David Brand and Joseph Riov
Yuval Eshed, Joseph Riov, and Nir Atzmon
Rooting of Quercus ithaburensis Deche. cuttings decreased significantly with increasing stock plant age. Gibberellin (GA3) applied as bark treatment on leafless pruned stems of 3-year-old stock plants improved rooting percentage 6- to 7-fold. GA3 application also enhanced bud release and particularly shoot growth, thus increasing the number of cuttings per stock plant.
Jian Xin Shi, Joseph Riov, Raphael Goren, Eliezer E. Goldschmidt, and Ron Porat
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.