图片来源：Cell
光是影响植物发育的一个最重因素，但目前人们还不了解光敏染料如何导致基因型因受外界影响而发生变化。光在植物发育过程中的一个首要作用是将红外/远红外光敏色素由细胞质转移至核质体中。目前人们还不了解核质体的功能，所以美国杜克大学的Meng Chen及其同事对这一课题进行了研究。他们发现具有不同色敏核质体的拟南芥突变体hemera的细胞核具备某个特殊的功能。
以前曾有报告称hemera是涉及转录的质体复合体的一部分，科学家此次发现hemera细胞核的信号传导具有特别之处。此外，他们的研究还表明光敏色素会在核体中发生水解。
推荐英文摘要：
Cell doi：10.1016/j.cell.2010.05.007
Arabidopsis HEMERA/pTAC12 Initiates Photomorphogenesis by Phytochromes
Meng Chen, Rafaelo M. Galv?o, Meina Li, Brian Burger, Jane Bugea, Jack Bolado, Joanne Chory
Light plays a profound role in plant development, yet how photoreceptor excitation directs phenotypic plasticity remains elusive. One of the earliest effects of light is the regulated translocation of the red/far-red photoreceptors, phytochromes, from the cytoplasm to subnuclear foci called phytochrome nuclear bodies. The function of these nuclear bodies is unknown. We report the identification of hemera, a seedling lethal mutant of Arabidopsis with altered phytochrome nuclear body patterns. hemera mutants are impaired in all phytochrome responses examined, including proteolysis of phytochrome A and phytochrome-interacting transcription factors. HEMERA was identified previously as pTAC12, a component of a plastid complex associated with transcription. Here, we show that HEMERA has a function in the nucleus, where it acts specifically in phytochrome signaling, is predicted to be structurally similar to the multiubiquitin-binding protein, RAD23, and can partially rescue yeast rad23mutants. Together, these results implicate phytochrome nuclear bodies as sites of proteolysis.
