Phytochrome: Immunocytochemical assay of synthesis and destruction.

The protein moiety of phytochrome, when assayed by an immunocytochemical technique, was not detected in dry oat (Avena sativa L., cv. Garry) and rye (Secale cereale L., cv. Balbo) grains or in grains hydrated 4 h at 25°. After 24 h of hydration immunochemical activity of phytochrome in situ was readily detectable. Immunocytochemical assays of destruction show that different regions of 3-day-old, single oat and rye seedlings have different destruction kinetics. Oat roots apparently exhibit much slower destruction than the rest of the seedling, while the nodal region of rye exhibits slower destruction than the upper part of the coleoptile. When experimentally feasible, parallel spectrophotometric assays of appearance and destruction gave results similar to those observed by immunocytochemistry.