Acid vacuolar invertase in dormant and germinating seeds of the horse chestnut

A high water content is maintained in the tissues of the axial organs of horse chestnut seeds after the fruit is shed and down to the time the seeds germinate. The plant cell vacuoles, features of whose metabolism can influence the cells’ preparation to initiate growth in germination, are preserved. It was shown that the activity of acid invertase and its capacity to hydrolyze both sucrose and raffinose remain stable throughout the period of dormancy and the transition to germination, as do the molecular weight of its subunits (63 and 65 kDa) and multimer (500 to 550 kDa). The activity of the enzyme increases when the seeds swell under optimal conditions for germination; this is associated with the synthesis of new molecules of the enzyme in long-lived mRNA templates. The storability of the enzyme in the vacuoles of dormant seeds, together with the increase in its activity when seeds coming out of dormancy swell, ensures the rapid hydrolysis of sucrose issuing from the seeds’ cotyledons, thus leading to increased osmotic pressure and, as a result, the beginning of cell elongation, i.e., germination.