Genetic diversity of the ordinary strain of Potato virus Y (PVY) and origin of recombinant PVY strains

The ordinary strain of Potato virus Y (PVY), PVY(O), causes mild mosaic in tobacco and induces necrosis and severe stunting in potato cultivars carrying the Ny gene. A novel substrain of PVY(O) was recently reported, PVY(O)-O5, which is spreading in the United States and is distinguished from other PVY(O) isolates serologically (i.e., reacting to the otherwise PVY(N)-specific monoclonal antibody 1F5). To characterize this new PVY(O)-O5 subgroup and address possible reasons for its continued spread, we conducted a molecular study of PVY(O) and PVY(O)-O5 isolates from a North American collection of PVY through whole-genome sequencing and phylogenetic analysis. In all, 44 PVY(O) isolates were sequenced, including 31 from the previously defined PVY(O)-O5 group, and subjected to whole-genome analysis. PVY(O)-O5 isolates formed a separate lineage within the PVY(O) genome cluster in the whole-genome phylogenetic tree and represented a novel evolutionary lineage of PVY from potato. On the other hand, the PVY(O) sequences separated into at least two distinct lineages on the whole-genome phylogenetic tree. To shed light on the origin of the three most common PVY recombinants, a more detailed phylogenetic analysis of a sequence fragment, nucleotides 2,406 to 5,821, that is present in all recombinant and nonrecombinant PVY(O) genomes was conducted. The analysis revealed that PVY(N:O) and PVY(N-Wi) recombinants acquired their PVY(O) segments from two separate PVY(O) lineages, whereas the PVY(NTN) recombinant acquired its PVY(O) segment from the same lineage as PVY(N:O). These data suggest that PVY(N:O) and PVY(N-Wi) recombinants originated from two separate recombination events involving two different PVY(O) parental genomes, whereas the PVY(NTN) recombinants likely originated from the PVY(N:O) genome via additional recombination events.     

Genetic Analysis of Isolates of Botrytis cinerea Sensitive and Resistant to Benzimidazole and Dicarboximide Fungicides

ABSTRACT A total of 56 isolates of B. cinerea collected from ornamental crops from commercial greenhouses were examined by random amplified polymorphic DNA (RAPD) fingerprint analyses. Isolates were examined as two independent sets of 35 and 36 isolates, with 15 isolates common to both sets. The isolates had four phenotypes: 17 were sensitive to two commonly used fungicides, thiophanate-methyl (a benzimidazole) and vinclozolin (a dicarboximide) (S(T)S(V)); 18 were resistant to both fungicides (R(T)R(V)); 16 were resistant to thiophanate-methyl but sensitive to vinclozolin (R(T)S(V)); and 5 were sensitive to thiophanate-methyl but resistant to vinclozolin (S(T)R(V)). Relationships among the isolates were determined by cluster analyses of mean character differences using the unweighted pair group method using arithmetic average and cladograms were constructed. Isolates were clustered primarily by fungicide-sensitivity phenotype. In one set of greenhouse isolates, 6 of 10 S(T)S(V) isolates clustered together with a bootstrap confidence value of 91%. In the other fingerprint set of greenhouse isolates, 9 of 11 S(T)S(V) isolates clustered together and had a bootstrap confidence value of 98%. Isolates resistant to thiophanate-methyl, vinclozolin, or both fungicides usually were not clustered with other isolates or were clustered with isolates of the same phenotype. To further elucidate these relationships, variant isolates resistant to one or both fungicides were produced on fungicide-amended agar medium from 14 S(T)S(V) greenhouse isolates. These 14 S(T)S(V) parent isolates, 57 resistant variant isolates, and 11 resistant greenhouse isolates were analyzed as three independent RAPD fingerprint sets. Variants selected from eight S(T)S(V) parent isolates were resistant to both thiophanate-methyl and vinclozolin even though parent isolates were exposed to only one of the fungicides. Isolates resistant only to vinclozolin (S(T)R(V)) had fingerprint patterns similar to and clustered with those of parent isolates, while fingerprint patterns of isolates resistant to thiophanate-methyl (i.e., R(T)R(V) or R(T)S(V)), regardless of sensitivity to vinclozolin, clustered differently from both those of S(T)S(V) parent isolates and those of S(T)R(V) isolates derived from the same parent. R(T)R(V) and R(T)S(V) variant isolates derived from the same fungicide-sensitive parents only clustered with other variants having the same phenotype.     

多杀菌素对小菜蛾体内多功能氧化酶和保幼激素酯酶活力的影响

采用生化分析方法,测定了不同浓度多杀菌素(spinosad)处理后小菜蛾体内多功能氧化酶(mixed-function oxidases/,MFO s)和保幼激素酯酶(juvenile hormone esterase,JHE)的活性,分析了酶活性的变化动态。结果表明,小菜蛾体内MFO s和JHE活性变化趋势受多杀菌素浓度影响。用LC50浓度处理后其保幼激素滴度变化趋势与对照相似,用LC80浓度处理后保幼激素滴度降低,并且滴度高峰出现时间比对照有所提前。不同浓度多杀菌素对氧化酶O-脱甲基活力的影响具有时间效应,用LC20浓度处理后的活力曲线上升拐点出现在24h,LC50浓度处理的则出现在12h。除LC80浓度处理在36h时活力值高于对照外,多杀菌素各处理都能抑制氧化酶N-脱甲基活力。高剂量(LC50、LC80)作用后小菜蛾体内保幼激素降解率与氧化酶N-或O-脱甲基活力有相似的变化趋势。     

取代双吡唑类化合物的合成及杀虫活性

以3-氯苯肼盐酸盐( 1 )和1,1,3,3-四甲氧基丙烷( 2 )为起始原料,经环化、Vilsmeier反应得1-(3-氯苯基)-1H-吡唑-4-甲醛( 4);(4 )与3-三氟甲基苯乙酮( 5 )经Claisen-Schmidt缩合反应得取代芳基烯酮类化合物( 6 ),再与水合肼发生环化反应得3-(3-三氟甲基苯基)-5-(3-氯苯基-1H-吡唑)-4,5-二氢吡唑( 7),其与取代异氰酸酯 作用,制得15个未见文献报道的结构新颖的取代双吡唑类化合物。利用核磁共振氢谱(1H NMR)和质谱(MS)对其结构进行了表征。初步生物活性测定结果表明,在 500 mg/L 质量浓度下,部分化合物对小菜蛾Plutella xylostella的致死率达100%,而对苜蓿蚜Aphis medicaginis、稻褐飞虱Nilaparvata lugens、朱砂叶螨Tetranychus cinnabarinus均无杀虫活性。     

Photolysis of Diuron

The major photoproducts observed in the photolysis of diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] ( 2 ) in aqueous solution resulted from a heterolytic substitution of chlorine by OH (photohydrolysis). A wavelength effect was observed: at 254 nm the formation of 3-(4-chloro-3-hydroxyphenyl)-1,1-dimethylurea ( 3 ) accounted for more than 90% of the conversion, whereas when the solution was irradiated in ‘black light’ (85% of photons emitted at 365 nm, about 7% at 334 nm), the major photoproduct was 3-(3-chloro-4-hydroxyphenyl)-1,1-dimethylurea ( 4 ). The presence of methanol favoured the photoreduction into 3-(3-chlorophenyl)-1,1-dimethylurea ( 5 ). Completely different reactions were observed when 2 was irradiated in dry aerobic conditions on silica. They resulted from elimination or oxidation of methyl groups. The main photoproducts initially formed were 3-(3,4-dichlorophenyl)-1-methyl urea ( 6 ) and 3-(3,4-dichlorophenyl)-1-formyl-1-methylurea ( 7 ). In the second stage ( 6 ) was transformed into (3,4-dichlorophenyl)-urea ( 8 ) and 3-(3,4-dichlorophenyl)-1-formylurea ( 9 ); some other minor products such as monuron ( 1 ) were also identified. The formation rate of 6 and 7 was much slower on clay (montmorillonite or kaolin) than on silica. In contrast with products 6 and 8 , the formation of 7 and 9 needed the presence of oxygen: they did not appear when diuron was irradiated in deoxygenated C₂Cl₃F₃. It can be concluded that the photolysis of diuron is highly dependent on the conditions of irradiation. © 1997 SCI.     

温度对伪钝绥螨实验种群的影响

本文研究了5个不同恒温条件下伪钝绥螨取食二斑叶螨时的发育和繁殖情况,并对该实验种群的生命参数进行了分析。结果表明,在19~31℃范围内,伪钝绥螨各螨态和整个未成熟期的发育历期随温度的升高而缩短,发育速率随温度的升高而加快;运用直线回归法计算出了伪钝绥螨各螨态的发育起点温度及有效积温。伪钝绥螨产卵期在22℃时最长,在31℃时最短;日均卵量随温度的升高而增大。伪钝绥螨净增殖率Ro在28℃时最高(60.256),在19℃时最低(4.174);内禀增长率rm和周限增长率λ皆是在31℃时最高,在19℃时最低;31℃时种群加倍时间t最短(2.79 d),19℃时最长(15.868 d)。     

用AMMI双标图分析西瓜品种的产量稳定性及试点分辨力

借助AMMI模型分析了2009年国家西瓜品种区域试验中的产量数据,结果表明：基因型与环境的互作效应小于基因效应和环境效应,但是也达到了极显著的水平,而且基因型的效应占比例较大,其次为环境效应。不同西瓜品种在各试点的品种稳定性和不同试点对品种的分辨力差异较大：品种G4（09-N2）的稳定性参数最大（D_g=15.53360）,G7（09-N9）的稳定性参数最小（D_g=2.56881）;8个西瓜品种中高产稳产的品种是G2（09-N1）和G1（09-N7）,产量低且不稳定的品种是G4（09-N2）和G6（09-N12）,产量高而稳定性一般的品种是G8(CK,09-N15),产量低而稳定的品种是G7（09-N9）,产量一般且稳定性一般的品种是G3（09-N5）,产量一般稳定性差的品种是G5（09-N8）;在4个参试点中,甘肃兰州试点对品种的分辨力强,宁夏中卫试点和宁夏中宁试点对西瓜品种的分辨力一般,宁夏海原试点对品种的分辨力较差。     

农药对人体健康影响的风险评估

介绍了有关农药对人体健康风险评估的基本原则及程序。农药对人体健康的风险评估被许多国家政府机构和国际组织用作农药登记评审和农药安全性评价的重要依据,其风险评估程序包括危害性鉴定、剂量-反应评定、接触评定和风险描述四个步骤。危害性鉴定主要是研究农药可能对人体健康产生的影响;剂量-反应关系主要是研究对农药的不同接触水平可能导致的相应的影响健康的程度;接触评定是研究人们从食物、饮用水和其他各种可能途径中接触到的农药量,其中包括:饮食接触评定、职业接触评定和居住环境接触评定;风险描述是将危险鉴定、剂量-反应评定和接触评定的结果进行综合分析,来描述农药对公众健康总的影响。     

Effects of antagonist cell concentration and two-strain mixtures on biological control of fusarium dry rot of potatoes

ABSTRACT Eighteen bacterial strains were individually assayed against Gibberella pulicaris (5 x 10(5) conidia per ml) by coinoculating antagonist and pathogen in wounds in cv. Russet Burbank potatoes. All antagonist concentrations (10(6), 10(7), and 10(8) CFU/ml) decreased disease (38 to 76% versus control, P < 0.05). When four strains were assayed at 11 concentrations (range 10(5) to 10(8) CFU/ml) against G. pulicaris, linear regression of the log-dose, log-response data was significant for all four strains (P < 0.001 to 0.01, R(2) = 0.50 to 0.74). Challenging G. pulicaris with all possible antagonist pairings within 2 sets of 10 antagonist strains (5 x 10(5) CFU of each strain per ml) resulted in 16 of 90 pairs controlling disease better than predicted based on averaging the performance of the individual strains making up the pair (P < 0.10). Successful pairs reduced disease by ~70% versus controls, a level of control comparable to that obtained with 100 times the inoculum dose of a single antagonist strain. Neither strain genus nor soil of origin were useful in predicting successful antagonist pairs. Factors potentially influencing dose-response relationships and the effectiveness of antagonist pairs in controlling disease are discussed.     

内蒙半干旱低山丘陵区林下植物群落数量特征研究

林下植物群落的物种组成和结构不但影响森林生态系统的稳定和可持续发展,也影响着其服务功能的发挥。根据对内蒙半干旱低山丘陵区(武川县东坡林区)的人工及天然林研究表明:(1)当地林下植物一般以一年生植物、隐芽植物和地面芽植物种占绝对优势,3项合计占到所有植物种数的72~100%;(2)各种林地林下灌木层和草本层盖度都很低,分别为0~5.02%和1.94~17.56%;林下植物(灌木层+草本层)的总盖度大小顺序为:云杉林(55.02%)>小叶杨林(17.56%)>白桦林、白榆林和山杨林(5.45~8.40%)>荒草地对照(4.63%)>油松林、落叶松林和油松+落叶松林(2.10~4.09%);(3)各种林地林下优势植物种类差异不大,灌木层优势种类以绣线菊(Spiraea salicifolia)、蒙古荚蒾(Viburnum mongoli-cum)为主,草本层优势种类以羊胡子草(Carex rigescens)为主,其次有各种蒿类(Artem isia)、冰草(Agropyron cristatum)、灰藜(Chenopodium album)、苦菜(Mulgedium tataricum)和红芪(Hedysarum polybotrys)等;(4)林下灌木既少且物种多样性极低,林下草本层物种多样性指数也不大。各林地林下植物(灌木层+草本层)总的物种多样性指数和(丰富度指数、多样性指数、均匀度指数之和)大小顺序为:小叶杨林(5.83)>白榆林、油松林、油松+落叶松林(5.03~5.50)>白桦林、荒草地对照(4.48)>山杨林(3.28)>落叶松(2.89)>云杉林(1.13)。     

Preliminary account of the phytosanitary status of stone-fruit trees in Lebanon

Investigations were carried out in the main stone-fruit growing areas of Lebanon to assess the phytosanitary condition of commercial orchards. The presence of virus and virus-like diseases and their identification was ascertained through: (i) field surveys, (ii) sap transmission to herbaceous hosts, (iii) graft transmission to woody indicators; and (iv) ELISA and IEM tests. The mean infection level was 25%. ranging from 5% in apricot to 45% in cherry. The following viruses were identified: apple chlorotic leaf spot trichovirus (ACLSV), prunus necrotic ringspot (PNRSV) and prune dwarf (PDV) ilarviruses. Plum pox potyvirus (PPV), apple mosaic ilarvirus (ApMV), and six nepoviruses tested for (SLRV, TBRV, RRV, CLRV, ArMV and ToRSV) were not encountered.     

棉花黄萎病菌致病型的AFLP分析

 选用41个棉花黄萎病菌(Verticillium dahliae)代表菌系,在温室条件下,对4个棉花品种鄂荆1号(感)、中棉所12(耐)、文-5(抗)和唐棉2号(抗)进行致病性测定,结果可将供试菌系分为落叶型与非落叶型2类。选取8对AFLP引物PCR扩增的结果中,统计带型稳定、清晰且有多态性的条带,共169条作系统聚类分析,将上述菌系分为2大类,第一类为非落叶型菌系,包括10个非落叶型菌系和1个过渡菌系;第二类为30个落叶型菌系。根据聚类分析建立树状图,发现菌系与地理来源存在一定的相关性,而依据菌系致病力强弱分类则相关关系不大。选用25对EcoRⅠ和MseⅠ引物组合,对供试的41个V.dahliae进行AFLP扩增,筛选到2对引物E64(GACTGCGTACCAATTCGAC)、M53(GATGAGTCCTGAGTAACCG)和E49(GACTGCGTACCAATTCCAG)、M65(GAT-GAGTCCTGAGTAAGAG),能分别扩增出433bp和110bp2条仅为V.dahliae非落叶型菌系独有的特异片段,可将落叶型与非落叶型菌系分开,这2条特异片段被命名为EM₄₃₃和EM₁₁₀。     

Enhancement of fungicidal and insecticidal activity by reductive alkylation of chitosan

A series of N-alkyl chitosan (NAC) derivatives were synthesized using a reductive alkylation reaction to examine their fungicidal and insecticidal activity. The chemical structures were characterized by IR and (1)H NMR spectroscopy, and the degree of substitution (DS) ranged from 0.02 to 0.37. Their fungicidal activity was evaluated against the grey mould Botrytis cinerea Pers ex Fr (Leotiales: Sclerotiniaceae) and the rice leaf blast pathogen Pyricularia grisea Sacc [Teleomorph: Magnaporthe grisea (Hebert) Barr] by a radial growth bioassay. It was of interest that most of the NAC derivatives were more active against both fungi than chitosan itself. The most active derivative was N-(2,2-diphenylethyl)chitosan with EC50 values of 0.031 and 0.23 g L(-1) against B. cinerea and P. grisea respectively. In addition, some derivatives, at higher concentrations up to 1.0 g L(-1), inhibited the mycelial growth and spore formation of P. grisea. Bioassays against larvae of the cotton leafworm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) with the NAC derivatives at a rate of 5.0 g kg(-1) in artificial diet demonstrated that N-(3-phenylbutyl)chitosan was the most active compound. In addition, N-propylchitosan, N-undecanylchitosan and N-(3-phenylpropyl)chitosan derivatives strongly inhibited larval weight gain in S. littoralis, with respective reductions of 76, 66 and 65% after 4 days of feeding on treated diet.     

Activated transformations of organophosphorus insecticides in the case of non-AChE inhibitory oxons

Many organophosphorus (OP) compounds are of the thiono form and in insects or animals are converted by microsomal mixed function oxidases (MFO) into the oxon forms which inhibit acetylcholinesterase (AChE) and give toxic activity. However, certain S-alkyl phosphorothiolates (RS-P(O) <) such as methamidophos, profenophos and prothiophos oxon are strongly insecticidal, but very poor inhibitors of AChE in vitro. Their oxons are converted further to the S-oxides, which either inhibit AChE or decompose, depending on the alkyl substituents on the sulfur atom. It is also inferred in the case of prothiophos oxon that its S-oxide not only inhibits AChE but also conjugates with glutathione (GSH) by the action of glutathione S-transferase (GST), and the conjugate inhibits AChE. Certain phosphoramidates (R2N-P(O) <) such as isofenphos oxon, schradan and propetamphos oxon are weak AChE inhibitors, but strongly insecticidal. It is well known that isofenphos oxon is converted into the stable N-desalkyl form (H2N-P(O) <) by oxidative dealkylation to inhibit AChE. The authors have studied activation of phosphoramidates using 2,4-dichlorophenyl methyl N-alkylphosphoramidates as model compounds using various approaches including computational chemistry, and these studies indicated that the O-aminophosphate structure (R2N-O-P(O) <) is an activated form.     

Acaricidal activity against Panonychus citri of a ginkgolic acid from the external seed coat of Ginkgo biloba

An acaricidal substance extracted from the external seed coat of Ginkgo biloba L. was identified by UV (ultraviolet), IR (infrared), EI-MS (electron impact ion source mass spectrometry), (1)H NMR (nuclear magnetic resonance) and (13)C NMR as 6-[(Z)-10-heptadecenyl]-2-hydroxybenzoic acid (compound 1). Laboratory bioassay on citrus red mite, Panonychus citri (Mcg), showed that compound 1 possessed the following properties. (i) Powerful contact toxicity with an LC(50) of 5.2 mg litre(-1) after 24 h that was similar to that of pyridaben (LC(50) = 3.4 mg litre(-1)) and significantly superior to that of omethoate (LC(50) = 122 mg litre(-1)). Furthermore, its LC(90) was 13.4 mg litre(-1) after 24 h, which is significantly superior to both pyridaben (LC(90) = 69.6 mg litre(-1)) and omethoate (LC(90) = 453 mg litre(-1)). (ii) Quick-acting acaricidal activity. At identical concentrations, compound 1 was much faster-acting than pyridaben or omethoate. (iii) Compound 1 had strong corrosive action on the cuticle of P. citri but no phytotoxicity to plants.     

Results of arbovirological examination of birds of the family Hirundinidae in Czechoslovakia

Migratory birds (swallow, Hirundo rustica; sand martin, Riparia riparia; house martin, Delichon urbica) caught in southern Moravia (Czechoslovakia) in 1984-87 were examined for arbovirus infections. Isolation experiments were carried out using blood samples of 183 birds (52 swallows, 107 sand martins, and 24 house martins). The results were negative. Serological examinations of 136 birds (36 swallows, 86 sand martins, and 14 house martins) were made by haemagglutination-inhibition test (HIT) using 6 arboviral antigens of the genera Alphavirus (Sindbis--SIN) and Flavivirus (tick-borne encephalitis--TBE, West Nile--WN) and of the family Bunyaviridae (Tahyna--TAH, Calovo, CVO, and Bhanja--BHA). Antibodies against all of the tested viruses were detected at different rates: SIN 2.9%, TBE 1.5%, WN 1.5%, TAH 4.4%, CVO 1.5%, and BHA 2.2%. The titres ranged from 1.20 to 1.80.     

Identification of the molecular make-up of the Potato virus Y strain PVY(Z): genetic typing of PVY(Z)-NTN

Potato virus Y (PVY) strains were originally defined by interactions with different resistance genes in standard potato cultivars. Five distinct strain groups are defined that cause local or systemic hypersensitive responses (HRs) in genetic background with a corresponding N gene: PVY(O), PVY(N), PVY(C), PVY(Z), and PVY(E). The nucleotide sequences of multiple isolates of PVY(O) and PVY(N) differ from each other by ≈8% along their genomes. Additionally, complete genome sequences of multiple recombinant isolates are composed of segments of parental PVY(O) and PVY(N) sequences. Here, we report that recombinant isolate PVY-L26 induces an HR in potato 'Maris Bard' carrying the putative Nz gene, and is not recognized by two other resistance genes, Nc and Ny(tbr). These genetic responses in potato, combined with the inability of PVY-L26 to induce vein necrosis in tobacco, clearly define it as an isolate from the PVY(Z) strain group and provide the first information on genome structure and sequence of PVY(Z). The genome of PVY-L26 displays typical features of European NTN-type isolates with three recombinant junctions (PVY(EU-NTN)), and the PVY-L26 is named PVY(Z)-NTN. Three typical PVY(NTN) isolates and two PVY(N) isolates, all inducing vein necrosis in tobacco, were compared with PVY-L26. One PVY(NTN) isolate elicited HR reactions in Maris Bard, similar to PVY-L26, while two induced a severe systemic HR-like reaction quite different from the quasi-symptomless reaction induced by two PVY(N) isolates. 'Yukon Gold' potato from North America produced HR against several PVY(NTN) isolates, including PVY-L26, but only late and limited systemic necrosis against one PVY(N) isolate. Consequently, according to symptoms in potato indicators, both PVY(Z) and PVY(NTN) isolates appeared biologically very close and clearly distinct from PVY(O) and PVY(N) strain groups.     

Penicillium digitatum Suppresses Production of Hydrogen Peroxide in Host Tissue During Infection of Citrus Fruit

ABSTRACT During the infection of citrus fruit by Penicillium digitatum there is little evidence of a host defense response. This suggests that P. digitatum has the ability to suppress host defenses. The current study demonstrates that P. digitatum suppresses a defense-related hydrogen peroxide (H(2)O(2)) burst in host tissue. In contrast, the nonhost pathogen, Penicillium expansum, triggers production of a significant amount of H(2)O(2) in citrus fruit exocarp. Using laser scanning confocal microscopy, we demonstrated that P. digitatum suppressed an elevation in H(2)O(2) up to 42 h after inoculation. Nevertheless, H(2)O(2) levels around wounds inoculated with P. expansum increased by 63-fold above the control. P. digitatum continued to suppress H(2)O(2) production in citrus fruit exocarp up to 66 h postinoculation and H(2)O(2) levels were actually threefold below that of noninoculated controls. In contrast, the H(2)O(2) level was still about 11-fold above the control value in wound sites inoculated with P. expansum. Studies on the effect of organic acids (as pH modulators) on the response of citrus fruit to compatible and noncompatible pathogens indicated that pathogenicity was enhanced only when host-tissue acidification was accompanied by the suppression of H(2)O(2). Additionally, pathogenicity of both P. digitatum and P. expansum on citrus fruit was significantly enhanced by the H(2)O(2)-scavenging enzyme catalase. Based on our study and previous reports regarding the potential involvement of citric acid and catalase in green mold pathogenesis, we suggest that these compounds are strongly associated with the virulence of P. digitatum.     

Biometric Analyses of the Inheritance of Resistance to Didymella rabiei in Chickpea

ABSTRACT Historically, the response of chickpea (Cicer arietinum L.) to Didymella rabiei (causal agent of Ascochyta blight) has been mainly related to as complete resistance and it was commonly assayed with qualitative (nonparametric) scales. Two reciprocal populations, derived from intra-specific crosses between a moderately resistant late flowering Israeli cultivar and a highly susceptible early flowering Indian accession, were tested at F(3) and F(4) generations in 1998 and 1999, respectively. A quantitative (parametric) assessment (percent disease severity) was used to evaluate the chickpea field response to Ascochyta blight. The transformed relative area under the disease progress curve (tRAUDPC) was calculated for each experimental unit for further analyses. Heritability estimates of the tRAUDPC were relatively high (0.67 to 0.85) in both generations for both reciprocal populations. The frequency distributions of tRAUDPC of the populations were continuous and significantly departed from normality (Shapiro-Wilk W test; P of W < 0.0001), being all platykurtic and skewed toward either the resistant or the susceptible parental lines. The presence of major genes was examined by testing the relationship between the F(3) and F(4) family means and the within-family variances (Fain's test). Analyses of these relationships suggested that segregation of a single (or few) quantitative trait locus with major effect and possibly other minor loci was the predominant mode of inheritance. The correlation estimates between the resistance and days to flower (r = -0.19 to -0.44) were negative and significantly (P = 0.054 to 0.001) different from zero, which represents a breeding constraint in the development of early flowering cultivars with Ascochyta blight resistance.     

几种分离技术在农药残留分析中的应用

本文介绍了样品现代前处理技术加速溶剂萃取(ASE)、超临界流体萃取(SFE)、固相萃取(SPE)、固相微萃取(SPME)、凝胶渗透色谱(GPC)的原理及其在农药残留分析中应用情况。