PARTIAL NUCLEOTIDE SEQUENCE OF PHYTOCHROME FROM THE ZYGNEMATOPHYCEAN GREEN ALGA Mougeotia

Abstract

Following polymerase chain reaction, a fragment of about 800 bp was amplified from genomic Mougeotia DNA using oligonucleotides directed to conserved regions of known phytochrome genes. The nucleotide sequence points to a different exon/intron structure in the neighborhood of the chromophore attachment site of this Mougeotia phytochrome gene, as compared to other phytochromes. Alignment of the derived amino acid sequence to phytochromes of higher and lower plants shows highest homology (> 60%) to type II (green type) phytochrome, while Northern blot analysis of total Mougeotia RNA indicates down-regulation of the phytochrome transcription in light. Signal pattern of hybridized genomic DNA after digestion reveals the presence of probably only one phytochrome gene in Mougeotia.