青海省海东地区小麦赤霉病致病菌种及致病性研究

1993～1995年在青海海东地区采集1005个麦类赤霉病标样 ,鉴定结果表明其分别属于镰刀菌属的 7个种 ,其中禾谷镰刀菌(Fusarium graminearum)出现频率为54.3% ,接骨木镰刀菌 (F .sambucinum)出现频率为19.3% ,锐顶镰刀菌(F .acuminatum)、燕麦镰刀菌(F .avenaceum)和黄色镰刀菌(F .culmorum)出现频率均为6.5%,三线镰刀菌(F .tricinctum)和茄病镰刀菌(F .solani)为3.2%。对小麦穗部致病力测定结果 ,禾谷镰刀菌为“强” ,接骨木镰刀菌、茄病镰刀菌为“中-强” ,三线镰刀菌为“弱-中” ,黄色镰刀菌、锐顶镰刀菌和燕麦镰刀菌为“弱”     

烟草赤星病危害烤烟产量产值损失测定

在烤烟生长中后期 ,应用40%菌核净500倍液人为控制烟草赤星病发生程度 ,形成不同危害梯度 ,以研究烟草赤星病对产量产值的影响。经试验分析 ,建立数学模型。中上等烟产量损失率(Y₁)与病情指数(X)的关系式:Y₁=0.1516+1.2824X;产值损失率(Y₂)与病情指数(X)的关系式:Y₂=0.3239+0.9831X。     

昆明市白车轴草上蓟马种群动态调查

对昆明市白车轴草上蓟马种类及其周年种群动态进行了调查。白车轴草上蓟马主要有西花蓟马(Fran-kliniella occidentalis)、丽花蓟马(F.intonsa)、八节黄蓟马(Thrips flavidulus)、端大蓟马(Megalurothrips distalis)、稻单管蓟马(Haplothrips aculeatus)和烟蓟马(T.tabaci),有时会出现黄胸蓟马(T.hawaiiensis)、玉米黄呆蓟马(Anaphothrips obscurus)、苏丹呆蓟马(A.sudanensis)和云南纹蓟马(Aeolothrips yunnanensis)。本文分析了前6种蓟马的周年种群动态,重点阐述了外来有害生物西花蓟马,该虫主要在3~6月发生,是此期间白车轴草上的蓟马优势种。     

玉米地昆虫及捕食性节肢动物群落结构及动态研究

南宁市郊玉米地害虫、捕食性昆虫、蜘蛛及中性昆虫由90科315种组成,害虫、蜘蛛及捕食性昆虫是玉米地节肢动物群落组成及功能作用的主要群落。禾谷缢管蚜(Rhopalosiphum padi)、玉米螟(Ostrinia furnacalis)、六斑月瓢虫(Menochilus sexmaculata)、龟纹瓢虫(Propylaea japonica)、食虫沟瘤蛛(Ummeliata insecticeps)、锥腹肖蛸(Tetragnatha maxillosa)、八斑鞘腹蛛(Coleosoma octomaculatum)、类奇异獾蛛(Trochosa ruricoloides)和脉娲蛛(Wadicosa fidelis)等是群落的主体。分析了4个亚群落的时空格局及数量变动规律以及天敌对害虫的控制作用。     

肾状线虫属重要种类的鉴定和特征描述

记述了目前世界上认可的肾状线虫属(Rotylenchulus sp.)已知的10个种的重要鉴定特征、世界分布和寄主范围。这10个种包括越南肾状线虫(R.anamictus)、短管肾状线虫(R.brevitubulus)、北方贝肾状线虫(R.borea-lis)、短尾肾状线虫(R.clavicaudatus)、离异肾状线虫(R.leptus)、大囊肾状线虫(R.macrodoratus)、长肾状线虫(R.macrosoma)、微小肾状线虫(R.parvus)、肾形肾状线虫(R.reniformis)和甘蔗肾状线虫(R.sacchari)。并对其最具经济意义的两种线虫的特征进行了描述。     

稻水蝇危害水稻产量损失研究

采用相关分析和通径分析法研究了稻水蝇危害与水稻产量损失的关系。结果表明:水稻产量(y,kg/hm²)与田间虫口密度(x,头 /m²)、穗损失率 (x₅,% )间0.01水平显著时的关系符合方程:y^=9433.965-6.6637x₁-402.7469x₅;产量损失(Y,kg/hm²)与田间虫口密度(x,头/m²)间关系符合下列方程 :Y^=-13.4989+6.0043x(r=0.9647^**)。通径分析显示 ,穗损失率和虫口密度对产量建成直接效应最大 ,分别为-0.9218和-0.1422     

玉米鼠耳病研究进展

玉米鼠耳病(maize wallaby ear disease,MWED)是近年在我国玉米上新出现的病害,已对四川北部、重庆及贵州等地的玉米生产造成严重危害。该病在玉米上引起显著矮缩,叶变小,僵硬,叶背面形成白色、扁平的腊泪状瘿瘤等典型症状。玉米鼠耳病毒(Maize Wallaby Ear Virus,MWEV)可能与我国发生的玉米鼠耳病有关,国外报道MWEV的昆虫介体有3种:二点叶蝉(Cicadula bipunctella)、斑翅二室叶蝉(Balclutha punctata)及Nephotettix pallida,但研究表明我国发生的MWEV仅与二点叶蝉及斑翅二室叶蝉有关。更新栽培技术、改变生态条件及传播介体暴发是引起MWED流行的重要原因。本文综述了MWED的分布与危害、病原致病因子的鉴定、病害流行及防治等方面的研究进展。     

河南和宁夏朱砂叶螨、截形叶螨对3种药剂的抗性检测

以玻片浸渍法检测河南和宁夏两地区朱砂叶螨(Tetranychus cinnabarinus)和截形叶螨T.truncatus对3种药剂的抗性。结果表明,河南的朱砂叶螨和截形叶螨对三氯杀螨醇、久效磷表现抗性;对氧化乐果仍处在敏感水平。宁夏的两种叶螨对3种药剂都表现敏感。同时,截形叶螨对3种药剂的LC₅₀均高于朱砂叶螨。大田防治时应减少三氯杀螨醇的使用次数。截形叶螨为优势种时,禁止使用久效磷防治。提倡氧化乐果在防治棉花叶螨和兼治棉蚜时应用。     

湘南烟蚜发生量趋势预测方法研究

据宁远、郴州、芝山 3地 15年烟田蚜量系统调查 ,湘南烟蚜种群消长均为单峰型 ,符合抛物线方程。以百株蚜量lg值为预报量(Y) ,以5个气象因子及烟草生育期作预报因子 (X_i) ,对Y及X_i作 0、1化处理 ,采用指标交叉法建立预报方程。结果表明 ,对蚜量波动影响最大的前 6项因子依次为日平均气温 (X₂)、日最高气温 (X₃)、两次调查期间的总日照时数 (X₅)及X₂X₅、X₃X₅、X₂X₃。在天气预报准确的条件下 ,蚜量变动趋势预报的准确率可达 88.9%。     

昆虫对植物源手性气味的立体选择性识别

昆虫对手性植物气味表现出立体选择性反应和行为,手性识别影响植物/昆虫的关系。3种鳞翅目雌蛾对寄主中(-)-D-杜鹃烯高度敏感和具有高选择性反应。棉铃虫对α-蒎烯对映异构体表现出立体选择性的行为反应和记忆。云杉八齿小蠹(Ips typographus)利用其寄主中的(-)-α-蒎烯合成其聚集信息素(S)-Z-马鞭草烯醇。虫瘿雄蜂(Antistrophus rufus)通过识别其幼虫危害诱导的手性单萜异构体比例作为性信息素寻找雌蜂。     

云南凹头苋上分离到的2种菜豆金色花叶病毒属病毒基因组结构特征

菜豆金色花叶病毒属(Begomovirus)病毒是热带亚热带地区多种作物的重要病原,杂草作为该属病毒的中间寄主在病害发生流行中具有重要作用。本研究通过克隆、测序和生物信息学分析,对3株具有曲叶症状的凹头苋(Amaranthus lividus)进行菜豆金色花叶病毒属病毒的分离分析。从这些凹头苋中共分离到2种菜豆金色花叶病毒属病毒和3种beta卫星。序列分析显示,其中一种病毒与云南番茄黄化曲叶病毒相似性最高(96%),另一种与中国胜红蓟黄脉病毒相似性最高(96.5%或91%)。Beta卫星的分析显示,其中一种与云南番茄黄化曲叶beta卫星相似性最高(94.3%),另一种与赛葵曲叶beta卫星相似性最高(92%),最后一种与中国番茄曲叶beta卫星相似性最高(91%)。重组分析表明,分离物YN4331-69是一个重组病毒,是由中国胜红蓟黄脉病毒YN4326-60和一个尚未发现的菜豆金色花叶病毒属病毒重组形成。这是首次报道凹头苋被不同的菜豆金色花叶病毒属病毒及其伴随的beta卫星侵染,表明凹头苋是一个适宜该属病毒的中间寄主。     

广西胜红蓟黄脉病样中发现多种菜豆金色花叶病毒属的病毒

 双生病毒科(Geminiviridae)病毒是一组植物单链DNA病毒,它的特点是病毒粒子形态为孪生颗粒状。双生病毒分为菜豆金色花叶病毒属(Begomovirus)、甜菜曲顶病毒属(Curtovirus)、玉米线条病毒属(Mastrevirus)和番茄伪曲顶病毒属(Topocuvirus)^[1]。     

中国番木瓜曲叶病毒南宁分离物的基因组结构特征

 从广西南宁田间表现曲叶症状的番木瓜植株上分离到病毒分离物G4,经三抗体夹心ELISA (TAS-ELISA)检测,G4与粉虱传双生病毒的抗体呈阳性反应。对G4 DNA-A全序列测定和分析表明,G4 DNA-A全长2 748个核苷酸,共编码6个ORFs。同源性比较及系统进化关系分析表明,G4 DNA-A与在亚洲发现的粉虱传双生病毒关系较近,其中与我国报道的中国番木瓜曲叶病毒(PaLCuCNV)同源性最高,达到98.0%。进一步比较发现,G4 DNA-A编码的AV1、AV2、AC1、AC2、AC3和AC4与PaLCuCNV相应ORFs的氨基酸同源性分别为98.4%、95.7%、97.5%、97.8%、94.1%和94.6%,表明G4应属于PaLCuCNV的一个分离物。G4编码的ORFs与中国胜红蓟黄脉病毒(AYVCNV)、辣椒曲叶病毒(PepLCV)及烟草曲茎病毒(TbCSV)有较高的氨基酸同源性,可能起源于共同的祖先。利用DNA-B及卫星DNAβ的保守引物均未能从G4分离物中扩增出相应的组分。     

不同番茄品种对5种植物双生病毒的抗病性鉴定

 由粉虱传双生病毒引起的番茄曲叶病［1］在我国最初仅分布在海南、云南、广东和广西,自2006年上海市和浙江省先后在番茄上发现番茄黄化曲叶病毒（Tomato yellow leaf curl virus,TYLCV）以来,该病害蔓延迅速,在多个省份的番茄上暴发成灾［2］。引起番茄曲叶病害的病原较复杂,在我国其主要病原为TYLCV、中国番木瓜曲叶病毒（Papaya leaf curl China virus, PaLCuCNV）、中国番茄黄化曲叶病毒(Tomato yellow leaf curl China virus, TYLCCNV)、泰国番茄黄化曲叶病毒（Tomato yellow leaf curl Thailand virus, TYLCTHV）和台湾番茄曲叶病毒（Tomato leaf curl Taiwan virus, ToLCTWV）［2~5］,而浙江省的主要病原为TYLCV和ToLCTWV。选育抗病品种是防治番茄黄化曲叶病最有效的手段。了解番茄品种对不同双生病毒的抗性,对因地制宜布局抗病品种具有重要意义。浙杂502、浙粉701、浙粉702是浙江省大规模种植的番茄品种,为了解这些品种对上述5种病毒的抗性,本研究利用5种病毒的侵染性克隆,在人工接种条件下,综合评定分析这3个番茄品种的抗病指标。     

北京地区番茄黄化曲叶病毒病的鉴定及防治对策

番茄黄化曲叶病毒病是一种由烟粉虱传播的病毒病,给番茄生产造成严重威胁。2009年在北京郊区调查时发现部分保护地种植的番茄植株表现典型黄化曲叶症状。通过提取典型症状样品总DNA利用粉虱传双生病毒检测简并引物PA/PB,进行PCR扩增到541bp的特异条带。通过测序和核苷酸序列比对表明该序列与番茄黄化曲叶病毒序列相似性最高为99%。分子检测结果表明北京郊区部分保护地种植的番茄已被烟粉虱传播的番茄黄化曲叶病毒侵染危害。     

A new approach to evaluate relative resistance and tolerance of tomato cultivars to begomoviruses causing the tomato yellow leaf curl disease in Spain

A simple procedure to evaluate relative resistance and tolerance of tomato cultivars to the begomoviruses causing tomato yellow leaf curl (TYLC) disease in Spain was developed. To estimate the resistance and tolerance levels of a cultivar, several formulae were developed based on the ratio of infected plants, virus titre (estimated by tissue–print hybridization) and symptom intensity. The formulae were applied to five commercial tomato cultivars (Amoretto, Birloque, Royesta, Tovigreen and Ulises) naturally infected by TYLC viruses. The analyses showed that Ulises, Birloque and Tovigreen exhibited a moderate resistance, and Ulises was also highly tolerant. There was a positive correlation between symptom intensity and virus titre in infected plants, suggesting that the hybridization technique could also be used as an early estimator of tolerance. Finally, molecular hybridization and nucleotide sequence analyses of the begomovirus intergenic region showed that the local TYLC virus population consisted of a single species, Tomato yellow leaf curl virus (TYLCV, formerly TYLCV-Israel), with low genetic variation (nucleotide identity between isolates higher than 97%).     

从福建分离的广东赛葵曲叶病毒的分子特征

 从中国福建省表现曲叶和脉突症状的赛葵上分离到病毒分离物FJ1~FJ6。利用菜豆金色花叶病毒属病毒的特异性简并引物PA/PB,在所有6个分离物中都分离到了约500bp长度的病毒部分DNA片段。这些DNA片段与已报道的广东赛葵曲叶病毒(Malvastrum leaf curl Guangdong virus,MLCuGdV)的核苷酸序列同源性高达90%-93%。随机挑选FJ3分离物进行全基因组DNA的克隆测序。结果表明,FJ3 DNA全长2765个核苷酸,具有典型的双生病毒科病毒的基因组结构特征,与MLCuGdV的同源性为92.9%,表明FJ3是MLCuGdV的一个分离物。系统进化分析表明,除了MLCuGdV,FJ3与其它赛葵上分离到的双生病毒的亲缘关系都较远,而与分离自中国南方番木瓜上的双生病毒聚成簇,有较近的亲缘关系。进一步比较分析各蛋白编码的氨基酸序列发现,FJ3可能是一个种间重组分子,它可能是由中国番木瓜曲叶病毒或广东番木瓜曲叶病毒和另外的未知病毒重组产生的。     

Tomato leaf curl Guangxi virus is a distinct monopartite begomovirus species

Three begomovirus isolates were obtained from tomato plants showing leaf curl symptoms in Guangxi province of China. Typical begomovirus DNA components representing the three isolates (GX-1, GX-2 and GX-3) were cloned and their full-length sequences were determined to be 2752 nucleotides. Nucleotide identities among the three viral sequences were 98.9–99.7%, but all shared <86.7% nucleotide sequence identity with other reported begomoviruses. The sequence data indicated that GX-1, GX-2 and GX-3 are isolates of a distinct begomovirus species for which the name Tomato leaf curl Guangxi virus (ToLCGXV) is proposed. Further analysis indicated that ToLCGXV probably originated through recombination among viruses related to Ageratum yellow vein virus, Tomato leaf curl China virus and Euphorbia leaf curl virus. PCR and Southern blot analyses demonstrated that isolates GX-1 and GX-2 were associated with DNAβ components, but not isolate GX-3. Sequence comparisons revealed that GX-1 and GX-2 DNAβ components shared the highest sequence identity (86.2%) with that of Tomato yellow leaf curl China virus (TYLCCNV). An infectious construct of ToLCGXV isolate GX-1 (ToLCGXV-GX) was produced and determined to be highly infectious in Nicotiana benthamiana, N. glutinosa, tobacco cvs. Samsun and Xanthi, tomato and Petunia hybrida plants inducing leaf curl and stunting symptoms. Co-inoculation of tomato plants with ToLCGXV-GX and TYLCCNV DNAβ resulted in disease symptoms similar to that caused by ToLCGXV-GX alone or that observed in infected field tomato plants.     

Ageratum yellow vein China virus Is a Distinct Begomovirus Species Associated with a DNAbeta Molecule

ABSTRACT Ageratum conyzoides plants exhibiting yellow vein symptoms, collected near Haikou, Hainan Province, China, contained begomoviral DNA-A-like molecules. The complete sequences of the molecules from two samples, Hn2 and Hn2-19, were shown to consist of 2,768 and 2,748 nucelotides (nt), respectively. These sequences have more than 97% nucleotide sequence identity, but less than 86% identity with other reported begomovirus sequences. In line with the taxonomic convention for begomoviruses, Hn2 and Hn2-19 are therefore considered to represent isolates of a distinct begomovirus species, for which the name Ageratum yellow vein China virus (AYVCNV) is proposed. Sequence alignment shows AYVCNV has arisen by recombination among viruses related to Ageratum yellow vein virus, Papaya leaf curl China virus, and an unidentified begomovirus. Southern blot analyses revealed that all plants sampled contained molecules resembling DNAbeta. DNAbeta molecules from three samples were 1,323 or 1,324 nt long and had >98% sequence identity but <81% identity with previously reported DNAbeta sequences. Infectious clones of Hn2 and its associated DNAbeta were constructed and agroinoculated to plants. Hn2 alone caused sporadic asymptomatic systemic infection of Nicotiana benthamiana, N. glutinosa, Lycopersicon esculentum, Petunia hybrida, and A. conyzoides but its accumulation was much enhanced in plants co-inoculated with DNAbeta. The co-inoculated N. benthamiana, N. glutinosa, P. hybrida, and L. esculentum plants developed leaf curling or leaf crinkling symptom; those in A. conyzoides were typical of ageratum yellow vein disease. When the DNAbeta molecules associated with four other Chinese begomoviruses were coinoculated with Hn2 to N. benthamiana and N. glutinosa, the DNAbeta molecules were replicated, and the plants developed systemic symptoms of types that were specific for each DNAbeta. This illustrates that there is less specific interaction between monopartite begomovirus and DNAbeta than between the DNA-A and DNA-B of begomoviruses with bipartite genomes.     

A phytoplasma representative of a new subgroup, 16SrXIII-E, associated with Papaya apical curl necrosis

Papaya apical curl necrosis (PACN) has frequently been observed in several Brazilian states. Affected plants exhibit foliar chlorosis, curvature of the apex, shortening of the internodes leading to bunching of the crown leaves, necrosis of the young apical parts, leaf drop, and dieback. Naturally infected plants were sampled and subjected to PCR assays, which confirmed that a phytoplasma was associated with the disease. Sequencing of the 16S rRNA gene, conventional and computer-simulated RFLP analyses, and phylogenetic analysis allowed the determination of the PACN phytoplasma as a representative of a new subgroup, designated 16SrXIII-E. The phytoplasmas of various 16Sr groups, including 16SrI, 16SrII, 16SrX, 16SrXII, and 16SrXVII, are known to be involved in anomalies in papaya plants in several countries. However, the present study reports, for the first time, the occurrence of a 16SrXIII phytoplasma in association with a papaya disease.