Transcriptome of the Gametophyte Thalli of Red Marine Algae, Pyropia tenera, Under Drought Stress Condition

Pyropia tenerea is an economically important and cultivated marin red algae in East asia including Korea. Pyropia grows on rocky intertidal zone, which under goes dynamic environmental changes including desiccation. In an effort of identifying drought stress response gene, gametophyte thalli of P. tenera were exposed to drought stress and then harvested at 0.5 hr, 1 hr, 2 hr, 4 hr and 8 hr time interval, respectively. Using 454 FLX+ sequencing platform, 817,451 high-quality RNA sequences were generated from the control and drought stress treated gametophyte. These sequences were assembled into 13,556 contigs consisting of 745,660 reads, whereas 71,791 reads remained as un-assembled ESTs. Only 46.3% of contigs shared significant similarity with the E-value of ≤ 1E-10 with NCBI Non Redundant database. Tri-nucleotide repeat was absolutely predominant (90.9%) and GGC was the most abundant motif. RPKM value based differentially expressed genes (DEG) analysis identified 192 drought stress response contigs which are consist of at least 50 reads and change more than 2 fold RPKM ratio. These drought transcriptome sequences will provide valuable information to understand the genomic structure and develop the functional genomics system for red algae including Pyropia species.