High short tandem repeat mutation recurrence in heat-stressed Arabidopsis thaliana lines

The rise of the annual average temperature presents a strong selection pressure for many species. Sessile organisms, such as the plant Arabidopsis thaliana ( A. thaliana ), need to adapt to elevated temperatures. Here, we conducted a mutation accumulation experiment in A. thaliana under high temperature to monitor genetic changes over nine generations in three parallel lines compared to three lines under normal growth conditions. Whole-genome sequencing of every sample allowed us to accurately capture mutations in troublesome regions by utilizing the genotypes of both parent and offspring. Our approach revealed that high temperature treatment disproportionally increased the rate of insertions and deletions in dimeric short tandem repeats (STRs) compared to the rate of single nucleotide variants. Recurrent mutations appeared more often than expected, indicating a mutation bias along the genome sequence. Our study sheds light on the mutational landscape of a plant genome when exposed to high temperature stress and points to STRs as key genomic elements that rapidly increase the standing genetic variation available for natural selection.