Affiliation:
1. Uppsala BioCenter, Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden
2. Department of Evolutionary Biology, Uppsala University, Uppsala, Sweden
Abstract
A heterokaryon is a tissue type composed of cells containing genetically different nuclei. Although heterokaryosis is commonly found in nature, an understanding of the evolutionary implications of this phenomenon is largely lacking. Here, we use the filamentous ascomycete
Neurospora tetrasperma
to study the interplay between nuclei in heterokaryons across vegetative and sexual developmental stages. This fungus harbours nuclei of two opposite mating types (
mat A
and
mat a
) in the same cell and is thereby self-fertile. We used pyrosequencing of
mat
-linked SNPs of three heterokaryons to demonstrate that the nuclear ratio is consistently biased for
mat A
-nuclei during mycelial growth (mean
mat A
/
mat a
ratio 87%), but evens out during sexual development (ratio ranging from 40 to 57%)
.
Furthermore, we investigated the association between nuclear ratio and expression of alleles of
mat
-linked genes and found that expression is coregulated to obtain a tissue-specific bias in expression ratio: during mycelial extension, we found a strong bias in expression for
mat A
-linked genes, that was independent of nuclear ratio, whereas at the sexual stage we found an expression bias for genes of the
mat a
nuclei. Taken together, our data indicate that nuclei cooperate to optimize the fitness of the heterokaryon, via both altering their nuclear ratios and coregulation genes expressed in the different nuclei.
Subject
General Agricultural and Biological Sciences,General Environmental Science,General Immunology and Microbiology,General Biochemistry, Genetics and Molecular Biology,General Medicine
Cited by
20 articles.
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