Phylogenetic relationships of four Puccinia species parasitic on Artemisia in Japan

Puccinia dioicae var. micropuncta and P. caricis-stipatae complete their life cycle by host-alternating between Artemisia (spermogonial-aecial stage) and Carex (uredinial-telial stage). These species are suggested to be biologically distinct by inoculation experiments and field observations. Two additional Puccinia ferruginosa and P. artemisiae-keiskeanae produce only telial stage on Artemisia. Similarities in the teliospore morphology and host relationship of the four Puccinia species suggest their close phylogenetic relationship. Nucleotide sequences of D1/D2 region and ITS2 regions with partial 5.8S rDNA were analyzed to depict possible phylogenetic relationships among the four Puccinia species. In D1/D2 analysis, both macrocyclic and microcyclic species were closely positioned in one clade, not permitting resolution of the phylogenetic relationship between the species. The DNA sequence of ITS2 including partial 5.8S rDNA was sufficiently variable to separate two macrocyclic species and P. artemisiae-keiskeanae; however, confident resolution of phylogenetic relationships of the three species was not possible. Nevertheless, the analysis suggested the derivation of P. artemisiae-keiskeanae from a macrocyclic, heteroecious ancestor that is most likely to be an ancestor of both P. caricis-stipatae and P. dioicae var. micropuncta. In contrast, three isolates of morphologically identifiable P. ferruginosa were variously positioned in the phylogenetic tree, suggesting that P. ferruginosa is not monophyletic.Contribution no. 192, Laboratory of Plant Parasitic Mycology, Graduate School of Life and Environmental Sciences, University of Tsukuba, Japan     

Taxonomy ofPuccinia species causing rust diseases on sugarcane

A taxonomic revision ofPuccinia species causing rust diseases on sugarcane was conducted to clarify their morphological characteristics. Specimens including previously reported species,Puccinia melanocephala, P. kuehnii andPuccinia sp.sensu Muta, 1987, were collected in Japan and the Philippines and borrowed from various herbaria worldwide. Morphological characteristics of these specimens were examined under light and scanning electron microscopes. Comparative morphological studies of the specimens showed that rust fungi infecting sugarcane could be classified into two species,Puccinia melanocephala andP. kuehnii. Puccinia sp.sensu Muta was morphologically identical withP. kuehnii. Results of this study corroborate previous phylogenetic analysis results of D1/D2 regions of LSU rDNA gene. Contribution No. 157, Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba     

Population divergence in the wheat leaf rust fungus Puccinia triticina is correlated with wheat evolution

Co-evolution of fungal pathogens with their host species during the domestication of modern crop varieties has likely affected the current genetic divergence of pathogen populations. The objective of this study was to determine if the evolutionary history of the obligate rust pathogen on wheat, Puccinia triticina, is correlated with adaptation to hosts with different ploidy levels. Sequence data from 15 loci with different levels of polymorphism were generated. Phylogenetic analyses (parsimony, Bayesian, maximum likelihood) showed the clear initial divergence of P. triticina isolates collected from Aegilops speltoides (the likely B genome donor of modern wheat) in Israel from the other isolates that were collected from tetraploid (AB genomes) durum wheat and hexaploid (ABD genomes) common wheat. Coalescence-based genealogy samplers also indicated that P. triticina on A. speltoides, diverged initially, followed by P. triticina isolates from durum wheat in Ethiopia and then by isolates from common wheat. Isolates of P. triticina found worldwide on cultivated durum wheat were the most recently coalesced and formed a clade nested within the isolates from common wheat. By a relative time scale, the divergence of P. triticinia as delimited by host specificity appears very recent. Significant reciprocal gene flow between isolates from common wheat and isolates from durum wheat that are found worldwide was detected, in addition to gene flow from isolates on common wheat to isolates on durum wheat in Ethiopia.     

The presence of <Emphasis Type="Italic">Zygina</Emphasis> sp. and <Emphasis Type="Italic">Puccinia myrsiphylli</Emphasis> reduces survival and influences oviposition of <Emphasis Type="Italic">Crioceris</Emphasis> sp.

A leaf beetle, Crioceris sp. (Coleoptera: Chrysomelidae), was introduced into Australia as a biological control agent of bridal creeper (Asparagus asparagoides L. Druce) during October 2002. Rearing of Crioceris sp. is labour intensive therefore all releases of Crioceris sp. have been under 1000 individuals, which may be too low to ensure establishment if high mortality and high competition with other agents occurs. The aim of this study is to understand how the presence of two well-established biocontrol agents, a rust fungus (Puccinia myrsiphylli (Thuem) Wint [Basidiomycota: Uredinales]) and a leafhopper (Zygina sp. [Hemiptera: Cicadellidae]), might influence Crioceris sp. establishment. Crioceris sp. neonate larvae were placed on bridal creeper plants with or without the leafhopper and/or rust. The number of larvae that pupated was reduced by 38 and 65% in the presence of the rust fungus and leafhopper, respectively and by 45% in the presence of both agents. As the area infected by the rust increased the area damaged by the leafhopper decreased. The rust appeared to be negatively impacted by the presence of the leafhopper. In a second experiment, female Crioceris sp. adults were given a choice between uninfested bridal creeper plants and those infested with the rust or the leafhopper. The females preferred to lay their eggs on plants without leafhoppers but did not seem to be deterred by the presence of the rust. Consequently, the performance and impact of Crioceris sp. on bridal creeper may be reduced if populations overlap with the other biocontrol agents in the field.     

Heteroecious life cycle of two graminicolouspuccinia (Uredinales)

Puccinia erythropus, whose uredinial-telial stage occurs onMiscanthus andEularia spp. (Gramineae), was found to have a heteroecious macrocyclic life cycle with the spermogonial-aecial stage onCynanchum sublanceolatum var.obtusum (Asclepiadaceae).Puccinia miyoshiana, which forms the uredinial-telial stage onBothriochloa, Capillipedium, Eccoilopus, andSpodiopogon (Gramineae), is known to form its spermogonial-aecial stage onBuplerum spp. (Umbelliferae). By field observations and artificial inoculations,Bupleurum komarovianum was proved to serve as an additional spermgonial-aecial host of this fungus.     

Morphological and molecular phylogenetic analysis of <Emphasis Type="Italic">Melampsora</Emphasis> species on poplars in China

Many species of Melampsora on Populus have been reported in China, based on morphological characteristics of both uredial and telial states, and on host species, but their morphology and taxonomy are still poorly defined. In this study, 196 specimens representing Melampsora species on poplars and collected from various areas of China were used for morphological observations. The morphological characteristics of urediniospores and teliospores were examined with light and scanning electron microscopy. The specimens could be classified into five groups based on their morphology. For the sequencing of the nuclear large subunit rDNA (D1/D2), 5.8S rDNA and their internal transcribed spacers, ITS1 and ITS2 region, 54 specimens were selected from the specimens used in morphological observations. These specimens were separated into six clades by phylogenetic analyses of the D1/D2 and ITS regions. Correlations among morphological groups and phylogenetic clades based on these results suggest a revision of these species. In particular, no evidence to discriminate specimens of M. acedioides, M. magnusiana, and M. rostrupii was found from either morphological characteristics or sequence analysis.Contribution no. 185 Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba, Japan     

马蹄纹天竺葵柄锈菌在中国的发现

马蹄纹天竺葵柄锈菌(Puccinia pelargonii-zonalisDoidge)最初在1926年发现于南非,随寄主植物已传播到新西兰、澳大利亚、欧洲和美洲,严重危害天竺葵属花卉。我们在昆明西南林学院校园内的天竺葵(Pelargo-niumhortorumBailey)上发现此菌,植株受害严重。此菌在我国从未报道过,可以肯定是外来入侵种,它通过何种渠道侵入我国,尚待考证。本文对此菌的形态特征作了描述,并对相关知识作了简要介绍。研究标本保存于西南林学院标本室(HMSFC)和中国科学院菌物标本馆(HMAS)。     

A new species of Melampsora on Populus yunnanensis from China

Melampsora nujiangensis, a rust fungus found on Populus yunnanensis in China, is described as a new species. Light and scanning electron microscopy with herbarium specimens of the rust fungus show that the shape of its urediniospores differs from that of other known species of Melampsora, and its urediniospore walls are thinner than the other species. Furthermore, in phylogenetic trees based on the DNA sequences (28S and ITS) the rust fungus is phylogenetically separated by high bootstrap values. These results indicate that the fungus is an isolated species among the genus Melampsora. Contribution no. 202 from the Laboratory of Plant Parasitic Mycology, Graduate School of Life and Environmental Sciences, University of Tsukuba, Japan     

Rust fungi (Uredinales) on <Emphasis Type="Italic">Grewia</Emphasis> species (Tilliaceae) in South Africa,with <Emphasis Type="Italic">Uredopeltis atrides</Emphasis> comb. nov. the new name for <Emphasis Type="Italic">Ravenelia atrides</Emphasis>

The holdings of rust fungi on Grewia species (Tiliaceae) housed in the South African National Collection of Fungi (PREM) were examined. They belong to three morphologically similar, but clearly separable, species of Uredopeltis, and a species of Uredo. Each rust species has a distinct and restricted host range. Ravenelia atrides is a species of Uredopeltis and is transferred accordingly. Several specimens previously accessioned under R. atrides however belong to U. chevalieri. The specimens previously accessioned under Uredo grewiae belong to U. flava, and not U. chevalieri. Three specimens are best placed in Uredo corbiculoides. Taxonomic novelties Uredopeltis atrides (Syd. & P. Syd.) A.R. Wood. comb. nov.