ARS | Publication request: Exploiting Synteny in Cucumis for Mapping of Psm, A Unique Locus Controlling Paternal Mitochondrial Sorting

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 5, 2008
Publication Date: June 3, 2008
Citation: Al-Faifi, S., Meyer, J.D., Garcia-Mas, J., Monforte, A.J., Havey, M.J. 2008. Exploiting Synteny in Cucumis for Mapping of Psm, A Unique Locus Controlling Paternal Mitochondrial Sorting. Theoretical and Applied Genetics. 117(4):523-529.

Interpretive Summary: In plants, DNA is located in three different places, the chloroplast, mitochondrion, and nucleus. Cucumber is a unique plant because the three genomes show different modes of transmission, nuclear DNA bi-parentally, plastid DNA maternally, and mitochondrial DNA paternally. The mosaic (MSC) phenotype of cucumber is associated with rearrangements in the mitochondrial DNA and is a valuable tool for studying mitochondrial DNA transmission. A nuclear locus (Psm) has been identified in cucumber that controls sorting of paternally transmitted mitochondrial DNA. The cucumber gene mis-match repair (MSH1) was cloned and it segregated independently of Psm, revealing that this candidate gene is not Psm. Comparative sequencing and mapping of cucumber and melon revealed extensive colinearity between the DNAs of these two plants near Psm and placed this locus on linkage group R of cucumber and G10 of melon. However the cucumber region near Psm was surprisingly monomorphic with an average of one single nucleotide polymorphism every 25 kilobases, requiring that a family from a more diverse cross is produced for mapping and eventual cloning of Psm. The similarities in the DNAs of cucumber and melon are important for geneticists and breeders to aid in the cloning of genes from both species, as well as allow for resources developed for one species to be used for analyses in other species.

Technical Abstract: The three genomes of cucumber show different modes of transmission, nuclear DNA bi-parentally, plastid DNA maternally, and mitochondrial DNA paternally. The mosaic (MSC) phenotype of cucumber is associated with mitochondrial DNA rearrangements and is a valuable tool for studying mitochondrial transmission. A nuclear locus (Psm) has been identified in cucumber that controls sorting of paternally transmitted mitochondrial DNA. The cucumber ortholog of Arabidopsis mis-match repair (MSH1) was cloned and it segregated independently of Psm, revealing that this candidate gene is not Psm. Comparative sequencing and mapping of cucumber and melon revealed extensive synteny on the recombinational and sequence levels near Psm and placed this locus on linkage group R of cucumber and G10 of melon. However the cucumber genomic region near Psm was surprisingly monomorphic with an average of one SNP every 25 kb, requiring that a family from a more diverse cross is produced for fine mapping and eventual cloning of Psm.