Premium
Lower prevalence but similar fitness in a parasitic fungus at higher radiation levels near Chernobyl
Author(s) -
Aguileta Gabriela,
Badouin Helene,
Hood Michael E.,
Møller Anders P.,
Le Prieur Stephanie,
Snirc Alodie,
Siguenza Sophie,
Mousseau Timothy A.,
Shykoff Jacqui A.,
Cuomo Christina A.,
Giraud Tatiana
Publication year - 2016
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/mec.13675
Subject(s) - biology , nonsynonymous substitution , low dose radiation , ploidy , pollinator , pollen , sterility , genetics , botany , genome , gene , pollination , cancer
Nuclear disasters at Chernobyl and Fukushima provide examples of effects of acute ionizing radiation on mutations that can affect the fitness and distribution of species. Here, we investigated the prevalence of Microbotryum lychnidis‐dioicae , a pollinator‐transmitted fungal pathogen of plants causing anther‐smut disease in Chernobyl, its viability, fertility and karyotype variation, and the accumulation of nonsynonymous mutations in its genome. We collected diseased flowers of Silene latifolia from locations ranging by more than two orders of magnitude in background radiation, from 0.05 to 21.03 μGy/h. Disease prevalence decreased significantly with increasing radiation level, possibly due to lower pollinator abundance and altered pollinator behaviour. Viability and fertility, measured as the budding rate of haploid sporidia following meiosis from the diploid teliospores, did not vary with increasing radiation levels and neither did karyotype overall structure and level of chromosomal size heterozygosity. We sequenced the genomes of twelve samples from Chernobyl and of four samples collected from uncontaminated areas and analysed alignments of 6068 predicted genes, corresponding to 1.04 × 10 7 base pairs. We found no dose‐dependent differences in substitution rates (neither dN , dS , nor dN / dS ). Thus, we found no significant evidence of increased deleterious mutation rates at higher levels of background radiation in this plant pathogen. We even found lower levels of nonsynonymous substitution rates in contaminated areas compared to control regions, suggesting that purifying selection was stronger in contaminated than uncontaminated areas. We briefly discuss the possibilities for a mechanistic basis of radio resistance in this nonmelanized fungus.