Aerobic fermentation in tobacco pollen |
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Authors: | Marcel Bucher Karl A Brander Sandro Sbicego Therese Mandel Cris Kuhlemeier |
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Institution: | (1) Institute of Plant Physiology, University of Berne, Altenbergrain 21, CH-3013 Berne, Switzerland;(2) Present address: Institut für Genbiologische Forschung Berlin GmbH, D-14195 Berlin, Germany |
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Abstract: | We characterized the genes coding for the two dedicated enzymes of ethanolic fermentation, alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC), and show that they are functional in pollen. Two PDC-encoding genes were isolated, which displayed reciprocal regulation: PDC1 was anaerobically induced in leaves, whereas PDC2 mRNA was absent in leaves, but constitutively present in pollen. A flux through the ethanolic fermentation pathway could be measured in pollen under all tested environmental and developmental conditions. Surprisingly, the major factor influencing the rate of ethanol production was not oxygen availability, but the composition of the incubation medium. Under optimal conditions for pollen tube growth, approximately two-thirds of the carbon consumed was fermented, and ethanol accumulated into the surrounding medium to a concentration exceeding 100 mM. |
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Keywords: | alcohol dehydrogenase fermentation gene expression pollen pyruvate decarboxylase respiration tobacco |
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