地表球囊霉诱发番茄抗早疫病的机理

丛枝菌根可以改善植物营养状况,提高宿主植物的抗病性.本文研究了番茄幼苗预先接种丛枝菌根真菌(AMF)地表球囊霉后对番茄植株保护酶活性和防御反应基因表达,以及对番茄早疫病抗性的影响.结果表明:被AMF侵染的番茄植株在接种早疫病病原菌茄链格孢菌后,其叶片内的超氧化物歧化酶(SOD)和过氧化物酶(POD)活性迅速提高.其中SOD酶活性在接种后18h达到最高,比只接种地表球囊霉(G)、茄链格孢菌(A)以及未接种AMF和病原菌的对照(CK)分别高28.6％、79.2％和82.8％;POD酶活性在接种后65 h达到最高,分别比G、A处理和CK高762％、18.3％和1710％.经荧光定量PCR检测表明,AMF侵染后的番茄植株再接种病原菌,其叶片中PR1(病程相关蛋白基因)、PR2(β-1,3-葡聚糖酶基因)和PR3(几丁质酶基因)基因的最高转录水平达到CK的9.67、8.54和13.4倍.与CK相比,先接种地表球囊霉再接种茄链格孢菌的番茄植株(GA)的早疫病发病率和病情指数分别降低了36.3％和61.4％.预先接种AMF的番茄植株在遇到病原菌袭击时诱导的防御反应强而迅速,诱发(priming)可能是菌根真菌提高宿主植物抗病性的重要机制.     

丛枝菌根真菌摩西管柄囊霉侵染增强番茄对机械损伤的响应

植食性昆虫取食会给植物造成机械损伤并激活植物的防御反应,而与有益微生物共生是否可以增强植物对机械损伤的响应对植物抗虫有重要意义.本研究在番茄根系被丛枝菌根真菌摩西管柄囊霉侵染后,研究机械损伤对番茄防御反应的影响.结果表明: 预先接种菌根真菌的番茄叶片受到机械损伤处理(FD)后,叶片苯丙氨酸解氨酶(PAL)、超氧化物歧化酶(SOD)、过氧化物酶(POD)、多酚氧化酶(PPO)和过氧化氢酶(CAT)活性,以及叶片和根系苯丙氨酸解氨酶基因(PAL)和β-1,3-葡聚糖酶基因(PR2)的转录水平均显著高于只进行机械损伤的处理(D)、只接种摩西管柄囊霉的处理(F),以及既未接种菌根菌也未进行机械损伤的健康番茄植株(CK).虽然D和 F处理也可诱导部分酶活性及基因转录水平升高,但FD处理诱导的防御反应更迅速和强烈.表明丛枝菌根真菌侵染可以警备(prime)番茄对机械损伤做出更快速和强烈的响应.     

外源钙和茉莉酸甲酯诱导番茄植株抗灰霉病研究

以‘辽园多丽’番茄幼苗为材料,研究了经钙(Ca)、钙螯合剂(EGTA)和茉莉酸甲酯(MeJA)处理后接种番茄灰霉病幼苗叶片的病情指数、活性氧(H2O2、O2.-)含量和过氧化氢酶(CAT)、超氧化物歧化酶(SOD)、过氧化物酶(POD)活性的变化。结果显示:(1)Ca、MeJA、MeJA+Ca处理番茄幼苗的灰霉病发病率分别比对照显著降低32.5%、38.0%和54.5%,而MeJA+Ca处理又显著低于Ca、MeJA处理32.6%和15.3%;MeJA+EGTA处理高于MeJA处理30.3%,但低于EGTA处理13.1%;Ca处理低于EGTA处理34.2%。(2)Ca、MeJA及MeJA+Ca处理番茄幼苗叶片中活性氧积累量高于对照,MeJA+Ca处理又高于Ca、MeJA处理;但MeJA+EGTA处理活性氧积累量低于MeJA处理,而高于EGTA处理;Ca处理的活性氧含量高于EGTA处理。(3)Ca、MeJA及MeJA+Ca处理幼苗叶片的SOD、CAT、POD的活性均比对照提高,且以MeJA+Ca处理最高;而MeJA+EGTA处理抗氧化酶活性低于MeJA处理,但高于EGTA处理;Ca处理抗氧化酶活性高于EGTA处理。研究表明,钙在茉莉酸甲酯诱导番茄抗灰霉病过程中具有重要调节作用,这种作用与钙促进茉莉酸甲酯诱导番茄活性氧积累和抗氧化酶活性有关。     

接种微生物对大豆生长及其根际土壤的影响

对沙土中的大豆接种丛枝菌根真菌及丛枝菌根真菌与解磷菌和根瘤菌联合接种, 动态监测大豆的生长状况和营养吸收情况。结果表明, 在沙土中, 根瘤菌与丛枝菌根真菌的组合效应对豆科植物营养元素的改善最为有效。接种丛枝菌根真菌以及丛枝菌根真菌与其他微生物联合应用对宿主矿质营养吸收尤其是磷吸收有明显的促进作用, 种植30 d、45 d 和64 d 接菌处理植物叶片的平均全磷含量比对照分别高1.45%、73%和56%。接种微生物使植物从土壤中吸收氮、磷、钾元素的强度比对照高, 接菌植物根际土壤养分浓度低于对照。接菌植物生物量显著高于对照, 单接种丛枝菌根真菌处理、双接种丛枝菌根真菌与解磷菌、双接种丛枝菌根真菌与根瘤菌以及丛枝菌根真菌、解磷菌与根瘤菌三种菌剂混合处理的总生物量分别比对照高出181%、134%、153%和89%。丛枝菌根真菌与解磷菌和根瘤菌三种菌剂混合接种对植物的促生作用并不明显。     

茄二十八星瓢虫为害对不同基因型番茄叶内三种抗性酶活性的影响

【目的】研究茉莉酸合成相关基因在番茄抗茄二十八星瓢虫Henosepilachna vigintioctopunctata Fabricius中的作用,探讨茉莉酸信号因子在植物防御过程中起到的作用。【方法】利用3种基因型番茄茉莉酸合成缺失突变体spr2、茉莉酸合成过量表达体35s、野生型番茄Wt为材料,通过经2龄茄二十八星瓢虫分别取食6、24、48 h后,利用分光光度计测定3种基因型番茄叶片内苯丙氨酸解氨酶(Phenylalanineammonialyase,PAL)、胰蛋白酶抑制剂(Protease inhibitors,PI)和脂氧合酶(Lipoxygenase,LOX)酶活性的动态变化。【结果】35s型番茄叶片内PI活性显著高于另两种番茄叶片,而spr2型番茄叶片PI活性最低。瓢虫为害后,3种基因型番茄PI酶活性明显提高,在35s和Wt型番茄中,PI和LOX酶活性在胁迫24 h和6 h达到最高值,而spr2型番茄没有显著变化。受到瓢虫侵染的系统叶中,PI和LOX酶活性也受到了诱导,系统叶变化趋势同危害叶相同,但诱导的PI和LOX酶活性明显低于危害叶。在危害处理过程中,均呈现上升-下降的趋势,在系统叶中,则PAL活性没有显著变化。番茄叶片受害后,PI和LOX酶活性上升辐度大于PAL,说明PI和LOX对取食胁迫响应比PAL更敏感。【结论】35s茉莉酸合成过量表达体的番茄对茄二十八星瓢虫有一定的抗虫作用,因此,茉莉酸在植物抗性中起了一定作用。     

外源茉莉酸甲酯诱导大麦对叶斑病抗性的研究

[目的]初步探讨不同浓度外源茉莉酸甲酯（MeJA）诱导大麦抗叶斑病效应差异及其分子机制,为应用MeJA防治大麦叶斑病提供理论依据。[方法]以‘蒙啤麦3号’大麦品种幼苗为材料,设置不接菌（无菌水处理叶片）、接菌（无菌水处理叶片接种麦根平脐蠕孢菌）和接菌+MeJA（0.5、1.0、1.5、2.0、2.5 mmol/L MeJA喷施叶片后接菌）3组处理,于三叶期调查叶斑病发病情况并据此筛选最适MeJA浓度,然后测定不接菌、接菌及接菌++ MeJA（最适浓度）处理不同处理时间叶片的抗氧化酶、抗病相关酶活性、丙二醛、渗透调节物质含量以及相关基因表达水平。[[结果]]：（1）叶面喷施外源MeJA提高了大麦对叶斑病的抗性,1.5 mmol/L MeJA处理叶片的病情指数较对照显著降低19.03%,诱导抗性效果最佳;（2）与单独接菌处理相比,1.5 mmol/L MeJA处理大麦叶片超氧化物歧化酶、过氧化物酶、过氧化氢酶、几丁质酶和β-,1,3-葡聚糖酶活性均显著提高,而其丙二醛、脯氨酸、可溶性糖和可溶性蛋白含量显著降低,同时其受MeJA调控转录因子及编码抗病相关酶的基因表达量显著上调。[结论]外源喷施1.5 mmol/L MeJA通过调节抗病相关酶活性和渗透调节物质含量,以及调控抗病相关酶基因及茉莉酸信号途径关键转录因子基因表达,进而提高大麦植株的叶斑病抗病性。     

不同基质中番茄菌根苗的培育及其抗南方根结线虫的效果

根结线虫病是番茄主要的土传病害,特别是保护地长期种植会加重病害的发生.接种丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)能提高植物抗根结线虫的能力,促进植株生长发育,减轻病害.本试验旨在评价常用基质配合施用一种生物有机肥对番茄苗生长和菌根定殖的影响,以获得菌根发育良好且生长健壮的菌根苗...     

AMF增强枳抗旱性作用机制的初步研究

丛枝菌根真菌(AMF)能增强寄主植物的抗旱性,但相关机制仍不清楚。本研究分析了正常水分和干旱处理对比下AM真菌Diversispora versiformis对盆栽枳(Poncirus trifoliata)生长、光合作用和叶片激素含量的影响。结果表明,6周的干旱处理强烈抑制D.versiformis对枳根系的侵染。干旱处理下,AM真菌接种处理均显著提高了叶、茎和根系生物量,显著增强了叶片光合速率、蒸腾速率和气孔导度,同时显著降低了叶片温度(P0.05)。AM真菌接种也增加了干旱条件下枳叶片内源脱落酸、吲哚乙酸、赤霉素、油菜素内酯、茉莉酸甲酯、玉米素核苷和一氧化氮含量。推测AM真菌通过改变植物内源激素平衡状况,进而诱导相关激素信号传导进程,从而参与菌根的形成、植物生长进程,并增强植物抗旱性。     

丛枝菌根菌丝桥介导的番茄植株根系间抗病信号的传递

菌根菌丝桥是植物间在地下进行物质交流的通道, 但它能否作为植物间地下化学通讯的通道来传递抗病信号则缺乏研究. 本文利用丛枝菌根真菌（AMF）摩西球囊霉在供体与受体番茄植株间建立菌丝桥, 对供体植株接种早疫病病原菌茄链格孢菌, 研究供体与受体番茄植株根系间是否存在抗病信号的传递. 荧光定量PCR检测表明, AMF侵染后的供体番茄植株再接种病原菌, 其根系中苯丙氨酸解氨酶基因（PAL)、脂氧合酶基因（LOX）和几丁质酶基因（PR₃）的转录水平显著高于仅接种病原菌、未接种病原菌和AMF, 以及只接种AMF的番茄植株. 更重要的是, 与供体有菌丝桥连接的受体番茄根系中PAL、LOX和PR₃的基因的表达量也显著高于无菌丝桥连接、菌丝桥连接被阻断以及有菌丝桥连接但供体植物未接种病原菌的处理,3个基因最高转录水平达到无菌丝桥连接对照受体植物的4.2、4.5和3.5倍. 此外, 供体植株根系启动防御反应的时间（18和65 h）比受体（100和140 h）早. 表明病原菌诱导番茄供体根系产生的抗病信号可以通过菌丝桥传递到受体根系.     

菌丝桥介入枳根系间抗溃疡病的信号物质响应

对两室根箱试验装置中一分室(供体室)定植的枳Poncirus trifoliata实生苗接种丛枝菌根(AM)真菌Paraglomus occultum,另一分室(受体室)不作任何处理。定植17周后,将溃疡病病菌Xanthomonas axonopodis(Xac)接种于供体植株,研究不同处理受体植株间的信号物质响应差异,揭示菌丝桥的功能。与不接种处理相比,单接种AM真菌、预先接种AM真菌后再接种Xac均显著提高了供体根系一氧化氮(NO)含量,单接种AM真菌只显著提高了受体根系NO含量;单接种Xac显著降低了供体根系脱落酸(ABA)含量,而单接种AM真菌、双接种(AM真菌+Xac)均增加了供体根系ABA含量。双接种处理显著提高了受体ABA含量;与不接种对照相比,接种处理均降低了供体根系玉米素核苷(ZR)含量,同时单接种AM真菌、双接种处理也降低了受体根系ZR含量;AM真菌显著降低了供体和受体根系茉莉酸(JA)含量,但双接种却显著提高了供体和受体根系JA含量;与不接种对照相比,单接种AM真菌或Xac、双接种处理均显著下调供体根系JA合成基因(PtLOX、PtAOS和PtAOC)的表达,单接种Xac显著下调了受体根系PtLOX和Pt AOC的表达,单接种AM真菌显著下调了受体根系PtAOC的表达,而双接种显著上调了受体根系PtAOS基因的表达。表明菌根真菌的菌丝桥传导JA并诱导受体植株中NO、ABA和ZR含量改变以抵御溃疡病菌危害。     

Variability of Lycopersicon hirsutum f. typicum and possible compounds involved in its resistance to Tuta absoluta

1 The resistance of Lycopersicon hirsutum f. typicum and L. esculentum to the leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) was investigated in two experiments. The first experiment assessed the resistance of L. hirsutum f. typicum (accession LA 1777) to T. absoluta, the second assessed the variability of the resistance among plants of this accession. 2 It was found that L. hirsutum f. typicum was resistant to the leafminer, which showed longer larval phase, higher larval mortality, smaller numbers of large mines and greater numbers of small mines/leaf than on L. esculentum. Seven plants of the accession LA 1777 showed lower number of small mines/leaf, but their results of larval mortality and length of larval and pupal phase were similar. Twenty-two peaks were observed in total ion chromatograms of L. hirsutum f. typicum hexane extracts of leaves subjected to a gas chromatographic-mass spectrometric analysis (CG-MS). However, the matches obtained between the peak spectra and the MS database were too low to justify even preliminary identification of the compounds.     

The contribution of tomato and alternative host plants to tomato leaf curl virus inoculum pressure in different areas of South India

Indian tomato leaf curl virus (ToLCV) (Geminiviridae: Sub-group III) was detected both in field-collected and laboratory-reared B. tabaci using a triple-antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA). ToLCV was detected in six of the 10 group samples of field collected B. tabaci. ToLCV was also identified in 13 weed species commonly found in Karnataka, both by symptom expression and TAS-ELISA. ToLCV from c. 61% of infected plants was transmitted successfully to tomato by B. tabaci. Tomato plots were planted at three locations on the University of Agricultural Sciences Campus, Bangalore. Indian tomato leaf curl virus disease (ToLCVD) incidence increased most rapidly when the tomato plot was situated adjacent to an older ToLCVD-infected tomato field. When the plots were positioned in a dryland or a wetland area, at least 500 m away from any infected tomato fields, the ToLCVD incidence increased less rapidly, although in all sites it was 100% by 11 wk after transplanting. The numbers of B. tabaci caught on yellow traps in all sites increased during weeks 1–3 after transplanting and thereafter remained at between 10–15 adults trap^-1 24 h^_1. Adult numbers recorded on tomato plants by direct counts remained approximately constant at 2–4 adults plant“”¹. Tomato fields were planted in three taluks (administrative areas) of Karnataka, that had different current and previous histories of tomato production. ToLCVD incidence increased most and least rapidly, respectively, in Kolar taluk where tomato is grown continuously and Doddaballapur tuluk where tomato was grown in the area for the first time. In Malur tuluk, where tomato was grown discontinuously (once a year), the incidence of ToLCVD increased at an intermediate rate. Weed host-plant species growing near the experimental sites had averages of between 1.5–10.0 B. tabaci nymphs per plant, whereas the tomato plants had only 0.3 nymphs per plant. The percentage parasitism of B. tabaci nymphs on tomato and weed species, respectively, was 0.7% and 2–6%. Nymphs and pupae were parasitised by an Encarsia sp. and Eretmocerus mundus Mercet. The relevance and implications of these findings for the epidemiology and management of ToLCVD in Karnataka State, South India is discussed.     

辽宁省番茄细菌性斑疹病的病原鉴定

[目的]对在辽宁部分地区采集的番茄细菌性病害病原菌进行鉴定.[方法]对病原菌进行革兰氏染色、培养性状、生理生化特性、16S rRNA基因序列测定以及hrpZpst基因特异性扩增.[结果]鉴定该病原菌为丁香假单胞杆菌番茄致病变种[Pseudomonas syringae pv.tomato (Okabe) Young,Dye & Wilkie].[结论]利用hrpZpst基因特异性扩增可以快速鉴定病原菌.     

Serological studies on the accumulation and localisation of three tomato leaf curl geminiviruses in resistant and susceptible Lycopersicon species and tomato cultivars

Accessions of wild Lycopersicon spp. and selected Fl hybrid tomato cultivars were compared for their resistance to three whitefly-transmissible geminiviruses: Indian tomato leaf curl virus (ITmLCV) and tomato yellow leaf curl viruses from Sardinia (TYLCV-Sar) and Senegal (TYLCV-Sen). The resistance of different plant lines was expressed in different ways but in most instances a given line reacted similarly to graft inoculation with the three viruses. L. pimpinellifolium LA1478 produced as much virus antigen, assessed by triple antibody sandwich-ELISA, as the susceptible cv. Moneymaker but developed only very mild symptoms and is therefore tolerant of infection. In L. hirsutum LA1777 and L. peruvianum CMV-INRA, very mild or no symptoms developed but antigen concentrations were substantially less than in Moneymaker. L. chilense LA1969 remained symptomless and its antigen concentration was < 1% of that in Moneymaker. Symptoms were mild or barely evident in the Fl hybrid cultivars. Cultivars Tyking and Fiona had antigen concentrations about 5–10% of those of Moneymaker, whereas TY20, Top 21 and Tyger had intermediate antigen concentrations. In a few instances, the extent to which virus accumulation was restricted depended on the challenge virus. Accumulation of TYLCV-Sen in TY20, Top 21 and Tyger was less affected than that of the other two viruses, and accumulation of TYLCV-Sar in accessions LA1777 and CMV-INRA was less affected than that of TYLCV-Sen or ITmLCV. Tissue-printing tests showed that ITmLCV and TYLCV-Sen antigens were confined to phloem tissue. In Tyking, the number of virus antigen-containing phloem traces and the antigen content of individual traces were less than in Moneymaker but the partitioning of antigen between internal and external phloem was unaffected.     

番茄黄化曲叶病毒对番茄叶片光合特性和叶绿体超微结构的影响

以番茄为试验材料,研究番茄黄化曲叶病毒(TYLCV)侵染对植株叶片叶绿素含量、净光合速率、气孔导度、胞间CO2浓度和叶绿体超微结构的影响.结果表明:TYLCV侵染番茄后,叶片叶绿素a、b以及总叶绿素含量分别下降50.2%、24.19%和43.84%,叶片净光合速率和气孔导度分别下降43.28%、27.07%,胞间CO2浓度增加13.04%.与健康叶片相比,叶绿体变形,叶绿体基质片层大部分消解,基粒结构消失,叶绿体外膜和内膜剥离,质壁分离和细胞膜内陷,细胞器消解.研究表明,TYLCV侵染破坏了番茄叶片的叶绿体结构,严重影响番茄叶片的光合作用.     

Antisense-Mediated Depletion of Tomato Chloroplast Omega-3 Fatty Acid Desaturase Enhances Thermal Tolerance

A chloroplast-localized tomato （Lycopersicon esculentum Mill.） ω-3 fatty acid desaturase gene （LeFADT） was isolated and characterized with regard to its sequence, response to various temperatures, and function in antisense transgenic tomato plants. The deduced amino acid sequence had four histidine-rich regions, of which three regions were highly conserved throughout the whole ω-3 fatty acid desaturasegene family. Southern blotting analysis showed that LeFAD7was encoded by a single copy gene and had two homologous genes in the tomato genome. Northern blot showed that LeFAD7 was expressed in all organs and was especially abundant in leaf tissue. Meanwhile, expression of LeFAD7 was induced by chilling stress （4 ℃）, but was inhibited by high temperature （45 ℃）, in leaves. Transgenic tomato plants were produced by integration of the antisense LeFAD7DNA under the control of a CaMV35S promoter into the genome. Antisense transgenic plants with lower 18 ： 3 content could maintain a higher maximal photochemical efficiency （Fv/Fm） and O2 evolution rate than wild-type plants. These results suggested that silence of the LeFAD7 gene alleviated high-temperature stress. There was also a correlation between the low content of 18 ： 3 resulting from silence of the LeFAD7 gene and tolerance to high-temperature stress.     

Induced systemic resistance to tomato leaf curl virus and increased yield in tomato by plant growth promoting rhizobacteria under field conditions

The talc-based formulation of two Pseudomonas fluorescens strains (Pf1 and VPT10) and its mixture (with and without chitin) were tested against tomato leaf curl virus in tomato under greenhouse and field conditions. The mean percentage of tomato leaf curl virus infected plants were significantly lower (25%) with less symptom severity and delayed symptom expression up to nine additional days in Pseudomonas with chitin (VPT10 + chitin) treated tomato plants compared to non-bacterised control plants upon challenge inoculation with tomato leaf curl virus. Tomato leaf curl virus was partially purified and antiserum was developed. Using the antiserum the tomato leaf curl virus was detected in symptomatic leaves and in whitefly vector through direct antigen coating enzyme linked immunosorbent assay which revealed the low virus titre in Pseudomonas treated plants (VPT10 + chitin) and insect vector compared to untreated tomato plants. The results indicate the potentiality of plant growth promoting rhizobacteria strains and talc-powder formulations in the effective management of this tomato leaf curl virus in tomato under field conditions.     

Screening additional wild tomatoes for resistance to the whitefly-borne tomato yellow leaf curl virus

Plants of 25 wild Lycopersicon accessions were screened in the greenhouse for resistance to the whitefly-borne tomato yellow leaf curl virus (TYLCV). High levels of resistance were detected in 7 of 9 accessions of L. peruvianum and in all 5 accessions of L. chilense tested. In contrast, plants of 7 accessions of L. hirsutum and 3 of 4 accessions of L. pimpinellifolium were highly susceptible. Plants of accession CIAS 27 (L. pimpinellifolium) showed moderate resistance to TYLCV.     

Genetic analysis of the roles of phytochromes A and B1 in the reversed gravitropic response of the lz-2 tomato mutant

The lz-2 mutation in tomato ( Lycopersicon esculentum ) causes conditional reversal of shoot gravitropism by light. This response is mediated by phytochrome. To further elicit the mechanism by which phytochrome regulates the lz-2 phenotype, phytochrome-deficient lz-2 plants were generated. Introduction of au alleles, which severely block chromophore biosynthesis, eliminated the reversal of hypocotyl gravitropism in continuous red and far-red light. The fri ¹ and tri ¹ alleles were introduced to specifically deplete phytochromes A and B1, respectively. In dark-grown seedlings, phytochrome A was necessary for response to high-irradiance far-red light, a complete response to low fluence red light, and also mediated the effects of blue light in a far-red reversible manner. Loss of phytochrome B1 alone did not significantly affect the behaviour of lz-2 plants under any light treatment tested. However, dark-grown lz-2 plants lacking both phytochrome A and B1 exhibited reduced responses to continuous red and were less responsive to low fluence red light and high fluence blue light than plants that were deficient for phytochrome A alone. In high light, full spectrum greenhouse conditions, lz-2 plants grew downward regardless of the phytochrome deficiency. These results indicate that phytochromes A and B1 play significant roles in mediating the lz-2 phenotype and that at least one additional phytochrome is involved in reversing shoot gravitropism in this mutant.     

Particle purification, properties and epitope variability of Indian tomato leaf curl geminivirus

A whitefly-transmissible stock isolate of Indian tomato leaf curl geminivirus (ITmLCV) was cultured in graft-inoculated tomato plants and its particles purified from chloroform-clarified extracts in citrate buffer by precipitation with 70 g/litre polyethylene glycol, ultracentrifugation and sucrose density gradient centrifugation. Contaminating helical filaments were eliminated by banding in caesium sulphate gradients. ITmLCV particles had the shape typical for geminiviruses, measured c. 30 × 20 nm and contained a single major protein of estimated mol. wt c. 32 000. They reacted in immunosorbent electron microscopy with antisera to four other whitefly-transmitted geminiviruses. ITmLCV reacted with one out of 17 monoclonal antibodies specific for different epitopes in the particle protein of African cassava mosaic geminivirus and five or six out of 10 monoclonal antibodies to the particle protein of Indian cassava mosaic geminivirus. Virus isolates from tomato at nine locations in Karnataka State showed only slight differences in epitope profile, and isolates from four weed species in tomato fields were similar or identical to those from tomato.