Plant and Cell Physiology Advance Access published online on January 2, 2009
Plant and Cell Physiology, doi:10.1093/pcp/pcn206
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Increase in Ascorbate Content of Transgenic Tobacco Plants Overexpressing Acerola (Malpighia glabra) Phosphomannomutase Gene
Graduate School of Biosphere Sciences, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, 739-8528 Hiroshima, Japan
*Corresponding author: Prof. Muneharu Esaka Hiroshima University Japan E-mail: mesaka{at}hiroshima-u.ac.jp
| Abstract |
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Phosphomannomutase (PMM; EC 5.4.2.8 [EC] ) catalyzes the interconversion of mannose-6-phosphate to mannose-1-phosphate in the Smirnoff-Wheeler pathway for the biosynthesis of L-ascorbic acid (AsA). We have cloned the PMM cDNA from acerola (Malpighia glabra), a plant containing enormous amount of AsA. The AsA contents correlate with the PMM gene expression of the ripening fruits and leaves. The PMM activities in the leaves of acerola, tomato and Arabidopsis correlate with their respective AsA contents. Transgenic tobacco plants overexpressing acerola PMM gene showed about 2-fold increase in AsA contents compared to the wild type, with corresponding correlation with the PMM transcript levels and activities.
Keywords: Acerola (Malpighia glabra) - Ascorbic acid - Enzyme activity - Phosphomannomutase - Phosphomannose isomerase - Transgenic tobacco
(Received November 17, 2008; Accepted December 23, 2008)
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