盐类对南方根结线虫迁移能力和侵入能力的影响

为探讨无机盐和有机盐对南方根结线虫的作用方式,在室内利用沙柱法和染色法测定了二者对南方根结线虫2龄幼虫迁移能力及侵入番茄根部能力的影响。结果表明,随着各盐处理浓度的增加,南方根结线虫2龄幼虫的迁移能力和侵入能力显著降低。在4μg/m L KSCN、C6H8O7、KCl、KH2PO4、KHCO3和Mn SO4·H2O沙柱中,15 d后2龄幼虫的平均迁移距离最小,分别为0、0.33、0.52、0.53、0.55和0.58 cm,而对照为0.94 cm。2龄幼虫在Ba NO3、K2HPO4、KHCO3、Cs Cl和KSCN各浓度沙柱中的平均迁移距离均小于0.94 cm。2μg/m L NH4NO3、KH2PO4、(NH4)2CO3、Cs Cl、(NH4)2SO4、Na SCN和NH4SCN处理15 d后,2龄幼虫对番茄根部的侵入率最低,分别为1%、2.33%、1.33%、2%、2%、1%和1.67%。表明对2龄幼虫侵入番茄根部抑制效果最明显的盐为NH4NO3、KH2PO4、(NH4)2CO3、Cs Cl、(NH4)2SO4、Na SCN和NH4SCN。     

四种无机盐对南方根结线虫卵囊、卵孵化及其幼虫存活的影响

为了明确NH4HCO3、CuSO4.5H2O、CsCl、NH4NO34种无机盐对南方根结线虫卵囊、卵孵化及其幼虫存活的影响。在室内条件下,采用浸渍法测试了4种无机盐在不同浓度和时间处理的作用效果。结果显示：各种无机盐均对线虫卵、卵囊孵化有抑制作用,对2龄幼虫有致死作用。随着无机盐浓度的增加和处理时间的延长,线虫卵、卵囊孵化的抑制率和2龄幼虫的死亡率显著提高。其中0.05 mol/L NH4HCO3对线虫卵囊孵化的抑制效果最好,处理16 h达81.17%,24 h后达100%;对线虫卵孵化也有很强的抑制作用,处理16 h达93.33%,24 h后达100%。各种无机盐在不同浓度和处理时间内均对2龄幼虫有致死效果,且半致死中浓度LC50不同,其中CuSO4.5H2O的LC50最小,NH4HCO3和CsCl次之。表明CuSO4.5H2O对南方根结线虫2龄幼虫有较强的致死活性,南方根结线虫2龄幼虫对CsCl的敏感性较高。     

青霉菌Snef1216发酵液诱导番茄抗南方根结线虫研究

 通过Snef1216发酵液处理番茄根系和包衣种子,研究番茄抗南方根结线虫的组织病理学变化和作用方式。结果显示:处理番茄根系且接种15 d,应答根系内根结线虫的数量减少47.5%,且巨细胞出现空泡;包衣番茄种子,接种4、8和12 d,根系内2龄幼虫分别减少54.1%、3.4%和41.7%,接种10、20和30 d,根系内2龄、3龄、4龄幼虫和雌虫的数量也均比对照组番茄明显减少。表明Snef1216发酵液诱导了番茄对南方根结线虫的抗性。     

铵类化合物对南方根结线虫2龄幼虫存活的影响

在实验室内寄主体外测定了铵类化合物对南方根结线虫2龄幼虫（Meloidogyne incognita J2）存活的影响。结果表明：供试的8种化合物在不同浓度下对南方根结线虫J2有不同程度的致死作用,并且随着浓度的升高致死效果均显著增加。其中NH4HCO3对J2作用最为敏感,浓度为0.025 mol/L（25 ℃,pH 7.95）时校正死亡率达53.5%,浓度达到0.05 mol/L（25 ℃,pH 8.20）时校正死亡率可达100%,而其他化合物只有在高浓度时致死效果才显现出来。致死浓度由低到高的顺序为：NH4HCO3＜(NH4)2SO4＜NH4CNS＜NH4NO3 ＜NH4H2PO4＜NH4Cl＜(NH4)3PO4•3H2O＜(NH4)2HPO4。同时测定了南方根结线虫J2的酸度适应范围是pH4.1~11.0。     

南方根结线虫二龄幼虫对不同类型盐离子的趋化反应

为了明确南方根结线虫对不同类型盐离子的趋化性,在琼脂糖平板培养基上测试了南方根结线虫2龄幼虫对37种无机盐和11种有机盐的趋化反应。结果表明,Cl-和SCN-盐对南方根结线虫均有排斥作用;对南方根结线虫有排斥作用的NO-3盐为Ba(NO3)2、NH4NO3、Mn(NO3)2;H2PO-4或HPO2-4盐为KH2PO4、K2HPO4;CO2-3或HCO-3盐为 Na2CO3、K2CO3、(NH4)2CO3 和KHCO3;OH-盐为KOH和 NaOH;有机酸为C2H4O2、C3H6O3和C4H6O6。含有相同阳离子的不同盐对南方根结线虫的吸引或排斥作用不受影响。阴离子对南方根结线虫的排斥作用大小为SCN->NO-3>Cl->OH->CO2-3> H2PO-4>有机酸>SO2-4。只有KCl、Ba(NO3)2、NH4NO3、Mn(NO3)2、(NH4)2CO3、C2H4O2和 C4H6O6对线虫的趋化性随浓度的增加而增加,而其他被测试的41种盐浓度对线虫的趋化性没有显著影响。     

长枝木霉菌株TL16防治南方根结线虫的作用机理

为探明长枝木霉Trichoderma longibrachiatum菌株TL16防治南方根结线虫Meloidogyne incognita的作用机理,采用原生质体转化法获得绿色荧光蛋白(green fluorescent protein,GFP)标记菌株GFP-TL16,通过测定菌株TL16和GFP-TL16对南方根结线虫卵和2龄幼虫(2nd-stage juvenile,J2)的寄生与致死作用,其发酵液对卵孵化的抑制作用和对J2的致死作用,以及菌株GFP-TL16在黄瓜根系的定殖情况和菌株TL16对番茄根结形成的抑制作用来综合分析其作用机理。结果显示:菌株TL16菌丝对南方根结线虫卵无寄生作用,处理19 d后卵降解率为26.33%,致死作用较低;菌株TL16分生孢子悬浮液处理南方根结线虫J2后72 h的致死率为1.65%,且无寄生作用。菌株TL16发酵液处理南方根结线虫J2后48 h的校正死亡率为10.71%,处理卵15 d后对卵孵化的相对抑制率为77.11%。菌株GFP-TL16可定殖于黄瓜根系中,经菌株TL16处理后接种南方根结线虫J2,番茄根结减退率为55.88%。表明长枝木霉菌株TL16可通过抑制根结线虫卵孵化和诱导番茄产生抗病性来防治根结线虫病。     

无机化合物对南方根结线虫行为的影响

利用体外生物测定方法,研究常见无机化合物对南方根结线虫Meloidogyne incognita 2龄幼虫(J_2)存活、趋性以及卵囊内卵孵化的影响.结果表明,不同化合物不同浓度处理对M.incognita的影响差异显著.随着无机化合物浓度的增加,J_2死亡率上升,NH_4HCO_3、Na_2SO_4、CuCl_2·2H_2O、CuSO_4·5H_2O和FeCl_3·6H_2O浓度分别为O.03、0.03、0.0003、0.0004和0.0007 mol/L即可抑制其存活.除Cu~(2+)化合物外,其它无机化合物在供试浓度下均对卵囊内卵的孵化有明显抑制作用.含Ca~(2+)化合物均对南方根结线虫J_2有吸引作用,而含NH_4~+的NH_4HCO_3和NH_4NO_3对J_2排斥.除碳酸氢铵LC_(90)抑制种子萌发外,其它化合物对番茄种子萌发无抑制作用,但对后期幼根的伸长有抑制作用.盆栽试验结果显示,CuSO_4·5H_2O防治效果最佳,在LC_(50)处理下与对照相比防效可达70.8%.     

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。     

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。     

无机化合物对南方根结线虫作用方式的研究

利用体外生物测定方法检测碳酸氢铵、硫酸铜和氯化铁在供试浓度下对南方根结线虫2龄幼虫（Meloidogyne incognita J2）存活的影响,以及药剂对其运动行为、个体发育、呼吸及体液外渗等的影响。结果表明,3种化合物在LC90浓度下使南方根结线虫2龄幼虫50% 致死时间不超过10.14 h,90%致死时间不超过22.66 h,离体条件下均对南方根结线虫2龄幼虫存活有强烈的抑制作用,显著降低了其运动行为,使其体长缩短、透明尾变长。并且,药剂处理均降低了线虫的呼吸作用,线虫悬浮液的电导率明显高于对照。     

Fenton试剂降解除草剂溴嘧草醚的反应动力学研究

探讨了Fenton试剂对超高效除草剂溴嘧草醚(ZJ0777)的降解反应。考察了溴嘧草醚、过氧化氢、硫酸亚铁的初始浓度和反应温度等因素对溴嘧草醚降解反应的影响,建立了Fenton试剂降解溴嘧草醚的动力学方程。结果表明:在溴嘧草醚初始浓度分别为0.12和0.24 mmol/L时,达到其降解率90%以上所需的时间分别为32和48 h,而在溴嘧草醚为0.48 mmol/L时,反应84 h只有87%的溴嘧草醚降解;过氧化氢初始浓度在150~300 mmol/L范围内,浓度增加有利于降解反应进行;溴嘧草醚降解反应随亚铁离子浓度的增加而加快(5~20 mmol/L),但过高的亚铁离子浓度对降解反应无效。温度在25~45℃范围内,反应的表观活化能Ea为75.34 kJ/mol。溴嘧草醚的氧化降解符合假一级反应动力学模型。     

Host-parasite relationships in tobacco plants infected with a root-knot nematode (<Emphasis Type="Italic">Meloidogyne incognita</Emphasis>) population from the Azores

During a nematode survey, severe infections of tobacco feeder roots and heavy soil infestations byMeloidogyne incognita race 1 were found in S. Miguel (Azores islands, Portugal). This is the first record ofM. incognita infection of tobacco in Azores. Morphology of various life stages, analysis of the esterase electrophoretic pattern and differential host tests were used for nematode characterization and identification. Nematode-induced mature galls were spherical and/or ellipsoidal and usually contained more than one female, males and egg masses with eggs. Feeding sites were characterized by the development of giant cells that contained granular cytoplasm and many hypertrophied nuclei. Giant cell cytoplasm was aggregated along a thickened cell wall. Vascular tissues within galls appeared disorganized. The relationship between the initial nematode population density and growth of tobacco plants was tested in a glasshouse experiment in which inoculum levels varied from 0 to 512 eggs and juveniles (J₂) cm⁻³ of soil. Seinhorst’s model was fitted to height and top fresh weight data of the inoculated and control plants. Tolerance limits with respect to plant height and fresh top weight of tobacco cv. ‘Erzegovina’ plants toM. incognita race 1 were estimated as 1.25 eggs and J₂ cm⁻³ of soil. The maximum nematode reproduction rate was 404.7 at an initial population density of 4 eggs and J₂ cm⁻³ of soil. http://www.phytoparasitica.org posting March 2, 2004.     

土壤中南方根结线虫的实时荧光PCR检测和定量

为了准确测定土壤中南方根结线虫Meloidogyne incognita的群体密度,根据序列特异性扩增区标记设计了南方根结线虫特异性引物和TaqMan探针,分别建立了卵和2龄幼虫的实时荧光PCR定量检测体系,并将该检测体系与显微镜计数法进行了比较.结果表明,引物Mi-F/R及探针Mi-probe对南方根结线虫具有高度特异性,建立的标准曲线循环阈值与卵和2龄幼虫数量的对数值之间具有良好的线性关系,相关系数分别为0.9771和0.9853,扩增效率均为90％,检测灵敏度为10-1个卵及10-3条2龄幼虫;对10个田间土壤样本的检测显示,实时荧光PCR定量检测与显微镜计数法测定的南方根结线虫卵和2龄幼虫数量呈显著正相关,且两种方法对2龄幼虫的测定结果无显著差异.     

Resistance to <Emphasis Type="Italic">Meloidogyne incognita</Emphasis> expresses a hypersensitive-like response in <Emphasis Type="Italic">Coffea arabica</Emphasis>

Root-knot nematodes (RKN) are obligate parasite species of the genus Meloidogyne that cause great losses in Arabica coffee (Coffea arabica L.) plantations. Identification of resistant genotypes would facilitate the improvement of coffee varieties aiming at an environmental friendly and costless nematode control. In this work, the C. arabica genotype ‘UFV 408-28’ was found to be resistant to the most destructive RKN species M. incognita. Pathogenicity assays indicated that the highly aggressive populations of M. incognita races 1, 2 and 3 were not able to successfully reproduce on ‘UFV 408-28’ roots and displayed a low gall index (GI = 2). An average reduction of 87% reduction of the M. incognita population was observed on ‘UFV 408-28’ when compared to the susceptible cultivar ‘IAC 15’. By contrast, ‘UFV 408-28’ was susceptible to the related species M. exigua and M. paranaensis (GI = 5 and 4, respectively). Histological observations performed on sections of UFV408-28 roots infected with M. incognita race 1 showed that nematode infection could be blocked right after penetration or during migration and establishment stages, at 6 days, 7 days and 8 days after infection (DAI). Fluorescence and bright field microscopy observations showed that root cells surrounding the nematodes exhibited HR-like features such as accumulation of phenolic compounds and a necrotic cell aspect. In the susceptible ‘IAC 15’ roots, 6 DAI, feeding sites contained giant cells with a dense cytoplasm. Necrotic cells were never observed throughout the entire infection cycle. The HR-like phenotype observed in the ‘UFV 408-28’—M. incognita interaction suggests that the coffee resistance may be mediated by a R-gene based immunity system and may therefore provide new insights for understanding the molecular basis of RKN resistance in perennial crops.     

Host-pathogen interaction of root-knot nematode <Emphasis Type="Italic">Meloidogyne incognita</Emphasis> on pepper in the southeast of Spain

The feeder roots of pepper plants (cv. California Wonder) in Campo de Cartagena (southeast Spain) were found to be severely infected by Meloidogyne incognita. Morphometric traits, differential host test and DNA analysis based on PCR were used to characterize the nematode. Naturally and artificially infected pepper plants showed severe yellowing and stunting, with heavily deformed and damaged root systems. Root galls were spherical and commonly contained more than one female and egg masses with eggs. Typical giant cells with a granular cytoplasm and many hypertrophied nuclei were observed in histological preparations. The relationship between initial nematode population density (Pi) and pepper plant growth was tested in greenhouse experiments with inoculum levels that varied from 0 to 64 eggs and second-stage juveniles (J₂) ml⁻¹ soil. A Seinhorst model was fitted to plant height and top fresh weight data of inoculated and non-inoculated plants. The tolerance limit with respect to plant height and fresh top weight of pepper to M. incognita was estimated as 0.85 eggs and J₂ ml⁻¹ soil. The minimum relative values (m) for plant height and top fresh weight were 0.15 and 0.16, respectively, at Pi ≥ 64 eggs and J₂ ml⁻¹ soil. The maximum nematode reproduction rate (Pf/Pi) was 315.4 at an initial population density (Pi) of 4 eggs and J₂ ml⁻¹ soil. The obtained results could be used as a base to establish field experiments that allow strategies to prevent surpassing the threshold of nematodes in fields that are infested.     

利用磷肥厂副产氟硅酸防治小麦锈病的研究

作者于1966半报告了氟硅酸对小麦条锈病具有良好药效,氰硅酸是磷肥厂副产,资源丰富、成本低廉。1971年又用氟硅酸与尿素制成便于运输和贮存的晶态的氟硅脲,其分子式为[(NH_2)_2CO]_4·H_2SiF_6。十多年来经过15个省市的田间试验,肯定了氟硅酸和氟硅脲对小麦三种锈病均有效。在山东烟台地区和四川内江地区的大面积推广试用均取得良好效果。防治有效浓度按H_2SiF_6计为0.05～0.10%,药液中须加入湿润剂。除扬花期不可喷药外,其它生育期均可喷药。对小麦的增产效果显著。小麦种子中未发现氟的反常残留。经卫生部门测定,十个样本中有6个氟残留量为0.71～1.98ppm,有1个样本中为3.47ppm,系过量喷药所致。其余3个样本中未检出氟。本文讨论了使用无机氟剂的环境保护问题。根据地球化学和环境化学的最近研究成果,在本文所建议采取的使用浓度下,用氟硅酸防治小麦锈病并无引起环境污染之虞。     

Pathogenicity and host‐parasite relationships of the root‐knot nematode Meloidogyne incognita on celery

Pathogenicity and host‐parasite relationships in root‐knot disease of celery (Apium graveolens ) caused by Meloidogyne incognita race 1 were studied under glasshouse conditions. Naturally and artificially infected celery cv. D’elne plants showed severe yellowing and stunting, with heavily deformed and damaged root systems. Nematode‐induced mature galls were spherical and/or ellipsoidal and commonly contained more than one female, males and egg masses with eggs. Feeding sites were characterized by the development of giant cells that contained granular cytoplasm and many hypertrophied nuclei. The cytoplasm of giant cells was aggregated along their thickened cell walls and consequently the vascular tissues within galls appeared disrupted and disorganized. The relationship between initial nematode population density (Pi) and growth of celery plants was tested in glasshouse experiments with inoculum levels that varied from 0 to 512 eggs and second‐stage juveniles (J₂) mL^?1 soil. Seinhorst's model y = m + (1 – m)z^P–T was fitted to height and top fresh weight data of the inoculated and control plants. The tolerance limit with respect to plant height and fresh top weight of celery to M. incognita race 1 was estimated as 0·15 eggs and J₂ mL^?1 soil. The minimum relative values (m) for plant height and top fresh weight were 0·37 and 0·35, respectively, at Pi ≥ 16 eggs and J₂ mL^?1 soil. The maximum nematode reproduction rate (Pf/Pi) was 407·6 at an initial population density (Pi) of 4 eggs and J₂ mL^?1 soil.