Johnson E., Bradley M., Harberd N. P., Whitelam G. C.
Department of Botany, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom (E.J., G.C.W.).
Plant Physiol. 1994 May;105(1):141-149. doi: 10.1104/pp.105.1.141.
Several aspects of the photophysiology of wild-type Arabidopsis thaliana seedlings were compared with those of a phytochrome A null mutant, phyA-1, and a mutant, fhy1, that is putatively involved in the transduction of light signals from phytochrome A. Although phyA seedlings display a near wild-type phenotype when grown in white light (W), they nevertheless display several photomorphogenic abnormalities. Thus, whereas the germination of wild-type and fhy1 seeds is almost fully promoted by a pulse of red light (R) or by continuous far-red light (FR), phyA seed germination is responsive only to R. Following growth under day/night cycles, but not under continuous W, the hypocotyls of light-grown phyA and fhy1 seedlings are more elongated than those of wild-type seedlings. For seedlings grown under low red/far-red (R/FR) ratio light conditions, phyA and fhy1 seedlings display a more marked promotion of hypocotyl elongation than wild-type seedlings. Similarly, seedlings that are doubly null for phytochrome A and phytochrome B(phyA phyB) also have more elongated hypocotyls under low R/FR ratio conditions than phyB seedlings. This indicates that phytochrome A action in light-grown seedlings is antagonistic to the action of phytochrome B. Although wild-type, fhy1, and phyA seedlings flower at essentially the same time under both short-day and long-day conditions, an obvious consequence of phytochrome A deficiency is a pronounced late flowering under conditions where a short day of 8 h of fluorescent W is extended by 8 h of low-fluence-rate incandescent light. The evidence thus indicates that phytochrome A plays a role in seed germination, in the control of elongation growth of light-grown seedlings, and in the perception of daylength.
将野生型拟南芥幼苗的光生理学的几个方面与一种光敏色素A缺失突变体phyA - 1以及一种可能参与来自光敏色素A的光信号转导的突变体fhy1进行了比较。尽管phyA幼苗在白光（W）下生长时表现出近乎野生型的表型，但它们仍然表现出一些光形态建成异常。因此，虽然野生型和fhy1种子的萌发几乎完全由红光（R）脉冲或连续远红光（FR）促进，但phyA种子萌发仅对R有反应。在昼夜循环下生长后，但不是在连续白光下，光照生长的phyA和fhy1幼苗的下胚轴比野生型幼苗的下胚轴更长。对于在低红/远红（R/FR）比光照条件下生长的幼苗，phyA和fhy1幼苗的下胚轴伸长比野生型幼苗更明显。同样，光敏色素A和光敏色素B双缺失（phyA phyB）幼苗在低R/FR比条件下也比phyB幼苗有更长的下胚轴。这表明光照生长的幼苗中光敏色素A的作用与光敏色素B的作用是拮抗的。虽然野生型、fhy1和phyA幼苗在短日和长日条件下基本同时开花，但光敏色素A缺乏的一个明显后果是在8小时荧光白光短日被8小时低光通量率白炽灯延长的条件下明显晚开花。因此，证据表明光敏色素A在种子萌发、光照生长幼苗的伸长生长控制以及日长感知中起作用。
