Abstract
In general, phototropic response in plants was induced by blue light, and wasmediated by a blue light receptor phototropin. In the fern Adiantum capillus-veneris, however, red as well as blue light are effective to induce positive phototropic response in protonemal cells. The red light effect on the tropistic response is mediated by phytochrome3 (phy3), which is a chimeric photoreceptor between phytochrome chromofore binding domein and full length phototropin. Recently, we have found negative phototropism in Adiantum rhizoid under red light. When half side of apical part of rhizoid cell was irradiated with red microbeam, the rhizoid bent towards the opposite side of light irradiation. Similar experiment was performed using rap mutants which are defective of PHY3 gene, and the lack of negative phototropism in rhizoid cell, was revealed meaning that positive and negative phototropisms in protonema and rhizoid, respectively, are mediated by the same photoreceptor phytochrome3.
