EMS ‐induced amino acid substitutions in Arabidopsis proteins: what we get and what we miss

The alkylating agent ethyl methanesulfonate (EMS) is commonly used in Arabidopsis genetics to induce point mutations. It has been known for decades that the mutational spectrum of EMS is highly biased (> 98% G/C→A/T base pair transitions). However, the consequences of this bias on protein sequences have been almost entirely overlooked until now. The graph illustrates this bias, showing that only 29 amino acid substitutions are possible.