Biochemical characterization of Pyropia yezoensis-AP1 strain accompanies the resistance reaction to the red rot disease pathogen, Pythium porphyrae

The biochemical profile of the Pyropia yezoensis-AP1 strain, a strain which shows resistance to red rot disease, was compared with that of a normal P. yezoensis cultivar. Levels of chlorophyll a, phycoerythrin, and phycocyanin were higher in P. yezoensis-AP1 than those in the normal P. yezoensis cultivar. Two-dimensional electrophoresis found a total of 132 and 128 distinct spots for total protein samples of P. yezoensis-AP1 and P. yezoensis, respectively. About 89.6 % of the total components were common to both P. yezoensis-AP1 and P. yezoensis, and 10.4 % were more abundant in the P. yezoensis-AP1 than P. yezoensis. The amount of total free amino acid in P. yezoensis-AP1 was less than that in the P. yezoensis cultivar, but taurine, glutamic acid, citrulline, and arginine content were higher in the P. yezoensis-AP1 strain. The porphyran content of P. yezoensis-AP1 (11.9 ± 0.5 % dry weight) was higher than that of P. yezoensis cultivar (9.5 ± 0.4 % dry weight). In the porphyran fraction, the content of 3,6-anhydro-L-galactose was higher in P. yezoensis-AP1 than P. yezoensis, and sulfate content was higher in the P. yezoensis cultivar than P. yezoensis-AP1. The results indicate that the difference of chemical composition between P. yezoensis-AP1 and P. yezoensis cultivar helps to explain the increased resistance to red rot disease in the AP1 strain. This finding provides a good starting point for the development of more resistant strains of P. yezoensis that will reduce the incidence of red rot disease on Pyropia farms.