Characterization of a radish introgression carrying the Ogura fertility restorer gene Rfo in rapeseed, using the Arabidopsis genome sequence and radish genetic mapping

Abstract

The radish Rfo gene restores male fertility in radish or rapeseed plants carrying Ogura cytoplasmic male-sterility. This system was first discovered in radish and was transferred to rapeseed for the production of F1 hybrid seeds. We aimed to identify the region of the Arabidopsis genome syntenic to the Rfo locus and to characterize the radish introgression in restored rapeseed. We used two methods: amplified consensus genetic markers (ACGMs) in restored rapeseed plants and construction of a precise genetic map around the Rfo gene in a segregating radish population. The use of ACGMs made it possible to detect radish orthologs of Arabidopsis genes in the restored rapeseed genome. We identified radish genes, linked to Rfo in rapeseed and whose orthologs in Arabidopsis are carried by chromosomes 1, 4 and 5. This indicates several breaks in colinearity between radish and Arabidopsis genomes in this region. We determined the positions of markers relative to each other and to the Rfo gene, using the progeny of a rapeseed plant with unstable meiotic transmission of the radish introgression. This enabled us to produce a schematic diagram of the radish introgression in rapeseed. Markers which could be mapped both on radish and restored rapeseed indicate that at least 50 cM of the radish genome is integrated in restored rapeseed. Using markers closely linked to the Rfo gene in rapeseed and radish, we identified a contig spanning six bacterial artificial chromosome (BAC) clones on Arabidopsis chromosome 1, which is likely to carry the orthologous Rfo gene.

Characterization of Raphanus sativus Pentatricopeptide Repeat Proteins Encoded by the Fertility Restorer Locus for Ogura Cytoplasmic Male Sterility

“…Furthermore, analysis of reference (and nontransgenic) restored lines indicated that, in the B 1 line, ORF138 suppression was comparable to that in the D81 restored radish line . By contrast, ORF138 suppression by PPR-B in the B 2 line was similar to that seen in the SamRfo rapeseed line, which carries a large DNA introgression from radish comprising the entire Rfo locus ( Figure 2C) (Delourme et al, 1998;Giancola et al, 2003).…”

“…All of the restored lines showed a drastic decrease in the ORF138 signal, but the level of inhibition appeared to vary between the different lines tested. The SamRfo rapeseed line, which contains a single copy of PPR-B on a large DNA region introgressed from radish (Delourme et al, 1998;Giancola et al, 2003), shows a nonhomogenous decrease in ORF138 synthesis in anther tissues. The sterility protein only (A) Analysis of total (Tot.…”

Physical localization and genetic mapping of the fertility restoration geneRfoin canola (Brassica napusL.)

“…Recent advances in canola genomics and molecular cytogenetics provide the possibilities to uncover the physical location of the Rfo locus in the canola genome. So far, a number of genetic maps have been constructed in canola and the molecular markers closely linked to the Rfo locus have been identified (Delourme et al 1994;Giancola et al 2003;Udall et al 2005;Hu et al 2008). The BAC clones linked to the Rfo locus have been identified from a large insert DNA library constructed from canola variety 'N1717', which carries the Rfo locus (Wu et al 2000).…”

Male Sterility

“…Recently, several papers have reported independently the cloning of the fertility restorer genes of Ogura and Kosena male sterility: Brown et al (2003), Desloire et al (2003), Giancola et al (2003), Koizuka et al (2003).…”