ISOLATION OF MITOCHONDRIAL-DNA SEQUENCES THAT DISTINGUISH MALE-STERILITY-INDUCING CYTOPLASMS IN SORGHUM-BICOLOR (L) MOENCH

We have demonstrated that sorghum DNA sequences of mitochondrial origi n can be used to distinguish different male-sterility-inducing cytopla sms. Six DNA clones containing single-copy mitochondrial sequences wer e hybridized on Southern blots to restriction enzyme-digested DNA of 2 8 sorghum lines representing sources of different cytoplasmic male-ste rility (CMS) groups. Four cytoplasmic types were defined on the basis of the pattern of DNA fragments detected. Similar analyses of 50 addit ional diverse sorghum accessions suggested that three of the four cyto plasmic types may be diagnostic for CMS. Also, three other cytoplasmic types were discovered. These and other mitochondrial DNA clones may b e useful molecular tools for ''fingerprinting'' sterility-inducing cyt oplasms in breeding programs, determining cytoplasmic diversity among germ plasm accessions, and identifying new sources of cytoplasm that i nduce male sterility.