Putative natural hybrid between Puccinia lagenophorae and an unknown rust fungus on Senecio madagascariensis in KwaZulu-Natal,South Africa

Several specimens of an aecial rust fungus were collected on Senecio madagascariensis during a field survey carried out in KwaZulu-Natal, South Africa. As telia were not present in the specimens collected, DNA sequence analyses were undertaken to determine the identity of the rust species. ITS and β-tub1 sequencing confirmed that one of the isolates recovered is Puccinia lagenophorae sensu lato. On the other hand, sequencing and RFLP analysis revealed the presence of two divergent copies of ITS and β-tub1 in all the other six isolates investigated. In both phylogenetic trees, one copy of the gene region grouped within a well supported clade with sequences of P. lagenophorae accessions from different geographical origins and hosts, and the Australian rusts Puccinia saccardoi and Puccinia stylidii. The other copy of these gene regions grouped within a separate clade comprising European accessions of Puccinia dioicae (ITS) and Uromyces sommerfeltii (β-tub1) that occur on Asteraceae hosts. Multiple copies of these gene regions were not observed in Australian isolates of P. lagenophorae. Our study provides some evidence that an interspecific hybrid rust fungus, with P. lagenophorae as one of its parents, may occur on S. madagascariensis in South Africa. The identity of the other parent remains unknown.     

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.     

Deciphering species complexes: Puccinia andropogonis and Puccinia coronata, examples of differing modes of speciation

Species of macrocyclic, heteroecious grass rusts often have been defined with wide host ranges and variation in spore morphology. Consequently, some are species complexes and contain genetically distinct forms. Molecular analyses, together with morphological and biological methods, provide powerful means to dissect these complexes. Puccinia coronata is a complex species that has a broad telial host range including more than 45 genera of grasses and a narrow aecial host range. Phylogenetic analysis of nuclear ribosomal internal transcribed spacer (ITS) DNA sequences from 15 aecial and telial collections grouped P. coronata into six distinct clades supporting separation of this complex into four distinct species. Puccinia andropogonis, a common rust of tall prairie grasses in North America, is also a complex species. However, in contrast to P. coronata, P. andropogonis has a narrow telial host range and a broad aecial host range. DNA sequence analysis grouped 15 collections of P. andropogonis into six distinct clades representing at least four distinct species. Speciation of P. coronata appears to have occurred primarily by radiation onto new telial hosts, whereas in P. andropogonis speciation appears to have occurred primarily by radiation onto new aecial hosts.     

Relatedness Among Agronomically Important Rusts Based on Mitochondrial Cytochrome b Gene and Ribosomal ITS Sequences

A fragment of the mitochondrial cytochrome b (cyt b) gene of 13 agronomically important plant pathogenic Basidiomycetes was sequenced, including several Puccinia spp., Uromyces appendiculatus, Phakopsora pachyrhizi, Hemileia vastatrix and Rhizoctonia solani. The deduced amino acid sequences (residues 142–266) were used to study the relatedness of these pathogens as compared to other species of the Basidiomycetes, Ascomycetes and Oomycetes. The relatedness was also studied at nuclear level using the Internal Transcribed Spacers (ITS) in the ribosomal DNA. Phylogenic trees were constructed with the maximum parsimony (MP) and the neighbour‐joining (NJ) methods. On the basis of both cytochrome b and ITS sequences, the Puccinia species pathogenic to graminaceous crop plants, such as Puccinia recondita f. sp. tritici, Puccinia graminis f. sp. tritici, Puccinia striiformis f. sp. tritici, Puccinia coronata f. sp. avenae, Puccinia hordei, P. recondita f. sp. secalis and Puccinia sorghi, together with Puccinia horiana from Chrysanthemum, were very closely related to each other, whereas Puccinia arachidis (from peanut) was closely related to U. appendiculatus (from beans) but more distant from the other Puccinia species. Both rusts on soybean (P. pachyrhizi) and coffee (H. vastatrix) were outside the Puccinia cluster. All rusts were separated from other Basidiomycetes such as R. solani and the strobilurin producing species Strobilurus tenacellus and Mycena galopoda. Our results demonstrate that the amino acid sequence of the mitochondrial cytochrome b is a valid tool to study phylogenic relatedness among plant pathogenic Basidiomycetes and supports taxonomic grouping based on morphological structures and host specificity. Because of their high variability, ITS sequences were able to discriminate Puccinia species, which were identical on the basis of the cytochrome b amino acid sequence. Thus, ITS sequences could better show differences among species or within a species, whereas cytochrome b is more suitable than ITS for phyologenic inference at family or genus level. In addition, the sequence data obtained during this study represent essential information for easy isolation of the cyt b gene and detection of point mutations conferring resistance to Qo Inhibitor fungicides that eventually may evolve.     

The rust fungi of <Emphasis Type="Italic">Luzuriaga</Emphasis> (Luzuriagaceae) with description of a new species, <Emphasis Type="Italic">Puccinia luzuriagae-polyphyllae</Emphasis>

Three species of rust fungi (Uredinales), Puccinia perforans, P. fuegiana (= Uromyces skottsbergii), and Aecidium callixenis have been described on members of Luzuriaga (Luzuriagaceae). Puccinia luzuriagae-polyphyllae is added as a new species on Luzuriaga polyphylla from Chile. The rust had been confused hitherto with P. perforans occurring on L. radicans. Both species differ from P. fuegiana on L. marginata by the absence of a uredinial state and several telial characters. The investigated collections of Puccinia species on Luzuriaga indicate that each is restricted to a single host species. A determination key is presented.     

New species, reports, observations and taxonomical changes of southern African rust fungi (Uredinales)

This work presents research on the diversity of the southern African rust mycobiota (Uredinales). It describes new species, lists new reports and adds new information on several rust fungi. Puccinia cornurediata, Puccinia dioscoreae-mundtii, Puccinia horti-kirstenboschi, Puccinia othonnoides, Puccinia rapipes, Puccinia subindumentana, Uredo otholobii and Uromyces lotononidicola are described as new; Puccinia verwoerdiana is assigned to Puccinia lycii as a synonym, and Uredo lotononi to U. lotononidicola. Comprehensive accounts and keys are presented for Puccinia species on Lycium (Solanaceae), Helichrysum and Othonna (Asteraceae). Puccinia butleri and Uromyces bidenticola are new reports for South Africa, and Puccinia spinulosa is new for Namibia. So far, the latter species has only been known from Madagascar, and P. butleri from the Indian subcontinent. Taxonomical novelties are P. cornurediata R. Berndt; P. dioscoreae-mundtii R. Berndt, A.R. Wood & E. Uhlmann; P. horti-kirstenboschi R. Berndt & E. Uhlmann; P. othonnoides R. Berndt, A.R. Wood & E. Uhlmann; P. rapipes R. Berndt & E. Uhlmann; P. subindumentana R. Berndt; U. otholobii R. Berndt, A.R. Wood & E. Uhlmann and U. lotononidicola R. Berndt     

Phylogenetic relationships among Puccinia hemerocallidis, P. funkiae, and P. patriniae (Uredinales) inferred from ITS sequence data

Puccinia hemerocallidis and P. funkiae resemble each other morphologically; however, they are biologically and taxonomically distinct, with telia of the former being restricted to species of Hemerocallis and the latter to Hosta species. However, both fungi share a macrocyclic and heteroecious life cycle with Patrinia villosa as the spermogonial and aecial host. An additional microcyclic rust fungus, P. patriniae, is also known on P. villosa. This microcyclic fungus is similar to the two macrocyclic fungi in its telial structure and teliospore morphology. These similarities in morphology and host relationships suggest the three fungi may also share a close evolutionary relationship. To determine the phylogenetic relationships of the three species, a portion of the nuclear ribosomal DNA repeat encoding the ITS and 5.8S subunit regions was amplified by PCR, sequenced, and analyzed. The resulting phylogenetic trees showed that P. hemerocallidis and P. funkiae share a recent common ancestor and that P. patriniae is closely allied with P. hemerocallidis. The results suggest a possible evolutionary derivation of microcyclic P. patriniae from macrocyclic heteroecious P. hemerocallidis, which fits the evolutionary interpretation of correlated species known as Tranzschel's law.     

New insight into the species diversity and life cycles of rust fungi (Pucciniales) affecting bioenergy switchgrass (<Emphasis Type="Italic">Panicum virgatum</Emphasis>) in the Eastern and Central United States

Research was undertaken to clarify the taxonomic identity of leaf rust (Pucciniales) fungi on bioenergy switchgrass in the Eastern and Central U.S. We integrated internal transcribed spacer 2 (ITS2) and partial 28S ribosomal RNA gene sequence data from collections taken from cultivated switchgrass and herbarium specimens, including purported aecial and telial states of Puccinia graminicola and Puccinia pammelii. Maximum likelihood and Bayesian analyses revealed four monophyletic clades: Puccinia emaculata sensu stricto (s.s.), P. pammelii, P. graminicola, and Puccinia novopanici. Results also indicated that P. emaculata s.s. was not affecting cultivated, bioenergy switchgrass. Aecidium pammelii and P. pammelii were distinct phylogenetically from P. emaculata s.s. and grouped within a well-supported clade, demonstrating aecial-telial host alternation for P. pammelii between Euphorbia corollata and switchgrass. Aecidium stillingiae on queen’s delight (Stillingia sylvatica)—a purported aecial state host for P. graminicola—shared identical sequences with the recently described species Puccinia pascua. The latter fungus, however, was recovered within a subclade of P. graminicola. Hence, queen’s delight likely is not an aecial host to P. graminicola s.s. Additional molecular studies are warranted to determine species boundaries within the P. graminicola complex. The majority of contemporary collections from cultivated switchgrass were recognized as P. novopanici. Collectively, bioenergy switchgrass is host to at least three phylogenetically distinct species, presenting a significant challenge to the future selection and breeding of switchgrass with improved rust resistance.     

Taxonomy, phylogeny, and distribution of Puccinia graminis, the black stem rust: new insights based on rDNA sequence data

Puccinia graminis (Uredinales) is an economically important and common host-alternating rust species on Berberidaceae/Poaceae (subfamilies Pooideae and Panicoideae) that has been spread globally by human activities from an unknown center of origin. To evaluate the taxonomic implications, phylogenetic relationships, and distribution/spread of this complex species, we sequenced and cladistically analyzed the ITS1, 5.8S, and ITS2 regions from herbarium specimens on various host plants from Iran (17), Europe (1), and North America (4). The ITS region plus the 5.8S gene ranged from 686 to 701 bp, including the flanking partial sequences of the 18S and 28S rDNA. Our phylogenetic analysis included 54 bp of the 18S sequence, the entire ITS1 + 5.8S + ITS2, and 58 bp of the 28S sequence. A second analysis used only the last 42 bp of ITS1, and all the 5.8S and ITS2, to incorporate data from additional sequences downloaded from GenBank. In addition to variation in sequence length, there was variation in sequence content. The analysis does not support classical morphology-based taxonomic concepts of the P. graminis complex. Also, host range, host taxonomy, and geographic origin provide minor information on taxonomic relationships. Puccinia graminis is most probably monophyletic. Coevolutionary aspects can hardly be discussed because of lack of sequence data from alternate host specimens. The occurrence of unrelated fungal taxa on the same host species suggests that, besides coevolution with the host, host jumps and hybridization may have played an important role in the evolution of P. graminis. From rDNA data we conclude that the pathogen was introduced to North America at least twice independently. For a new taxonomic concept, we think the complex has to be split into at least two species. New morphological features and further features other than sequence data, however, must be checked for taxonomic value first and, if necessary, be considered.     

Materials for the rust flora of Japan VI

Ten rust species are reported with new information on range of distribution and host relations. Among these,Puccinia fagopyricola andUromyces junci were new to Japan, andAecidium araliae was newly found in northern Honshu. Additional collections were made ofBlastospora smilacis, Puccinia malvacearum andP. orbicula in northern Honshu. New hosts were added toColeosporium solidaginis, C. tussilaginis, Phragmidium miyakeanum andPuccinia caricis, and a new Japanese host toPuccinia malvacearum.V: Trans. Mycol. Soc. Japan29: 471–478, 1988.     

Delimitation of central and northern European species of the <Emphasis Type="Italic">Phellinus igniarius</Emphasis> group (Basidiomycota,Hymenochaetales) based on analysis of ITS and translation elongation factor 1 alpha DNA sequences

The Phellinus igniarius group comprises several closely related wood-decaying basidiomycetes with poroid hymenophores that are sometimes difficult to identify on a morphological basis. The delimitation of pileate species belonging to the group was the subject of ITS (internal transcribed spacer of ribosomal DNA) and tefa (translation elongation factor 1 alpha) DNA sequence analyses applied to specimens from central and northern Europe. The results confirmed the distinctiveness of P. alni, P. igniarius, P. lundellii, P. nigricans, P. populicola, P. tremulae, and P. tuberculosus in Europe. The specimens of the previously distinguished species P. cinereus were found to be identical with either P. nigricans or P. alni. Thus, Phellinus cinereus does not follow the species criteria of phylogenetic species recognition. In addition, a recently described species, P. neolundellii, was grouped within the P. alni clade. The ITS and tefa analyses produced a different topology for P. populicola and P. igniarius. P. alni had the largest spectrum of hosts, including woody plants from nine families, and records on Aesculus hippocastanum and Ulmus glabra are reported for the first time. P. igniarius s.s. has been collected not only on Salix spp. as expected but also, though rarely, on Populus nigra, and it has been observed once on Malus domestica. The host specificity of the remaining species resembles previous data. An additional analysis of basidiospore dimensions did not reveal any differences between P. alni and P. igniarius, but both are distinguishable from those of P. nigricans.     

Comparative morphology of uredinia and urediniospores of six Puccinia species parasitic on Poaceae in Saudi Arabia

Uredinia and urediniospores of six Puccinia species growing on Poaceae in southwestern Saudi Arabia were morphologically compared by light and scanning electron microscopy (SEM). Puccinia cenchri, P. fragosoana and P. isiacae were recorded for the first time in Saudi Arabia. Many differences between uredinia and urediniospores of studied Puccinia species were recorded. These differences are not related to host plant but may be due to the species of Puccinia itself. Observations by SEM led to more information in distinguishing between these Puccinia species particularly the presence of paraphyses and density and length of spines.     

Evaluation of Lespedeza germplasm genetic diversity and its phylogenetic relationship with the genus Kummerowia

The genetic diversity of the genus Lespedeza is not well known and the phylogenetic relationship of Lespedeza with the genus Kummerowia is unclear. We report the first study in which polymorphic expressed sequence tag-simple sequence repeat (EST-SSR) markers derived from Medicago, cowpea and soybean were used to assess the genetic diversity of the USDA Lespedeza germplasm collection and clarify its phylogenetic relationship with the genus Kummerowia. Phylogenetic analysis partitioned 44 Lespedeza accessions into three main groups some of which were species-specific and eight subgroups. This data set revealed some misidentified accessions, and indicated that the two species in the genus Kummerowia are closely related to the genus Lespedeza. Morphological reexamination was used to correct the misidentified accessions within the genus Lespedeza. Our results demonstrated that phylogenetic analysis with morphological reexamination provides a more complete approach to classify accessions in plant germplasm collection and conservation.     

Are the microcyclic rust species Puccinia melampodii and Puccinia xanthii conspecific?

The taxonomic relationship between two microcyclic rust species, Puccinia melampodii and Puccinia xanthii, recorded from a number of Asteraceae hosts, was explored by comparing teliospore morphology, host specificity and sequence data. Teliospore morphology varied between and within individual rust accessions but, in general, teliospores of P. xanthii were larger than those of P. melampodii. Field observations and cross-inoculation greenhouse studies showed that P. melampodii accessions were highly specific to their original host species and unable to establish compatible interactions with related Asteraceae species. Though small amounts of genetic variation were detected between P. melampodii and P. xanthii accessions, the ITS and TEF phylogenetic analyses comprising several other rust species grouped these accessions within a well supported clade. Our data indicate that despite differences between P. xanthii and P. melampodii accessions these rusts cannot readily be separated at the species level, supporting earlier taxonomic conclusions and the recent proposal to group them into a morphospecies. Based on host-specificity data, the name Puccinia xanthii var. parthenii-hysterophorae is proposed to accommodate all Mesoamerican records of P. melampodii associated with the host Parthenium hysterophorus.     

Phylogenetic relationships of sugarcane rust fungi

The phylogenetic positions of Puccinia spp. infecting sugarcane (a complex hybrid of Saccharum spp.) were determined using 38 newly generated rust sequences and 26 sequences from GenBank. Rust specimens on sugarcane were collected from 164 locations in 23 countries and identified based on light microscopy. The morphology for all samples matched that of Puccinia kuehnii or P. melanocephala, the orange and brown rust pathogens of sugarcane, respectively. Nuclear ribosomal DNA sequences (rDNA) including portions of the 5.8S rDNA, the complete internal transcribed spacer 2 (ITS2) and 5′ region of the large subunit (nLSU) rDNA were obtained for each species along with 36 additional rust taxa. Despite a shared host, the two Puccinia spp. on sugarcane are not closely related within the Pucciniales. Phylogenetic analyses place P. melanocephala most closely to P. miscanthi, P. nakanishikii, and P. rufipes infecting Miscanthus sinensis, Cymbopogon citratus, and Imperata cylindrica, respectively. Puccinia kuehnii is basal to a clade of Poaceae-infecting rusts including P. agrophila, P. polysora, P. substriata, and Uromyces setariae-italicae infecting Schizachyrium spp., Zea mays, Digitaria spp., and Urochloa mosambicensis, respectively. Light and scanning electron microscopy images highlight morphological differences distinguishing the two sugarcane-infecting species. This study confirms the separation of rust species infecting Poaceae from Cyperaceae- and Juncaceae-infecting rusts and also provides support for the presence of an additional group that includes P. kuehnii and other grass-infecting relatives.     

Molecular and morphological evidence for multiple species within Paranoplocephala omphalodes (Cestoda, Anoplocephalidae) in Microtus voles (Arvicolinae)

Haukisalmi, V., Wickström, L. M., Henttonen, H., Hantula, J. & Gubányi, A. (2004). Molecular and morphological evidence for multiple species within Paranoplocephala omphalodes (Cestoda, Anoplocephalidae) in Microtus voles (Arvicolinae). —Zoologica Scripta, 33, 277–290. The present study was designed to test the hypothesis that the anoplocephalid cestode Paranoplocephala omphalodes (Hermann, 1783), a Holarctic parasite of Microtus voles, is a complex of host‐specific species, rather than a single host‐generalist species, using uni‐ and multivariate morphometrics and DNA sequence data from the mitochondrial cytochrome oxidase I gene. The phylogenetic methods applied to the mtDNA sequence data showed consistently that the cestodes morphologically recognizable as P. omphalodes include four well‐supported monophyletic groups, representing at least three distinct, largely host‐specific species. Multivariate morphometrics (discriminant analysis) successfully distinguished the four main mtDNA clades of P. omphalodes‐like cestodes. The true P. omphalodes is shown to be a parasite of Microtus arvalis, M. agrestis and Clethrionomys glareolus in Europe. Microtus oeconomus harbours two host‐specific, allopatric and possibly conspecific clades, one with a Holarctic and another with an (eastern) Beringian (Alaskan) distribution. The eastern Beringian endemic M. miurus is also parasitized with a host‐specific, morphologically divergent species of Paranoplocephala. The cestode clades recognized in M. oeconomus and M. miurus represent 2–3 undescribed species. Molecular phylogenetic analyses supported the monophyly of the ‘northern clade’ of Paranoplocephala spp., an assemblage including P. kalelai from Clethrionomys spp., P. macrocephala from Microtus spp. and all clades of P. omphalodes‐like cestodes except those representing the true P. omphalodes from Europe. The intra‐ and interspecific phylogeny within the northern clade is compared tentatively with the known evolutionary history of the hosts.     

Variation in host specificity and gene content in strains from genetically isolated lineages of the ectomycorrhizal fungus Paxillus involutus s. lat.

Ectomycorrhizal fungi are known to vary in host range. Some fungi can enter into symbiosis with multiple plant species, while others have restricted host ranges. The aim of this study was to examine variation in host specificity among strains from the basidiomycete Paxillus involutus s. lat. Recent studies have shown that this fungus consists of at least four genetically isolated lineages, phylogenetic species (PS) I (which corresponds to the morphological species Paxillus obscurosporus), PS II (P. involutus s. str.), PS III (Paxillus validus), and PS IV (not yet supported by any reference material). Thirty-five Paxillus strains of PS I to IV were examined in microcosms for their capacity to infect birch (Betula pendula) and spruce (Picea abies). Seventeen strains were compatible and formed mycorrhizae with both tree species. Seven strains were incompatible with both birch and spruce. The gene content in three pairs of incompatible and compatible strains PS I, II, and III were compared using microarray-based comparative genomic hybridizations. Of 4,113 P. involutus gene representatives analyzed, 390 varied in copy numbers in at least one of the three pairwise comparisons. Only three reporters showed significant changes in all three pairwise comparisons, and none of these were changed in a similar way in three comparisons. Our data indicate that changes in host range have occurred frequently and independently among strains in P. obscurosporus, P. involutus s. str., and P. validus. No evidence was obtained demonstrating that these changes have been associated with the gain or loss of similar genes in these three species.