Characterization of nannochloropsis oceanica rose bengal mutants sheds light on acclimation mechanisms to high light when grown in low temperature

Avraham Ben-Sheleg, Inna Khozin-Goldberg, Beery Yaakov, Avigad Vonshak

Research output: Contribution to journalArticlepeer-review

Abstract

A barrier to realizing Nannochloropsis oceanica's potential for omega-3 eicosapentaenoic acid (EPA) production is the disparity between conditions that are optimal for growth and those that are optimal for EPA biomass content. A case in point is temperature: higher content of polyunsaturated fatty acid, and especially EPA, is observed in low-Temperature (LT) environments, where growth rates are often inhibited. We hypothesized that mutant strains of N. oceanica resistant to the singlet-oxygen photosensitizer Rose Bengal (RB) would withstand the oxidative stress conditions that prevail in the combined stressful environment of high light (HL; 250 μmol photons m-2 s-1) and LT (18°C). This growth environment caused the wild-Type (WT) strain to experience a spike in lipid peroxidation and an inability to proliferate, whereas growth and homeostatic reactive oxygen species levels were observed in the mutant strains. We suggest that the mutant strains' success in this environment can be attributed to their truncated photosystem II antennas and their increased ability to diffuse energy in those antennas as heat (non-photosynthetic quenching). As a result, the mutant strains produced upward of four times more EPA than the WT strain in this HL-LT environment. The major plastidial lipid monogalactosyldiacylglycerol was a likely target for oxidative damage, contributing to the photosynthetic inhibition of the WT strain. A mutation in the NO10G01010.1 gene, causing a subunit of the 2-oxoisovalerate dehydrogenase E1 protein to become non-functional, was determined to be the likely source of tolerance in the RB113 mutant strain.

Original languageEnglish GB
Pages (from-to)1478-1493
Number of pages16
JournalPlant and Cell Physiology
Volume62
Issue number9
DOIs
StatePublished - 28 Jun 2021

Keywords

  • 2-Oxoisovalerate dehydrogenase e1 protein
  • Eicosapentaenoic acid
  • Light-response curve
  • Low temperature
  • Nannochloropsis oceanica
  • Photoinhibition
  • Variable florescence

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology

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