This article briefly reviews the history of white pine blister rust, attributed to Cronartium ribicola, and addresses current research and management issues in South Korea, Japan and other regions of eastern Asia (China, Russia and Himalaya). For each region, the distribution, damage, aecial hosts, telial hosts and management of C. ribicola and other blister rust fungi on native and introduced white pines are summarized. In addition, blister rust behaviours in eastern Asia and North America are compared; and the potential evolutionary and management implications are discussed.

Summary Since the myrtle rust pathogen (Austropuccinia psidii) was first reported (as Puccinia psidii) in Brazil on guava (Psidium guajava) in 1884, it has been found infecting diverse myrtaceous species. Because A. psidii has recently spread rapidly worldwide with an extensive host range, genetic and genotypic diversities were evaluated within and among A. psidii populations in its putative native range and other areas of myrtle rust emergence in the Americas and Hawaii. Microsatellite markers revealed several unique multilocus genotypes (MLGs), which grouped isolates into nine distinct genetic clusters [C1–C9 comprising C1: from diverse hosts from Costa Rica, Jamaica, Mexico, Puerto Rico, and USA‐Hawaii, and USA‐California; C2: from eucalypts (Eucalyptus spp.) in Brazil/Uruguay and rose apple (Syzygium jambos) in Brazil; C3: from eucalypts in Brazil; C4: from diverse hosts in USA‐Florida; C5: from Java plum (Syzygium cumini) in Brazil; C6: from guava and Brazilian guava (Psidium guineense) in Brazil; C7: from pitanga (Eugenia uniflora) in Brazil; C8: from allspice (Pimenta dioica) in Jamaica and sweet flower (Myrrhinium atropurpureum) in Uruguay; C9: from jabuticaba (Myrciaria cauliflora) in Brazil]. The C1 cluster, which included a single MLG infecting diverse host in many geographic regions, and the closely related C4 cluster are considered as a “Pandemic biotype,” associated with myrtle rust emergence in Central America, the Caribbean, USA‐Florida, USA‐Hawaii, Australia, China‐Hainan, New Caledonia, Indonesia and Colombia. Based on 19 bioclimatic variables and documented occurrences of A. psidii contrasted with reduced sets of specific genetic clusters (subnetworks, considered as biotypes), maximum entropy bioclimatic modelling was used to predict geographic locations with suitable climate for A. psidii which are at risk from invasion. The genetic diversity of A. psidii throughout the Americas and Hawaii demonstrates the importance of recognizing biotypes when assessing the invasive threats posed by A. psidii around the globe.

Kim, M.-S.; and Klopfenstein, N. B., "Current and future molecular approaches to investigate the white pine blister rust pathosystem" (2010 SummaryMolecular genetics is proving to be especially useful for addressing a wide variety of research and management questions on the white pine blister rust pathosystem. White pine blister rust, caused by Cronartium ribicola, is an ideal model for studying biogeography, genetics, and evolution because: (1) it involves an introduced pathogen; (2) it includes multiple primary and alternate hosts occurring in large, relatively undisturbed ecosystems; (3) some hosts exhibit endemic resistance; and (4) the disease interaction is long enduring. Molecular techniques are used to investigate population genetics, phylogenetics, hybrids, and proteomics in white pine (Pinus, subgenus Strobus) and blister rust (Cronartium) and the genetics of resistance and virulence in the blister rust pathosystem. These techniques include genetic markers,

Summary Armillaria species display diverse ecological roles ranging from beneficial saprobe to virulent pathogen. Armillaria solidipes (formerly A. ostoyae), a causal agent of Armillaria root disease, is a virulent primary pathogen with a broad host range of woody plants across the Northern Hemisphere. This white‐rot pathogen grows between trees as rhizomorphs and attacks sapwood as mycelial fans under the bark. Armillaria root disease is responsible for reduced forest productivity due to direct tree mortality and non‐lethal infections that impact growth. Here, we characterize a transcriptome of a widespread, virulent genet (vegetative clone) of A. solidipes isolated from a mycelial fan on a natural grand fir (Abies grandis) sapling in northern Idaho, USA. cDNA from polyA+‐purified total RNA was sequenced using a single‐end read approach on the Illumina GAIIx platform which generated 24 170 384 reads. A BLASTx search against the NCBI nr database using 39 943 de novo assembled contigs resulted in 24 442 sequences with significant hits (e‐value < 1e−3), predominantly to fungi (85%). A filtered data set of 20 882 assembled transcripts that encoded putative homologous fungal proteins was created and used for all subsequent analyses. Signal P identified 10 668 putative signal peptides from these fungal transcripts, and 14 360 were annotated with gene ontology terms. Several sequences showed strong homology to annotated genes with functions in pathogenesis, specifically those involved in plant cell wall degradation and response to the post‐infection host environment. This transcriptome contributes to the growing body of resources for studies on fungal pathogens of woody plants, and our results provide useful insights towards identifying specific genes with potential roles associated with pathogenesis and other metabolic functions.

Incidence of peach [Prunus persica (L.) Batsch] tree mortality attributed to Armillaria root disease was assessed from 2009 to 2011 in 15 orchards in the State of Mexico, Mexico. Incidence increased gradually every year of assessment, reaching average values of 9.7, 15.3 and 20.3% tree mortality and 23.2, 24.7 and 28.3% disease-impacted area of the orchards during 2009, 2010 and 2011, respectively. The cultivars 'Nemaguard' and 'Criollo of La Goleta', a local rootstock used in the region, were both susceptible to the disease. To identify species of Armillaria isolated from infected peach trees, two nuclear rDNA regions (partial 5.8S-ITS2-LSU D-domains and partial 3′ LSU-IGS1) and the translation elongation factor-1a (tef-1a) gene were sequenced and compared with sequences of known Armillaria species. DNA sequence analysis from 49 Armillaria isolates revealed that five isolates (10.2%) were Armillaria mellea and eight isolates (16.3%) were Armillaria gallica. DNA sequences from the remaining 36 isolates (73.5%) showed no close similarity to Armillaria sequences in GenBank, and apparently represent an undescribed Armillaria species. This undescribed species was the most widely distributed in the region of study. Separate phylogenetic analyses of the LSU region (D1-D3 domains concatenated with the partial 3′ end) and the tef-1a region show that the undescribed species is quite distinct from other Armillaria spp. reported in North America.