CONTROL OF EXPRESSION OF A GENE ENCODING AN EXTENSIN BY PHYTOCHROME AND A BLUE-LIGHT RECEPTOR IN SPORES OF ADIANTUM-CAPILLUS-VENERIS L

In the present study, using a newly developed fluorescent differential display technique, we have carried out large-scale screening for gene s whose expression was regulated by phytochrome and antagonistically b y a blue light receptor in the spores of the fern Adiantum capillus-ve neris L. Spores after imbibition were briefly irradiated with red, red /blue or blue light and collected 8 h after the irradiation. Total RNA was isolated from each sample and used to make cDNA with an oligo-dT primer. The cDNA was then used as a template for PCR with the oligo-dT primer and 80 arbitrary primers. The resulting PCR products were anal yzed by an automated fluorescent DNA sequencer. Among 8000 displayed b ands, we identified 15 upregulated and four down-regulated bands by re d light, and this red light effect was irreversibly reversed by blue l ight. We cloned one of the up-regulated cDNA fragments and used it to screen a cDNA library prepared from the spores. The isolated insert is predicted to encode Ser-(Pro)(n) repeats and showed homology with cel l wall-associated extensins. The expression of this cDNA was induced 8 h after a red light treatment and the red light induction was photore versibly prevented by far-red light and photoirreversibly by blue ligh t. The mRNA of this gene was detectable 4 h after red light irradiatio n and gradually increased in germinating spores.