The amount and molecular weight of fragments of mtDNA digested by Hind Ⅲ, BamH I, and Sal I of BT male sterile and maintainer lines can be distinguished by using agarose gel electrophoresis. Theresults showed that. 1) the minimum size was 300kb, no distinct length difference was found on mtDNAbetween MS line and maintainer; 2) Homologous sequences of mtDNA were found between MS and maintainer lines by using 9 probes of maize and rice to hybridize with digested mtDNA. The mtDNAs of MS and maintainer lines ha...