Abstract
[Truncated] Mitochondria, together with chloroplasts are the major site of ATP synthesis in plant cells. Together with the conventional cytochrome chain of respiration, plant mitochondria encompass multiple enzymes that reduce the yield of ATP synthesis. Such non phosphorylating respiration has been linked to thermogenesis, limiting mitochondrial production of reactive oxygen species and allowing substrate metabolism to continue unhindered by ATP:ADP. Despite such broad functions, little is known of these enzymes, their mechanisms and interaction during normal plant development.The expression of two enzymes, the alternative oxidase (Aox) and uncoupling protein (Ucp) were investigated during ripening in mango fruit, which displays a six-fold climacteric, and during development in soybean cotyledons, which are an established model of mitochondrial biogenesis. The diversity of Aox genes and their expression patterns was also surveyed between monocot and dicot angiosperms. A PCR-based approach, using primers designed to conserved regions, was used to assess genomic copy number of Aox and Ucp in mango and soybean. Southern analysis confirmed a multigene family encoding Aox in both genomes and Ucp in soybean, with mango Ucp likely to be encoded by a single nuclear gene. The same approach, combined with a survey of available genomic and EST data of five monocots and eight dicots, demonstrated that monocot species lack an Aox2-type gene and that stress-induced isozymes were Aox1-type. Implications for the role and function that various Aox proteins play across different species were discussed.
Original language | English |
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Qualification | Doctor of Philosophy |
Awarding Institution |
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DOIs | |
Publication status | Unpublished - 2002 |
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