Phytochrome Modification and Light-enhanced, In Vivo-induced Phytochrome Pelletability

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Abstract
Phytochrome that was induced by red irradiation in vivo to pellet with subcellular material [from 5-day-old oat (Avena sativa L., cv. Garry) shoots] and that was released from the pellet by removal of divalent cations exhibited altered characteristics. Compared to phytochrome extracted in a soluble red-absorbing form from etiolated tissue, pelleted and released phytochrome, which was also assayed in the red-absorbing form even though pelleted in the far-red-absorbing form, showed 50% greater micro complement fixation activity, eluted closer to the void volume of a Sephadex G-200 column, and electrophoresed more slowly on sodium dodecyl sulfate-polyacrylamide gels. Data presented here document that phytochrome pelleted in the far-red-absorbing form differs from soluble phytochrome extracted from nonirradiated tissue. These data, however, do not permit the conclusion that there is a causal relationship between pelletability and phytochrome modification.