INTERACTION OF MITOCHONDRIAL RNA EDITING AND NUCLEOLYTIC PROCESSING IN THE RESTORATION OF MALE-FERTILITY IN SORGHUM

Nucleolytic processing of transcripts within mitochondrial orf107, ass ociated with male sterility in sorghum, is regulated by the fertility restoration gene Rf3, conferring 75% cleavage of whole-length transcri pts. Two transcript editing sites are 81% and 61% edited in rf3rf3 lin es, while these sites are 41% and 10% edited in the remaining whole-le ngth transcripts in an Rf3Rf3 line. RNA editing and processing efficie ncy in F-1 progeny were similar to the Rf3Rf3 parent, and analyses of backcross progeny indicated that all rf3rf3 lines were characterized b y high editing efficiency. We postulate that highly edited transcripts within the population are quickly processed in lines carrying Rf3, ge nerating a residual population of poorly edited transcripts. Thus, act ion of Rf3 may have no direct affect on RNA editing, and may be depend ent on a substrate of highly edited transcripts. These data indicate a potentially novel role of RNA editing in gene expression through an i nfluence on the efficiency of transcript processing.