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

Table 2 Tajima test results for SAMDC non-coding upstream and downstream DNA sequences

Type of sequences	Total number of sequences (m)	Total number of sites (N) in the final dataset	Total number of segregating sites (S)	Number of segregating sites/number of nucleotide sites pS = S/N	Mean number of pairwise differences among sequences (Θ)	Nucleotide diversity or nucleotide differences per site (π)	Tajima D-Value	Inference based on Tajima D-Value
AtSAMDC promoters	5	394	333	0.845178	0.405685	0.524112	2.229599*	Positive selection
AtSAMDC 5’UTRs	5	12	6	0.500000	0.240000	0.283333	1.240997	Positive selection
AtSAMDC 3’UTRs	5	43	32	0.744186	0.357209	0.441860	1.774392	Positive selection

Tajima test [43] was conducted in MEGA Version 7 on an aligned sequence dataset by choosing nucleotide in the substitutions type. N is the total number of nucleotide positions considered by test statistic for the analysis. Any nucleotide site that shows two or more nucleotides among the total number of sequences was considered as a segregating site, which is a default setting. The mean number of pairwise differences between the sequences was represented as θ. The nucleotide differences per site among the sequences was represented as π and was collectively termed as nucleotide diversity. A high positive Tajima D-value of (>2) with * indicates a significant (P < 0.05) positive selection in these sequences

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