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Light-harvesting complex gene regulation by a MYB-family transcription factor in the marine diatom, Phaeodactylum tricornutum


Unicellular photoautotrophs adapt to variations in light intensity by changing the abundance of light harvest pigment-protein complexes (LHCs) on time scales of hours to days. This process requires a feedback signal between the plastid (where light intensity is sensed) to the nucleus (where the genes for LHCs are encoded). The signals must include heretofore unidentified transcription factors that modify the expression level of the LHCs. Analysis of the nuclear genome of the model diatom Phaeodactylum tricornutum revealed that all the lhc genes have potential binding sites for transcription factors belonging to the MYB-family proteins. Functional studies involving antisense RNA interference of a hypothetical protein with a MYB DNA-binding domain were performed. The resultant strains with altered photosynthetic and physiological characteristics lost their ability to acclimate to changes in irradiance; i.e., cellular chlorophyll content became independent of growth irradiance. Our results strongly suggest that the inter-organellar signaling cascade was disrupted, and the cell could no longer communicate the environmental signal from the plastid to the nucleus. Here, we identify, for the first time, an LHC Regulating Myb (LRM) transcription factor, which we propose is involved in lhc gene regulation and photoacclimation mechanisms in response to changes in light intensity.

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We thank Ehud Zelzion and Nicole Wagner (Rutgers, The State University of New Jersey) for the transcriptome sequencing and its analysis and to Shaun Bailey and Orly Levitan for discussions. This work, in its entirety, was included in the thesis of Agarwal A. (2021), titled “Inter-organellar signaling in a diatom” (Rutgers University 2021).


This research was supported by the Rutgers University Professional Development Fund, the James G. Gibson (Biodiesel) Fund to PGF, and the Bennett L. Smith Endowment in Business and Natural Resources at Rutgers University to PGF.

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AA and RD designed research. AA and RD performed research. AA, RD and PGF analyzed data. AA wrote first draft of manuscript. All authors contributed to manuscript revision, read, and approved the submitted version.

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Correspondence to Paul G. Falkowski.

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The authors declare no conflict of interest.

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Agarwal, A., Di, R. & Falkowski, P.G. Light-harvesting complex gene regulation by a MYB-family transcription factor in the marine diatom, Phaeodactylum tricornutum. Photosynth Res 153, 59–70 (2022).

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  • Diatom
  • Phaeodactylum
  • Light intensity
  • Photoacclimation
  • MYB
  • Transcription factor
  • Light harvesting complex LHC
  • Signaling