|Authors: ||C. Davies, C. B÷ttcher, P.K. Boss, T. Peat, J. Newman|
|Keywords: ||Vitis vinifera L., plant growth regulators, ethylene, abscisic acid, auxins|
Fruit ripening is a complex process and experimental evidence suggests it is regulated by plant growth regulators (PGRs). In contrast to climacteric fruit, the ripening of non-climacteric grape (Vitis vinifera) berries is less dependent on ethylene and appears to be controlled by several other PGRs.
While the application of some PGRs, for example abscisic acid and brassinosteroids can advance the onset of grape berry ripening others, like auxins, delay it.
PGRs are therefore important for two main reasons.
First, endogenous PGRs play important roles in the control of berry development and a greater knowledge of their action is crucial to understanding processes that affect fruit composition at harvest.
Second, this knowledge can be used to develop methods to alter berry development in useful ways.
For example, exogenous PGRs provide potential tools with which to manipulate the timing of harvest and could be used to overcome a variety of problems associated with the increased season compression and higher temperatures during ripening caused by changing climatic conditions.
Of particular interest is the effect of synthetic auxins like 1-naphthalene acetic acid (NAA) on sugar accumulation, skin colouration, acid metabolism, ripening synchronicity and wine aroma.
The family of indole-3-acetic acid (IAA)-amido synthetases, important to the maintenance of IAA levels, appears to be a critical factor in the effectiveness of different auxins in controlling ripening.
The 3-D structure for one of the grape IAA-amido synthetases has recently been elucidated and provides insights at the molecular level into an important mechanism involved in auxin homeostasis.
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