Physiological and molecular biological analyses of dichroic phytochrome unique to lower green plants

两类生理上不同的光敏色素似乎调节着蕨类植物单相中许多不同的红光刺激反应。这些分类包括二色性光敏色素和非二色性光敏色素。前者调控的反应在偏振光下表现为行为二向色性，而后者调控的反应则不表现为行为二色性。二向色性光敏色素在向光性和叶绿体定位反应中的作用尤为明显。在本工作中，我们分离了蕨类植物铁线蕨红光致光(RAP)突变体，并对其进行了生理和分子生物学研究。从EMS诱变的孢子中获得了5个RAP突变体：Rap2、Rap7、Rap32、Rap33、Rap39。RAP突变体缺乏红光偏光性，但仍保持正常的蓝光偏光性和偏光性。用光敏色素发色团的前体胆绿素处理对RAP突变体的红光趋光性没有影响。对其他PHOT…的分析更多的反应表明，光敏色素介导的叶绿体定位运动在突变体中缺失，而蓝光诱导的反应是正常的。在RAP菌株中，光敏色素对孢子萌发、顶端生长和细胞分裂的调节也是正常的。这些结果表明，向光性和叶绿体定位运动具有相同的二色性光敏色素和以下信号转导步骤。此外，这一途径不同于控制孢子萌发、顶端生长和细胞分裂的途径。RAP突变体可能在光感受器分子本身、与稳定结构的结合机制或参与二色性光敏色素介导的信号转导途径的早期元件上存在缺陷(S)。接下来，从重离子束诱变的孢子中分离到另一株RAP突变体(hRap11和hrapl3)。利用光敏色素cDNA进行基因组Southern杂交分析表明，hrapl3突变体中的光敏色素基因PHY3缺失。现在我们正在测试是否通过用PHY3转化hRap13突变体来挽救表型。较少

Two physiologically distinct classes of phytochrome seem to regulate the many diverse red light-stimulated responses in the fern haplophase. The classes include dichroic phytochrome and non-dichroic phytochrome. The responses regulated by the former show action dichroism under polarized light while those regulated by the latter do not. The involvement of dichroic phytochrome is particularly evident in phototropism and the chloroplast relocation response. In the present work, red-light aphototropic (rap) mutants of the fern Adiantum capillus-veneris were isolated and characterized physiologically and molecular biologically. Five rap mutants, rap2, rap7, rap32, rap33, rap39 were obtained from EMS-mutagenized spores. The rap mutants lacked red light polarotropism but still retained normal blue light phototropism and polarotropism. Treatment with biliverdin, a precursor of phytochrome chrormophore had no effect on the red-light aphototropic nature of rap mutants. Analyses on the other phot … More oresponses revealed that phytochrome-mediated chloroplast relocation movement was missing in the mutants whereas the response induced by blue light was normal. Phytochrome regulation of spore germination, tip growth and cell division were also normal in the rap strains. These results indicate that phototropism and chloroplast relocation movement share the same dichroic phytochrome and the following signal transduction steps. Moreover, it shows that this pathway is distinct from that controlling spore germination, tip growth and cell division. The rap mutants may have defect(s) in the photoreceptor molecule itself, in the binding mechanism to a stable structure, or in elements involved early in the dichroic phytochrome-mediated signal transduction pathway. Next, another rap mutants (hrap11 and hrapl3) were isolated from the spores mutagenized by heavy ion beam. Genomic Southern blot analysis using phytochrome cDNAs revealed that one of the phytochrome genes, PHY3 was missing in hrapl3 mutant. Now we are testing whether the phenotypes are rescued by transforming hrap13 mutant with PHY3. Less