title: Fertility restoration and mitochondrial nucleic acids distinguish at least five subgroups among cms-S cytoplasms of maize (Zea mays L.).
abstract: Differences in fertility restoration and mitochondrial nucleic acids permitted division of 25 accessions of S-type male sterile cytoplasm (cms-S) of maize into five subgroups: B/D, CA, LBN, ME, and S(USDA). S cytoplasm itself (USDA cytoplasm) was surprisingly not representative of cms-S, since only two other accessions, TC and I, matched its mitochondrial DNA pattern. CA was the predominant subgroup, containing 18 of the 25 accessions. The B/D and ME subgroups were the most fertile and LBN the most sterile. The exceptional sterility of LBN cytoplasm makes it the most promising of the 25 cms-S accessions for the production of hybrid seed. The most efficient means of quantifying the fertility of the subgroups was analysis of pollen morphology in plants having cms-S cytoplasm and simultaneously being heterozygous for nuclear restorer-of-fertility (Rf) genes. This method took advantage of the gametophytic nature of cms-S restoration. The inbred NY821LERf was found to contain at least two restorer genes for cms-S. Fertility differences were correlated with mitochondrial nucleic acid variation in the LBN, ME, and S (USDA) subgroups.
authors.affiliation: Department of Plant Breeding and Biometry, Cornell University, 14853, Ithaca, NY, USA.
authors.forename: P H
authors.initials: PH
authors.lastname: Sisco
authors.forename: V E
authors.initials: VE
authors.lastname: Gracen
authors.forename: H L
authors.initials: HL
authors.lastname: Everett
authors.forename: E D
authors.initials: ED
authors.lastname: Earle
authors.forename: D R
authors.initials: DR
authors.lastname: Pring
authors.forename: J W
authors.initials: JW
authors.lastname: McNay
authors.forename: C S
authors.initials: CS
authors.lastname: Levings