two evaluation dates (eight and 13 weeks after inoculation). Root growth, but not nematode multiplication, was influenced by the choice of substrate. Evaluation of the differences in root weight and nematode numbers between the different cultivars, substrates and dates of inoculation suggested that an optimal condition could be defined. The best discrimination between susceptible and resistant plants was found in the experiment where inoculation occurred at 2 weeks after planting and evaluation occurred at 8 weeks after inoculation. Because the total duration of this experiment was only 3 months, high-throughput evaluation was possible, opening up new possibilities for screening large germplasm collections and studying the genetic control of root-knot nematode resistance in coffee.     

Hypersensitive-like reaction conferred by the Mex-1 resistance gene against Meloidogyne exigua in coffee

The response of a susceptible coffee cultivar (Caturra) to infection by the root-knot nematode Meloidogyne exigua was compared histologically with that of cv. Iapar 59 possessing the recently identified Mex-1 resistance gene. The reproductive behaviour of the nematode was also compared in the two cultivars. Penetration and development in resistant plants were reduced in comparison with susceptible plants. Several cell features, including dark-stained cytoplasm and altered organelle structure, were observed in the resistant cultivar, indicating a hypersensitive-like (HR) response of the infested host cells. Features of giant cells were sometimes found beside necrotic-like areas, but the corresponding feeding sites were frequently associated with nematodes displaying abnormal shape. Six weeks after inoculation, root systems of cv. Caturra contained significantly more nematodes than those of cv. Iapar 59 (mean values 1574 and 41, respectively). The susceptible cultivar presented a minimum of 11 galls per plant, compared with only one or two galls per plant in the resistant cultivar. The findings are discussed in the context of plant–pathogen interactions.     

Protection of olive planting stocks against parasitism of root-knot nematodes by arbuscular mycorrhizal fungi

The effects were investigated, under controlled conditions, of single and joint inoculation of olive planting stocks cvs Arbequina and Picual with the arbuscular mycorrhizal fungi (AMF) Glomus intraradices , Glomus mosseae or Glomus viscosum , and the root-knot nematodes Meloidogyne incognita and Meloidogyne javanica , on plant performance and nematode infection. Establishment of the fungal symbiosis significantly increased growth of olive plants by 88·9% within a range of 11·9–214·0%, irrespective of olive cultivar, plant age and infection by M. incognita or M. javanica . In plants free from AMF, infection by Meloidogyne spp. significantly reduced the plant main stem diameter by 22·8–38·6%, irrespective of cultivar and plant age. Establishment of AMF in olive plants significantly reduced severity of root galling by 6·3–36·8% as well as reproduction of both Meloidogyne spp. by 11·8–35·7%, indicating a protective effect against parasitism by root-knot nematodes. Infection by the nematodes influenced root colonization by AMF, but the net effect depended on the AMF isolate–olive cultivar combination. It is concluded that prior inoculation of olive plants with AMF may contribute to improving the health status and vigour of cvs Arbequina and Picual planting stocks during nursery propagation.