USE OF THE STABILITY OF VACUOLES ISOLATED FROM THE STORAGE PARENCHYMA CELLS OF DORMANT AND FRESHLY HARVESTED RED BEETS (BETA-VULGARIS L) TO TEST FOR POPULATION DIFFERENCES

We find that vacuoles isolated by slicing from storage tissue of red beets (Beta vulgaris L.) may consist of different populations depending on the region sampled, or how the beets were stored. Because the average size of isolated vacuoles was less than that seen in tissue slices, many vacuoles are altered during isolation. Isolated vacuoles of at least 32-mu-m diameter might represent those least physically altered by isolation. The persistence of these large isolated vacuoles was examined in various media over 2 h. Maximum persistence was observed with sorbitol at or above 1.5 M, pH 7.25, and KCl at 100 mM or higher. DTT (0-10 mM), or EDTA (0-12.5 mM), did not improve the persistence of isolated vacuoles. The optimized isolation medium gave high vacuole persistences in most cases, but a medium modified from that used by others (R.A. Leigh and D. Branton, Plant Physiol., 58 (1976) 656-662) showed lower persistences for isolated vacuoles from fresh compared with dormant beets. Vacuoles from the fifth to sixth intervascular ring of fresh beets had a lower persistence than did those from the second to third ring. The same storage organ may yield different vacuole populations depending on how it is stored, or the region sampled.