GA_3对老化花椰菜种子活力和几种相关生理生化性状的影响

用10、50、100、150和200mg·L-15种浓度赤霉素（GA3）溶液处理于10℃冰箱中贮藏5年的花椰菜老化种子。结果表明,100mg·L-1GA3浸种22h的效果最佳,老化种子的发芽率、发芽势、活力指数、根长均有提高,畸形苗率下降;过氧化物酶（POD）、过氧化氢酶（CAT）和脱氢酶活性提高,可溶性蛋白和叶绿素含量也提高,种子浸出液的电导率和丙二醛（MDA）含量则下降。另外,100mg·L-1GA3处理后的种子在温度为25℃条件下贮藏时间不宜超过25d。     

Development of insect-resistant transgenic cauliflower plants expressing the trypsin inhibitor gene isolated from local sweet potato

Agrobacterium-mediated transformation was used to introduce a trypsin inhibitor gene into Taiwan cauliflower (Brassica oleracea var. botrytis L.) cultivars. The TI gene was isolated from a well-adapted Taiwan sweet potato cultivar and was expected to be especially effective in combating local pests. In vitro regeneration studies indicated that 4-day-old cauliflower seedling hypocotyl segments, pretreated with 2,4-dichlorophenoxyacetic acid for 3 days and incubated on a silver-ion-containing shoot induction medium, gave regeneration rates greater than 95%. Optimum transformation conditions were determined. G418 selection at 15 mg/l was initiated 1 week after cocultivation, and the dose was doubled 1 week later. Over 100 putative transgenic plants were produced. Transgenic status was confirmed by in vitro TI activity, and Southern and Western hybridization assays. The transgenic plants demonstrated in planta resistance to local insects to which the control plants were vulnerable. Received: 21 July 1997 / Revision received: 27 February 1998 / Accepted: 16 March 1998     

Reaction of Some Coffea arabica Genotypes to Strains of Colletotrichum kahawae, the Cause of Coffee Berry Disease

Pathogenicity tests were performed on 11 genotypes of Coffea arabica using single‐isolate suspensions of Colletotrichum Kahawae obtained from 90 monoconidial isolates. The objective of this study was to estimate the proportion of pathogenic variation corresponding 10 differences in aggressiveness and virulence (races). A large part of the variation in the pathogen population was due to aggressiveness. The differential effects were too small to suggest conclusively that races exist. This paper discusses the possible causes for the observed small differential interaction and suggests breeding strategies that not only prevent possible adaptation of the pathogen to resistant varieties but also limit variation for resistance due to differences in aggressiveness of the pathogen.     

根癌农杆菌介导B.t.基因和CpTI基因对花椰菜的转化

用根癌农杆菌介导的方法 ,将B .t.基因和Cp TI基因分别导入花椰菜“杂交 75天”的父本和母本的无菌苗下胚轴切段细胞 ,都获得了转基因植株。经过预培养的下胚轴切段用根癌农杆菌 (LBA44 0 4/ pG BI4A2B ,含B .t .基因 ;LBA44 0 4/pBRLC ,含CpTI基因 )进行感染后 ,共培养 48h ,继续培养 30d后 ,将分化芽转移至筛选培养基上。 10d后 ,大多数分化芽的顶端变成紫色 ,2 0d后紫色芽逐渐变白死亡 ,而转化芽在选择培养基上长成小植株。小植株移至大田能正常生长、开花、结籽。PCR和Southernblot分析表明B .t和CpTI基因已整合在植物基因组中     

几种影响羽衣甘蓝小孢子胚状体成苗的因素

羽衣甘蓝成熟小孢子胚转到固体培养基上可直接萌发成苗。成苗率与基因型、培养基成分和培养温度有关。MS+1.0%琼脂+3%蔗糖是适宜的成苗培养基;100MG·L-1活性炭对鱼雷形胚成苗起促进作用;10℃低温培养10D可提高成苗率。     

Population Structure of Geosmithia morbida,the Causal Agent of Thousand Cankers Disease of Walnut Trees in the United States

The ascomycete Geosmithia morbida and the walnut twig beetle Pityophthorus juglandis are associated with thousand cankers disease of Juglans (walnut) and Pterocarya (wingnut). The disease was first reported in the western United States (USA) on several Juglans species, but has been found more recently in the eastern USA in the native range of the highly susceptible Juglans nigra. We performed a comprehensive population genetic study of 209 G. morbida isolates collected from Juglans and Pterocarya from 17 geographic regions distributed across 12 U.S. states. The study was based on sequence typing of 27 single nucleotide polymorphisms from three genomic regions and genotyping with ten microsatellite primer pairs. Using multilocus sequence-typing data, 197 G. morbida isolates were placed into one of 57 haplotypes. In some instances, multiple haplotypes were recovered from isolates collected on the same tree. Twenty-four of the haplotypes (42%) were recovered from more than one isolate; the two most frequently occurring haplotypes (H02 and H03) represented 36% of all isolates. These two haplotypes were abundant in California, but were not recovered from Arizona or New Mexico. G. morbida population structure was best explained by four genetically distinct groups that clustered into three geographic regions. Most of the haplotypes isolated from the native range of J. major (Arizona and New Mexico) were found in those states only or present in distinct genetic clusters. There was no evidence of sexual reproduction or genetic recombination in any population. The scattered distribution of the genetic clusters indicated that G. morbida was likely disseminated to different regions at several times and from several sources. The large number of haplotypes observed and the genetic complexity of G. morbida indicate that it evolved in association with at least one Juglans spp. and the walnut twig beetle long before the first reports of the disease.     

The Effect of Chitinase on Didymella applanata, the Causal Agent of Raspberry Cane Spur light

In vitro and in vivo studies were conducted to assess the efficacy of the two microbial chitinases Chi I (from Streptomyces sp.) and Chi II (from Serratia marcescens) on Didymella applanata (Niessl.) Sacc., the fungus which causes spur blight of raspberry (Rubus idaeus L.). D. applanata was isolated from canes of diseased raspberries in a plantation in Novosibirsk, Russia. In vitro, the effective concentration of Chi I that reduced the growth of D. applanata was 0.4 U/ml (p = 0.05), but Chi II had no influence on the growth of the fungus in medium. In inoculation experiments on raspberry canes, both chitinases at the rate 0.5 U/ml reduced fungal development. In plantation where canes were inoculated after spraying with chitinase, fruiting bodies of fungus failed to form in all enzyme treatments, whereas a significant number of these fungal fruiting bodies (12.8 per cm²) developed in control treatments lacking chitinases spraying. The chitinases reduced the size of lesions and limited the infection of internal tissues of canes. Field testing of Chi I under natural conditions showed a significant suppression of the independent spur blight. These studies form the basis for further evaluation of ecologically benign control measures for raspberry spur blight.     

Effects of In-furrow and Water-run Oxamyl on Paratrichodorus allius and Corky Ringspot Disease of Potato in the Klamath Basin

Corky ringspot disease (CRS) of potato (Solanum tuberosum) is caused by the tobacco rattle virus (TRV), which is vectored by stubby-root nematodes, Paratrichodorus spp. and Trichodorus spp., and is a significant threat to potato quality and production in many areas of the western United States. Between 2002 and 2005, fields with a history of CRS were planted to potato and treated with various combinations of in-furrow (IF) and chemigated (water run, WR) oxamyl [Methyl N'N'-dimethyl-N-[(methyl carbamoyl)oxy]-1-thiooxamimidate] applications. Soil samples were collected to determine how Paratrichodorus allius populations responded to the various treatment regimes (2002-2004); potato tubers were evaluated for symptoms of CRS in 2004-2005. Applications of oxamyl to potato (1.1 kg a.i./ha) did not cause significant mortality of P. allius but did prevent the populations from increasing. Oxamyl applications that began at 55 days after planting (DAP) or later did not control CRS and were not different from the untreated control. However, application schedules that began early-season, either IF at planting, early WR (33 - 41 DAP), or both, significantly reduced CRS expression in cv. Yukon Gold. Therefore, oxamyl applications must be made early in the growing season to be effective in controlling CRS. Effects of oxamyl on CRS may be due to nematostatic action that suppresses feeding activity during early field season when most virus transmission probably occurs.     

养殖牙鲆淋巴囊肿病病原的研究

近几年我国海水养殖鱼发生病毒性传染病,病鱼鳍、鳃及体表皮肤出现乳头瘤样赘生物。将发病牙鲆（Ｐａｒａｌｉｃｈｔｈｙｓ ｏｌｉｖａｃｅｕｓ）表皮瘤组织进行超薄切片,电镜下在病变组织明显肥大的细胞胞浆内一球状病毒,呈二十面体对称,具包膜,直径约２１０ｎｍ。根据虹彩病毒主要衣壳蛋白（ｍａｊｏｒ ｃａｐｓｉｄ ｐｒｏｓｅｉｎ,ＭＣＰ）基因中间保守区序列设计简并引物,应用ＰＣＲ方法从病变组织中扩增出长６３６ｂ     

Physiological and Biochemical Characteristics of Iranian Strains of Xanthomonas axonopodis pv. citri, the Causal Agent of Citrus bacterial Canker Disease

Twenty-four strains of Xanthomonas axonopodis pv. citri ( Xac ), the causal agent of bacterial canker of citrus, isolated from Mexican lime ( Citrus aurantifolia ) and lemon ( Citrus limon ) in southern Iran, were characterized phenotypically. Strains were all pathogenic on C. aurantifolia . Sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis revealed slight differences in soluble protein profiles among the strains. Based on host range specificity and phenotypic characteristics, representative strains were differentiated into two groups of Asiatic (A) and atypical Asiatic (aA) forms. DNA fingerprinting analysis using Eco RI as the restriction endonuclease showed a negligible difference in restriction pattern between the two groups. On the basis of isozymic analysis, the two groups were distinct with respect to superoxide dismutase (SOD) and esterase (EST) banding patterns. Plasmid DNA profile analysis showed that the bacterial strains were different from each other in terms of plasmid number and molecular weight. Phage typing study revealed that most of group A strains were susceptible to Cp1 and/or Cp2 and some were resistant to both phage types including the strain in aA group. Bacteriocin production test indicated that there was a variation among Xac strains using different indicators for each bacteriocin producer. It is concluded that the Iranian strains of Xac are heterogeneous and constitute a subgroup(s) within the pathotype A.     

A damaging outbreak of arabis mosaic nepovirus in blackcurrant, the occurrence of other nepoviruses in Ribes species, and the demonstration that alfalfa mosaic virus is the cause of interveinal white mosaic in blackcurrant

In a crop of blackcurrant (Ribes nigrum), cv. Baldwin in Eire, chlorotic mottling and ringspot symptoms in leaves on plants and severe crop loss was associated with infection with arabis mosaic nepovirus (ArMV) and the presence in the soil of its nematode vector, Xiphinema diversicaudatum. This is only the second report of ArMV damaging a crop of blackcurrant. Tomato black ring (TBRV) and raspberry ringspot nepoviruses were detected in single plants of redcurrant (R. rubrum) in England and flowering currant (R. sanguineum) in Scotland respectively; each of these infected plants showed foliar chlorotic line-pattern symptoms. This is the first record of TBRV in redcurrant. A single blackcurrant plant in New Zealand showing symptoms typical of those described for interveinal white mosaic disease, contained alfalfa mosaic virus (AMV). When AMV particles were purified and concentrated from herbaceous test plants and mechanically inoculated to young blackcurrant plants, several became infected with AMV and most infected plants developed systemic symptoms typical of the original disease. This provides the strongest evidence to date that AMV is the causal agent of interveinal white mosaic disease.     

Analysis of Weather Effects on Variability in Lyme Disease Incidence in the Northeastern United States

In this study, variability in reported Lyme disease incidence between 1993 and 2001 was analyzed in seven states in the northeastern part of the USA. Positive significant correlations at p < 0.05 were found in all states between early summer disease incidence and the June moisture index in the region two years prior. These correlations may reflect an enhanced nymphal Ixodes scapularis survival under wetter conditions. In some states, significant correlations were observed related to warmer winter weather a year and a half prior to disease incidence, which may have been due to higher survival and activity levels of the white-footed mouse, an important host for I. scapularis ticks. This revised version was published online in July 2006 with corrections to the Cover Date.     

The Prevalence of <Emphasis Type="Italic">Trypanosoma cruzi</Emphasis>, the Causal Agent of Chagas Disease,in Texas Rodent Populations

Rodent species were assessed as potential hosts of Trypanosoma cruzi, the etiologic agent of Chagas disease, from five sites throughout Texas in sylvan and disturbed habitats. A total of 592 rodents were captured, resulting in a wide taxonomic representation of 11 genera and 15 species. Heart samples of 543 individuals were successfully analyzed by SybrGreen-based quantitative PCR (qPCR) targeting a 166 bp fragment of satellite DNA of T. cruzi. Eight rodents representing six species from six genera and two families were infected with T. cruzi. This is the first report of T. cruzi in the pygmy mouse (Baiomys taylori) and the white-footed mouse (Peromyscus leucopus) for the USA. All infected rodents were from the southernmost site (Las Palomas Wildlife Management Area). No differences in pathogen prevalence existed between disturbed habitats (5 of 131 tested; 3.8%) and sylvan habitats (3 of 40 tested; 7.5%). Most positives (n = 6, 16% prevalence) were detected in late winter with single positives in both spring (3% prevalence) and fall (1% prevalence). Additionally, 30 Triatoma insects were collected opportunistically from sites in central Texas. Fifty percent of these insects, i.e., 13 T. gerstaeckeri (68%), and two T. lecticularia (100%) were positive for T. cruzi. Comparative sequence analyses of 18S rRNA of samples provided identical results with respect to detection of the presence or absence of T. cruzi and assigned T. cruzi from rodents collected in late winter to lineage TcI. T. cruzi from Triatoma sp. and rodents from subsequent collections in spring and fall were different, however, and could not be assigned to other lineages with certainty.     

Conservation Management of Tasmanian Devils in the Context of an Emerging, Extinction-threatening Disease: Devil Facial Tumor Disease

An emerging infectious facial cancer threatens Tasmanian devils with extinction. The disease is likely to occur across the range of the devil within 5 years. This urgent time frame requires management options that can be implemented immediately: the establishment of insurance populations, in captivity, wild-living on islands, and aiming for eradication in areas that can be isolated. The long-term options of the spontaneous or assisted evolution of resistance or development of a field-deliverable vaccine are unlikely to be available in time. The disease’s characteristic allograft transmission through intimate contact simplifies isolation of insurance populations and breaking transmission in suppression trials. Better knowledge of contact matrices in wild devils will help focus timing and demographic targets of removals. A metapopulation approach is needed that integrates captive and wild-living island and peninsula (disease suppression) populations to minimize the loss of genetic diversity over 50 years until either extinction and reintroduction can occur, resistance evolves or a field-deliverable vaccine is developed. Given the importance of the insurance populations and the low genetic diversity of devils, a conservative target for retention of 95% genetic diversity is recommended. Encouraging preliminary results of the first disease-suppression trial on a large peninsula show fewer late stage tumors and no apparent population decline. Limiting geographic spread or suppressing the disease on a broadscale are both unlikely to be feasible. Since the synergy of devil decline and impending fox establishment could have devastating consequences for Tasmanian wildlife, it is crucial to manage the dynamics of new and old predator species together.     

应用电子探针研究黄叶生理病的水稻根内硅和铁分布

利用电子探针研究黄叶生理病的水稻根中一些元素的含量和分布,结果表明,硅和铁元素与稻叶发黄密切相关。通常稻根表皮层富集铁而内皮层富集硅,生理失调稻根表皮层中的铁远高于正常稻,而内皮层中的硅则较少。发病稻根高铁低硅的特征为深入研究发病的机理和土壤条件提供了线索。     

金瓜和白瓜花叶病毒病病原的初步鉴定

崇明是上海出口蔬菜生产基地之一,也是国家级的绿色食品园区之一,具有生产绿色蔬菜商品的生态环境和资源优势。特色出口蔬菜金瓜(Cucurbita pepo L.var.ovifera)、白瓜(Cucumis melo L.var.conomon,又名盐渍菜瓜)1997～1999统计病毒病发病率为23％,被感染的金瓜、白瓜田     

The Effect of the Sequence of Infection of the Causal Agents of Sweet Potato Virus Disease on Symptom Severity and Individual Virus Titres in Sweet Potato cv. Beauregard

Sweet potato virus disease (SPVD) is caused by dual infection of plants with Sweet Potato Feathery Mottle Virus (SPFMV) and Sweet Potato Chlorotic Stunt Virus (SPCSV). Because SPFMV and SPCSV are transmitted by aphids and whiteflies, respectively, infection in nature occurs independently rather than simultaneously. To investigate the effect of consecutive infection on symptom development and individual virus titres, plants infected with a single virus were later inoculated with the second virus. Symptoms were significantly more severe in plants infected with SPCSV followed by SPFMV compared to plants infected with SPFMV followed by SPCSV. Virus titres were not significantly different for SPCSV, but SPFMV titres, in plants infected with SPCSV followed by SPFMV, were significantly higher than all other treatments. The results indicate that the sequence of infection of sweetpotato plants with the causal agents of SPVD influence the severity of symptoms and SPFMV titres in SPVD affected plants.     

用黄瓜花叶病毒卫星RNA生防制剂大面积防治麦茬辣椒病毒病

用黄瓜花叶病毒（ＣＭＶ）卫星ＲＮＡ生防制剂Ｓ＿（５２）免疫辣椒,能防治辣椒由ＣＭＶ引起的病毒病。用Ｓ＿（５２）免疫接种辣椒的大田对比试验,防效达５９．５－７１．０％,产量比对照增加２６．１－３２．２％,产值增加３３．５－４５．２％。小区对比试验,用Ｓ＿（５２）免疫接种５０天的辣椒,防效达７１．３－９２．９％,免疫接种８０天,防效达５５．９－７８．５％,产量比对照增加３６．０－６５．３％,产值增加４９．３－９３．５％,还有刺激生长,促进早熟和增强对真菌、细菌病害抵抗作用。