An avirulence gene homologue in the tomato wilt fungus Fusarium oxysporum f. sp. lycopersici race 1 functions as a virulence gene in the cabbage yellows fungus F. oxysporum f. sp. conglutinans

Six4, a small protein secreted by Fusarium oxysporum f. sp. lycopersici (Fol) in tomato xylem sap during infection, triggers Fol race 1-specific resistance (I) in tomato. SIX4 is regarded as an avirulence gene. Although SIX4 is considered unique to Fol race 1, we detected this gene in the cabbage yellows fungus F. oxysporum f. sp. conglutinans (Foc) by PCR. Because the genes from Foc and SIX4 in Fol were >99 % identical at the nucleotide level, the Foc gene was designated FocSIX4. The expression of FocSIX4 was detected by RT-PCR in stems and roots of cabbage 8 days after infection with Foc. In contrast with Fol, disruption of FocSIX4 in Foc did not increase virulence to Foc-resistant cabbage cvs. Shutoku-SP and Koikaze. On the contrary, the disruptants had reduced virulence not only on Foc-resistant cultivars but also on Foc-susceptible cv. Shikidori. These results suggested that FocSIX4 is involved in virulence, but not in avirulence, in the cabbage yellows fungus.     

Measures aimed at controlling the invasion of Simulium damnosum Theobald s.l. (Diptera: Simuliidae) into the Onchocerciasis Control Programme Area. III. Searches in the Upper Niger Basin of Guinea for additional sources of flies invading south‐eastern Mali

Abstract

Very large breeding sites of the onchocerciasis vector, Simulium sirbanum were discovered along the Rivers Niger, Mafou, Kouya, Niandan and Milo in the Upper Niger Basin of Guinea. Flies reared from these breeding sites and caught biting man nearby were found to be in the same size range as those collected in the south‐eastern Mali invasion zone of the Onchocerciasis Control Programme Area. The periodicity of the Mali invasion appeared to be related to the hydrological conditions in the Upper Niger Basin during the early monsoon. During this period, rising water levels greatly increase vector breeding in the principal rapids of the Niger and its tributaries which lie upwind and to the south‐west of the invasion sites in south‐eastern Mali. The Mali invasion ceases towards the height of the rainy season when many of these rapids are flooded. It was concluded that the very large breeding sites associated with the principal rapids in the Upper Niger Basin were the main sources of the S. sirbanum invading south‐eastern Mali.     

P.D.A.

P.D.A.是三个英文字的缩写,P.=patato(马铃薯),D.=Dextrose(萄葡糖)A.=Agar(洋菜或称琼脂),是一种微生物培养基的代表符号。 不同种类的微生物,所要求的营养物质有差异,因此培养基的种类很多,P.D.A.是培养基中最常用的一种,适于植物病害中多种真菌、细菌的正常生长,因此又称普通培养基。     

Sequence of the 3′-terminal region of the RNA of a mite transmitted potyvirus fromHordeum murinum L.

The 3026 nucleotides upstream of the 3-polyadenylated tract of a mite transmitted virus fromHordeum murinum L. were cloned and sequenced, and portions of the sequence were expressed inEscherichia coli. Sequence comparisons with wheat streak mosaic virus (WSMV), Agropyron mosaic virus (AgMV) and Hordeum mosaic cirus (HoMV), three mite transmitted potyviruses, and potato virus Y (PVY), the type member of the genusPotyvirus, revealed that the virus is probably a potyvirus, but distinct from WSMV, AgMV, HoMV, and PVY. Serological tests further demonstrated these differences and that the virus is serologically related to another potyvirus, brome streak mosaic virus (BrSMV). We conclude that the virus should be named as the Hordeum isolate of BrSMV.     

Studies on the induction of rat uterine ornithine decarboxylase by DDT analogs. I. Comparison with estradiol-17β activity

The effect of DDT analogs and estradiol-17β on uterine ornithine decarboxylase activity in the immature intact and ovariectomized rat was studied. Pretreatment with various doses of o,p′DDT [1-(o-chlorophenyl)-1-(p-chlorophenyl)-2,2,2-trichloroethane] or estradiol-17β caused a marked increase in the specific activity of ornithine decarboxylase in the 20,000g supernatant fraction of uterine homogenates but not in liver homogenates. Doses as low as 0.5 mg of o,p′DDT or 0.002 μg of estradiol-17β stimulated uterine ornithine decarboxylase activity in the ovariectomized rat. The peaks of activity after treatment with o,p′ DDT and estradiol-17β occurred at 6 and 5 hr, respectively. The level of ornithine decarboxylase activity in untreated groups was consistently lower in ovariectomized rats than in intact immature animals. Treatment with o,p′ DDT (10 mg/100 g body weight) of ovariectomized and intact immature rats demonstrated at 131-fold and an about 20-fold increase in uterine ornithine decarboxylase activity, respectively. Treatment of ovariectomized rats with cycloheximide or actinomycin D effectively blocked the increase in ornithine decarboxylase caused by o,p′ DDT. Similar results were obtained with cycloheximide in the intact immature rat. Animals subjected to both adrenalectomy and ovariectomy demonstrated an increase in ornithine decarboxylase activity when treated with either estradiol-17β or o,p′ DDT. Dose-response curves obtained for estradiol-17β and o,p′ DDT suggest a similar mechanism of action for the two compounds. Graphic analysis of the dose-response curves for estradiol-17β and o,p′ DDT demonstrated an ED₅₀ of 0.038 μg/100 g body weight and 1.8 mg/100 g body weight, respectively. The examination of various DDT analogs in intact and ovariectomized animals showed that o,p′ DDT was the most potent inducer of ornithine decarboxylase. The order of decreasing potency of DDT analogs was o,p′ DDT, o,p′ DDD. p,p′ DDT, p,p′ DDD, and p,p′ DDE.     

Margaritaella gracilis gen. n. et sp. n. (Eucestoda: Proteocephalidea), a parasite of Callichthys callichthys (Pisces: Siluriformes) from the Paraná River basin, Argentina

Margaritaella gracilis gen. n. et sp. n. (Proteocephalidea: Proteocephalinae) found in the intestine of Callichthys callichthys (Linnaeus) from the Paraná River basin is described. The new genus is placed in the Proteocephalinae because of the medullary position of the genital organs. It differs from all known genera included in the Proteocephalinae by the following combination of characters: 1) scolex with a conspicuous cluster of drop-shaped gland cells posterior to suckers; 2) strobila with a low number of proglottides, all much longer than wide; 3) testes arranged in one field, composed of two parallel rows of testes separated by the uterus; 4) ovary delicate, H-shaped, with branches slender and deeply folliculate at the edges, located at 25-35% from the posterior end; 5) uterus largely extended posterior to the ovary but not reaching the end of proglottis; and 6) vitelline follicles in two narrow lateral bands, largely extended posterior to the ovary. Scanning electron microscopy revealed three types of microtriches on the tegument surface: acicular and capiliform filitriches and gladiate spinitriches. The relative size of the ovary, a character recently used in the systematics of the proteocephalidean cestodes, was calculated for the new species and compared with other species of the group. M. gracilis is the first record of a proteocephalidean cestode parasitizing a callichthyid catfish.     

Pomphorhynchus omarsegundoi sp. n. (Acanthocephala:Pomphorhynchidae), parasite of the banded knifefish Gymnotus carapo (Gymnotiformes:Gymnotidae) from the Paraná River basin, Argentina

Pomphorhynchus omarsegundoi sp. n. from Gymnotus carapo Linnaeus from the Paraná River basin in Argentina is described in this paper. The new species is characterised by having a small body; a non-spirally twisted long neck forming an inconspicuous asymmetrical bulb more developed dorsally than ventrally; a proboscis almost cylindrical, with 11 to 12 longitudinal rows of 5 to 7 (usually 6) hooks each; presence of an apical organ; a mean neck/body ratio of about 1/8; and a post-equatorial male reproductive system, occupying 35-42% of total length. The new species can be easily distinguished from the other four South American pomphorhynchid species by the inconspicuous asymmetrical bulb and the lower number of hooks per row. Pomphorhynchus omarsegundoi is the second acanthocephalan recorded from G. carapo in the Paraná River basin.     

C.d.a.–Controlled Droplet Application

Abstract

Efficiency of pesticide application can be improved if more consideration is given to where and when the active ingredient is most needed, and the optimum droplet size selected for a given target. Even when minimal volumes of spray are applied concentrate sprays are not justified as a greater proportion of the spray is collected on the target. Sprays with a narrow range of droplet size can be produced from ligaments thrown from centrifugal energy nozzles; droplet size being inversely proportional to the rotational speed.     

Impact of arbuscular mycorrhiza on the St. John’s wort (Hypericum perforatum) wilt disease induced by Colletotrichum cf. gloeosporioides

Journal of Plant Diseases and Protection - The importance of herbal plants is evident in the prevalent use as flavoring ingredients in food. However, meeting the growing demand for organic grown...     

Neotropical Monogenoidea. 56. New species of Anacanthorus (Dactylogyridae) from the gills of matrinchã, Brycon orthotaenia (Characiformes: Characidae), in the Rio São Francisco, Brazil

Anacanthorus franciscanus sp. n. and Anacanthorus brevicirrus sp. n. (Dactylogyridae) are described from the gills of the matrinch?, Brycon orthotaenia Günther (Characidae), from the Rio S?o Francisco in Brazil. Anacanthorusfranciscanus most closely resembles Anacanthorus e[egans and A. kruidenieri from the matrinch?, Brycon melanopterus, of the Amazon River Basin. It differs from these species in part by having the bulbous proximal end of the hook shank with two translucent regions. Anacanthorus brevicirrus resembles A. franciscanus, A. kruidenieri and A. elegans but is differentiated from these species by its short straight male copulatory organ and by having one translucent region in the bulbous base of the hook shank.     

猪殃殃Galium aparine L.var.tenerum(Gren.et Godr.)Rchb.发生规律观察

猪殃殃是我省分布广泛,危害严重的麦田恶性杂草。近年来,发生数量和危害面积还在不断上升,是麦子增产的障碍之一。笔者从1979年秋播开始对其生物学特性和发生规律作了调查观察,现将观察结果简报如下: 一、分布特点猪殃殃的分布和土质有很大关系,据在本地区9个县46个公社调查1561亩麦田(代表面积一万七千余亩)每平方尺发生10株以上的危害面积,沙土地区占调查面积的12.2％,粘土     

B.t.乳剂防治蔬菜害虫技术

B．t．杀虫剂是由苏云金杆菌发酵生产的一种微生物杀虫剂，能在细胞内形成菱形伴抱晶体的芽抱杆菌。其伴抱晶体是一种强毒性蛋白，在昆虫中肠碱性环境下释放出后，可使昆虫瘫痪致死。芽炮也能在虫体内萌发繁殖，从而加速昆虫死亡。B．t．杀虫剂具有化学农药不可替代的优越性，其治虫效果好，对害虫天敌和作物安全，使害虫不易产生抗药性，对生态系统无不良影响等优点，是生物防治蔬菜害虫的首选杀虫剂。我县自1992年将B．t．应用于蔬菜害虫的防治，取得了良好的防治效果和效益。特别是应用干蔬菜地防治菜青虫、小菜蛾和棉铃虫等害虫，防治…