Co-Authors:
Shi, J.X., Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agricultural, Food and Environmental Quality Sciences, Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel, Institute of Farm Product Storage, Shanxi Academy of Agricultural Sciences, Taiyuan 030031, Shanxi, China
Riov, J., Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agricultural, Food and Environmental Quality Sciences, Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel
Goren, R., Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agricultural, Food and Environmental Quality Sciences, Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel
Goldschmidt, E.E., Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agricultural, Food and Environmental Quality Sciences, Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel
Porat, R., Department of Postharvest Science of Fresh Produce, Agricultural Research Organization (ARO), Volcani Center, P.O. Box 6, Bet-Dagan 50250, Israel
Abstract:
Molecular aspects of ethanol fermentation in citrus fruit were investigated in immature and mature 'Star Ruby' grapefruit (Citrus paradisi Macf.) and 'Murcott' mandarin (Citrus reticulata Blanco). Transcript levels of pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH), which play a central role in ethanol fermentation, were detectable in all stages of fruit development, but accumulation of acetaldehyde (AA) and ethanol was evident only as fruit approached maturation or after several weeks of storage. Treatment of mature fruit with ethylene enhanced ethanol fermentation in grapefruit but not in mandarin. Immature fruit of both cultivars, on the other hand, responded to ethylene by prominent, although transient, enhancement of ethanol fermentation. Exposure of mature or immature fruit to anaerobic conditions (N2 atmosphere) upregulated the expression of PDC and ADH, and increased the levels of AA and ethanol. Exposure of mature fruit to anaerobic conditions also increased the enzymatic activities of PDC and ADH. The data indicate that the potential for ethanol fermentation exists in citrus fruit throughout development, even under aerobic conditions, but AA and ethanol are detected mainly toward maturation or under prolonged storage. However, prominent, long-term molecular induction of ethanol fermentation occurs only under anaerobic conditions imposed by N2 atmosphere.