{
  "abstract": "Photosynthetic organisms protect themselves from excess light through non-photochemical quenching (NPQ), a process that safely dissipates excess light energy as heat. Current understanding of NPQ is largely drawn from a few model systems, leaving it unclear how universal NPQ mechanisms are across the green lineage. We characterize the slow, sustained NPQ of the green alga, Auxenochlorella protothecoides x symbiontica (UTEX 250-A). The Auxenochlorella genome lacks Light-Harvesting Complex Stress Related (LHCSR), one of the two proteins required for the fast energy-dependent quenching (qE) component of NPQ. Mutants lacking the Photosystem II Subunit S (PSBS)-like gene (psbsl1) in Auxenochlorella had no effect on NPQ, indicating this alga lacks canonical qE. We identified two candidate enzymes associated with zeaxanthin-dependent quenching (qZ), which has slower kinetics: a plant-type Violaxanthin De-Epoxidase (VDE) and an algal-type Chlorophycean Violaxanthin De-Epoxidase (CVDE). High light did not trigger the expected conversion of violaxanthin to zeaxanthin, a pigment change that is a hallmark of qZ. Mutants lacking VDE (vde1), CVDE (cvde1), or both enzymes (vde1 cvde1) still displayed slow, reversible NPQ. However, when the Auxenochlorella VDE1 and CVDE1 were expressed in a VDE-deficient mutant of Nicotiana benthamiana, both enzymes restored zeaxanthin production and NPQ, confirming they are catalytically functional de-epoxidases. Together, these results reveal an alga that retains two functional, evolutionarily distinct xanthophyll-cycle enzymes yet does not rely on typical xanthophyll pigment dynamics for photoprotection. This points to a biological function that is decoupled from de-epoxidase activity, highlighting unexplored diversity in green algal photoprotection.",
  "abstract_shown": true,
  "affiliations": [
    "HHMI, University of California"
  ],
  "article_type": "New results",
  "arxiv": null,
  "author_total": 11,
  "authors": [
    {
      "name": "K. W. Cunningham"
    },
    {
      "name": "S. Wakao"
    },
    {
      "name": "J. L. Hall"
    },
    {
      "name": "C. Blaby-Haas"
    },
    {
      "name": "R. Ivatury"
    },
    {
      "name": "L. Gleeson"
    },
    {
      "name": "D. Chuang"
    },
    {
      "name": "J. J. Kim"
    },
    {
      "name": "J. L. Moseley"
    },
    {
      "name": "G. R. Fleming"
    },
    {
      "affs": [
        0
      ],
      "name": "K. K. Niyogi"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/2xkg3w1176mj1.bib",
  "cited_by": 0,
  "doi": "10.64898/2026.09.26.754548",
  "fulltext_url": "https://www.biorxiv.org/content/10.64898/2026.09.26.754548v1.full",
  "id": "2xkg3w1176mj1",
  "issns": [],
  "landing_url": "https://www.biorxiv.org/content/10.64898/2026.09.26.754548v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "biorxiv",
      "plant biology"
    ],
    [
      "openalex",
      "1312|Photosynthetic Processes and Mechanisms"
    ]
  ],
  "openalex": "W7216472860",
  "pdf_url": "https://www.biorxiv.org/content/10.64898/2026.09.26.754548v1.full.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-26",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/2xkg3w1176mj1.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:25:49Z",
      "native_id": "10.64898/2026.09.26.754548",
      "source": "biorxiv",
      "url": "https://www.biorxiv.org/content/10.64898/2026.09.26.754548v1"
    }
  ],
  "subjects": [
    {
      "field": "biology",
      "origin": "biorxiv:plant biology",
      "subfield": "plant-biology"
    }
  ],
  "title": "A Natural qE- and qZ-Deficient Alga Retains Functional Plant-Like and Chlorophycean Violaxanthin De-Epoxidases",
  "title_text": "A Natural qE- and qZ-Deficient Alga Retains Functional Plant-Like and Chlorophycean Violaxanthin De-Epoxidases",
  "type": "preprint",
  "updated_at": "2026-10-30T12:25:49Z",
  "url": "https://research.draconitic.com/paper/2xkg3w1176mj1",
  "venue": "bioRxiv",
  "versions": []
}