南方根结线虫不同接种密度对灯盏花抗氧化系统的影响

通过室内接种方法,测定了南方根结线虫2龄幼虫在不同接种时间(25、35d)和不同接种密度(0、500、700、1 000、1 200、1 500头/株)下对灯盏花生长和根系及叶片丙二醛(MDA)、超氧化物歧化酶(SOD)、过氧化物酶活性(POD)及过氧化氢酶活性(CAT)的影响。研究结果表明,南方根结线虫接种密度为1 000头/株时,接种后25d与35d的根结指数达到最大,分别为87.2及65.6;接种密度500头/株,对根结指数影响较大。接种后25d,接种量对灯盏花病根与病叶的过氧化物酶活性影响不大;接种后35d,灯盏花病根的过氧化物酶活性(POD)随接种密度的增加先降低后升高,病叶中的POD活性除了接种密度为1 000头/株时低于健康叶部外,其他均高于健康组;接种密度对灯盏花的过氧化氢酶(CAT)活性影响较大,在1 000头/株时,病根和病叶中的过氧化氢酶活性都明显高于对照。接种密度对于灯盏花叶片的丙二醛(MDA)含量影响不大,当密度为1 000头/株接种35d对根部丙二醛的影响最大,其含量明显高于对照;接种密度对于灯盏花病叶和病根中的超氧化物歧化酶(SOD)活性影响较大,病叶中的超氧化物歧化酶(SOD)普遍高于健康组,而病根中的SOD活性普遍低于健康组。综合研究结果,当南方根结线虫接种密度为500头/株时,对灯盏花有一定危害,随着接种密度的增加,危害逐渐加重,当接种密度为1 000头/株时,根结指数最大,几种酶活性都显著高于健康植株,接种密度大于1 000头/株时,酶活性逐渐下降。接种初期,南方根结线虫对灯盏花叶部危害较大,随着种植时间的推移,对根部危害逐渐加重。     

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。     

红灰链霉菌HDZ-9-47对番茄生长及其防御酶的影响

 红灰链霉菌Streptomyces rubrogriseus HDZ-9-47分离自根结线虫的卵,它既可寄生南方根结线虫,又可产生具杀线虫活性的代谢产物。本研究通过田间试验评价了HDZ-9-47发酵液对南方根结线虫的防治效果,以及对番茄产量和品质的影响;并测定了施用HDZ-9-47对番茄根部几种防御酶的影响。结果表明,在番茄移栽90 d后,穴施HDZ-9-47发酵液处理的防效达61.5%,并且促进番茄增产17.9%,增加了番茄果实中可溶性糖的含量,但对番茄茎粗无显著影响。此外,施用HDZ-9-47发酵液可提高番茄根部多酚氧化酶(PPO)、过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)和超氧化物歧化酶(SOD)的活性,进而诱导番茄产生抗性。     

南方根结线虫Col基因分子克隆及其VIGS效应分析

为了明确线虫角质层胶原蛋白基因(Col)与根结线虫病害的关系,利用从线虫基因组中预测的Col设计特异引物,克隆了南方根结线虫Meloidogyne incognitacol基因MiCol.该基因完整编码区长903bp,编码300个氨基酸.克隆的MiCol与预测的MiCol基因序列一致性高达99.67％,氨基酸序列一致性高达100％.利用病毒介导的基因沉默技术,将其导入番茄植株并接种南方根结线虫,60 d后,沉默载体pTV-MiColi处理番茄植株的根结数比空载体对照及清水对照分别减少49.4％和49.2％,表明MiCol基因沉默显著降低了南方根结线虫的侵染数量.     

AM真菌和根结线虫互作对黄瓜生长及生理特征的影响

通过盆栽试验研究了丛枝菌根真菌Arbuscularmycorrhiza（AM）和南方根结线虫Meloidogyneincognita互作对黄瓜幼苗生长及生理特征的影响。结果表明,预先接种地表球囊霉Glomusversi—forme再接种线虫处理的鲜、干重较只接种线虫的处理显著增加;预先接种AM真菌再接种线虫处理的根结线虫病情指数、AM真菌侵染率较只接种线虫的处理明显降低;接种线虫使黄瓜植株的过氧化物酶（POD）、过氧化氢酶（CAT）及苯丙氨酸解氨酶（PAL）、总酚含量有不同程度提高,其中预先接种根内球囊霉G．intraradices对黄瓜植株起到了较好的保护作用;与对照相比,只接种线虫处理的叶片磷含量降低了25．26％,预先接种AM真菌再接种线虫处理的叶片磷含量较只接种根结线虫的含量高。     

不同植物秸秆对番茄及南方根结线虫的影响

为有效防治南方根结线虫,本试验研究了添加不同剂量的玉米秸秆(8.32、4.16、2.08g/kg)、辣椒秸秆(4.16、2.08、1.04g/kg)和茵陈蒿秸秆(4.16、2.08、1.04g/kg)对温室大棚番茄及根结线虫的影响。结果显示,在根结线虫侵染的土壤中添加植物秸秆后30d,玉米秸秆(4.16、2.08g/kg)对番茄株高有显著影响,辣椒(4.16、1.04g/kg)和茵陈蒿(4.16、2.08g/kg)秸秆对番茄茎粗影响显著;60d时经茵陈蒿处理的番茄植株比对照生长发育良好,对形态指标的影响程度依次为茎粗开花分枝;120d时番茄的茎粗、分枝和果实重量均显著高于对照。末次接种后20d调查,每种作物秸秆处理以高剂量对根结线虫的防治效果最好,防治效果依次为:茵陈蒿秸秆辣椒秸秆玉米秸秆,分别为79.60%、71.32%、68.89%,表明茵陈蒿秸秆处理既可降低根结线虫危害程度,又可提高番茄产量。本研究为温室大棚有效防治根结线虫提供了依据。     

PGPR对番茄南方根结线虫病的影响

于温室盆栽条件下初步研究了4种根围促生细菌（PGPR）对番茄植株生长和南方根结线虫Meloidogyne incognit病发生情况的影响。结果表明接种多粘芽孢杆菌Bacillus polymyxa或芽孢杆菌菌株B697的番茄植株高度、地上部和地下部干重均显著大于对照,而巨大芽孢杆菌B. megaterium和固氮螺菌Azospirillum sp.菌株A135无促生作用。接种多粘芽孢杆菌＋南方根结线虫和B697菌株＋南方根结线虫两处理的二龄幼虫数、雌虫数、线虫总数、根上卵囊数、卵囊含卵量、发病率和病情指数显著低于只接种南方根结线虫的对照。多粘芽孢杆菌、B697菌株、巨大芽孢杆菌和A135菌株对南方根结线虫的防效分别达65.4%、68.2%、53.8%和53.8%。     

烟粉虱取食感染TYLCV番茄对其解毒酶和保护酶活性的影响

为了明确感染番茄黄化曲叶病毒(Tomato yellow leaf curl virus,TYLCV)的番茄对烟粉虱生理防御的影响,本文采用生化分析法研究了烟粉虱取食感染TYLCV的番茄植株后解毒酶和保护酶活性的变化。结果表明,B型烟粉虱在带毒番茄上取食72h及30d(长期饲养种群)后,其谷胱甘肽S-转移酶(GSTs)和羧酸酯酶(CarE)活性呈现先升高后下降的趋势,而P450酶活性则持续上升,取食30d种群是对照种群的1.99倍;三大保护酶系超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)则在取食72h后,酶活性高于对照,而在感染TYLCV番茄上取食30d后,保护酶活性则持续高于72h及对照处理,分别是对照种群的1.45倍、8.42倍和5.03倍,差异显著;Q型烟粉虱表现趋势与B型烟粉虱相似。研究结果为进一步明确入侵烟粉虱与双生病毒之间的互作、揭示烟粉虱的适应性机制等补充了资料。     

大豆早熟耐病品种对大豆胞囊线虫耐病机制的初步研究

经2012年和2013年大田试验筛选,选择对大豆胞囊线虫具有耐病性的大豆早熟品种Красноградская,以感病品种黑河52作对照进行了耐病机制初步研究。结果表明,室内人工接种大豆胞囊线虫,接种后6、12、18、24、30 d,大豆耐病品种和感病品种植株根内多酚氧化酶(PPO)活性均略高于未接种的对照,但差异不显著;受大豆胞囊线虫感染,耐、感大豆品种植株根内过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)活性都比同期的对照显著升高,且耐病品种POD活性始终高于感病品种,活性增高维持的时间比感病品种长。同时,PAL活性比感病品种高峰值出现的早。叶绿素含量变化结果显示,大豆胞囊线虫的侵染显著影响其光合作用,但随接种时间的延长,品种间变化规律不同。在接种后的12~24 d,无论耐、感品种叶绿素的含量与各自的对照相比都有所升高,而且耐病品种的上升幅度明显高于感病品种,24 d以后,感病品种的叶绿素含量开始下降,而耐病品种则继续维持在一个较高的水平。     

茄子砧木根系苯丙烷类代谢与抗南方根结线虫水平的关系

采用盆栽幼苗人工接种方法,研究南方根结线虫侵染对茄子砧木幼苗根系苯丙氨酸解氨酶(PAL)、酪氨酸解氨酶(TAL)及多酚氧化酶(PPO)活性和总酚、木质素含量的影响.结果表明,无论是否遭受南方根结线虫侵染,幼苗根系PAL、TAL、PPO活性及总酚、木质素含量均以托鲁巴姆显著高于赤茄.虽然南方根结线虫侵染使2个茄子砧木幼苗根系苯丙烷类物质含量及相关酶活性均有所增加,但以托鲁巴姆增幅较大,其PAL、TAL、PPO活性及总酚、木质素含量的最大增幅较对照分别高67.87%、82.13%、32.19%、62.14%和20.91%,而赤茄仅分别较对照高47.13%、45.52%、18.08%、35.38%、14.86%.整个侵染进程中,托鲁巴姆始终表现出强烈的抗性反应,而赤茄除在初次侵染前期表现出一定的抗性反应外,其余时间反应较弱,尤其在遭受二次侵染时,抗性反应显著低于初次侵染.表明苯丙烷类代谢产物及关键酶与茄子砧木抗南方根结线虫水平密切相关.     

AM真菌诱导的番茄信号物质及其对根结线虫的 抑制 效应

丛枝菌根(AM)真菌能诱导植物合成一些信号物质,如茉莉酸(JA)、水杨酸(SA)、一氧化氮(NO)、H2O2等,这些信号在AM真菌与植物识别、共生体建立和激活植物防御系统过程中发挥着重要作用[1].     

Pathozone dynamics of Meloidogyne incognita in the rhizosphere of tomato plants in the presence and absence of the nematophagous fungus, Pochonia chlamydosporia

Pathozone dynamics were derived for approx. 50 Meloidogyne incognita juveniles infecting a single root of tomato under controlled conditions from a point source of inoculum and described using simple, non-linear models. The pathozone decayed sigmoidally with distance, but increased over time as progressively more nematodes were able to infect the root. Despite the reported ability of M. incognita juveniles to travel up to 50 cm in some conditions, the maximum width of the pathozone for a single tomato root was estimated as 18·1 mm. It is conjectured that this was because of (i) diffusion from a point source of inoculum, (ii) a small infection court (a single root tip) and (iii) the limited life span of the nematode. A second experiment was used to assess the effect of the nematophagous fungus Pochonia chlamydosporia on the pathozone dynamics of the nematode. This fungus is known to produce nematicidal products in vitro , which may affect invasion of roots by the free-living nematode. To examine the possibility of a change in the position of the site of infection, changes in the probability of gall formation along the root length were also examined. In the absence of P. chlamydosporia , the pathozone dynamics of M. incognita were very similar to those of the first experiment. It was shown that P. chlamydosporia did not significantly affect the pathozone dynamics of M. incognita nor the site of gall formation, which appear to have little importance for the role of the fungus as a biological control agent.     

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.     

The response of commercial cucurbit rootstocks to (a)virulent isolates of Meloidogyne incognita

Journal of Plant Diseases and Protection - Meloidogyne incognita is the predominant root-knot nematode (RKN) species infecting cucurbit plants. It causes galling on the roots of plants and...     

Systemically induced resistance and microbial competitive exclusion: implications on biological control

The root-knot nematode, Meloidogyne incognita, is among the most damaging agricultural pests, particularly to tomato. The mutualistic endophytes Fusarium oxysporum strain Fo162 (Fo162) and Rhizobium etli strain G12 (G12) have been shown to systemically induce resistance toward M. incognita. By using triple-split-root tomato plants, spatially separated but simultaneous inoculation of both endophytes did not lead to additive reductions in M. incognita infection. More importantly, spatially separated inoculation of Fo162 and G12 led to a reduction in Fo162 root colonization of 35 and 39% when G12 was inoculated on a separate root section of the same plant in two independent experiments. In an additional split-root experiment, spatial separation of Fo162 and G12 resulted in a reduction of Fo162 root colonization of approximately 50% over the water controls in two independent experiments. The results suggested that the suppressive activity of G12 on Fo162 and M. incognita is possibly related to the induction of specific plant defense mechanisms. Thus, although Fo162 and G12 have the ability to systemically repress M. incognita infection in tomato, they can be considered incompatible biocontrol agents when both organisms are present simultaneously on the same root system.     

Effects of simulated acid rain and root-knot nematode on tomato

Effects were examined of simulated acid rain and of root-knot nematode, Meloidogyne incognita race 1, on plant growth, yield, photosynthetic pigments and leaf epidermal characters of tomato ( Lycopersicon esculentum cv. Pusa Ruby). Sequential inoculation exposures (pre-, post-, and concomitant with nematode inoculation) were carried out in a greenhouse. Intermittent treatments of simulated acid rain at pH 3.2 caused white-to-tan irregular lesions on both the upper and lower surfaces of tomato leaves. The foliar symptoms were more pronounced on nematode-infected plants. Simulated acid rain (pH 3.2) and/or nematode infection suppressed plant growth, yield and pigment synthesis, the effects being greatest in post-inoculation treatments compared with simulated acid rain at pH 6.8. The total weight of fruits per plant was greatly suppressed owing to simulated acid rain or nematode infection. Chlorophyll a was found to be more sensitive to simulated acid rain or nematode infection than other leaf pigments. Root penetration, galling, egg mass production, and fecundity (number of eggs per egg mass) of M. incognita were enhanced at pH 5.6 and suppressed at pH 3.2 compared with pH 6.8. Nematode infection or simulated acid rain at pH 3.2 suppressed stomata and trichome development (number and size). Simulated acid rain treatments at pH 5.6 had a positive effect on number and size of trichomes, but a negative effect on stomata. The apertures of stomata were wider on tomato leaves exposed to simulated acid rain, especially at pH 3.2, than at pH 6.8.     

南方根结线虫侵染对黄瓜植株生长和抗氧化系统的影响

为探明野生黄瓜对南方根结线虫的抗性机制,采用温室盆栽苗期人工接种技术,研究了线虫侵染对黄瓜抗感品种植株生长和抗氧化系统的影响。南方根结线虫的侵染显著降低了感病品种津春4号的株高、叶面积、地上部鲜重与干重及根系活力,并显著增加其根系鲜重与干重,而对抗病品种西印度瓜的各项生长指标均未造成明显影响。西印度瓜中超氧阴离子(O.2-)、过氧化氢(H2O2)、电导率和丙二醛(MDA)含量增加幅度均小于津春4号,超氧化物歧化酶(SOD)活性降低,过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)活性增加幅度均显著高于津春4号。研究表明西印度瓜遭受的氧化胁迫较小,其抗氧化系统有效清除了氧化损伤。     

南方根结线虫拮抗链霉菌的筛选和鉴定

通过生物测定和温室防病试验 ,对分离自江苏省南京、淮阴和上海三地 3 0份土样的 3 44株放线菌菌株进行筛选 ,得到了 1株对南方根结线虫有较高生物活性的链霉菌菌株LH1 2 1。其培养滤液在离体条件下对南方根结线虫二龄幼虫有较强的触杀作用 ,4h内击倒率达 1 0 0 % ,1 2h内致死率达 1 0 0 % ;番茄植株上的活体防病试验表明 ,2ml/株培养滤液对根结和卵块形成的抑制率分别为52 .8%和 63 .5%。遗传稳定性试验表明LH1 2 1菌株能稳定产生杀线活性物质。LH1 2 1培养滤液主要通过直接触杀二龄幼虫或干扰其侵入植株而达到防治目的。根据形态、培养和生理生化特性的分析 ,将LH1 2 1鉴定为玫瑰暗黄链霉菌