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Title: Cucumber possesses a single terminal alternative oxidase gene that is upregulated by cold stress and in the mosaic (MSC) mitochondrial mutants

Author
item MROZ, TOMASZ - Warsaw University Of Life Sciences
item Havey, Michael
item BARTOSZEWSKI, GRZEGORZ - Warsaw University Of Life Sciences

Submitted to: Plant Molecular Biology Reporter
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2015
Publication Date: 4/21/2015
Publication URL: http://handle.nal.usda.gov/10113/61812
Citation: Mroz, T.L., Havey, M.J., Bartoszewski, G. 2015. Cucumber possesses a single terminal alternative oxidase gene that is upregulated by cold stress and in the mosaic (MSC) mitochondrial mutants. Plant Molecular Biology Reporter. 33(6):1893-1906. doi:10.1007/s11105-015-0883-9.

Interpretive Summary: In plants alternative oxidase (AOX) is an important nuclear-encoded enzyme active in the mitochondrial electron-transport chain, transferring electrons from ubiquinol to alternative oxidase instead of the cytochrome pathway to yield ubiquinone and water. AOX protects against unexpected inhibition of the cytochrome c oxidase pathway and plays an important role in stress tolerance. Two AOX subfamilies (AOX1 and AOX2) are known in higher plants and are usually encoded by a small gene family. In this study, genome-wide searches and cloning were completed to identify and characterize AOX in cucumber, and revealed that cucumber possesses a single AOX2 gene located on chromosome 4. AOX2 transcripts and proteins were detected in both leaves and flowers of wild-type plants, with higher levels in the mitochondrial mosaic (MSC) mutants and after cold treatments. This study shows that a single AOX2 is present in cucumber and is constitutively expressed. Expression of AOX increases under stress and in the MSC mutants, making cucumber unique model to study AOX expression and regulation, particularly in the context of mitochondria-to-nucleus signaling. These results will be useful for researchers studying organellar genetics and abiotic stress tolerances.

Technical Abstract: In plants alternative oxidase (AOX) is an important nuclear-encoded enzyme active in the mitochondrial electron-transport chain, transferring electrons from ubiquinol to alternative oxidase instead of the cytochrome pathway to yield ubiquinone and water. AOX protects against unexpected inhibition of the cytochrome c oxidase pathway and plays an important role in stress tolerance. Two AOX subfamilies (AOX1 and AOX2) are known in higher plants and are usually encoded by a small gene family. In this study, genome-wide searches and cloning were completed to identify and characterize AOX in cucumber (Cucumis sativus L.), and revealed that cucumber possesses a single AOX2 gene located on chromosome 4. AOX2 transcripts and proteins were detected in both leaves and flowers of wild-type plants, with higher levels in the mitochondrial mosaic (MSC) mutants and after cold treatments. This study shows that a single AOX2 is present in cucumber and is constitutively expressed. Expression of AOX increases under stress and in the MSC mutants, making cucumber unique model to study AOX expression and regulation, particularly in the context of mitochondria-to-nucleus signaling.