Epidemic increase of Endophyllum osteospermi (Uredinales, Pucciniaceae) on Chrysanthemoides monilifera

The epidemiology of the rust fungus Endophyllum osteospermi was investigated. This rust fungus is considered to be a candidate biological control agent for Chrysanthemoides monilifera ssp. monilifera, which is an invasive alien weed of native vegetation in south-eastern Australia. Between 10 and 20 plants of C. monilifera were marked at each of five sites in the Western Cape Province of South Africa, where both organisms are native. The infection levels and number of witches' brooms were determined every 2 months over a 2-year period. Additionally, at three of these sites, the infection levels and number of witches' brooms of all bushes in the host population was determined annually over 4 years. The increase in number of witches' brooms per bush ranged between 0 and 282 within 1 year, with an average increase per bush of 28 (SE±4.8) in 1993, and 39 (SE±9.2) in 1994. The average r_s for all bushes during 1993 was 0.015 month^-1 (SE±0.0041, n=72) and 0.0098 month^-1 (SE±0.0073, n=43) during 1994. When host bushes that either died back or died during the course of each year were excluded, then the average r_s during 1993 was 0.023 month^-1 (SE±0.0048, n=45) and 0.0348 month^-1 (SE±0.0106, n=20) during 1994. Under suitable conditions in South Africa, E. osteospermi undergoes epidemic increase within its host plant's populations. This rust fungus should therefore be considered as a suitable candidate biological control agent for use in Australia against C. monilifera ssp. monilifera.     

Tilletia vankyi, a new species of reticulate-spored bunt fungus with non-conjugating basidiospores infecting species of Festuca and Lolium

A bunt fungus, exhibiting a spore germination pattern unique to known reticulate-spored species of Tilletia was found infecting plants in seed production fields of Festuca rubra ssp. rubra (red fescue) and F. rubra ssp. fallax (Chewing's fescue) in Oregon, and in seed lots of Lolium perenne (perennial ryegrass) from Australia and Germany. Teliospores germinated to form 20–40 uninucleate, non-conjugating basidiospores, and colonies derived from single basidiospores produced teliospores in culture. In inoculation studies using single basidiospore colonies, perennial ryegrass and L. perenne ssp. multiflorum (Italian or annual ryegrass) were infected. A phylogenetic analysis, based on ITS region rDNA, eukaryotic translation elongation factor 1 alpha, and the second largest subunit of RNA polymerase II demonstrated that the fescue and ryegrass bunts are conspecific, and distinct from known species of Tilletia.     

Host specificity of Puccinia spegazzinii (Pucciniales: pucciniaceae), a biological control agent for Mikania micrantha (Asteraceae) in Australia

The biology and host specificity of the rust fungus Puccinia spegazzinii, a biological control agent for Mikania micrantha, was studied in a quarantine laboratory in Brisbane, Australia. Nineteen plant species, all from the family Asteraceae were inoculated during host specificity trials. Spore formation occurred only on M. micrantha and no other plant was infected. The first signs of infection (white spots on leaves, petioles and stems) occurred 7 days after exposure to inoculum, becoming yellow by day 11. Mature pustules containing teliospores had developed by 20 days. Results obtained here support testing in other countries showing that P. spegazzinii is host specific to M. micrantha and no that other plant in Australia would be at risk if it were to be released in the environment. Recommendations on assessing pathogens to improve trials were proposed. Counting infected plants, plant parts and pustules formed can demonstrate that all test plants would have been adequately exposed to inoculum and thus increase the confidence in host specificity of pathogens in weed biological control.     

Selection of Cassida spp. from southern Africa for the biological control of Chrysanthemoides monilifera in Australia

Four species of tortoise beetle (Chrysomelidae, Cassidinae) (Cassida spatiosa Spaeth and three undescribed Cassida species, labelled 1. 2 and 3) from South Africa, were assessed as potential biological control agents against Chrysanthemoides monilifera monilifera (L.) T. Norl. and C. m. rotundata (DC.) T. Norl. These southern African plants are important weeds of conservation areas in Australia. In South Africa, Cassida spatiosa was found feeding on C monilifera subcanescens (DC.) T. Norl., Cassida sp. 1 on Chrysanthemoides monilifera pisifera (L.) T. Norl. and C m. monilifera, Cassida sp. 2 on C m. pisifera and Chrysanthemoides incana (Burm.f.) T. Norl. and Cassida sp. 3 on C. m. rotundata. The life cycle of each species was completed in about three months on the leaves of the host. Cassida species 1, 2 and 3 were tested against eight species of plant and only fed and completed development on Chrysanthemoides species and the related species. Calendula officinalis L. Cassida species 1 and 3 showed no preference between Calendula officinalis and Chrysanthemoides species for oviposition. Cassida species 3 was selected for further assessment as a biological control agent based on match to the host subspecies and target climate in Australia.     

Uromycladium tepperianum, the gall rust fungus from Falcataria moluccana in Malaysia and Indonesia

Batai (Falcataria moluccana) is a valuable tree species for forest plantations in Malaysia and Indonesia. Since 1993, a gall rust disease has caused severe damage to all growth stages, from seedlings in the nursery to mature trees in the field. To identify the fungus causing gall rust disease on F. moluccana in Malaysia and Indonesia, study of the mode of infection and changes in the anatomy of infected cells were carried out in the anatomy laboratory. The disease in Malaysia and Indonesia is caused by Uromycladium tepperianum. The fungus produces three longitudinally ridged teliospores on each head, with spores measuring 13–20 μm wide and 17–28 μm long. The fungus is microcyclic, completing its entire life cycle on F. moluccana. This study confirmed that the teliospores themselves cannot infect the host. Under favorable conditions, about 10 h after inoculation, teliospores germinate to produce basidiospores that form penetration pegs about 6 h later, and it is this peg which penetrates the host cells directly through the epidermis. Pycnia, recognized as small brown pustules, break through the epidermis about 7 days after inoculation.     

Life cycle and life strategy features of Puccinia glechomatis (Uredinales) favorable for extending the natural range of distribution

The objective of this study was to find features in microcyclic rust fungi (Uredinales) on wild host plants favorable for extension of the natural range of distribution. Puccinia glechomatis, a leptosporic rust fungus and its herbal host Glechoma hederacea (Lamiaceae), both natives to Eurasia and introduced in North America, were used for this study. Although the host has been known from North America since the beginning of the nineteenth century, the rust fungus was first observed there only in recent years. Favorable features were identified by studying the life cycle of the rust, including nuclear conditions and seasonal characteristics as well as its spread in North America. The life cycle was studied macroscopically by inoculation experiments, by various light microscope techniques, and by scanning electron microscopy. The spread of the pathogen and its host were reconstructed by evaluating host plant herbarium specimens and databases, literature, and field study data. The studies on P. glechomatis show that, generally for microcyclic rust fungi, establishment and potential for spread are based on several favorable features of both the host (e.g., synanthropic occurence and dispersal, genetic stability, regeneration of vegetative plant parts) and the rust fungus (asexual reproduction/genetic stability, homothallism, propagation with host plant, formation of both leptospores and thick-walled teliospores).     

Rust fungi causing galls, witches' brooms, and other abnormal plant growths in northwestern Argentina

Conspicuous galls and witches' brooms frequently are symptoms of rust infections on plant hosts in the ecologically diverse northwestern region of Argentina. These symptoms are caused by systemic or locally systemic spermogonial-aecial infections, although uredinial and telial infections also might be involved. Sixteen species of rust fungi are treated in this paper, most of which cause a plant response that results in enlarged growth. Ypsilospora tucumanensis J.R. Hern. & J.F. Hennen on Inga edulis is described as a species new to science. Puccinia cordiae Arthur is cited as a new record for Argentina. These rusts also are included: Chaconia ingae, Gerwasia imperialis, Kuehneola loeseneriana, Prospodium appendiculatum, Prospodium elegans, Prospodium perornatum, Puccinia bougainvilleae, Puccinia pampeana, Ravenelia argentinica, Ravenelia hieronymi, Ravenelia papillosa, Ravenelia spegazziniana, Uromyces cestri and Uropyxis rickiana. For some of the scientific names, lectotype specimens have been designated.     

The geographic distribution and host range of Capillaria hepatica (Bancroft) (Nematoda) in Australia.

The geographic distribution, host range and prevalence of Capillaria hepatica were recorded in 4629 house mice, Mus domesticus, 263 black rats, Rattus rattus, and 58 Norway rats, R. norvegicus. The parasite was found at five localities, all in or near large towns along the coast. The two Rattus species appeared to be the primary hosts of C. hepatica in Australia. Published and unpublished data on helminth infections of Australian native mammals from 1162 murids (26 species), 3018 marsupials (67 species) and 99 monotremes (two species) were compiled. Only seven animals from three murid species were infected with C. hepatica; all were from the same rainforest in northern Queensland. C. hepatica was distributed widely, occurring in the house mouse, black rat and Norway rat on a 10,850 ha farm but there was no infection in cattle, sheep or goats (abattoir records). Also, 52 rabbits, four cats and one fox (shot samples) and 27 marsupial mice, Sminthopsis crassicaudata (museum specimens), had no sign of C. hepatica infection. Overall, the results indicate that transmission of C. hepatica to native, domestic and feral mammals is rare, presumably because of ecological constraints on egg embryonation and survival. In the light of these findings, the potential use of C. hepatica as a biological agent to control mouse plagues in Australia is discussed.     

Aggressive interactions between three species of freshwater crayfish of the genus Cherax (Decapoda: Parastacidae)

The freshwater crayfish, Cherax destructor Clark, native to southeastern Australia, was first introduced to farm dams in southwestern Western Australia in 1932. The geographic range of the crayfish in Western Australia has increased substantially since then, and in recent years it has become established in natural waterways where it co-occurs with species of freshwater crayfish endemic to southwestern Australia, Cherax cainii and Cherax quinquecarinatus. The potential for competitive exclusion of these endemic species by C. destructor was investigated through laboratory experiments measuring aggressive behaviour. Body mass and species were found to be important factors governing aggressive dominance between C. cainii and C. destructor, with C. cainii winning significantly more interactions only when they were larger in body mass than their opponent. In trials between C. quinquecarinatus and C. destructor of similar body mass, there was no difference between the number of interactions 'won' by the two species. The implications for natural populations are discussed.     

The biology and host specificity of the onion weed rust, Puccinia barbeyi, a potentially useful agent for biological control in Australia

Onion weed, Asphodelus fistulosus L., (Liliaceae) a weed of Mediterranean and Middle Eastern origin is widespread in southern Australia where it invades pastures making them unsuitable for grazing. A program of research is underway to discover natural enemies of this plant and to study their possible role in the biological control of onion weed. A rust fungus Puccinia barbeyi (Roum.) Magnus has been found to severely attack A. fistulosus . Observations on the biology of the rust confirmed that it is monoecious and microcyclic and multiplied essentially by aecial and telial stages, although occasionally urediniospores also appeared among teliospores. Several members of the Liliaceae exposed to the aeciospores of the rust remained unattacked indicating that it is most probably specific to Asphodelus spp. and thus its potential for the biological control of A. fistulosus in Australia should be studied further.     

Taxonomy and phylogeny of Puccinia lagenophorae: a study using rDNA sequence data, morphological and host range features

Puccinia lagenophorae is a rust fungus originating from Australasia which has spread throughout the world. A phylogenetic analysis of taxa related to this species was performed using rDNA (LSU, ITS) sequence data. The analyses revealed a well-supported cluster including all specimens of P. lagenophorae. By evaluating morphological and sequence data, the species is taxonomically re-defined and a list of synonyms is provided. Puccinia distincta on Bellis perennis, a species recently separated from P. lagenophorae, P. saccardoi, a species on the Goodeniaceae, and P. byliana, a species so far only known from South Africa, are reduced to synonymy in P. lagenophorae, as are several other species. Our analysis indicates that P. lagenophorae is likely not derived from the northern hemisphere species P. obscura, but from a species from Australia host-alternating between Asteraceae (aecial host) and Cyperaceae/Juncaceae (telial host). Another related species, P. stylidii (on Stylidium sp., Stylidiaceae) may have been derived from the same parental species as P. lagenophorae. From ontogenetical and morphological studies, the presence of pycnia could not be confirmed in the life cycle of this species, and the width of the pedicel of teliospores at the point of attachment was found to be highly variable and not a taxonomic character. The number of known host species is approximately 150, including 41 new host plants recorded herein.     

Biotic resistance to Chrysanthemoides monilifera ssp. monilifera in Tasmania

Boneseed, Chrysanthemoides monilifera ssp. monilifera (Asteraceae) is concentrated in and near cities and towns on the north and east coasts of Tasmania. Its absence from intervening rural and bushland areas cannot be attributed to environmental conditions or a lack of time for dispersal from introduction points. The hypothesis tested in the present paper is that the range of boneseed in Tasmania is limited by biotic resistance through herbivory. Cafeteria experiments and field observations showed that sheep (Ovis aries), cattle (Bos taurus), Tasmanian pademelons (Thylogale billardierii), Bennett's wallabies (Macropus rufogriseus), garden weevils (Phlyctinus callosus) and native invertebrates all consumed boneseed, while common brushtail possums (Trichosurus vulpecula) did not. A boneseed population subjected to sheep grazing for 168 days suffered high mortality, while an adjacent ungrazed population survived intact. A replicated exclosure experiment showed that 75 days of grazing by cattle reduced the size of boneseed plants. Observations of a population subject to Bennett's wallaby and Tasmanian pademelon grazing over 1 year and 2 months showed consistently high leaf damage to foliage within pademelon reach and a decline in population, with high mortality rates in the driest and coldest times. Leaf loss attributable to invertebrates did not prevent a nearby population without wallabies from growing. The distributions of the taxa were consistent with biotic resistance, with those demonstrating no severe effect on boneseed individuals widespread, while those with evidence of severe effects more common in rural areas than in urban areas. Boneseed seemed unlikely to survive for very long at normal stocking levels. Macropod grazing, particularly that of T. billardierii, may also inhibit the invasion of boneseed. Thus, the recent introduction of foxes to Tasmania may not only cause the extinction of species such as T. billardierii, but also may cause an expansion of the range of boneseed.     

分泌型蛋白介导白念珠菌与宿主相互作用分子机制的研究进展

白念珠菌是人类最常见的条件性致病真菌之一,主要定植于人体粘膜表面。在白念珠菌与宿主相互作用过程中,分泌型蛋白起着非常重要的作用。针对分泌蛋白功能及其作用机理的研究有助于阐明白念珠菌致病分子机制,并为诊断、预防和治疗真菌感染提供新的理论策略。本文综述了白念珠菌分泌型蛋白在介导病原与宿主相互作用分子机制方面的最新研究进展,概括了分泌蛋白在组织侵入损伤、营养获取、细胞壁维持以及免疫逃避等方面的功能,同时对未来值得重点关注的研究方向进行了探讨。     

新疆不同来源金黄壳囊孢的多样性

为明确新疆不同寄主及地理来源的金黄壳囊孢(Cytospora chrysosperma)的多样性, 探讨种内亲缘关系和多样性差异。作者通过记录菌株在PDA培养基上的菌落颜色、形状、子实体形态等特征, 并应用Biolog-FF技术及ISSR分子标记技术, 比较了来自新疆5个地区5种寄主上的47株金黄壳囊孢的培养特征、生理生化特征及遗传多样性。结果表明47株金黄壳囊孢依据培养特征可划分为15种类型。不同类型菌株在碳源利用及代谢能力上存在差异, 各菌株对碳源的利用数量随着培养时间的增长逐渐增多。菌株882利用的碳源数量最多, 培养120 h可利用28种不同碳源, 碳源代谢能力中等; 菌株812-1利用的碳源数量最少, 培养120 h仅利用7种碳源, 代谢能力较低; 菌株1074-2、847、934、891-1、896、740具有单独利用碳源的能力。基于遗传相似性系数进行聚类分析, 结果显示遗传相似性系数为0.58时, 47个菌株被划分为两大类群, 其中第二类群菌株的培养特征为: 菌落白色、子实体较小且分布密集。供试金黄壳囊孢的多样性主要受自身遗传结构的影响, 不同寄主种类和地理来源对多样性的影响不显著。     

Morphological and molecular characterisation of Puccinia lagenophorae, now present in central North America

In June 2004, a rust fungus not previously reported for Oklahoma was found occurring naturally on the weed, common groundsel, Senecio vulgaris, in pots in a commercial container nursery in northeastern Oklahoma. Host symptoms and morphology of teliospores and aeciospores of the fungus were consistent with those of Puccinia lagenophorae, a recent introduction into North America that has, as yet, been reported only on the East and West Coasts of the USA. This is the first report of the rust in central regions of North America. The rust is believed to be native to Australia and New Zealand and subsequently reported in most continents on numerous species and genera of the Asteraceae. Some authors in Europe consider the rust on Bellis as different from the one on Senecio, naming it Puccinia distincta. Our ITS1‐5.8S‐ITS2 ribosomal DNA sequence data, however, show homology with P. distincta sequences from Europe, indicating there is only one morphologically‐variable polyphagous species. Presumably, the rust was introduced into Oklahoma on infected plants from the West Coast of the USA, the source of most plant material in the commercial nursery where it was found. The rust is potentially important on several ornamental Asteraceae in North America as it has become in Europe, where it spreads rapidly throughout that continent following its introduction there in the early 1960s.     

Melampsora salicis-sinicae (Melampsoraceae,Pucciniales), a new rust fungus found on willows in China

Based on morphological characteristics and molecular phylogeny, a rust fungus on Salix hsinganica, S. sinica, S. starkeana, S. wallichiana and S. xerophila in China is described as a new species, Melampsora salicis-sinicae. This new species morphologically resembles M. capraearum and M. epiphylla in having subcuticular teliospores with a thickened apical wall, but it differs from these two species in its amphigenous telia. In addition, this new species differs from M. capraearum in its slender teliospores and thinner apical thickness of teliospores, and it also differs from M. epiphylla in the dimension of urediniospores, the position of teliospores and the apical thickness of teliospores. Phylogenetic analyses using partial sequences of the D1/D2 region of nuclear large subunit and the internal transcribed spacer (ITS1 and ITS2) regions including 5.8S of ribosomal RNA gene and the translation elongation factor 1 alpha (EF-1α) gene revealed that this rust fungus was distinct from its morphologically similar species, M. capraearum and M. epiphylla.     

Quest to elucidate the life cycle of Puccinia psidii sensu lato

There is controversy surrounding the described life cycle of the rust fungus Puccinia psidii sensu lato, which causes disease on several plant species in the family Myrtaceae. The objective of this study was to determine whether P. psidii s.l. is autoecious by performing basidiospore inoculations, and microscopically examining the fate of basidiospores on the leaf surface and nuclear condition at different stages of rust development. No spermogonia developed on leaves of Agonis flexuosa inoculated either with a teliospore suspension or basidiospores naturally discharged from telia. Uredinial sori that developed in all three inoculations with teliospore suspensions and in one of the five inoculations with naturally-discharged basidiospores from telia were most likely the result of urediniospore infections. Microsatellite analysis revealed that isolates made from these uredinial sori had the same multilocus genotype as that of the original isolate. No signs of penetration of plant cells by basidiospores were observed on A. flexuosa and Syzygium jambos. The nuclear condition of mycelia of uredinial sori, urediniospores, teliospores, and four-celled metabasidia was typical of that in many rust fungi. Our study could not provide unequivocal proof that P. psidii s.l. is autoecious. While it is possible that it could be heteroecious, with an unknown alternate aecial host, it is also possible that basidiospores have lost the ability to infect Myrtaceae or are infrequently operational.     

内生真菌感染对宿主羽茅及邻生植物抗病性的影响

Epichloë内生真菌能够影响宿主植物的抗病性, 但目前关于内生真菌感染对宿主邻生植物抗病性影响的研究很少。该研究首先调查了内蒙古呼伦贝尔天然草地中植物病害发生情况, 发现在常见牧草中禾本科植物病害最为严重, 其中感染内生真菌的羽茅(Achnatherum sibiricum)的总病情指数最低。进一步比较了与羽茅邻生及非邻生植物的病害差异, 结果显示羽茅显著降低了邻生羊草(Leymus chinensis)、狼针草(Stipa baicalensis)和冰草(Agropyron cristatum)的褐斑病病情指数。为探究羽茅对邻生植物病害的影响是否与其内生真菌有关, 分别从内生真菌发酵液、离体叶片和植株层面进行了室内验证试验。结果表明: 羽茅的2种内生真菌Epichloë gansuensis和Epichloë sibiricum发酵液显著抑制了新月弯孢(Curvularia lunata)、根腐离蠕孢(Bipolaris sorokiniana)、核盘菌(Sclerotinia sclerotioru)和三叶草核盘菌(Sclerotinia trifoliorum)的生长; 对于离体叶片, E. gansuensis和E. sibiricum显著减小了宿主叶片受4种病原真菌侵染后的病斑长度。在新月弯孢和根腐离蠕孢的植株接种条件下, 内生真菌显著降低了宿主羽茅及邻生植物羊草的病害程度。该研究首次发现并验证了羽茅内生真菌对邻生禾草抵御褐斑病有一定的增益作用。