Abstract
The nature of anthocyanoplasts (ACPs) from colored skin tissues of 'Kyoho' grapes was investigated under a microscope in relation to their development, membrane and anthocyanin.
1. ACPs in the subepidermal cells enlarged rapidly by repeated coalescence of the smaller ones. The volume of a coalesced ACP was almost the same as the sum of volumes of respective ACPs before coalescence.
2. It was confirmed by using protoplasts and/or isolated ACPs that ACPs were located in the vacuoles and each possessed a transparent membrane which could be clearly observed under a microscope.
3. A few minutes after a piece of skin tissue was permeated with 40 or 70% ethanol, anthocyanin began to leak out from ACP into the vacuole of the epidermal cell, and the vacuole turned red. The ACP then decreased in size and eventually collapsed, leaving almost no trace. The vacuole also burst soon after the collapse of the ACP.
4. When a piece of skin tissue was permeated with redistilled acetone, ACP in the vacuole of the epidermal cell collapsed. However, the vacuole did not burst, and smaller ACPs soon reappeared in the vacuole and rapidly coalesced together, resulting in larger ACPs. Throughout the formation of smaller ACPs and their coalescence, anthocyanin accumulated in a few larger ACPs, while the vacuole became near colorless.
5. The data indicate that each ACP is surrounded by a membrane which maintains the concentration of anthocyanin within an ACP higher than that in the vacuole, and that the formation and coalescence of ACPs are means by which anthocyanin accumulates in ACPs.
