A red/blue optoswitch for temporal control of chloroplast transcription and biogenesis in Arabidopsis.

Abstract

Photosynthesis genes in plant chloroplasts are transcribed by the plastid-encoded RNA polymerase called PEP. Consequently, PEP-deficient mutants cannot generate a photosynthetic apparatus and develop non-viable albino seedlings. Inducible complementation of such mutants thus could provide interesting insights in PEP action and chloroplast biogenesis. Here we show the effects of photo-inducible complementation in the albino Arabidopsis mutant pap7-1 using a red/blue optoswitch with monochromatic LEDs. Expression of a blue-light-induced PAP7 construct that is silent under red light reconstitutes PEP at any time point of pap7-1 development resulting in proper chloroplast biogenesis that rescues the non-viable mutant. Induction of chloroplast biogenesis, however, can only occur in very young leaf tissues indicating the existence of a cell-autonomous, biogenic coupling between cell and organelle development. We further uncover that initial PEP formation and function is independent of photosynthesis. The optoswitch termed blue-light valved biogenesis opens experimental avenues to study non-viable plant mutants.

AI evidence extraction

Main findings

Using a red/blue optoswitch with monochromatic LEDs, blue-light-induced expression of a PAP7 construct (silent under red light) reconstituted PEP at any developmental time point in the Arabidopsis pap7-1 mutant and enabled proper chloroplast biogenesis that rescued the non-viable albino mutant. Induction of chloroplast biogenesis was only possible in very young leaf tissues, and initial PEP formation/function was reported to be independent of photosynthesis.

Outcomes measured

• PEP (plastid-encoded RNA polymerase) reconstitution
• chloroplast biogenesis
• rescue of non-viable albino phenotype
• timing/tissue window for induction of chloroplast biogenesis
• dependence of initial PEP formation/function on photosynthesis

Limitations

• Sample size not reported in abstract
• Exposure parameters (wavelengths, irradiance/intensity, duration) not reported in abstract
• Study is not about EMF health effects; uses visible light as an experimental control mechanism

{
    "study_type": "other",
    "exposure": {
        "band": null,
        "source": "monochromatic LEDs (red/blue light)",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": "Arabidopsis (pap7-1 mutant)",
    "sample_size": null,
    "outcomes": [
        "PEP (plastid-encoded RNA polymerase) reconstitution",
        "chloroplast biogenesis",
        "rescue of non-viable albino phenotype",
        "timing/tissue window for induction of chloroplast biogenesis",
        "dependence of initial PEP formation/function on photosynthesis"
    ],
    "main_findings": "Using a red/blue optoswitch with monochromatic LEDs, blue-light-induced expression of a PAP7 construct (silent under red light) reconstituted PEP at any developmental time point in the Arabidopsis pap7-1 mutant and enabled proper chloroplast biogenesis that rescued the non-viable albino mutant. Induction of chloroplast biogenesis was only possible in very young leaf tissues, and initial PEP formation/function was reported to be independent of photosynthesis.",
    "effect_direction": "unclear",
    "limitations": [
        "Sample size not reported in abstract",
        "Exposure parameters (wavelengths, irradiance/intensity, duration) not reported in abstract",
        "Study is not about EMF health effects; uses visible light as an experimental control mechanism"
    ],
    "evidence_strength": "insufficient",
    "confidence": 0.66000000000000003108624468950438313186168670654296875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "Arabidopsis",
        "chloroplast",
        "plastid-encoded RNA polymerase",
        "PEP",
        "PAP7",
        "optoswitch",
        "blue light",
        "red light",
        "LED",
        "photo-inducible complementation",
        "chloroplast biogenesis"
    ],
    "suggested_hubs": []
}

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