Short tandem repeat length variants accumulate at high temperatures over generations in Arabidopsis

In wild populations, some short tandem repeats (STRs) may vary in length. Recent studies have demonstrated that length variation in STRs imposes an impact on gene expression and protein function in Arabidopsis thaliana. Such length differences have been correlated to climate conditions and may be involved in local adaptation and response to environmental changes and fluctuations. Here, we have performed an experiment to monitor whole genome STR variability over nine generations in Arabidopsis lines subjected to normal and high temperatures. Our results from whole genome sequencing of plants over all generations revealed a higher frequency of homozygous STR length changes under high temperature compared to normal temperature. The effect of high temperature was more profound for STRs compared to SNPs. The homozygous STR length variation was observed mostly in STRs with a unit size of 2 bp and AT/TA motifs. The finding that STR variants occur at higher frequency at high temperatures, a pattern not observed for SNPs, suggest that STRs can contribute to heat stress adaptation.