Fine-scale genetic diversity and relatedness in fungi associated with the mountain pine beetle

Abstract

The mountain pine beetle (MPB; Dendroctonus ponderosae Hopkins, 1902) forms beneficial symbiotic associations with fungi. Here we explored the fine-scale spatial genetic structure of three of those fungi using single nucleotide polymorphism. We found that single mated pairs of beetles carry not only multiple fungal species, but also multiple genotypes of each species into their galleries. We observed genetic diversity at a fine spatial scale. Most of the diversity was found within and among galleries with nonsignificant diversity among trees. We observed clonal propagation almost exclusively within galleries. Ophiostoma montium (Rumbold) Arx possessed a larger expected number of multilocus genotypes and lower linkage disequilibrium than Grosmannia clavigera (Rob.-Jeffr. & R.W. Davidson) Zipfel, Z.W. de Beer & M.J. Wingf. and Leptographium longiclavatum S.W. Lee, J.J. Kim & C. Breuil. More than 80% of fungal samples were genetically unrelated, a result that parallels what has been observed in the beetles. The proportion of genetically related samples within galleries was higher in O. montium (40%) than in G. clavigera (20%) or L. longiclavatum (6%), likely the consequence of within-gallery sexual recombination in O. montium. The underlying genetic diversity reported here and the differences among fungal species could enable the symbiont community to quickly respond to new environmental conditions or changes in the host, enhancing the maintenance of this multipartite relationship and allowing the MPB to colonize new habitats.

High-Throughput Microsatellite Markers Development for Genetic Characterization of Emerging Sporothrix Species

“…Therefore, the low marker-marker LD levels found for Sporothrix suggest expressive recombination estimates (mean r 2 = 0.02–0.05), supporting that alleles can freely recombine into new genotypes during the mating process [ 136 ], a scenario previously reported using AFLP markers [ 78 ] and mating-type distributions [ 74 , 103 , 137 , 138 ]. High genetic diversity scenarios with low LD values, suggestive of significant sexual recombination, have been observed in Ophiostoma montium [ 139 ], Fusarium graminearum [ 140 ], Zymoseptoria tritici [ 141 ], Glomus claroideum [ 142 ] and are associated with the ability to quickly respond to new environmental conditions or changes in the host. This scenario would be a force driving the emergence of Sporothrix species.…”

Phylogeography of post-Pleistocene population expansion in Dasyscyphella longistipitata (Leotiomycetes, Helotiales), an endemic fungal symbiont of Fagus crenata in Japan

“…4). Few population level genetic analyses are available for non-model fungal species, with most of the literature focusing on species of public interest such as phytopathogens (Benne tt et al 2019), human pathogens (Cogliati et al 2019), insect pathogens (Tsui et al 2019), and mycorrhiza (Savary et al 2018). As a result, comparisons are difficult to obtain.…”

TRIA-Net: 10 years of collaborative research on turning risk into action for the mountain pine beetle epidemic

“…Much of our work focused on harnessing modern highthroughput sequencing technologies to examine the individual components of the outbreak system, as well as their interactions, through the lens of genetics. Tsui et al (2019) describe genetic diversity in beetle-associated symbiotic fungi at a fine spatial scale. In describing these spatial genetic patterns, the authors illustrate the flexibility and potential adaptive capacity of the symbiont community to novel environmental conditions and explore how that flexibility might contribute to outbreak spread.…”