University of Illinois

University of Florida

Recent studies of CMS-S restorers-of-fertility have led to a change in nomenclature

--Gabay-Laughnan, S, Chase, CD

In maize genetics nomenclature, loci are indicated in lower case italics, e.g., the rf3 locus. Alleles at a locus are also indicated in italics, with the first letter capitalized for dominant alleles, e.g., the Rf3 allele. Restoring alleles for CMS-S act in haploid pollen, i.e., fertility restoration is gametophytic (Buchert, Proc. Natl. Acad. Sci. USA 47:1436–1440, 1961), and dominance relationships of restoring and nonrestoring alleles cannot be directly assessed (Kamps et al., Genetics 142:1001–1007, 1996). Based on our finding that a homozygous-lethal restoring allele is recessive to the nonrestoring allele in diploid pollen produced by CMS-S tetraploid plants (Wen et al., Genetics 165:771–779, 2003), we have adopted the symbol restorer-of-fertility lethal (rfl) for homozygous-lethal restorers. Therefore, the symbol rfl1 replaces the previously published symbol RfIII (Laughnan and Gabay, Genetics and the Biogenesis of Cell Organelles, Ohio State Univ. Press, Columbus, pp. 330–349, 1975), while the symbol rfl2 replaces the previously published symbol RfVI (Laughnan and Gabay, 1975). In addition, we have adopted the symbol restorer-of-fertility viable (rfv) for homozygous-viable restorer-of-fertility alleles that arise via spontaneous mutation or transposon mutagenesis because these alleles are also likely to be recessive. The symbol rfv1 replaces the previously published symbol RfIV (Laughnan and Gabay, 1975). The symbol restorer-of-fertility nonfunctional (rfn) has been adopted for restorers that circumvent S cytoplasm pollen abortion but result in shed pollen that is nonfunctional (Gabay-Laughnan and Laughnan, Maydica 28:251–263, 1983); the symbol rfn1 replaces the previously published symbol Rf-nf 81-296-12 (Gabay-Laughnan, Maydica 42:163–172, 1997). The mutation by which a gene is identified is designated the reference allele. We will refer to that allele by the symbol -1, e.g., rfl1-1, rfl2-1. Because there are multiple, independent restorer-of-fertility loci for CMS-S, we anticipate that we will have a series of genes with the rfl, rfv, and rfn designations. New alleles at these loci that have arisen by independent mutational events will be identified by a laboratory number that indicates the year of isolation and the row number, e.g., rfl1-99829 and rfl2-911066. The symbol rfl2-911066 replaces the previously published symbol Rf*-91-1066-3 (Gabay-Laughnan and Chase, MNL 74:73–74, 2000). Restorer alleles that have yet to be placed to chromosome, and tested for allelism with those already mapped and designated, will be given temporary symbols that also indicate the year of isolation and the row number, e.g. rfl*-003379, and rfv*-991181.