Genetic Analyses Suggest Separate Introductions of the Pine Pathogen Lecanosticta acicola Into Europe

Abstract

Lecanosticta acicola is a heterothallic ascomycete that causes brown spot needle blight on native and nonnative Pinus spp. in many regions of the world. In this study we investigated the origin of European L. acicola populations and estimated the level of random mating of the pathogen in affected areas. Part of the elongation factor 1-α gene was sequenced, 11 microsatellite regions were screened, and the mating type idiomorphs were determined for 201 isolates of L. acicola collected from three continents and 17 host species. The isolates from Mexico and Guatemala were unique, highly diverse and could represent cryptic species of Lecanosticta. The isolates from East Asia formed a uniform and discrete group. Two distinct populations were identified in both North America and Europe. Approximate Bayesian computation analyses strongly suggest independent introductions of two populations from North America into Europe. Microsatellite data and mating type distributions indicated random recombination in the populations of North America and Europe. Its intercontinental introduction can most likely be explained as a consequence of the movement of infected plant material. In contrast, the spread of L. acicola within Europe appears to be primarily due to conidial dispersion and probably also ascospore dissemination.

Planting exotic relatives has increased the threat posed by Dothistroma septosporum to the Caledonian pine populations of Scotland

“…() that LPR has been introduced into Scotland on needle debris accompanying lodgepole pine seed imports from North America. Although seed importation is generally considered a low biosecurity risk, there are at least two other examples where it has led to transfer of important pine pathogens between North America and Europe ( Lecanosticta acicola (Janoušek et al., ); Gremmeniella abietina (Hamelin, Lecours, & Laflamme, )).…”

Lecanosticta acicola: A growing threat to expanding global pine forests and plantations

“…In the population genetic study of Janoušek et al . (), the microsatellite markers amplified poorly for the L. acicola isolates from Mexico and Central America. A later study (van der Nest et al ., ) showed that these isolates were L. variabilis , a new and recently described species.…”

“…He therefore hypothesized that Central America could be the centre of origin of Lecanosticta . This was later supported by analysis of TEF 1 sequence data that revealed high genetic diversity in this geographical region (Janoušek et al ., ). An extensive collection of isolates from Central America was recently studied using a phylogenetic approach (van der Nest et al ., ).…”

Detection of pine needle diseases caused by Dothistroma septosporum, Dothistroma pini and Lecanosticta acicola using different methodologies

“…The opposite was found in Northern Spain, where more than 80% of the diseased plots were infected with L. acicola (de Urbina et al, 2017). Nevertheless, L. acicola has been reported in South (Gibson, 1980), Central (Evans, 1984), and North America (Sinclair & Lyon, 2005;Stanosz, 1990;Thümen, 1878), China (Huang, Smalley, & Guries, 1995), as well as several countries in Europe including Austria, Croatia, Czech Republic, Estonia, France, Germany, Italy, Lithuania, Poland, Slovakia, Slovenia, Spain and Switzerland (Ivanová & Bernadovičová, 2010;Janousek et al, 2016;Jurc & Jurc, 2010;Martinez, 1942;Novak-Agbaba & Halambek, 2015;Pusz et al, 2014). (Drenkhan et al, 2016) is missing for L. acicola.…”