Isolation, Morphological Characteristics and Proteomic Profile Analysis of Thermo-tolerant Pyropia yezoensis Mutant in Response to High-temperature Stress

Elevated temperature is considered an important abiotic stressor affecting the growth and survival of intertidal organisms, such as red algae. In this study, a mutation for enhanced growth and temperature tolerance in Pyropia yezoensis was isolated using gamma irradiation, and temperature tolerance-related proteins were identified by proteomic analysis. The mutant strain (Py500G) selected at a dose of 500 Gy exhibited approximately four times the foliage at 12 degrees C compared to the wild type (WT), and had rapid growth rates even at high temperatures of 20 degrees C and 25 degrees C. There was performed a proteomic analysis to identify overexpressing novel proteins at hightemperature in Py500G, a temperature-tolerant mutant compared to the WT. From all temperature conditions (12, 20, and 25 degrees C), we detected 218 proteins through image analysis and identified 25 differentially expressed proteins. These proteins were classified into five categories: protein metabolism, photosynthesis and energy metabolism, protein transcription and translation, redox homeostasis, and cytoskeleton. Py500G overexpressed photosynthesis, energy metabolism, and redox homeostasis proteins at high temperatures, suggesting that this increase in proteins in Py500G was closely related to high growth and the temperature-stress defense system. These results suggest that the isolated mutant Py500G could possibly grow even at high temperatures and would be useful in the Pyropia industry.