APHOTOTROPIC MUTANTS OF THE MOSS CERATODON PURPUREUS WITH SPECTRALLY NORMAL AND WITH SPECTRALLY DYSFUNCTIONAL PHYTOCHROME

Following UV mutagenesis of protonemal tissue of the moss Ceratodon pu rpureus we have isolated different aphototropic mutant lines that can be divided into two distinct classes, One class, represented by the li ne ptr1, shows characteristic features of phytochrome chromophore defi ciency, ptr1 shows negligible photoreversibility (<5% of wild type), w hereas immunoblots show normal apoprotein levels, The aphototropic phe notype could be partially restored with biliverdin, a precursor of the phytochrome chromophore, It was found that, whereas in wild type form ation of Pfr leads to suppression of gravitropism, there is no such su ppression in ptr1, In addition, ptr1 shows lower chlorophyll levels th an the wild type, These findings indicate that, as expected for a chro mophore-deficient mutant, multiple phytochrome effects are lost, The o ther class of mutants, represented by the line ptr103, shows more spec ific effects, In this mutant, only phototropism is affected, Suppressi on of gravitropism, the content of chlorophyll and photoreversibility of phytochrome were similar to those of the wild type.