DNA sequence incongruence and inconsistent morphology obscure species boundaries in the Teratosphaeria suttonii species complex

Wide Distribution of Teratosphaeria epicoccoides and T. destructans Associated with Diseased Eucalyptus Leaves in Plantations in Southern China

Species of Mycosphaerellaceae and Teratosphaeriaceae represent over 40% of the fungi identified on eucalypt leaves worldwide. These include some important pathogens that mainly cause leaf blight and spot, and result in increasingly negative impacts on global commercial eucalypt industries. Eucalyptus plantations are commonly cultivated in southern China for solid wood and pulp products. However, the species diversity and geographic distribution of Mycosphaerellaceae and Teratosphaeriaceae, associated with diseased plantation Eucalyptus leaves in China, have not been clarified. In this study, we conducted the first systematic surveys and sample collections of Mycosphaerellaceae- and Teratosphaeriaceae-like fungi from diseased plantation Eucalyptus leaves in southern China. In total, 558 isolates were obtained from 59 sampled sites in five provinces. One isolate was isolated from each tree. According to the disease symptoms, conidia morphological characteristics, and DNA sequence comparisons of ITS, tef1 and tub2 gene regions. The 558 isolates were identified as Teratosphaeria epicoccoides (312 isolates; 55.9%) and T. destructans (246 isolates, 44.1%). Both species were widely distributed in the sampled regions in southern China. The genotypes of T. epicoccoides and T. destructans were determined based on ITS, tef1, and tub2 sequences. The results showed that multiple genotypes of each species of T. epicoccoides and T. destructans exist in China. Additionally, isolates with multiple genotypes were obtained in all five sampled provinces. These results suggest that both T. epicoccoides and T. destructans are not clonal. This study proved that both T. epicoccoides and T. destructans are dominant species and widely distributed on diseased Eucalyptus leaves in southern China. The wide geographic distribution and potential high genetic diversity pose challenges for the disease management of Teratosphaeria leaf blight and leaf spot in China.

Recommended names for pleomorphic genera in Dothideomycetes

This paper provides recommendations of one name for use among pleomorphic genera in Dothideomycetes by the Working Group on Dothideomycetes established under the auspices of the International Commission on the Taxonomy of Fungi (ICTF). A number of these generic names are proposed for protection because they do not have priority and/or the generic name selected for use is asexually typified. These include: Acrogenospora over Farlowiella; Alternaria over Allewia, Lewia, and Crivellia; Botryosphaeria over Fusicoccum; Camarosporula over Anthracostroma; Capnodium over Polychaeton; Cladosporium over Davidiella; Corynespora over Corynesporasca; Curvularia over Pseudocochliobolus; Elsinoë over Sphaceloma; Excipulariopsis over Kentingia; Exosporiella over Anomalemma; Exserohilum over Setosphaeria; Gemmamyces over Megaloseptoria; Kellermania over Planistromella; Kirschsteiniothelia over Dendryphiopsis; Lecanosticta over Eruptio; Paranectriella over Araneomyces; Phaeosphaeria over Phaeoseptoria; Phyllosticta over Guignardia; Podonectria over Tetracrium; Polythrincium over Cymadothea; Prosthemium over Pleomassaria; Ramularia over Mycosphaerella; Sphaerellopsis over Eudarluca; Sphaeropsis over Phaeobotryosphaeria; Stemphylium over Pleospora; Teratosphaeria over Kirramyces and Colletogloeopsis; Tetraploa over Tetraplosphaeria; Venturia over Fusicladium and Pollaccia; and Zeloasperisporium over Neomicrothyrium. Twenty new combinations are made: Acrogenospora carmichaeliana (Berk.) Rossman & Crous, Alternaria scrophulariae (Desm.) Rossman & Crous, Pyrenophora catenaria (Drechsler) Rossman & K.D. Hyde, P. dematioidea (Bubák & Wróbl.) Rossman & K.D. Hyde, P. fugax (Wallr.) Rossman & K.D. Hyde, P. nobleae (McKenzie & D. Matthews) Rossman & K.D. Hyde, P. triseptata (Drechsler) Rossman & K.D. Hyde, Schizothyrium cryptogamum (Batzer & Crous) Crous & Batzer, S. cylindricum (G.Y. Sun et al.) Crous & Batzer, S. emperorae (G.Y. Sun & L. Gao) Crous & Batzer, S. inaequale (G.Y. Sun & L. Gao) Crous & Batzer, S. musae (G.Y. Sun & L. Gao) Crous & Batzer, S. qianense (G.Y. Sun & Y.Q. Ma) Crous & Batzer, S. tardecrescens (Batzer & Crous) Crous & Batzer, S. wisconsinense (Batzer & Crous) Crous & Batzer, Teratosphaeria epicoccoides (Cooke & Massee) Rossman & W.C. Allen, Venturia catenospora (Butin) Rossman & Crous, V. convolvularum (Ondrej) Rossman & Crous, V. oleaginea (Castagne) Rossman & Crous, and V. phillyreae (Nicolas & Aggéry) Rossman & Crous, combs. nov. Three replacement names are also proposed: Pyrenophora grahamii Rossman & K.D. Hyde, Schizothyrium sunii Crous & Batzer, and Venturia barriae Rossman & Crous noms. nov.

Multiple introductions from multiple sources: invasion patterns for an important Eucalyptus leaf pathogen

Many population studies on invasive plant pathogens are undertaken without knowing the center of origin of the pathogen. Most leaf pathogens of Eucalyptus originate in Australia and consequently with indigenous populations available, and it is possible to study the pathways of invasion. Teratosphaeria suttonii is a commonly occurring leaf pathogen of Eucalyptus species, naturally distributed in tropical and subtropical regions of eastern Australia where it is regarded as a minor pathogen infecting older leaves; however, repeated infections, especially in exotic plantations, can result in severe defoliation and tree deaths. Nine polymorphic microsatellite markers were used to assess the genetic structure of 11 populations of T. suttonii of which four where from within its native range in eastern Australia and the remaining seven from exotic Eucalyptus plantations. Indigenous populations exhibited high allele and haplotype diversity, predominantly clonal reproduction, high population differentiation, and low gene flow. The diversity of the invasive populations varied widely, but in general, the younger the plantation industry in a country or region, the lower the diversity of T. suttonii. Historical gene flow was from Australia, and while self-recruitment was dominant in all populations, there was evidence for contemporary gene flow, with South Africa being the most common source and Uruguay the most common sink population. This points distinctly to human activities underlying long-distance spread of this pathogen, and it highlights lessons to be learned regarding quarantine.