Interaction of mitochondrial RNA editing and nucleolytic processing in the restoration of male fertility in sorghum.

Nucleolytic processing of transcripts within mitochondrial orf107, associated with male sterility in sorghum, is regulated by the fertility restoration gene Rf3, conferring 75% cleavage of whole-length transcripts. Two transcript editing sites are 81% and 61% edited in rf3rf3 lines, while these sites are 41% and 10% edited in the remaining whole-length transcripts in an Rf3Rf3 line. RNA editing and processing efficiency in F1 progeny were similar to the Rf3Rf3 parent, and analyses of backcross progeny indicated that all rf3rf3 lines were characterized by high editing efficiency. We postulate that highly edited transcripts within the population are quickly processed in lines carrying Rf3, generating a residual population of poorly edited transcripts. Thus, action of Rf3 may have no direct affect on RNA editing, and may be dependent on a substrate of highly edited transcripts. These data indicate a potentially novel role of RNA editing in gene expression through an influence on the efficiency of transcript processing.