Molecular-Genetic Characterization of CMS-SRestorer-of-FertilityAlleles Identified in Mexican Maize and Teosinte

Abstract

Restorer-of-fertility (Rf ) alleles for S-type cytoplasmic male sterility (CMS-S) are prevalent in Mexican races of maize and teosinte. Forty-five Rf alleles from 26 races of maize and 6 Rf alleles from different accessions of teosinte were found to be homozygous viable, consistent with the hypothesis that they are naturally occurring Rf alleles. Mapping and allelism studies were performed to assess the number of genes represented by these 51 alleles. Forty-two of the Rf alleles mapped to the long arm of chromosome 2 (2L), and 5 of these were further mapped to the whp1-rf3 region. The Rf3 restoring allele, found in some U.S. maize inbred lines, cosegregates with internal processing of CMS-S mitochondrial transcripts. Three of the 5 mapped Rf alleles were associated with a similar RNA processing event. Allelism or tight linkage was confirmed between Rf3 and 2 teosinte alleles (Rf K-69-6 and Rf 9477) and between Rf3 and the Cónico Norteño allele Rf C-N (GTO 22). The rf3 region of 2L potentially encodes a complex of linked rf genes. The prevalence of restoring alleles in this chromosomal region, among normal-cytoplasm accessions of Mexican maize and teosinte, supports the conclusion that these alleles have functions in normal mitochondrial gene expression that by chance allow them to restore male fertility in S cytoplasm.

Isolation and Analysis of Rice Rf1-Orthologus PPR Genes Co-segregating with Rf3 in Maize

“…Gabay- Laughnan et al (2004) reported that 42 restorer alleles for CMS-S in Mexican maize and teosinte mapped to the long arm of chromosome 2; five of them were further mapped to the whp1-rf3 region. These results indicated that rf3 may be a complex locus similar to some disease resistance genes (Li et al 1998).…”

QTL involved in the partial restoration of male fertility of C-type cytoplasmic male sterility in maize

“…The QTL region in bin 2.09 collocates with a cluster of multiple restorer genes for S-CMS, including the major restorer gene Rf3 (Gabay- Laughnan et al 2004), and Rf8 and Rf*, which restore T-CMS in the presence of Rf2 (Dill et al 1997). The QTL in bins 3.05 and 3.06 are linked to Rf1 of T-CMS in bin 3.04.…”

Fine mapping of Rf2, a major locus controlling pollen fertility restoration in sorghum A1 cytoplasm, encodes a PPR gene and its validation through expression analysis

“…The CMS phenotype is a maternally inherited trait caused by incompatibility between the nuclear and cytoplasmic genomes (Ruiz & Daniell, ). Classical genetic studies have reported that CMS is associated with aberrant recombination in the mitochondrial genome (Conde, Pring, Schertz, & Ross, ; Das et al., ; Eckardt, ; Hanson & Bentolila, ; Lee, Muthukrishnan, Sorensen, & Liang, ; Levings & Pring, ; Luo et al., ; Pring, Conde, & Schertz, ; Smith & Chowdhury, ) and fertility was restored by nuclear‐encoded fertility restorer ( Rf ) genes in a number of crop species like rice, soybean, maize, sunflower (Ahmadikhah & Karlov, ; Dong et al., ; Gabay‐Laughnan, Chase, Ortega, & Zhao, ; Yue, Vick, Cai, & Hu, ) including sorghum (Jordan et al., , ; Klein et al., ; Praveen, Suneetha, Umakanth, Patil, & Madhusudhana, ).…”