University of Reading Horticultural Research Laboratories, Shinfield, Berkshire, UK.
Planta. 1969 Mar;89(1):9-22. doi: 10.1007/BF00386493.
As measured by in vivo spectrophotometry the phytochrome content in etiolated turnip seedlings was higher in cotyledons than in hypocotyls; in the latter, it is confined to the apical part. During early growth in darkness the amount increased in both tissues to a maximum, reached about 40 hours after sowing; the levels then gradually declined. Separation of seedlings into hypocotyl and cotyledons increased the rate of phytochrome loss in the former, but not in the latter.Following 5 minutes of red light P frdecayed very rapidly in darkness; after 1.5 hours all of the phytochrome was present as P r, which was presumably not converted initially. In continuous red light the total phytochrome was reduced to below the detection level within 3 hours. Seedling age markedly affected the loss of phytochrome following red light; more was destroyed in older than in younger hypocotyls and apparent new synthesis occurred only in young seedlings. The capacity to synthesise phytochrome differed in cotyledons and hypocotyl. In cotyledons, synthesis occurred following shots of red light varying from 10 seconds, to 6×I minute, but the amount of newly formed phytochrome was not related to the amount destroyed: after 5 hours of continuous red light no new synthesis occurred. In hypocotyls, the amount of phytochrome synthesised was related to the amount previously destroyed, and the phytochrome content after 24 hours of darkness was similar following all red light treatments of 1 minute or longer: new synthesis occurred following 5 hours of continuous red light.In far-red light phytochrome decayed very slowly, approaching the limit of detection after 48 hours. In cotyledons some loss was already observed after 5 hours of far-red and, in hypocotyls, after about 10 hours.These results are discussed in relation to the possible role of phytochrome as the pigment mediating anthocyanin synthesis in prolonged far-red light.
体内分光光度法测定结果表明，黄化萝卜幼苗的子叶中光敏素含量高于下胚轴；而下胚轴中的光敏素仅局限于顶端部分。在黑暗中早期生长过程中，两种组织中的光敏素含量均增加到最大值，大约在播种后 40 小时达到；然后水平逐渐下降。将幼苗分离为下胚轴和子叶会增加前者中光敏素的损失率，但不会增加后者的损失率。在黑暗中，红光处理 5 分钟后 Pfr 迅速降解；1.5 小时后，所有的光敏素都以 P r 的形式存在，推测最初没有转化。在连续的红光下，3 小时内总光敏素降低到检测水平以下。幼苗年龄显著影响红光后光敏素的损失；在较老的下胚轴中破坏的更多，而在年轻的下胚轴中仅发生明显的新合成。子叶和下胚轴的光敏素合成能力不同。在子叶中，红光照射 10 秒到 6×1 分钟均可合成光敏素，但新形成的光敏素数量与破坏的数量无关：连续红光照射 5 小时后，不再发生新合成。在下胚轴中，合成的光敏素数量与先前破坏的数量有关，并且在黑暗中 24 小时后，所有持续 1 分钟或更长时间的红光处理后的光敏素含量相似：连续红光照射 5 小时后发生新合成。在远红光中，光敏素降解非常缓慢，48 小时后接近检测极限。在子叶中，5 小时的远红光处理后已经观察到一些损失，在下胚轴中，约 10 小时后观察到损失。这些结果与光敏素作为在长时间远红光中介导花色素苷合成的色素的可能作用有关。
