|Schnable, Patrick - ISU|
|Cui, X - ISU|
Submitted to: Plant Mitochondrial Workshop Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: April 7, 1996
Publication Date: N/A
Technical Abstract: The T cytoplasm of maize has been particularly well studied because it was once widely used in the production of hybrid seed and it is associated with an increased susceptibility to specific fungal toxins. The male sterility associated with T cytoplasm is due to the action of a chimeric mitochondrial gene, T-urf13, unique to the T cytoplasm. Restoration of pollen fertility in T cytoplasm requires the complementary action of dominant alleles (Rf1 and Rf2) of two nuclear-restorer genes. It is known that Rf1 has a marked effect on the transcription and/or translation of T-urf13. However, this Rf1-mediated alteration of T-urf13 transcription or translation is not sufficient for fertility restoration, since Rf2 is essential for restoration, and there is no evidence that Rf2 affects expression of T-urf13. As a first step towards unravelling the molecular processes involved in cms restoration, a collection of rf2 and rf1 mutants have been generated via transposon tagging. A 3.4-kb rf2 fragment containing a Mu1 transposon has been cloned from one of the rf2 mutants. The identity of this clone was verified via allelic cross-referencing experiments. Genomic and cDNA Rf2 clones have been isolated. A partial Rf2 cDna obtained from a tassle library exhibits 70% amino acid sequence similarity to aldehyde dehydrogenases. This finding has led to the development of a model to explain the role of Rf2 in fertility restoration.