Polyphosphate accumulation in the senescing mushroom Agaricus bisporus

In the common mushroom a peak in its high respiration rate is observed during postharvest development at the moment of cap opening. It is assumed that both the basic high respiration rate and an additional peak in respiration rate is necessary to provide the need of energy for cap opening during postharvest. In this paper we show that the actual cap opening takes place between 48 and 72 hours after harvest. In this period the respiration rate is declining, instead of an expected increase. So high respiration rates are not correlated with cap opening. The respiration activity is mainly located in gill tissue and it is in this tissue that polyphosphates, with high energy phosphate bonds, are found. According to our data, more than 75% of this high energy compound is synthesized before any sign of cap opening. This is the first report on the occurrence of polyphosphates in the common mushroom Agaricus bisporus. Because of the high energy phosphate-bond content of these compounds, it explains, at least partly, the high respiration rates of the mushroom during postharvest development.