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。     

南方根结线虫Me3毒性与非毒性群体对寄主趋向性和侵染能力的比较

 探究南方根结线虫Me3毒性与非毒性群体对抗感寄主趋向性和侵染能力,为揭示毒性群体致病机理及防治根结线虫策略提供理论依据。使用以水琼脂为介质的研究方法,通过对比分析辣椒抗病品种HDA149和感病品种茄门根尖附近聚集的2龄幼虫(J2)数量,来揭示南方根结线虫对抗感辣椒品种根尖的趋向性效应,并利用实时荧光定量 PCR 检测侵入到辣椒根系的毒性与非毒性线虫数量,对其侵染能力进行比较。J2 趋向性试验结果显示,在相同的时间点,HDA149 和茄门辣椒根尖处附近聚集的毒性群体 J2 数量总是显著多于非毒性群体的 J2数量;J2 对抗感辣椒的选择性结果表明,不论是毒性群体还是非毒性群体的 J2,在相同的时间点,茄门根尖附近聚集的线虫数量显著多于HDA149根尖附近的线虫数量;荧光定量 PCR 检测线虫侵染结果显示,毒性群体 J2侵入到辣椒根系的数量相对非毒性群体的 J2 更多。总之,相比南方根结线虫Me3非毒性群体,毒性群体的 J2 对寄主根系有较强的趋向性,并且侵染效率更高;相比于抗性寄主,Me3毒性群体和非毒性群体的 J2 对感病寄主有更强的选择性。     

南方根结线虫中国分离群体种内变异分析

为调查我国不同地区和不同寄主上的根结线虫Meloidogyne spp.种类分布以及群体变异情况,基于酯酶和苹果酸脱氢酶同工酶图谱及SCAR分子标记技术对2017—2019年从6省19种植物根部组织分离到的40个根结线虫群体进行鉴定,针对南方根结线虫M.incognita群体分别通过寄主鉴别法进行生理小种鉴别,利用携带Mi抗性基因的番茄进行毒力测试,对2龄幼虫的口针长度和体长进行测量,并对核糖体ITS和线粒体Nad5基因序列进行比较分析。结果显示：根结线虫分离群体经鉴定包括38个南方根结线虫群体和2个象耳豆根结线虫M.erterolobii群体;38个南方根结线虫群体中有35个群体被鉴别为1号生理小种,其余3个群体被鉴别为2号生理小种;发现1个南方根结线虫群体CN19可在携带Mi抗性基因的番茄上侵染繁殖,为毒性群体,其余群体无法进行侵染和繁殖,为无毒群体。南方根结线虫群体2龄幼虫的口针长度和体长均差异较大,而不同寄主来源分离群体的ITS和Nad5基因序列也存在一定变异。基于ITS和Nad5基因序列构建的系统发育树将所有根结线虫群体归为南方根结线虫和象耳豆根结线虫组成的2个独立分支,但不能确定南方根结线虫不同群体的分子进化与其寄主来源和地理分布之间的相关性。     

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。     

温度和初始种群密度对象耳豆根结线虫侵染番茄的影响

通过室内接种方法,研究了不同温度和接种密度对象耳豆根结线虫侵染番茄能力的影响。研究结果表明,28~30 ℃是象耳豆根结线虫侵染番茄的最适温度。随着温度的下降,其侵染能力明显降低。当象耳豆根结线虫2龄幼虫接种密度大于10条/100 cm3土壤时,番茄的生长会受到显著的抑制,随着线虫接种密度的增加,根结指数显著增加、线虫对番茄的危害也逐渐加重。研究结果将为广东省蔬菜产区制定象耳豆根结线虫防治指标提供理论依据。     

华南地区主要番茄品种对南方根结线虫的抗性评价

通过人工接种方式, 对华南地区番茄主要栽培品种对优势根结线虫——南方根结线虫（Meloidogyne incognita）的抗性进行了评价。结果表明,广东栽培品种年丰、红宝石、新星、福安、粤红玉、穗丰、金丰、益丰、丰顺、大丰顺、满丰和法国品种SAINT PIERRE均高度感病; 而法国品种 PIERSOL VFN高度抗病,根结率为0。根据SAS8.0多重比较分析表明,在F0.01的水平上, 品种PIERSOL VFN与其余品种之间对根结线虫的抗性均存在显著性差异,而其他12个品种间对根结线虫的抗性差异不显著。     

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。     

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。     

活性氧与木质素对细菌Sneb825诱导番茄抵抗南方根结线虫侵染的响应

 根结线虫病严重威胁各类蔬菜作物的生产,是世界上最难防治的土传病害之一。利用生防细菌能够有效地控制蔬菜根结线虫种群数量并降低危害。荧光假单胞菌Sneb825是本实验室筛选出的对南方根结线虫病具有较高防效的生防细菌。本研究通过盆栽试验、裂根试验和温室试验验证了荧光假单胞菌Sneb825诱导番茄抗南方根结线虫侵染的防治效果;通过酶联免疫法(ELISA)和实时荧光定量PCR检测了番茄根系内活性氧与木质素含量及其相关基因表达量的变化。研究发现,Sneb825菌株发酵液不但能够有效降低南方根结线虫对番茄的侵染,而且对番茄植株有显著的促生作用。Sneb825菌株发酵液灌根处理并接种南方根结线虫二龄幼虫后,番茄根系内活性氧(10 dpi)和木质素含量(5 dpi)显著高于空白对照;活性氧合成相关基因RBOH1(10 dpi)和过氧化物酶基因Ep5C(10 dpi)以及木质素合成相关基因Tpx1(5 dpi)的表达量均达到最高值。研究结果表明活性氧和木质素的大量积累是荧光假单胞菌Sneb825诱导番茄抑制南方根结线虫侵染的防御对策之一。荧光假单胞菌可以有效的防治根结线虫病,在农业生产实践中具有潜在的应用前景。     

南方根结线虫对生姜生长及内源激素的影响

 试验结果表明,南方根结线虫侵染生姜后,首先损伤根系,进而显著降低生姜植株的株高、地上鲜重、根系鲜重和根茎重,减产47.96%。南方根结线虫侵染可使生姜叶片中赤霉素(GA)、吲哚乙酸(IAA)、玉米素核苷(ZR)含量显著降低,感病生姜的脱落酸(ABA)则表现为前期降低,后期增加的趋势,并促使叶片中GA/ABA的迅速下降,严重影响了生姜的生长,使感病植株矮小、叶片黄化,提前衰老。感病生姜根茎GA、IAA、ZR、ABA的变化规律与叶片相似,但9月份ZR、IAA含量的迅速上升,与根结线虫建立侵染据点、形成巨型细胞,从而造成根茎的局部疣裂有关。南方根结线虫侵染可引起病株根系GA/ABA升高以及GA含量在生长后期上升,促进营养物质向根部运输,从而造成根系的补偿性生长;但IAA和ZR含量的下降不利于根结线虫建立侵染据点,不能在根系中形成过多的根结。     

Histological Characterization of Resistance to Different Root-Knot Nematode Species Related to Phenolics Accumulation in Capsicum annuum

ABSTRACT In the pepper Capsicum annuum CM334, which is used by breeders as a source of resistance to Phytophthora spp. and potyviruses, a resistance gene entirely suppresses reproduction of the root-knot nematode (Meloidogyne spp.). The current study compared the histological responses of this resistant line and a susceptible cultivar to infection with the three most damaging root-knot nematodes: M. arenaria, M. incognita, or M. javanica. Resistance of CM334 to root-knot nematodes was associated with unidentified factors that limited nematode penetration and with post-penetration biochemical responses, including the hypersensitive response, which apparently blocked nematode migration and thereby prevented juvenile development and reproduction. High-performance liquid chromatography analysis suggested that phenolic compounds, especially chlorogenic acid, may be involved in CM334 resistance. The response to infection in the resistant line varied with root-knot nematode species and was correlated with nematode behavior and pathogenicity in the susceptible cultivar: nematode species that quickly reached the vascular cylinder and initiated feeding sites in the susceptible cultivar were quickly recognized in CM334 and stopped in the epidermis or cortex. After comparing our data with those from other resistant pepper lines, we suggest that timing of the resistance response and the mechanism of resistance vary with plant genotype, resistance gene, and root-knot nematode species.     

Control of root-knot nematodes (Meloidogyne spp.) in Hungary1

Under Hungarian climatic conditions, root-knot nematodes, and other phytoparasitic nematodes, generally cause damage in certain plant growing areas. These pests are present in glasshouses throughout the country. In the field the nematodes occur in sandy soil in the vegetable-growing areas of southern and central Hungary. The following species of root-knot nematodes have so far been reported to occur in Hungary: Meloidogyne incognita, M. arenaria, M. hapla, M. javanica, M. incognita acrita, M. thamesi and M. naasi. There are 10 specific nematicides registered for nematode control in the country. These chemicals are mainly applied in glasshouses where their use produces most economic return. Nematoderesistant cultivars are only available in the case of tomato. The nematodes cause the heaviest damage on glasshouse cucumber.     

辽宁省保护地蔬菜根结线虫发生规律及防治对策*

2008-2009年,对辽宁省蔬菜主产区保护地蔬菜根结线虫病的危害程度进行调查,以辽宁省的辽中、辽西、辽南、辽东4个地区的黄瓜大棚为对象,对棚内土壤中根结线虫的发生规律进行系统研究。结果表明：辽宁省保护地蔬菜根结线虫病为南方根结线虫危害。该病在辽宁省保护地蔬菜上发生已相当普遍,其中以连作7年以上的黄瓜、番茄、苦瓜易感寄主为主的老菜棚的发病率达到100%,病情指数达到80以上。4个地区大棚土壤中根结线虫数量普遍随土层的加深呈明显减少的趋势;并且根结线虫数量普遍随着大棚前边缘向内的距离加大呈明显增加的趋势。结合辽宁省根结线虫发病特点,提出相应的防治措施。     

Meloidogyne virulence locus molecular marker for characterization of selected mi-virulent populations of Meloidogyne spp. is correlated with several genera of betaproteobacteria

Resistance to root-knot nematodes in tomato is conferred by the Mi resistance gene to the three most important species of Meloidogyne: M. arenaria, M. incognita, and M. javanica. Nevertheless, the Mi gene is unable to inhibit the reproduction of selected and naturally Mi-virulent populations of root-knot nematodes. As pathogenicity assays are time consuming, molecular markers were developed for the easy identification of Mi-virulent populations of Meloidogyne. The sequence characterized amplified region-Meloidogyne virulence locus (MVC) molecular marker is reported to differentiate Mi-avirulent and naturally Mi-virulent from selected Mi-virulent populations. This marker was used to compare acquired virulence in populations of M. javanica from Spain. The original populations used to develop the MVC marker were included as control for reference. Results showed that this marker did not amplify genomic DNA extracted from single juveniles or females of any of the populations tested either from Spain or Japan. In silico analyses performed with the recently published complete genome of M. incognita, indicated that the MVC marker is not correlated to a MVC or to any eukaryotic organism but to several betaproteobacteria genus from the family Comamonadaceae.     

海南省蔬菜根结线虫发生种类与分布

2014年-2018年, 对海南省蔬菜根结线虫病害进行了田间随机采样调查和病原种类分子鉴定?结果显示, 蔬菜根结线虫病在海南18市县均有发生, 且大部分旱田连作地块病株率达到80%以上?进一步对采集的295份根结线虫样本种类进行了分子鉴定, 共鉴定出象耳豆根结线虫?南方根结线虫和爪哇根结线虫3种病原种?其中, 象耳豆根结线虫单一检出率达到62.37%, 南方根结线虫单一检出率为23.39%, 爪哇根结线虫的检出率仅为5.76%, 象耳豆根结线虫和南方根结线虫复合侵染检出率为8.47%?除五指山市样本以外, 海南其余17市县样本均检测到象耳豆根结线虫侵染为害?本研究显示象耳豆根结线虫为海南省蔬菜上的优势病原根结线虫种类, 该结果对指导品种布局?制定根结线虫病害的防治策略具有重要意义?     

Variation in resistance to the root-knot nematode Meloidogyne incognita in tomato genotypes bearing the Mi gene

Root-knot nematodes ( Meloidogyne spp.) are among the main pathogens of tomato ( Lycopersicon esculentum ) worldwide. Plant resistance is currently the method of choice for controlling these pests and all the commercially available resistant cultivars carry the dominant Mi gene, which confers resistance to the three main species Meloidogyne arenaria , M. incognita and M. javanica . However the emergence of virulent biotypes able to overcome the tomato resistance gene may constitute a severe limitation to such a control strategy. To date, little was known of the possible influence of the homozygous vs heterozygous allelic state of the Mi locus, or the tomato genetic background, on the expression of the resistance. In order to test both these factors, the resistance was evaluated of a large panel of L. esculentum genotypes (selected from the Vilmorin germplasm stock collection) to seven M. incognita lines avirulent or virulent against the Mi gene. Plant resistance was estimated by counting the egg masses on the root systems after inoculation with second-stage juveniles (J₂). Reproduction of the nematodes was similar or, more often, significantly higher on heterozygous tomato genotypes than on homozygous ones, suggesting a possible dosage effect of the Mi gene. Data also indicated that the tomato genetic background had a major effect on the variations observed in nematode reproduction, especially when tomato genotypes were heterozygous for the Mi gene. These results have important consequences in terms of breeding strategies and durability of the resistance conferred by the Mi gene.     

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.     

番茄抗性品种与黄瓜轮作对根结线虫的防治作用

通过室内盆栽试验探讨对根结线虫具有不同抗性的番茄品种与黄瓜轮作减轻根结线虫病危害的可行性。试验结果表明:抗性品种多菲亚能极大降低土壤中根结线虫2龄幼虫和卵的密度,减轻黄瓜根结线虫病的危害;抗性砧木Beaufort也能显著地降低土中根结线虫和卵的密度,但下茬黄瓜根结线虫的危害与对照相比没有显著差异。表明抗性品种与感病品种轮作能有效地防止根结线虫的发生。     

西南部分地区荞麦根结线虫种类与地理分布

近年来,随着我国荞麦面积的迅速增加,根结线虫病呈逐年加重趋势,严重影响了荞麦的产量与品质。本研究于2014年对西南10个地区17个乡镇秋播苦荞麦根结线虫的分布、发生种类以及危害程度进行了调查。结果表明,西南地区危害荞麦的根结线虫种类有南方根结线虫(Meloidogyne incognita)、爪哇根结线虫(M.javanica)和花生根结线虫(M.arenaria)3种,其中南方根结线虫为优势种群。田间根结线虫种群大多数为单一种群,23.5%的样品为南方根结线虫与爪哇根结线虫(或花生根结线虫)组成的混合种群。调查发现前作为烟草或马铃薯的地块,荞麦根结线虫发生危害严重,平均被害株率为6.0%~77.5%,病情指数为1.4~26.1,而前作为玉米的荞麦根结线虫则较轻,被害株率最高为16.0%,相应病情指数为2.3。     

茶苗根结线虫病研究

 茶苗根结线虫病主要发生于一、二年生实生苗上,重病地发病率可达100%,死苗率在50%以上。据在浙江省的不完全调查,已知有18个县(市)发现此病。病原线虫经初步鉴定,主要为南方根结线虫(Meloidogyne incognita)与花生根结线虫(M.arenaria),而爪哇根结线虫(M.javanica)与泰晤士根结线虫(M.thamesi)均少见。试验表明,杭州茶区病原线虫一年发生不完整8代,大约20~30天完成一代,世代重叠明显。