Distribution and genetic diversity of Dothistroma septosporum in Pinus brutia forests of south‐western Turkey

• Published in: Plant pathology 2020-10, Vol.69 (8), p.1551-1564
• Main Authors: Oskay, Funda, Tunalı, Zeynep, Lehtijärvi, Asko T., Doğmuş‐Lehtijärvi, Hatice Tuğba, Woodward, Steve, Mullett, Martin
• Format: Article
• Language: English
• Subjects: Blight; Conidia; Dothistroma septosporum; Fungi; Genetic analysis; Genetic diversity; Genetic markers; Haplotypes; invasive forest pathogens; Invasive species; Mating; Mediterranean pine forests; Microsatellites; Needle blight; Pine needles; Pine trees; Pinus brutia; Plant tissues; population genetics; Recombination; red band needle blight; SSR
• ISSN: 0032-0862; 1365-3059
• DOI: 10.1111/ppa.13242

Dothistroma needle blight (DNB) is a serious disease of the Pinaceae, mainly Pinus species, caused by the fungi Dothistroma septosporum and D. pini. Both species are regarded as invasive forest pathogens worldwide, with rising incidence in central and northern Europe over the last three decades. In this work, 29 sites were investigated between 2013 and 2015 in south‐western Turkey. Morphological examination of needles confirmed DNB infection (i.e., Dothistroma conidiospores observed) at 18 sites, and a total of 108 Dothistroma sp. isolates were obtained from 11 of the sites. Host age seemed to be an important factor in both occurrence and severity of DNB in Pinus brutia forests. Continuous rainy days, especially in December, may increase severity of disease; however, extreme rain events may reduce available conidiospores on plant tissues or in the air. Species‐specific mating type primers showed that all isolates were D. septosporum; D. pini was not detected. The mating type ratio was close to 1:1, indicating sexual recombination was occurring. Eleven microsatellite markers revealed 59 unique multilocus haplotypes (MLHs) among the 73 isolates originating from different conidiomata. The majority of MLHs were represented by a single isolate (n = 52) and only one MLH was shared between two localities. Analyses showed high genetic diversity, isolation‐by‐distance, and clear population clusters. These findings suggest that D. septosporum is well established in south‐western Turkey and is probably not a recent introduction. Dothistroma septosporum, causal agent of dothistroma needle blight, is widespread in young Pinus brutia forests of south‐western Turkey with well‐established populations with high genetic diversity and clear population clusters.