A factor in a wild isolated Neurospora crassa strain enables a chromosome segment duplication to suppress repeat-induced point mutation

Abstract

Repeat-induced point mutation (RIP) is a sexual stage-specific mutational process of Neurospora crassa and other fungi that alters duplicated DNA sequences. Previous studies from our laboratory showed that chromosome segment duplications (Dps) longer than (approx.) 300 kbp can dominantly suppress RIP, presumably by titration of the RIP machinery, and that although Dps less than 200 kbp did not individually suppress RIP, they could do so in homozygous and multiply heterozygous crosses, provided the sum of the duplicated DNA exceeds (approx.) 300 kbp. Here we demonstrate suppression of RIP in a subset of progeny carrying the normally sub-threshold 154 kbp Dp(R2394) from a cross of T(R2394) to the wild isolated Carrefour Mme. Gras strain (CMG). Thus, the CMG strain contains a factor that together with Dp(R2394) produces a synthetic RIP suppressor phenotype. It is possible that the factor is a cryptic Dp that together with Dp(R2394) can exceed the size threshold for titration of the RIP machinery and thereby causes RIP suppression.

An RNA Recognition Motif-Containing Protein Functions in Meiotic Silencing by Unpaired DNA

“…However, MSUD may be more common in ascomycete fungi than it is currently suggested to be by the available literature. For example, research on wild N. crassa isolates has shown that MSUD can be difficult to detect, even when it is known to exist within a species ( Ramakrishnan et al 2011a ). Therefore, it is possible that SAD-7 performs similar functions in MSUD and sexual reproduction in a diverse range of ascomycete fungi.…”

Identification Of Novel Nuclear Proteins Required For Meiotic Silencing By Unpaired Dna In Neurospora Crassa

“…Alternatively, MSUD may be more common in ascomycete fungi than is currently suggested by the available literature. For example, research on wild N. crassa isolates has shown that MSUD can be difficult to detect even when it is known to exist within a species (Ramakrishnan et al 2011a). Therefore, it is possible that SAD-7 performs similar functions in MSUD and sexual reproduction in a diverse range of ascomycete fungi.…”