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

两个生理上不同的类光敏色素似乎调节许多不同的红光刺激的反应，在蕨类植物单倍相。光敏色素的种类包括二色性光敏色素和非二色性光敏色素。前者所调节的反应在偏振光下呈现作用二色性，而后者所调节的反应则不呈现。二色性光敏色素的参与在向光性和叶绿体迁移反应中特别明显。在本工作中，红光背光（RAP）突变体的蕨类植物铁线蕨capillus-veneris的分离和生理和分子生物学特征。从EMS诱变的芽孢中获得了5个rap 2、rap 7、rap 32、rap 33、rap 39突变体。rap突变体缺乏红光向极性，但仍保持正常的蓝光向光性和向极性。胆绿素，光敏色素发色团的前体处理没有影响的红光背光性质的rap突变体。对另一个phot的分析 关于我们 结果表明，突变体中光敏色素介导的叶绿体移位运动缺失，而蓝光诱导的反应正常。光敏色素对油菜孢子萌发、根尖生长和细胞分裂的调控也正常。这些结果表明，向光性和叶绿体移位运动具有相同的二色性光敏色素和随后的信号转导步骤。此外，它表明，这条途径是不同的控制孢子萌发，顶端生长和细胞分裂。RAP突变体可能在感光分子本身、与稳定结构的结合机制或在二色性光敏色素介导的信号转导途径的早期参与的元件中具有缺陷。然后，从重离子束诱变的孢子中分离得到了另一株rap突变体（hrap 11和hrap 13）。利用光敏色素cDNA的基因组Southern印迹分析显示，光敏色素基因之一PHY 3在hrap 13突变体中缺失。现在我们正在测试是否通过用PHY 3转化hrap 13突变体来拯救表型。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