Effect of nitrogen and phosphorus on the development and differentiation of vegetative cells of Porphyra yezoensis on solid agar medium

Abstract

To identify the optimal nitrogen and phosphorus concentrations for development and differentiation of vegetative cells of Porphyra yezoensis cultured on solidified agar medium, vegetative cells were isolated with marine gastropod enzymes from mature thalli and varied concentrations of nitrogen and phosphorus were added to the culture media. Our results showed that: (1) nitrate is a good nitrogen source in solid culture even at a concentration as high as 18.80 mM. In contrast, ammonium is not, because few vegetative cells developed into germlings over 14 days in medium containing this ion; (2) at 0.47 mM and higher nitrogen concentrations, isolated cells produced large numbers of normal leafy thalli within 14 days, while at lower concentrations of 0.23 mM–0.47 mM, regenerated cells showed obvious nitrogen deficiency after 20 days in culture; (3) optimum phosphorus concentrations were between 0.07 mM–0.14 mM and produced >52% normal vegetative cells within 14 days. Most germlings were abnormal and showed no further development when the phosphorus concentration was below 0.03 mM or over 0.30 mM, and (4) the differentiation of germlings was significantly correlated to the ratio of N and P (a ratio of 5:1 produced best results).