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Title: The mosaic mutants of cucumber: A system to produce mitochondrial knock-downs

Author
item DEL VALLE-ECHEVARRIA, ANGEL - University Of Wisconsin
item BARTOSZEWSKI, GRZEGORZ - Warsaw University Of Life Sciences
item Havey, Michael

Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: 11/14/2014
Publication Date: 1/11/2015
Citation: Del Valle-Echevarria, A.R., Bartoszewski, G., Havey, M.J. 2015. The mosaic mutants of cucumber: A system to produce mitochondrial knock-downs [abstract]. Plant and Animal Genome Conference. Paper No. W545.

Interpretive Summary:

Technical Abstract: The mitochondrial (mt) DNA of cucumber has several unique attributes, including paternal transmission and large size due in part to the accumulation of repetitive DNAs. Recombination among these repetitive motifs generates structural rearrangements in the mt DNAs. When the highly inbred line ‘B’ of cucumber is passed through cell cultures, regenerated plants occasionally possess paternally transmitted, strongly mosaic (MSC) phenotypes which show low seed production and germination, misshapen cotyledons and leaves, higher levels of alternative oxidase expression, and lower amounts of ATP as compared to inbred B. Independently derived MSC lines possess different mt DNA conformations. We used the Roche 454 platform to sequence mt DNAs from wild-type ‘B’ and three MSC lines (3, 12 and 16) independently derived from inbred B. Reads were aligned to the mitochondrial reference of the cucumber ‘Calypso’. By comparing read-depth coverages, we identified regions that were under-represented in the MSC lines relative to inbred B. None of the three MSC lines possessed identical assemblies, indicating that they do not trace back to a single sublimon in ‘B’. Under-represented mt genes included exon 4 of nad5 and atp4 in MSC3, rrn5 in MSC12, and rps7 in MSC12 and 16 as compared to wild-type ‘B’. Quantitative PCR supported the read depth coverages and established lower transcription of genes in under-represented regions. Our results support the use of cucumber to generate mitochondrial-gene “knock downs” to study genetic responses in a highly inbred nuclear background.