Fungal Infection Increases the Rate of Somatic Mutation in Scots Pine (Pinus sylvestrisL.)

Abstract

Somatic mutations are transmitted during mitosis in developing somatic tissue. Somatic cells bearing the mutations can develop into reproductive (germ) cells and the somatic mutations are then passed on to the next generation of plants. Somatic mutations are a source of variation essential to evolve new defense strategies and adapt to the environment. Stem rust disease in Scots pine has a negative effect on wood quality, and thus adversely affects the economy. It is caused by the 2 most destructive fungal species in Scandinavia: Peridermium pini and Cronartium flaccidum. We studied nuclear genome stability in Scots pine under biotic stress (fungus-infected, 22 trees) compared to a control population (plantation, 20 trees). Stability was assessed as accumulation of new somatic mutations in 10 microsatellite loci selected for genotyping. Microsatellites are widely used as molecular markers in population genetics studies of plants, and are particularly used for detection of somatic mutations as their rate of mutation is of a much higher magnitude when compared with other DNA markers. We report double the rate of somatic mutation per locus in the fungus-infected trees (4.8×10(-3) mutations per locus), as compared to the controls (2.0×10(-3) mutations per locus) when individual samples were analyzed at 10 different microsatellite markers. Pearson's chi-squared test indicated a significant effect of the fungal infection which increased the number of mutations in the fungus-infected trees (χ(2) = 12.9883, df = 1, P = 0.0003134).

Somatic mutations substantially increase the per-generation mutation rate in the coniferPicea sitchensis

“…Extrapolating our estimates to other trees may not be straightforward if mutations accumulate in a nonlinear manner with age or height (e.g., if older trees are more or less susceptible to mutagens such as fungal infections; Ranade et al. ) or if some environmental conditions result in higher mutation rates (e.g., at high elevations due to higher UV levels).…”

The ecology of subindividual variability in plants: patterns, processes, and prospects

“…Genetic mosaicism (i.e., withinplant heterogeneity in DNA sequences) caused by the vegetative propagation within individuals of somatic mutations was once proposed as a major driver of subindividual heterogeneity in plants (Whitham and Slobodchikoff, 1981). The rarity of documented instances of genetic mosaicism in wild plants, however, makes it unlikely that this will provide a universal mechanism for ubiquitous subindividual variation in plant communities (O'Connell and Ritland, 2004;Herrera, 2009;Padovan et al, 2013;Ranade et al, 2015). Nevertheless, genetic mosaicism is not the only possible mechanism causing stable or metastable subindividual genomic heterogeneity in plants.…”

The mutation nrpb1‐A325V in the largest subunit of RNA polymerase II suppresses compromised growth of Arabidopsis plants deficient in a function of the general transcription factor IIF

“…Recent studies show that quiescence in the QC is required to sustain growth upon genotoxic stress, allowing the QC to act as a reservoir for replenishing stem cells after injury (Gaillochet and Lohmann, ). The meristem cell death therefore is viewed as an output of a stem cell quality control mechanism that protects a plant from somatic genetic instability, which is a known consequence of biotic and abiotic stresses (Ranade et al ., ; Santos et al ., ). The readout of the genetic lesions is the activity of the DDR pathway that in plants involves the transcriptional induction of genes with a role in DNA repair and genome stability maintenance (Donà and Mittelsten Scheid, ).…”