Localization of phytic acid in the floral structure of Petunia hybrida and relation to the incompatibility genes.

In three clones of Petunia hybrida with different incompatibility genes, phytic acid is detected exclusively in pollen, stigma and style. These are all parts of the floral structure involved in the incompatibility reaction. Phytase activity was detected in these tissues as well as in the ovary. The level of phytic acid and phytase activity varied between clones with different S alleles. This difference was most evident in stigma and style. The pattern of phytic acid breakdown following pollination depends on whether pollen and style form a compatible or incompatible combination. Incompatible pollination results in a higher rate of degradation. Consideration is given to the relationship between breakdown of phytic acid to myo-inositol and cell wall thickening and plug formation, which occurs to a greater extent in the incompatible combination.