N6-adenine methyltransferase which modifies the AA dinucleotide at the plant mitochondrial 18S rRNA nucleotides A1914 and A1915. Not active as mitochondrial transcription factor. adenosine(1914)/adenosine(1915) in 18S rRNA + 4 S-adenosyl-L-methionine = 4 H(+) + N(6)-dimethyladenosine(1914)/N(6)-dimethyladenosine(1915) in 18S rRNA + 4 S-adenosyl-L-homocysteine No visible phenotype when grown under normal conditions or under cold stress, but lack of methylation of the adenosine dinucleotide present in the mitochondrial 18S rRNA. Belongs to the class I-like SAM-binding methyltransferase superfamily. rRNA adenine N(6)-methyltransferase family.