Relationships between endogenous polyamines, cellular structure and arrested growth of grape berries

The condition known as 'millerandage' occurs when the growth of grape berries is interrupted early in their development. By harvest, berries in the same bunch will be different sizes, and some will be particularly small. Anatomical studies have revealed that interrupted growth can occur at different stages of berry development, and hormonal factors might be involved. Polyamines are one class of hormones that play an important role in plant morphogenesis, but analysis of polyamine content and composition indicated that berries of bunches with millerandage had the same polyamine composition as those at different stages of development. However, there were differences in relationships between wall-bound polyamine, especially wall-bound DAP, and arrested growth of berries. One key cytological difference was the negative PAS staining of cell walls in very small and in mid-size berries. In biochemical terms, wall-bound polyamine (and in particular wall-bound DAP content), was higher in berries from bunches with millerandage than in normal berries during their development. The present study therefore clearly demonstrates a positive correlation between wall-bound polyamine, especially wall-bound DAP, and arrested growth of berries in bunches with millerandage.