Marion K. Seier

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.

Puccinia komarovii var. glanduliferae var. nov.: a fungal agent for the biological control of Himalayan balsam (Impatiens glandulifera)

Clearly defining the taxonomic identity of a potential biocontrol agent is an essential component of any biological control programme. As part of such a programme against Impatiens glandulifera, a highly invasive annual weed in both Europe and North America, the rust fungus Puccinia komarovii was collected on this host plant in its native Himalayan range. However, current literature indicates that P. komarovii is a pathogen of a number of Impatiens species globally and was described originally from I. parviflora, a species native to Asia and now naturalized in Europe. Morphological comparisons, based on urediniospore and teliospore measurements, were generally inconclusive in showing any clear differences between the accession from I. glandulifera and those from other Impatiens species. Both, nrDNA ITS and ITS2-LSU sequence analyses indicated a difference between the rust infecting I. glandulifera compared to accessions on other hosts. However, the large variations in both ITS and 28S (ITS2-LSU) sequences determined within single accessions in this study, makes a clear separation difficult. Cross-inoculation experiments, using one accession of P. komarovii ex I. glandulifera (from India) and two accessions of P. komarovii ex I. parviflora (from China and Hungary), confirmed the specificity of these strains to their original hosts. Two Himalayan Impatiens species, I. scabrida and I. brachycentra, showed varying levels of susceptibility to these rust accessions, where the former was weakly susceptible to all three accessions and the latter was weakly susceptible only to P. komarovii ex I. parviflora (from China). However, commercial cultivars of I. balsamina proved to be fully susceptible to all rust accessions, although this has not been demonstrated under field conditions in India. Based on these host specificity differences between the rust accessions, we propose a new variety: Puccinia komarovii var. glanduliferae var. nov. associated with I. glandulifera in the Himalayas.

A review of the distribution and recorded natural enemies of Eurasian watermilfoil (Myriophyllum spicatum L.) in Eurasia, and the potential for classical biological control in North America.

In the context of possible biological control of Eurasian watermilfoil (Myriophyllum spicatum L.), available information is summarized on the distribution of M. spicatum and closely related species, and the known insect and pathogen natural enemies recorded from Eurasia. Research gaps identified include (1) lack of adequate understanding of frequency, distribution and ecological differences resulting from hybridization between M. spicatum and other Myriophyllum spp., (2) that surveys to date have been limited geographically and temporally, and have neglected organisms attacking the roots, and (3) preliminary studies to date on promising biological control agents have not considered potential impact on non-target species indigenous to North America.

Molecular identification and pathogenicity assessment of a rust fungus infecting common ragweed (Ambrosia artemisiifolia) in its native North American range

A rust fungus collected from common ragweed (Ambrosia artemisiifolia) in Texas, USA, was identified as belonging to the Puccinia xanthii morphospecies based on its nrDNA ITS sequence. Pathogenicity studies carried out with this rust accession under quarantine conditions in the UK showed that the fungus was highly virulent on A. artemisiifolia plants from Australia. Recently, P. xanthii has been proposed as a potential classical biological control agent (CBCA) for common ragweed in its invasive range, focusing on Europe, despite previous doubts about its biocontrol potential. The results of the pathogenicity tests reported here support the suitability of this pathogen as a CBCA for common ragweed.

Deciphering the biology of Cryptophyllachora eurasiatica gen. et sp. nov., an often cryptic pathogen of an allergenic weed, Ambrosia artemisiifolia

A little known, unculturable ascomycete, referred to as Phyllachora ambrosiae, can destroy the inflorescences of Ambrosia artemisiifolia, an invasive agricultural weed and producer of highly allergenic pollen. The fungus often remains undetectable in ragweed populations. This work was conducted to understand its origin and pathogenesis, a prerequisite to consider its potential as a biocontrol agent. The methods used included light and transmission electron microscopy, nrDNA sequencing, phylogenetic analyses, artificial inoculations, and the examination of old herbarium and recent field specimens from Hungary, Korea, Ukraine and USA. The Eurasian and the North American specimens of this fungus were to represent two distinct, although closely related lineages that were only distantly related to other lineages within the Ascomycota. Consequently, we describe a new genus that includes Cryptophyllachora eurasiatica gen. et sp. nov. and C. ambrosiae comb. nov., respectively. The pathogenesis of C. eurasiatica was shown in A. artemisiifolia. No evidence was found for either seed-borne transmission or systemic infection. Two hypotheses were developed to explain the interaction between C. eurasiatica and A. artemisiifolia: (i) as yet undetected seed-borne transmissions and latent, systemic infections; or (ii) alternative hosts.

Erratum to: Species-Specific Detection of Mycosphaerella polygoni-cuspidati as a Biological Control Agent for Fallopia japonica by PCR Assay (Molecular Biotechnology, (2016), 58, 10, (626-633), 10.1007/s12033-016-9962-x)

The ascomycete fungus Mycosphaerellapolygoni-cuspidati has been undergoing evaluation as a potential classical biological control agent for the invasive weed Fallopia japonica (Japanese knotweed), which has become troublesome in Europe and North America. In advance of the potential release of a biocontrol agent into a new environment, it is crucial to develop an effective monitoring system to enable the evaluation of agent establishment and dispersal within the target host population, as well as any potential attacks on non-target species. Therefore, a primer pair was designed for direct, rapid, and specific detection of the Japanese knotweed pathogen M. polygoni-cuspidati based on the sequences of the internal transcribed spacer regions including the 5.8S rDNA. A PCR product of approximately 298 bp was obtained only when the DNA extracted from mycelial fragments of M. polygoni-cuspidati was used. The lower limit of detection of the PCR method was 100 fg of genomic DNA. Using the specific primer pair, M. polygoni-cuspidati could be detected from both naturally and artificially infected Japanese knotweed plants. No amplification was observed for other Mycosphaerella spp. or fungal endophytes isolated from F. japonica. The designed primer pair is thus effective for the specific detection of M. polygoni-cuspidati in planta.

Similar experiment – different conclusion; a response to the recent proposition of Septoria lepidii as a potentially important biological control agent for weedy species of Lepidium in North America

ABSTRACT Following preliminary host-specificity testing Septori lepidii Desm. was recently proposed as a potentially important biological control agent for invasive Lepidium species in North America. Conversely, a previous, unpublished assessment of S. lepidii for biocontrol of Lepidium latifolium found the pathogen to be unsuitable due to infection of the American native Lepidium huberi.

Erratum: Puccinia komarovii var. glanduliferae var. nov.: a fungal agent for the biological control of Himalayan balsam (Impatiens glandulifera) [Eur J Plant Pathol, DOI 10.1007/s10658-014-0539-x]

Clearly defining the taxonomic identity of a potential biocontrol agent is an essential component of any biological control programme. As part of such a programme against Impatiens glandulifera, a highly invasive annual weed in both Europe and North America, the rust fungus Puccinia komaroviiwas collected on this host plant in its native Himalayan range. However, current literature indicates that P. komarovii is a pathogen of a number of Impatiens species globally and was described originally from I. parviflora, a species native to Asia and now naturalized in Europe. Morphological comparisons, based on urediniospore and teliospore measurements, were generally inconclusive in showing any clear differences between the accession from I. glandulifera and those from other Impatiens species. Both, nrDNA ITS and ITS2-LSU sequence analyses indicated a difference between the rust infecting I. glandulifera compared to accessions on other hosts. However, the large variations in both ITS and 28S (ITS2-LSU) sequences determined within single accessions in this study, makes a clear separation difficult. Cross-inoculation experiments, using one accession of P. komarovii ex I. glandulifera (from India) and two accessions of P. komarovii ex I. parviflora (from China and Hungary), confirmed the specificity of these strains to their original hosts. Two Himalayan Impatiens species, Eur J Plant Pathol (2015) 141:247–266 DOI 10.1007/s10658-014-0539-x R. A. Tanner (*) : C. A. Ellison :M. K. Seier : S. Varia : D. Djeddour :H. C. Evans CABI, Bakeham Lane, Egham, Surrey TW20 9TY, UK e-mail: r.tanner@cabi.org G. M. Kovács : E. Kassai-Jáger : Z. Berecky : L. Kiss (*) Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences (MTA), 1525 Budapest, P.O. Box 102, Hungary e-mail: kiss.levente@agrar.mta.hu G. M. Kovács Institute of Biology, Department of Plant Anatomy, Eötvös Loránd University, 1117 Pázmány Péter sétány 1/C, Budapest, Hungary E. Kassai-Jáger Faculty of Health Sciences, Institute of Health Promotion and Clinical Methodology, Department of Epidemiology, Semmelweis University, 1085 Üllői út 26, Budapest, Hungary M. C. Singh National Bureau of Plant Genetic Resources, Pusa Campus, New Delhi, India Á. Csiszár Department of Botany and Nature Conservation, Faculty of Forestry, University of West Hungary, Sopron, Hungary P. Csontos Institute for Soil Science and Agricultural Chemistry, Centre for Agricultural Research, Hungarian Academy of Sciences (MTA), Budapest, Hungary I. scabrida and I. brachycentra, showed varying levels of susceptibility to these rust accessions, where the former was weakly susceptible to all three accessions and the latter was weakly susceptible only to P. komarovii ex I. parviflora (from China). However, commercial cultivars of I. balsamina proved to be fully susceptible to all rust accessions, although this has not been demonstrated under field conditions in India. Based on these host specificity differences between the rust accessions, we propose a new variety: Puccinia komarovii var. glanduliferae var. nov. associated with I. glandulifera in the Himalayas.