Adenine·cytosine substitutions are an alternative pathway of compensatory mutation in angiosperm ITS2

Comparisons of substitution rates and base-pair frequencies between AC (CA) and GU (UG) intermediate base pairs in CBCs. All results are shown based on the best-fit double-substitution rate matrix. (A) Frequency-mutability scatter plot of AC and GU base pairs and their chemical structures. (B) Box-plots for single-substitution rates from AC to six other base pairs. (C) Comparisons of rate heterogeneity between AC- and GU-mediated CBCs. The two substitution-rate ratios for AC-mediated CBCs are generally higher than those for GU-mediated CBCs. (D) Comparisons of the total probabilities of change from AU (UA) to GC (CG) based on multiplying the pairs of single-substitution rates. α₁*β₁ and µ₁*γ₁ represent the probability of GU- and AC-mediated CBCs, respectively (Fig. 1).