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Table 3 Number of synonymous to non-synonymous substitutions among coding sequences of the SAMDC genes estimated using K-estimator software by Yang and Nielson method [45]

From: Polyamines in the life of Arabidopsis: profiling the expression of S-adenosylmethionine decarboxylase (SAMDC) gene family during its life cycle

Sequence compared Ka Ks Ka/Ks P-Value Type of selection S N Divergence-Time
AtSAMDC1vs2 2.24 2.50 0.89 0.73 Purifying 156 468 2.30
AtSAMDC1vs3 2.03 3.94 0.52 0.0001** Purifying 159 420 2.49
AtSAMDC1vs4 4.75 2.06 2.31 0.01** Positive 158 432 3.95
AtSAMDC2vs4 2.89 4.11 0.70 0.72 Purifying 154 452 3.19
AtSAMDC3vs5 3.19 1.59 2.01 0.03* Positive 130 420 2.78
  1. Ka - rate of non-synonymous substitutions; Ks - rate of synonymous substitutions; Ka/Ks - ratio of non-synonymous to synonymous substitutions; S - number of synonymous substitutions; N - number of non-synonymous substitutions. Divergence time per site per year is estimated by Ka/Ks – Calculator, which is a weighted average of synonymous substitution rate and non-synonymous substitution rate. Significance is tested by Fisher exact test; * denotes P < 0.05, ** denotes P < 0.01. A significant value for positive selection indicates higher rate of non-synonymous substitutions and purifying indicates higher rate of synonymous substitutions