Submitted to: Plant Mitochondrial Workshop Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 4/7/1996
Publication Date: N/A
Technical Abstract: Cytoplasmic male sterility (cms) is a maternally inherited trait characterized by the inability to produce functional pollen. Maize plants that carry Texas (T) cytoplasm are male fertile only if they carry dominant alleles at both of two nuclear restorer loci, Rf1 and Rf2. As a first step in dissecting the molecular basis of fertility restoration, we have initiated a program to isolate the genetic components of this system. The mitochondrial component of this system (T-urf13) has previously been cloned and well characterized. We have recently cloned the Rf2 nuclear component via transposon tagging. In addition, we have recently identified transposon-tagged alleles of Rf1. To date, two rf1-m alleles (rf1-m3207 and Rf1-m3310) have been shown to be heritable. Three additional putative rfl-m alleles await final testing in our summer nursery. Cosegregation analysis revealed 5.5- and 2.4-kb Mul-hybridizing EcoRI-restriction fragments in all of the male-sterile and none of the male-fertile plants in families segregating for rfl-m3207 and rfl-m3310, respectively. Both rfl-m3207 and rfl-m3310 alter T-urf13 transcription patterns. A1.6-kb T=urf13 transcript is absent or much less abundant in plants carrying either mutant. By confirming previous reports that the 1.6-kb T-urf13 transcript is absent in rfl/rfl plants, these studies using novel rfl alleles establish that the 1.6-kb transcript is Rf1 dependent.