Identification and Analysis of HSP70 Gene Family in Marine Red Algae, Pyropia seriata

Heat shock proteins (HSP) are key components contributing to survival in the abiotic stress response. We isolated six cDNAs encoding HSP70 from Pyropia seriata, marine red algae and named as PsHSP70A ~ F. Expression pattern analysis of the PsHSPs showed that PsHSP70B and PsHSP70D are strongly response to high temperature, Transcript of the PsHSP70C was not detected in tested tissues. Analysis of amino acid sequence of the PsHSP70s show that PsHSP70B and PsHSP70D may be locating in the chloroplast and cytosol, respectively. We are tried to confirm the biological function of the HSP70B and HSP70D by heterologous expression in Chlamydomonas reinharditt. When the PsHSP70B was introduced and overexpressed in Chlamydomonas, transformed cells show much higher rates of survival and growth than those of the wild-type under high temperature conditions. Constitutive overexpression of the PsHSP70B gene increases the transcription of the CrHSF1 as well as the CrHSP20 and CrHSP70 gene. These results indicate that PsHSP70B is involved in tolerance to high temperature stress and the effects on transcription of the CrHSP20 and CrHSP70 genes.