Study : Inheritance and instability of 45S rRNA gene copy number in Arabidopsis thaliana
Inheritance and instability of 45S rRNA gene copy number in Arabidopsis thaliana
The considerable genome size variation in Arabidopsis thaliana has been shown largely to be due to copy number variation (CNV) in 45S ribosomal RNA (rRNA) genes. Surprisingly, attempts to map this variation by means of genome-wide association studies (Long et al. 2013) failed to identify either of the two likely sources, namely the nucleolar organizer regions (NORs). Here we investigated the inheritance of rRNA gene copy number using linkage mapping in F2 crosses and a recombinant inbred line population. Our results clearly show that rRNA gene CNV can be mapped to the NORs themselves, with both loci contributing equally to the variation.