Overexpression of OHPs in Neopyropia yezoensis (Rhodophyta) reveals their possible physiological roles

Abstract

The red macroalga Neopyropia yezoensis is a model organism, and an economically important seaweed widely cultured in eastern Asian countries. Transgenic research on N. yezoensis is difficult and limited to reporter genes and selection markers due to the specificities of this species. In this study, plasmids were constructed to overexpress six one helix protein (OHP) coding genes in N. yezoensis, and four transgenic lines with high expression levels of the target genes were obtained. The photosynthetic parameters were determined and it was found that the overexpression of OHPs altered electron transport in photosystem I and photosystem II, which was indicated by the increased 1-qL values and decreased P700+ reduction rates. The results also showed that the non-photochemical quenching (NPQ) kinetics in N. yezoensis could not be stimulated by high light (HL) treatment. Two of the four transgenic lines showed stimulated NPQ, and they did not exhibit an obvious increased ability to resist to HL, which was shown by the decreased Fv/Fm values. The increased H2O2 content and decreased peroxidase (POD) activity were considered the possible results of the overexpressed OHPs, and they were responsible for the enhanced NPQ and HL sensitivity in those two transgenic lines.