Changes of the activity of IAA oxidase, tryptophansynthetase and cytokinin oxidase in sterile anther, leaf and ovule were similar to those of phytohormones.
The activity of IAA oxidase and cytokinin oxidase was significantly higher in CMS anther, but the activity of tryptophansynthetase was lower than in fertile anther.
These results suggest that MK-447 may selectively enhance the prostaglandin I2 (PGI2) level by acting as a tryptophan-like cofactor of PG endoperoxide synthetase.