%A Yuuki Sakai, Shin-ichiro Inoue, Akiko Harada, Ken-ichiro Shimazaki, and Shingo Takagi %T Blue-light-induced rapid chloroplast de-anchoring in Vallisneria epidermal cells %0 Journal Article %D 2015 %J J Integr Plant Biol %R 10.1111/jipb.12284 %P 93-105 %V 57 %N 1 %U {https://www.jipb.net/CN/abstract/article_21359.shtml} %8 2015-01-01 %X

In the outer periclinal cytoplasm of leaf epidermal cells of an aquatic angiosperm Vallisneria, blue light induces “chloroplast de-anchoring”, a rapid decline in the resistance of chloroplasts against centrifugal force. Chloroplast de-anchoring is known induced within 1 min of irradiation with high-fluence-rate blue light specifically, preceding the commencement of chloroplasts migration toward the anticlinal cytoplasm. However, its regulatory mechanism has remained elusive, although pharmacological analysis suggested that a calcium release from intracellular calcium stores is necessary for the response. In search of the responsible photoreceptors, immunoblotting analysis using antibodies against phototropins demonstrated that cross-reactive polypeptides of 120-kDa exist in the plasma-membrane fraction prepared from the leaves. In vitro phosphorylation analysis revealed that 120-kDa polypeptides were phosphorylated by exposure to blue light in a fluence-dependent manner. The blue-light-induced phosphorylation activity was sensitive to a Ser/Thr kinase inhibitor, staurosporine, and unusually was retained at a high level for a long time in darkness. Furthermore, phototropin gene homologs (Vallisneria PHOTOTROPIN1 and PHOTOTROPIN2) expressed in leaves were isolated. We propose that calcium-regulated chloroplast de-anchoring, possibly mediated by phototropins, is an initial process of the blue-light-induced avoidance response of chloroplasts in Vallisneria.

 

Sakai Y, Inoue SI, Harada A, Shimazaki KI, Takagi S (2015) Blue‐light‐induced rapid chloroplast de‐anchoring in Vallisneria epidermal cells. J Integr Plant Biol 57: 93–105. doi: 10.1111/jipb.12284