ALLIUM, CUCUMIS, AND DAUCUS GERMPLASM ENHANCEMENT, GENETICS, AND BIOCHEMISTRY
Location: Vegetable Crops Research Unit
Title: Mapping of Mitochondrial Sorting Locus in Cucumber
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 14, 2009
Publication Date: June 30, 2009
Citation: Al-Faifi, S., Garcia-Mas, J., Havey, M.J. 2009. Mapping of Mitochondrial Sorting Locus in Cucumber [abstract]. Plant Genomics and Beyond Conference 2009. p. 59.
In plants, DNA is located in three different places, the chloroplast, mitochondrion, and nucleus. Most angiosperms transmitted their organellar DNA through the egg (mitochondrial DNA), and through the egg and/ or pollen (chloroplast DNA). Transmission of the organellar DNA in cucumber is unique because the organellar genomes show different modes of transmission, chloroplast DNA shows maternal transmission, while the mitochondrial (mt) DNA is paternally transmitted. Passage of highly inbred (S22) line B of cucumber through cell culture induces mitochondrial rearrangements. Mt DNA rearrangements in cucumber generate unique mosaic (MSC) phenotypes. The mosaic (MSC) phenotype of cucumber is a valuable tool for studying mitochondrial DNA transmission. A nuclear locus (Psm for Paternal Sorting of Mitochondria) has been identified in cucumber that controls sorting of paternally transmitted mitochondrial DNA. The wild-type (+) allele at Psm does not sort wild-type or mutated mitochondria. However, the (-) allele at Psm preferentially selects or amplifies rare substoichoimetric wild-type mt DNAs in cucumbers showing the MSC phenotype. 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. The cucumber ortholog of Arabidopsis mis-match repair (MSH1) which acts on mtDNA was cloned and it segregated independently of Psm, revealing that this candidate gene is not Psm. Our findings showed that the synteny at the DNA level between cucumber and melon can be exploited 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.