Characterization and Distribution of Mating Type Genes in the Dothistroma Needle Blight Pathogens

Abstract

Dothistroma septosporum and D. pini are the two causal agents of Dothistroma needle blight of Pinus spp. in natural forests and plantations. Degenerate primers amplified portions of mating type genes (MAT1-1-1 and MAT1-2) and chromosome walking was applied to obtain the full-length genes in both species. The mating-type-specific primers designed in this study could distinguish between the morphologically similar D. pini and D. septosporum and between the different mating types of these species. Screening of isolates from global collections of D. septosporum showed that only MAT2 isolates are present in Australian and New Zealand collections, where only the asexual form of the fungus has been found. In contrast, both mating types of D. septosporum were present in collections from Canada and Europe, where the sexual state is known. Intriguingly, collections from South Africa and the United Kingdom, where the sexual state of the fungus is unknown, included both mating types. In D. pini, for which no teleomorph is known, both mating types were present in collections from the United States. These results provided new insights into the biology and global distribution of two of the world's most important pine pathogens and should facilitate management of the diseases caused by these fungi.

The rise of Ramularia from the Mycosphaerella labyrinth

“…The amplification of CAL and bTUB often resulted in multiple bands, despite the attempts of protocol optimization and were not used in the multigene analysis. The amplification of the mating-type loci was not successful for all the strains (Table 1) and was particularly challenging for the MAT1-2-1 with the use of the degenerate primers ( Table 2) that were reported successful for other Mycosphaerellaceae Groenewald et al, 2007). Due to the observed variation of the position of these loci in other species, an attempt was made to amplify the loci using the forward primer for MAT1-1-1 and the reverse primer of MAT1-2-1 and vice-versa.…”

Spore dispersal and infection of lodgepole pine by Dothistroma septosporum in northwest British Columbia.

“…It is also possible that during outbreak periods, the production of ascospores declines in favour of the production of conidia. The evidence from the previous studies (Braun, 2009;Dale et al, 2011;Groenewald et al, 2007) suggest the sexual spores of the fungus exist in northwest BC, but results from this study indicate that at least during outbreak periods, they are not as common as the asexual spores.…”

“…However, in 2008, Dale et al (2011) found a high level of genotypic variability between isolates obtained among and within sites, and even from isolates taken from infected needles within a single tree. They concluded that sexual reproduction was the main reason for this variability, which is supported by the findings of Groenewald et al (2007) which showed that both mating types of the fungus were present in isolates from the same area. Despite this evidence which supports the existance of sexual reproduction in the population of D. septosporum in northwest BC, only asexual spores were detected in the current study.…”

“…The abundance of conidia may be the result of selection pressure and a reduced need for sexual reproduction (Evans, 1984). Screening of isolates of D. septosporum by Groenewald et al (2007) showed that both mating types of the fungus were present in the collections from British Columbia (BC), Canada. In contrast, Barnes et al (2004) reported that the teleomorph Mycosphaerella pini was not observed in Dothistroma samples collected from different areas including BC.…”

The role of weather and topography in the development of Dothistroma septosporum.

“…Thus, its appearance in high frequencies may help explain the severity of the current outbreak in northwestern BC where the fungus is thought to be endemic and historically was not problematic. Both the anamorph and teleomorph have been found within the D. septosporum population in northwestern BC (Groenewald et al 2007). High levels of genetic variability have been observed in the current outbreak, indicating that sexual reproduction in northwestern BC is common (Dale 2008).…”