Identification of <Emphasis Type="Italic">Globodera rostochiensis</Emphasis> and <Emphasis Type="Italic">G. pallida</Emphasis> in the Ukraine by PCR

Multiplex polymerase chain reaction was used to identify the potato cyst nematodes in soil samples from the Ukraine. The results show the occurrence of Globodera pallida in the Uzhhorod region (Zakarpatska oblast), where only G. rostochiensis had been previously reported. In the mixed potato cyst nematode (PCN) populations, G. pallida was less prevalent (2–5%) than G. rostochiensis (95–98%). A phylogenetic analysis based on ribosomal DNA internal transcribed spacer sequences showed that the Ukrainian population of G. pallida had >99% sequence identity with other G. pallida pa2/3 isolates from Europe. This study has demonstrated that polymerase chain reaction-mediated amplification of specific regions of the potato cyst nematode genome is not only highly effective as a species diagnostic tool but is also a sensitive method which can be used for taxonomic purposes with cyst collections which vary in age.     

Infection of <Emphasis Type="Italic">Sorghum bicolor</Emphasis>, selected grass species and <Emphasis Type="Italic">Zea mays</Emphasis> by G<Emphasis Type="Italic">loeocercospora sorghi</Emphasis>, causal pathogen of zonate leaf spot

Zonate leaf spot (Gloeocercospora sorghi) is a common disease in Sorghum bicolor producing areas of the U.S., but little is known about its biology, virulence and severity on S. bicolor, Zea mays, and related crop grassweeds. Greenhouse studies were conducted to determine and compare the virulence and severity of G. sorghi on 10 commercially available sorghum hybrids, four Z. mays hybrids and selected grassweed species including Sorghum bicolor (grain sorghum and shattercane biotypes) and Sorghum halepense (Johnsongrass), two of the most problematic arable weeds. Plants from the respective species were inoculated with a local G. sorghi isolate and maintained in a dew-chamber at 24 °C for 24 h and then incubated under greenhouse conditions for 4 weeks. Plants were observed for lesion expression and rated using a modified Horsfall-Barrett scale (0–10). The first symptoms of infection were visible within 24 h following inoculation on shattercane and S. bicolor hybrids. Symptoms consisted of small, non-diagnostic purple lesions on the leaves. Results showed that S. bicolor, S. halepense and shattercane were susceptible to G. sorghi. All other species tested in this study were not infected. More particularly, disease severity, increased from a rating of 3 to 10 on sorghum and from 2 to 7 on S. halepense between 2 and 23 days after inoculation, respectively. However, disease severity on shattercane increased rapidly from 3.5 to 10 between 2 and 8 days after inoculation, respectively. Among the sorghum hybrids tested, FFR-322 appeared to be the most resistant to G. sorghi while Pioneer 83G66 appeared to be the most susceptible. Z. mays hybrids were not infected by the fungus used in this study. G. sorghi could be used effectively to manage shattercane and S. halepense infestations occurring in Z. mays and S. bicolor fields consisting of specific G. sorghi-resistant hybrids.     

Infection process of <Emphasis Type="Italic">Gilbertella persicaria</Emphasis> in papaya (<Emphasis Type="Italic">Carica papaya</Emphasis> L.) fruits

Gilbertella persicaria is a pathogenic fungus recently reported as a causative agent of soft rot in papaya fruits. Here the interactions between G. persicaria and papaya fruits was analyzed under laboratory conditions using histological techniques and optical microscopy to elucidate the process of pathogenesis. Healthy and disinfested fruits of papaya cv. Maradol were also inoculated with a suspension of sporangiospores of G. persicaria. Tissue sections were cut, which were subjected to differential staining with safranin-fast green for different times. Sporangiospores presumably adhered to the cuticle of the fruit by 3 h post inoculation (hpi) and germinated by 6 hpi; invasive intracellular hyphae were growing in host cells by 9 hpi. By 15 hpi, fruit epidermis was macerated, presumably by enzymatic activity reported for mucoral fungal species and appeared as a wet-looking lesion on the cuticle. Fruit mesocarp was colonized by 30 hpi, and asexual reproduction structures had formed by 48 hpi. This process of infection and disease development of G. persicaria in papaya fruits corresponds to that used by pathogens with a necrotrophic lifestyle.     

Distinguishing Galactomyces citri-aurantii from G. geotrichum and characterizing population structure of the two postharvest sour rot pathogens of fruit crops in California

A growth assay in lemon juice and polymerase chain reaction amplifications using newly designed species-specific primers from endopolygalacturonase and β-tubulin genes rapidly differentiated isolates of the morphologically similar fruit sour rot pathogens Galactomyces citriaurantii and G. geotrichum. Isolates of both species were collected from agricultural soils and decaying fruit at locations within and outside California, including worldwide locations, and were used in population genetic studies based on amplified fragment length polymorphic (AFLP) DNA markers. For all four geographically defined subpopulations (three counties of California and locations outside California) among 97 isolates of G. citri-aurantii and for the two subpopulations (origin within or outside California) among 35 isolates of G. geotrichum, the proportion of polymorphic loci and haplotypic diversity was high. In total, 82 unique haplotypes were identified for G. citri-aurantii for the four subpopulations and, of these, 80 haplotypes were unique among subpopulations. For G. geotrichum, 25 unique haplotypes were identified among the two subpopulations and no haplotype was shared. Indices of genetic differences (F(ST)) between subpopulations within each species were all low (e.g., 0.038 for G. geotrichum and 0.085 to 0.226 for G. citriaurantii), indicating a low level of genetic differentiation. Following clone correction, mating type segregation ratios for G. citri-aurantii did not significantly (P > 0.1) deviate from a 1:1 ratio for all four subpopulations or the entire population. Tests of the index of association (I(A)) and parsimony tree-length permutation tests (PTLPT) supported a random mating structure for clone-corrected data for the Kern, Tulare, and Ventura County subpopulations and the null hypothesis of random mating could not be rejected. Additionally, PTLPT also supported random mating for the "outside of California" population. For G. geotrichum, random mating was only tested using I(A) and PTLPT and the null hypothesis of random mating was not rejected (P > 0.05) using clone-corrected data. Further evidence that sexual recombination likely occurs in both species of Galactomyces was the lack of grouping consistency in the unweighted pair-group method with arithmetic mean clustering of AFLP data. A high confidence based on bootstrap values was obtained for only a few of the nodes in each of the two trees. A mixed reproduction system with an out-crossing sexual mating system and a prolific asexual phase is proposed for both species.     

Cytochrome b gene structure and consequences for resistance to Qo inhibitor fungicides in plant pathogens

The cytochrome b (cyt b) gene structure was characterized for different agronomically important plant pathogens, such as Puccinia recondita f sp tritici (Erikss) CO Johnston, P graminis f sp tritici Erikss and Hennings, P striiformis f sp tritici Erikss, P coronata f sp avenae P Syd & Syd, P hordei GH Otth, P recondita f sp secalis Roberge, P sorghi Schwein, P horiana Henn, Uromyces appendiculatus (Pers) Unger, Phakopsora pachyrhizi Syd & P Syd, Hemileia vastatrix Berk & Broome, Alternaria solani Sorauer, A alternata (Fr) Keissl and Plasmopara viticola (Berk & Curt) Berlese & de Toni. The sequenced fragment included the two hot spot regions in which mutations conferring resistance to QoI fungicides may occur. The cyt b gene structure of these pathogens was compared with that of other species from public databases, including the strobilurin-producing fungus Mycena galopoda (Pers) P Kumm, Saccharomyces cerevisiae Meyer ex Hansen, Venturia inaequalis (Cooke) Winter and Mycosphaerella fijiensis Morelet. In all rust species, as well as in A solani, resistance to QoI fungicides caused by the mutation G143A has never been reported. A type I intron was observed directly after the codon for glycine at position 143 in these species. This intron was absent in pathogens such as A alternata, Blumeria graminis (DC) Speer, Pyricularia grisea Sacc, Mycosphaerella graminicola (Fuckel) J Schr?t, M fijiensis, V inaequalis and P viticola, in which resistance to QoI fungicides has occurred and the glycine is replaced by alanine at position 143 in the resistant genotype. The present authors predict that a nucleotide substitution in codon 143 would prevent splicing of the intron, leading to a deficient cytochrome b, which is lethal. As a consequence, the evolution of resistance to QoI fungicides based on G143A is not likely to evolve in pathogens carrying an intron directly after this codon.     

De structuur van de kegeltop als taxonomisch kenmerk bij heterodera-soorten met citroenvormige cysten

Summary Referring to an earlier communication of the authors additional data are furnished on the taxonomical value of the structure of the vulva cone in lemonshapedHeterodera cysts (figs 1–5, table 1).InH. avenae=H. major the transparent lip tops of the cone are narrow and have a very short touching line, forming together the shape of an 8. The vulvar split is extremely short, probably too short to enable the deposition of eggs in the gelatinous egg sac around the cyst vulva which phenomenon normally occurs in other lemon-shapedHeterodera-species. These characters are useful, in addition to others, to separateH. avenae from mixed populations. H. schachtii shows smaller transperent patches on the lip tops thanH. trifolii and this character is probably useful for separating these species in practical advisory work. The average length of the patches (1 in the drawing of table 1) proved to be 32,1 and 45,6 . An average of 5 specimens is adequate to place a population below or above 38.7 , which is the limiting value between the two species, according to statistical treatment of the presented data.     

Rapid Identification of Clavibacter michiganensis Subspecies sepedonicus Using Two Primers Random Amplified Polymorphic DNA (TP-RAPD) Fingerprints

Twenty strains of Clavibacter michiganensis subsp. sepedonicus from different geographic origins and other reference strains of the same and different species, including other potato pathogens, were analysed with a new procedure named TP-RAPD that originates fingerprints of bacterial species. This procedure uses two primers to amplify the 16S rDNA gene. At 45 °C of annealing, the PCR product electrophoresed in agarose gels produced a band pattern that was different in all bacterial species studied as well as in the subspecies of C. michiganensis. All strains of C. michiganensis subsp. sepedonicus displayed the same TP-RAPD number of pattern. Unlike Gram negative bacteria, Gram positives of high G + C content, such as Clavibacter, produced low bands in TP-RAPD. By using a different set of two primers also based in the 16S rDNA sequence from Escherichia coli a more adequate amplification of Gram positives of high G + C including a greater number of bands was obtained. TP-RAPD patterns using the new set of primers described in this work is a reliable and fast method to identify C. michiganensis subsp. sepedonicus.     

9种珍稀濒危保护植物营养器官解剖学的观察

合理利用野生植物资源,保护珍稀濒危植物,对于发展经济,开展科学研究,改善自然环境,维护生态平衡,丰富人民生活皆具重要作用。因此,近些年来围绕着这些植物的研究日趋繁多,有关报导也屡见不鲜。本文力图通过9种新疆的珍稀濒危植物营养器官解剖学的     

Effects of grassland management on the community structure,aboveground biomass and stability of a temperate steppe in Inner Mongolia,China

Plant community structure responds strongly to anthropogenic disturbances, which greatly influence community stability. The changes in community structure, aboveground biomass(AGB), biodiversity and community stability associated with different management practices were studied with a three-year field investigation in a temperate steppe of Inner Mongolia, China. The species richness, Shannon-Wiener index, evenness, plant functional type abundance, AGB, temporal community stability, summed covariance, scaling coefficient and dominant species stability were compared among areas subjected to long-term reservation(R), long-term grazing(G), mowing since enclosure in 2008(M) and grazing enclosure since 2008(E). Site R had higher perennial grass abundance and lower species richness than sites G, M and E, although the AGB was not significantly different among the four sites. The species structure varied from a single dominant species at site R to multiple dominant species at sites G, M and E. The long-term reservation grassland had lower biodiversity but higher stability, whereas the enclosed grassland with/without mowing had higher biodiversity but lower stability. Different stability mechanisms, such as the compensatory dynamics, mean-variance scaling and dominant species stability were examined. Results showed that community stability was most closely related to the relative stability of the dominant species, which supports the biomass ratio hypothesis proposed by Grime.     

Chitinolytic <Emphasis Type="Italic">Streptomyces griseorubens</Emphasis> E44G enhances the biocontrol efficacy against <Emphasis Type="Italic">Fusarium</Emphasis> wilt disease of tomato

Streptomyces griseorubens E44G is a chitinolytic bacterium isolated from cultivated soil in Saudi Arabia (a hot, arid climatic region). In vitro, antifungal potential of S. griseorubens E44G was assessed against the phytopathogenic fungus, Fusarium oxysporum f. sp. lycopersici (the causative agent of the Fusarium wilt disease of tomato). An inhibition zone of 24 mm was recorded. The chitinolytic activity of S. griseorubens E44G was proved when the colloidal chitin agar plate method was used. A thermostable chitinase enzyme of 45 kDa molecular weight was purified using gel filtration chromatography. The optimum activity was obtained at 60 °C and pH 5.5. The purified enzyme has shown a very pronounced activity against the phytopathogenic fungus, F. oxysporum. The molecular characterization of the chitinase gene indicated that it consists of 1218 bp encoding 407 amino acids. The phylogentic analysis based on the nucleotide DNA sequence and the deduced amino acids sequence showed high similarity percentages with other chitinases isolated from different Streptomyces species. In the field evaluation, application of both S. griseorubens E44G treatments significantly increased all tested growth and yield parameters and decreased the disease severity compared with the infected-untreated tomato plants suggesting potential as a biocontrol agent.     

旱生条件下柠条锦鸡儿AM真菌生态学研究

通过从分布于山西、陕西和内蒙古三省区12个样地中的柠条锦鸡儿(Caragana korshinskii)根围采集土样和根样,系统研究了柠条锦鸡儿AM真菌种类组成和生态分布.试验结果表明,在已分离鉴定出的12种AM真菌中,球囊霉属(Glomus)6种,无梗囊霉属(Acaulospora)3种,巨孢囊霉属(Gigaspora)1种,盾巨孢囊霉属(Scutellospora)2种,而摩西球囊霉(Glomus mosseae)和缩球囊霉(Glomus constrictum)是优势菌种. AM真菌能与柠条锦鸡儿形成良好的共生结构,AM真菌平均总定殖率59.98%,平均孢子密度为830.59个/100 g土.不同采样地之间的AM真菌种类和分布差异显著.孢子密度与菌丝和总定殖率呈显著正相关;孢子密度与土壤速效N呈极显著正相关,丛枝定殖率与土壤有机质呈显著正相关,总定殖率和菌丝定殖率与土壤pH呈极显著正相关.     

不同季节鹅喉羚昼间活动节律特征

2007年10月至2008年10月,采用焦点动物取样法,在卡拉麦里山有蹄类自然保护区观察了鹅喉羚的昼间活动节律.共观察鹅喉羚有效个体1 917只,采集行为数据319.5 h,将鹅喉羚的行为分为采食、移动、警戒、休息和其他5种类型.结果表明:采食是各季节鹅喉羚最主要的活动类型,每天有2～3个采食高峰,一般出现在晨昏和正午...     

鹅掌柴真菌病害鉴定

 调查鉴定了广州地区鹅掌柴(Schefflera actinophylla (Endl.) Harms.)上12种真菌病害及其病原菌,以叶疫病和炭疽病危害较重。病原菌中有3个新种:鹅掌柴小球腔菌Leptosphaeria schefflerae P.G.X i,P.K.Chi et Z.D.Jiang,鹅掌柴生尾孢Cercospora schefflericola P.G.Xi,P.K.Chi et Z.D.Jiang,鹅掌柴拟茎点霉Phomopsis schefflerae P.G.Xi,P.K.Chi et Z.D.Jiang和一个新组合:鹅掌柴茎点霉Phoma scheffleri (Chen) P.G.Xi et P.K.Chi。新种提供了拉丁文简介、描述和绘图,研究的标本保存在华南农业大学真菌标本室。     

G—P复合生物杀虫剂对蚜虫四种优势种天敌不同发育阶段的毒力

本文报道Ｇ－Ｐ杀虫剂对蚜虫的４种中天敌不同发育阶段的室内毒效测定结果，Ｇ－Ｐ杀虫剂对４种天敌的成虫和蛹只具弱效；对幼虫和卵的毒力则因天敌种类不同而不同。其中对大灰食蚜蝇的毒性相对较强。     

河北珍稀濒危药用植物资源研究

利用IUCN国际标准和二级模糊评判法确定河北省级濒危保护植物基础上,对其中的珍稀濒危药用植物资源进行了初步研究,以期为开发利用提供依据。研究表明:河北省有药用价值的珍稀濒危植物共计121种,隶属55科,90属。其中一级保护植物33种,二级保护植物46种,三级保护植物42种。系统分析了河北珍稀濒危药用植物的种类组成、药用部位及药用价值,并结合本省药用植物的实际生存状况,提出了具体的保护建议。     

Improved assessment of mycelial growth stimulation by low doses of mefenoxam in plant pathogenic <Emphasis Type="Italic">Globisporangium</Emphasis> species

Globisporangium Uzuhashi, Tojo & Kakish. (syn. Pythium Pringsheim) species cause many plant diseases, including Pythium damping-off, leaf and fruit blights, and root rots. Fungicide resistant isolates are selected by repeated use of a single active ingredient on infected crops without rotation. Previous studies demonstrated increased pathogenicity and radial growth in a mefenoxam resistant isolate of Pythium aphanidermatum when exposed to sub-lethal doses of fungicides and ethanol. In those studies, reproducibility of in vitro assays was difficult to achieve due to large variations among trials. This study aimed to examine two protocols for improved reproducibility during the assessment of biphasic dose-responses in mefenoxam-resistant isolates of Globisporangium ultimum and G. irregulare. Two different growth related endpoints, total growth area and total dry mass weight, were assessed. Assays were conducted using ten concentrations of mefenoxam ranging from 0.01 to 1,000 μg/ml. Statistically-significant stimulatory effects were observed in the two Globisporangium species using the two growth related endpoints. Because of its better reproducibility, mycelial growth area is recommended as an endpoint for future studies of chemical hormesis on growth of Globisporangium spp.     

Neotropical Monogenoidea 37. Redescription of Gyrodactylus superbus (Szidat, 1973) comb. n. and description of two new species of Gyrodactylus (Gyrodactylidea: Gyrodactylidae) from Corydoras paleatus and C. ehrhardti (Teleostei: Siluriformes: Callichthyidae) of Southern Brazil

Two new species of Gyrodactylus (Gyrodactylidae) are described from Corydoras paleatus (Jenyns) and Corydoras ehrhardti Steindachner (Callichthyidae) of Rio Piraquara, Municipality of Piraquara, near Curitiba, Paraná, Brazil: Gyrodactylus anisopharynx sp. n. and Gyrodactylus samirae sp. n. These species are unique among the known Neotropical species of Gyrodactylus by the combination of several characters. Gyrodactylus anisopharynx is characterised by having hooks with point evenly curved, toe moderately pointed, round convex heel, straight sloping shelf, superficial bar with anterolateral projections and male copulatory organ armed with two rows of spinelets. Two variants of G. anisopharynx, of distinct pharynx size, are recognised: forma "large-pharynx" and forma "small-pharynx". Gyrodactylus samirae is characterised by having hook with straight shaft, short slightly recurved point, truncate toe, trapezoidal heel, shelf slightly concave, orthogonal to shaft; anchors with relatively short superficial root; superficial bar with extremities lightly expanded; and male copulatory organ armed with two rows of spinelets. Paragyrodactyloides superbus (Szidat, 1973) is redescribed and transferred to Gyrodactylus based on examination of type and new specimens. Features previously considered as diagnostic for the genus are misinterpretations or primitive characters for Gyrodactylus spp.     

On the problem of variable numbers of hosts in the life-cycles of helminths.

The authors analyze the phenomena underlying the variation of host numbers in the life-cycle of several helminth species. Variation of host number in the cycle is effected by alternative shortening of the cycle (with this the cycle turns out either without or with a polyvalent obligatory host or, in rarer cases, without or with appearing of neogeny) or by facultative widening of the cycle (without or with participation of additional hosts, namely para-paratenic, paradefinitive, metaparatenic, or euparatenic hosts). The term of metaparatenic host is made precise by limitation to a "hemistadiogenous" additional host (sensu Barus and Rysavy 1977).     

Chaetotaxy applied to Norwegian Gyrodactylus salaris Malmberg, 1957 (Monogenea) clades and related species from salmonids

Gyrodactylus salaris Malmberg, 1957 is a major pathogen of wild Salmo salar L. parr populations in Norway, and its delimitation from non-pathogenic species is important. The present study was undertaken to test the power of chaetotaxy to differentiate between three populations belonging to both the same and different clades (as stated by mtDNA) of G. salaris, in addition to three different species of gyrodactylids (G. salaris, G. thymalli and G. caledoniensis). The gyrodactylids were processed for chaetotaxy in situ and a maximum of 50 specimens per collection site were used to construct a generalised map over the sensilla. The sensilla were found in all populations to be symmetrically distributed around the median longitudinal axis, according to a formula of 7 dorsal (34 sensilla) and 8 ventral (44 sensilla) clusters on each side of the median line. The three Norwegian populations of G. salaris were found identical, as were the population of G. thymalli. The specimens of G. caledoniensis from Scotland, however, were found to differ from the Norwegian species G. salaris and G. thymalli by the position of one sensillum in two of the clusters. A comparison of the sensillum pattern of laboratory maintained G. salaris (River Lierelva) with results obtained ten years earlier, questions the temporal stability of the chaetotaxy pattern. The present results indicate that chaetotaxy can be used to discriminate between certain Gyrodactylus spp. but not generally.