546 / 2019-03-14 22:53:48

A determinant of mutational landscape in Arabidopsis

mutation,natural variants

全体主题 > Evolution & Ecology

Mutation is the ultimate source of genetic variation. Mutation rates vary across the Arabidopsis genome and therefore could be a major determinant of the level of genetic variation among natural variants. It has been widely reported that nucleosome binding plays an important role in determining the local mutation rate, but its effect remains controversial. On the one hand, nucleosome binding prevents mutagens from accessing DNA, therefore reducing mutation rate. On the other hand, it also precludes the mismatch repairing machinery from approaching, therefore elevating mutation rate. To compare the relative importance of these two opposite forces, we quantified the variability of the intergenic sequences among accessions in the 1001 Arabidopsis genome projects. Surprisingly, the mutation landscape overturns as latitude increases; while the 10-nucleotide periodicity of mutation rate over a nucleosome persists for most Arabidopsis accessions the phase is reversed between south and north. The overturn likely results from the tug-of-war between the two forces mentioned above, more specifically, from the shift of the relative importance of these two forces. We will discuss the environmental and molecular mechanisms for the phenomenon as well as its biological implications.