Simultaneous measurement of ABA, IAA and GAs in citrus: Role of ABA in relation to sink ability
1995
Kojima, K. (Fruit Tree Research Station, Nagasaki (Japan). Kuchinotsu Branch)
Simultaneous measurement of concentrations of ABA, IAA and GAs from one extract was investigated. A simply assay of total GAs content could be obtained, as only the early effluent on HPLC from ether and ethyl acetate extracts was collected, diluted gradually and applied for the bioassay together. This method was found to be suitable for application to citrus fruits and seedlings. Next, the distribution and changes in ABA and IAA concentrations in Valencia orange fruits were analyzed. Seeds showed a large peak of ABA (21 nmol/g fresh weight). In the central vascular axis, the IAA concentration reached a peak 119 days after full bloom. It is suggested that ABA in the seed and IAA in the central vascular axis play a role in the accumulation of assimilates. The effects of exogenous ABA on the changes in fruit drop, ABA catabolism, and the contents of sugars and organic acids of citrus fruits were evaluated in vivo by injection. Exogenously applied ABA was catabolized to about 10% in the fruits within 4 days. Injections of ABA resulted in the increase in the glucose and fructose concentrations, but not in that of the organic acids in juice. ABA appears to play a role in the increase of the sugar concentration in juice
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