Genetic and molecular analysis of the restoration of fertility (Rf) genes for Ogura male-sterility from a Japanese wild radish (Raphanussativus var. hortensis f. raphanistroides Makino)

• Published in: Euphytica 2008-11, Vol.164 (2), p.395-404
• Main Authors: Yasumoto, Keita, Nagashima, Takaharu, Umeda, Tetsuya, Yoshimi, Maiko, Yamagishi, Hiroshi, Terachi, Toru
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Amino acids; Biological and medical sciences; Biomedical and Life Sciences; Biotechnology; Brassicaceae; Fertility; Fundamental and applied biological sciences. Psychology; Generalities. Genetics. Plant material; Genetic resources, diversity; Genetics; Genetics and breeding of economic plants; Genotype & phenotype; Heterosis. Floral biology applications: apomixy, male sterility, incompatibility, varia; Hybridization; Life Sciences; Male sterility; Molecular biology; Plant breeding: fundamental aspects and methodology; Plant Genetics and Genomics; Plant material; Plant Pathology; Plant Physiology; Plant reproduction; Plant Sciences; Proteins; Raphanus sativus
• ISSN: 0014-2336; 1573-5060
• DOI: 10.1007/s10681-008-9687-4

Ogura male-sterile cytoplasm is one of the most extensively studied cytoplasms in Brassicaceae . In this study, in order to gain better understanding of the variation and evolution of the restoration of the fertility ( Rf ) gene for Ogura male-sterile cytoplasm, the nucleotide sequence of the orf687 homologue in the Japanese wild radish ( Raphanus sativus var. hortensis f. raphanistroides Makino) was analyzed using an F 2 population made with a cross between a Japanese wild radish plant containing the Rf gene and ‘Uchiki-Gensuke’ (a maintainer of Ogura-male sterility). Segregation of male-fertile/-sterile plants in the F 2 generation suggested that another unidentified Rf gene unlinked to orf687 exists in the Japanese wild radish. The genotype of orf687 was determined for each F 2 plant by Southern hybridization with an orf687 gene probe, mismatch-specific endonuclease digestion of PCR products, and direct sequencing of a PCR product. Genotyping revealed that some fertility-restored plants are homozygotic for the ‘Uchiki-Gensuke’ type orf687 allele, supporting the idea that another gene different from orf687 also functions as an Rf gene for Ogura male-sterility. Protein analysis using an antibody raised against the Ogura-specific ORF138 protein suggests a mechanism of fertility restoration by the unidentified Rf similar to that by orf687 . Sequence analysis of orf687 from a Japanese wild radish plant and ‘Uchiki-Gensuke’ revealed that both orf687 regions encode a mitochondrially-targeted protein consisting of 687 amino acids with 16 PPR motifs. Comparison of the deduced amino acid sequences with those of the known orf687 sequences from ‘Yuan hong’ and ‘Kosena’ containing Rf and recessive one ( rf ), respectively, showed that three unique amino acid replacements are present in ORF687 of the Japanese wild radish. Two of the three replacements, that from lysine to isoleucine at position 232 and from asparagine to asparate at position 240, confer negative charges to the protein. Since the Rf of ‘Yuan hong’ was reported to have a unique replacement that confers a negative charge to ORF687 (from asparagine to aspartate at position 170), it is proposed that the amino acid replacements conferring a negative charge to ORF687 are important for determining the status of the Rf / rf gene.