Production of patchouli mild mosaic virus resistant patchouli plants by genetic engineering of coat protein precursor gene

Patchouli (Pogostemon cablin (Blanco) Benth), an aromatic crop which yields an essential oil, is widely cultivated in South-east Asia. Patchouli mild mosaic virus (PaMMV) infects patchouli plants and causes decrease in leaf biomass and essential oil yield. Transgenic patchouli plants with PaMMV coat protein precursor (CP-P) gene have been produced by Agrobacterium-mediated transformation. PaMMV CP-P gene integration into the patchouli genome was confirmed by the PCR method and by Southern blot analysis. The transformants were estimated to contain one to three copy genes using Southern blot analysis. The transformant with three copy genes was tested for the resistance to PaMMV by artificially inoculating plants grown in an environmentally controlled cabinet, and this transformant was found to be highly resistant to PaMMV. The transgenic patchouli plant with PaMMV CP-P gene should provide valuable material for protecting against PaMMV.     

Essential oil production increased by using virus-free patchouli plants derived from meristem-tip culture

For the production of virus-free patchouli ( Pogostemon cablin ), isolated meristem tips were cultured on a medium supplemented with 0·2 ppm 6-benzylaminopurine. Multiple shoot proliferation was initiated during the culture. Complete plantlets were regenerated by transferring multiple shoots to a medium devoid of phytohormones. Plantlets thus produced were transplanted to soil with a high rate of survival and tested by enzyme-linked immunosorbent assay (ELISA) to check elimination of patchouli mild mosaic virus. Following further propagation by stem cuttings, virus-free plants were grown in the northern and southern parts of Mindanao Island, Philippines. Significant increases in biomass and essential oil yield were observed in virus-free plants grown at both localities. Using gas chromatographic analyses, a full set of major sesquiterpenes was detected in the essential oils recovered from virus-free patchouli plants. Reinfection of healthy clones with the virus took place within 4 months of cultivation in the field.     

Effects of patchouli and wormwood oils on the bioassays and behaviors of Tetranychus cinnabarinus (Boisduval) (Acari: Tetranychidae)

Abstract

The fumigation bioassays, the oviposition inhibition and repellent bioassays of patchouli and wormwood oils to T. cinnabarinus were determined in the laboratory with the methods of fumigation and repellency. Ethovision XT6 was used to analyze the effects of two essential oils at sublethal dosages on the behaviors of T. cinnabarinus. Based on the results, compared with wormwood oil, the fumigation bioassay of patchouli oil was stronger against T. cinnabarinus. In a simultaneous fumigation experiment, the effects of patchouli oil on the inhibition of oviposition of T. cinnabarinus were significantly higher (P?<?0.01) than those of wormwood oil at the tested dosages. When T. cinnabarinus was exposed to the two essential oils at LD₁₀, LD₂₀, and LD₃₀, the spontaneous movement tracks of T. cinnabarinus changed significantly, with the highest mobility frequencies at LD₁₀. Moreover, the effects of exposure to patchouli oil on the spontaneous movement abilities of T. cinnabarinus were greater than those on movements following exposure to wormwood oil. Thus, patchouli oil is a promising candidate as a green vegetable, botanical acaricide.     

Measures of durability of resistance

ABSTRACT Conventional models for the durability of resistant cultivars focus on the dynamics of the frequency of resistance genes. This leads to a definition of the durability of resistance as the time from introduction of the cultivar to the time when the frequency of the virulence gene reaches a preset threshold. It is questionable whether this is the most appropriate way to measure durability. Here we use a simple epidemiological model to link population dynamics and population genetics to compare three measures of durability: (i) the expected time until invasion of the virulent genotype, by mutation or immigration, and subsequent establishment of a population (T(invasion)); (ii) the virulence frequency related measure of the time for the virulent genotype to take-over the pathogen population ( T(take-over)); and (iii) the additional yield, measured by the additional number of uninfected host growth days (T(additional)). Specifically, we show how the measures of durability are affected by deployment and epidemiological parameters. We use a combination of numerical solution and analytical approximation of a model for the population dynamics of avirulent and virulent genotypes of a pathogen growing in dynamically changing populations of resistant and susceptible cultivars. The three measures of durability are compared. Some consequences of the results for durable resistance in multilines and mixtures and the regional deployment of resistant cultivars are discussed.     

Investigation of the Mode of Action of Nematode Neuropeptides

The neuropeptide AF2 has a complex set of actions on the dorsal muscle strip of Ascaris suum, including a potentiation of the acetylcholine-stimulated muscle contraction. Caffeine at 100 μm and 5 mm inhibited this potentiation, as did 100 μm theophylline in two out of six studies. The cyclic-AMP-potentiating compounds IBMX, dibutyryl cAMP and forskolin had no effect on the AF2-induced potentiation of the acetylcholine-stimulated muscle contraction. These preliminary data suggest that the potentiating action of AF2 is not mediated by a cAMP pathway.     

Localization of metabolic sites of action of herbicides

Time- and concentration-course studies were conducted to determine the effect of thirteen herbicides on photosynthesis, respiration, RNA synthesis, protein synthesis, and lipid synthesis using isolated single leaf cells. Each herbicide was from a different chemical class. Appropriate ¹⁴C-substrates and product purification procedures were used for each process prior to liquid scintillation counting. The most sensitive metabolic site of inhibition was photosynthesis for atrazine, bromacil, dichlobenil, monuron, and paraquat; RNA synthesis for dalapon and dinoseb; protein synthesis for chlorpropham; and lipid synthesis for CDAA, chloramben, 2,4-D, EPTC, and trifluralin. However, with several herbicides, one or more process was almost as sensitive as the one mentioned above. All herbicides inhibited more than one process, and the most sensitive site of inhibition may not be the same process that was inhibited the greatest at the maximum concentration and maximum exposure time used. Therefore, a concept of metabolic sites of action, rather than a primary site of action, appears to be more meaningful for herbicides.     

Effects of timing and method of application of Penicillium oxalicum on efficacy and duration of control of Fusarium wilt of tomato

The effects of timing and method of application of Penicillium oxalicum on the control of fusarium wilt of tomato were investigated. Application of P. oxalicum to tomato seedlings in seedbeds reduced disease caused by Fusarium oxysporum f.sp. lycopersici in a growth chamber by 45–49% and in glasshouse experiments by 22–69%. Disease suppression was maintained for 60–100 days after inoculation with the pathogen in the glasshouse. No disease reduction was observed in tomato plants where P. oxalicum was applied to seeds. Treatment with P. oxalicum did not affect the population of F. oxysporum f.sp. lycopersici in the rhizosphere.     

百合地下害虫主要种类调查及生物（源）农药筛选

调查了甘肃省临洮县为害百合的地下害虫种类, 并以主要发生为害种类为供试对象, 采用拌土法测定了几种生物（源）农药对主要害虫的室内毒力和致死中时。调查发现小云斑鳃金龟Polyphylla gracilicornis、棕色鳃金龟Holotrichia titanis为主要发生及为害种类, 不同时间发生种类存在差异, 9月份以小云斑鳃金龟幼虫发生为害为主, 发生量占地下害虫总数的66.16%, 平均种群密度为10.48头/m2, 10月份, 则以棕色鳃金龟幼虫发生为主, 发生量占地下害虫总数的96.86%, 平均种群密度为7.79头/m2, 主要取食百合根系和鳞茎, 造成根系数量减少, 鳞茎出现不规则褐色缺口或凹陷斑。药剂筛选结果表明, 1.8%阿维菌素乳油、200亿孢子/g球孢白僵菌粉剂对两种蛴螬均具有较高的杀虫活性和速效性, 药后7 d时, 校正死亡率在82.22%以上, 对小云斑鳃金龟幼虫和棕色鳃金龟幼虫的LC50分别为0.161、0.060 mg/g和5.558×107、0.362×107孢子/g, LT50分别为2.237 d（2.2 mg/g）、1.393 d（2.2 mg/g）和6.645 d（40.0×107孢子/g）、4.940 d（2.0×107孢子/g）, 这两种生物（源）农药对两种蛴螬的LC50和LT50值均略大于两种化学农药25%二嗪磷乳油、40%辛硫磷乳油处理的, 且对小云斑鳃金龟幼虫的杀虫活性均低于对棕色鳃金龟幼虫的杀虫活性, 致死中时则长于对棕色鳃金龟幼虫的致死中时。     

Systems of designation of pathotypes of plant pathogens12

A variety of systems of designation has evolved to name pathotypes of plant pathogens. The systems were evaluated to determine those best suited for particular purposes. Virulence and avirulence/virulence formulae of pathotypes have advantage over the use of consecutive numbers or letters given in chronological order of pathotype discovery. As soon as pathotype information exceeds a certain level of complexity, mathematical codes are most advantageous, in particular two codes, octal notation and coded triplets. A more universal adoption of the most appropriate codes is recommended to ease communication and comparisons of results.     

宁夏枸杞炭疽病发生流行的气象条件分析

根据宁夏枸杞主产区中宁县和银川市芦花台园林试验场2000～2004年不同批次的成熟枸杞果实炭疽病病情指数和气象资料,运用主成分分析结合逐步回归方法,分析了宁夏枸杞炭疽病爆发流行的主要气象因子及其影响.结果表明:影响炭疽病发生的气象因子主要是温度和空气相对湿度,其次是风力和降水.在一定温度范围内,温度越高,对炭疽病的发生越不利;空气湿度越大,越有利于枸杞炭疽病的发生.     

Mode of action of etoxazole

The mode of action of the 2,4-diphenyl-1,3-oxazoline acaricide/insecticide etoxazole has been argued to be moulting inhibition, but experimental results supporting this hypothesis are lacking. This study investigated the effect of etoxazole on chitin biosynthesis in the fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae). Etoxazole induced moulting defects in fall armyworm larvae similar, if not identical, to those caused by benzoylphenylureas, a well-known class of insecticidal chitin biosynthesis inhibitors. Furthermore, in contrast to untreated larvae, the chitin content in the integuments of larvae several days after treatment did not differ from that in freshly ecdysed individuals, thus suggesting strong chitin biosynthesis inhibition in vivo. A more detailed investigation of the inhibitory potential by incubating cultured integument pieces from larvae of S. frugiperda with [14C]N-acetyl-D-glucosamine, a radiolabelled chitin precursor, revealed I50 values of 2.95 and 0.071 microM for etoxazole and triflumuron respectively. The incorporation of radiolabel into potassium hydroxide-resistant material was inhibited by etoxazole in a dose-dependent manner. Based on these results, it is concluded that the acaricidal and insecticidal mode of action of etoxazole is chitin biosynthesis inhibition.     

Mode of action of famoxadone

Famoxadone is a preventative and curative fungicide recently developed for plant disease control. The molecule and its oxazolidinone analogs (OADs) are potent inhibitors of mitochondrial electron transport, specifically inhibiting the function of the enzyme ubiquinol:cytochrome c oxidoreductase (cytochrome bc₁). Visible absorbance spectral studies on the purified enzyme suggested that famoxadone bound close to the low potential heme of cytochrome b. This binding mode was confirmed in competitive binding experiments by studying the displacement of a radiolabelled OAD from submitochondria. EPR studies on the binding of famoxadone to submitochondria and purified bc₁ suggested its binding mode was more like that of myxothiazol than that of stigmatellin (ligands known to bind near the low potential heme). Zoospores of Phytophthora infestans, when given low concentrations of famoxadone and other OADs, were observed to cease oxygen consumption and motility within seconds and later the cells disintegrated, releasing the cellular contents. Famoxadone was a potent inhibitor of the growth of Saccharomyces cerevisiae when grown on non-fermentable carbon sources and it was an approximately 50-fold less potent inhibitor of growth when the yeast was grown on a fermentable carbon source, glucose. Such physiological observations are consistent with the loss of mitochondrial function imposed by famoxadone and OADs. Single amino acid changes in the apocytochrome b of baker's yeast cytochrome b located near the low potential heme altered the inhibition constants for the inhibitors famoxadone, myxothiazol, azoxystrobin and kresoxim-methyl differentially, thus strongly suggesting different binding interactions of the protein with the inhibitors. © 1999 Society of Chemical Industry     

图们江干流区间流域径流变化特征

以图们江干流区间为研究对象，应用Mann-Kendall非参数检验法分析干流区间4个水文站点径流年际与年内变化趋势。在此基础上，采用R/S分析方法分析年径流、季节径流和月径流变化趋势在未来的可持续性，利用Mann-Kendall突变检验方法分析各水文站点年径流、季节径流和月径流发生突变的年份。结果表明：图们江干流区间各水文站径流年际和年内变化趋势均与干流径流变化趋势一致，呈下降趋势，非汛期径流下降的贡献主要来自春季和冬季径流的下降；Hurst指数表明，上游径流变化趋势的持续性最强，下游的持续性相对较弱；1985年是图们江干流区间年径流发生突变的年份，且降水量也发生了变化，可以推测降水量可能是径流不断减少的重要因素。     

厚朴病虫害种类的初步调查

采用标准地法和线路调查法,对湖北恩施市新塘乡双河厚朴基地的厚朴病虫害进行了系统调查,记录主要虫害13种,其中叶部害虫9种,枝干害虫2种,根部害虫2种。厚朴主要病害5种。藤壶蚧、厚朴枝角叶蜂和厚朴新丽斑蚜为湖北省首次报道,小绿叶蝉为厚朴新寄主记录种。同时记录了藤壶蚧的天敌6种,其中寄生小蜂2种,瓢虫4种;厚朴新丽斑蚜的天敌昆虫8种。对藤壶蚧、厚朴枝角叶蜂和厚朴苗木根腐病等重要病虫害的发生规律进行了初步调查,同时提出了防治建议。     

陕北地区水资源可持续利用评价

以水资源复合系统为基础,建立了陕北地区水资源可持续利用评价指标体系,应用模糊综合评判方法和人工神经网络方法对该地区1996~2005年的水资源可持续利用水平进行了定量评价。结果表明:陕北地区除本身干旱缺水以外,水污染、生态环境恶化、用水效率低和经济水平不高是影响该区水资源可持续利用的主要因素;1996~2005延安市和榆林市的水资源可持续利用水平均处于较弱和中等之间,且呈上升趋势,提高陕北地区水资源可持续利用水平有很大潜力。     

极旱环境中两种梭梭蒸腾的生理生态学特点

白梭梭(Haloxylon persicum)和梭梭(H.ammodendron)是我国干旱荒漠区的优良固沙植物,列入我国第一批保护植物,白梭梭主要分布在新疆北部的古尔班通古特沙漠,梭梭除了分布在新疆外,还分布在青海、甘肃、内蒙古等地,对于它们的生物生态学特性的研究,国内已先后做过不少工作,关于生理方面的研究也有报导。本项工作是从水分生理观点着手,结合     

杀虫剂混合使用的增效作用评判分析

用共毒因子重新评价共毒系数大于100的281个混配组合,发现有29.18%的混配组合没有增效作用。根据单剂的LC-P线和共毒因子公式,求出混剂的期望死亡率和"相加作用区间"(期望死亡率±20%期望死亡率),根据混剂的实测死亡率求出95%置信区间,画出期望LC-P线及"相加作用区间"和实测LC-P线及"95%置信区间",发现当共毒系数大于100、共毒因子小于20时,实测LC-P线和期望LC-P线彼此交缠,期望LC-P线的"相加作用区间"和实测LC-P线的"95%置信区间"能高度重叠,表明两条LC-P线之间没有毒力差异;当共毒系数大于100、共毒因子大于20,或者共毒系数小于100、共毒因子小于-20时,实测LC-P线的"95%置信区间"和期望LC-P线的"相加作用区间"只有少量重叠或完全不重叠,体现出了实测LC-P线和期望LC-P线对供试害虫的毒力差异。因此,为了获得有稳定增效作用的混配组合,共毒系数须大于100,同时共毒因子也要大于20。     

Mode of action of meturine

The effect of meturine on the light processes of photosynthesis was studied.Meturine is a herbicide for weed control in potato and cotton crops. It is a N-phenyl—N-hydroxy—N′-methylurea.The experiments were carried out on isolated pea and spinach chloroplasts.When examining photosystem I, reduced DPIP was used as an electron donor, whereas methyl-viologen served as an electron acceptor. When examining photosystem II, DPIP represented the electron acceptor.The obtained experimental results have pointed to the absence of the effect of meturine upon the photoreaction I.Unlike N-phenyl—N′, N′-dimethylureas (CMU, DCMU) meturine has been a very weak inhibitor of photoreaction II.The authors explain the photoreaction II inhibition of chloroplasts from plants treated with herbicidal doses of meturine by conversion of N-phenyl—N-hydroxy—N′-methylurea into Hill reaction inhibitor(s). N-Phenyl—N′-methylurea can be one of such meturine metabolites.Meturine herbicidal action is accounted for by meturine transformation into Hill reaction inhibitor(s) in the plant tissues.     

Evaluation of Likelihood of Co-Occurrence of Erwinia amylovora with Mature Fruit of Winter Pear

ABSTRACT Phytosanitary concerns about fire blight prohibit export of U.S.-grown pears to some countries without this disease. To examine these concerns, we evaluated the potential for co-occurrence of Erwinia amylovora with mature, symptomless winter pear fruit by inoculation experiments and by survey of commercial orchards. Immature pear and apple fruit were inoculated in orchards with E. amylovora strain 153N as resuspended lyophilized cells or as ooze from diseased tissues. Regardless of inoculum source, population size of Ea153N on fruit declined by an order of magnitude every 3 to 4 days during the first 2 weeks after inoculation; at 56 days after inoculation, Ea153N was not detected, except on 1 of 450 fruit with 4 colony forming units (CFU). After inoculation of flowers, calyx-end survival of Ea153N on pear and apple fruit declined from high populations at petal fall to a few cells at harvest, with no detection of the pathogen after a 7-week cold storage. Migration of Ea153N into symptomless pear fruit from diseased branches was evaluated by enrichment assay and nested polymerase chain reaction of internal fruit core tissues; these assays failed to detect the pathogen in healthy fruit from diseased trees. At harvest, E. amylovora could not be detected on 5,599 of 5,600 fruit of d'Anjou pear sampled from commercial orchards in major production areas of the Pacific Northwest; one fruit yielded 32 CFU of the pathogen. Postharvest, mature pear fruit contaminated with Ea153N and subsequently wounded required a dose of >10,000 cells at the wound site to allow for persistence of the pathogen through a 7-week-cold storage. We conclude that epiphytic E. amylovora shows similar survival characteristics on both pear and apple fruit, this pathogen is not an endophyte within mature symptomless pear fruit, its presence is exceptionally rare on commercially produced fruit, and that epiphytic survival of E. amylovora through a postharvest chilling period is unlikely given the unrealistically high population size required for persistence.     

Comparison of methods of assessing field populations of Heterodera schachtii

Population assessment methods for Heterodera schachtü were compared in two tests. In the first there were no consistent differences between numbers of H. schachrü extracted by Fenwick cans (at two laboratories), a flotation column and an automatic cyst extraction apparatus, from dried soils from three sites containing no other cyst nematodes. The second, made on 54 commercial sugar beet fields, compared numbers of H. schachtü extracted from dried soil samples by Fenwick cans (at two laboratories) with results of a bioassay of soil samples and a subsequent examination of roots in the field. Most samples were placed into the same broad groups by the cyst extraction and bioassay methods and the two techniques were equally good at predicting field infestations.