BSM1a and BSM1b are highly conserved in land plants. Single nucleotide polymorphisms (SNPs) in AtNAD-ME1 (A) and AtNAD-ME2 (B) genes from 1,135 wild inbred A. thaliana accessions. (Left) Positions of BSM1a and BSM1b are highlighted by dashed blue lines; UTRs, exons, and introns are denoted by black, gray, and white bars, respectively, on the x axis. (Right) Expanded area representing exon 1, intron 1, and exon 2 is shown, with BSM1a and BSM1b marked within the blue dashed lines. For both genes, no SNPs were detected in either motif. (C) The presence of each motif was investigated in gene sequences of NAD-ME1, mMDH, and GOX1 retrieved from 44 species in Phytozome (v10.1) (51). Each pie chart shows the percentage of motif instances that were identical (green), or had one base pair (yellow), two base pair (orange) substitutions, or no similarity (white) detected.