WHIRLY1-deficient chloroplasts display enhanced formation of cyclobutane pyrimidine dimers during exposure to UV-B radiation.

The single-stranded DNA/RNA binding protein WHIRLY1 is a major chloroplast nucleoid-associated protein required for the compactness of nucleoids. Most nucleoids in chloroplasts of WHIRLY1-knockdown barley plants are less compact compared to nucleoids in wild-type plants. The reduced compaction leads to an enhanced optical cross-section, which may cause the plastid DNA to be a better target for damaging UV-B radiation. To investigate this hypothesis, primary foliage leaves, chloroplasts, and nuclei from wild-type and WHIRLY1-knockdown plants were exposed to experimental UV-B radiation. Thereafter, total, genomic and plastid DNA were isolated, respectively, and analyzed for the occurrence of cyclobutane pyrimidine dimers (CPDs), which is a parameter for genome stability. The results of this study revealed that WHIRLY1-deficient chloroplasts had strongly enhanced DNA damages, whereas isolated nuclei from the same plant line were not more sensitive than nuclei from the wild-type, indicating that WHIRLY1 has different functions in chloroplasts and nucleus. This supports the hypothesis that the compaction of nucleoids may provide protection against UV-B radiation. © 2023 The Authors. Physiologia Plantarum published by John Wiley & Sons Ltd on behalf of Scandinavian Plant Physiology Society.

Citation

Monireh Saeid Nia, Christine Desel, Frauke Pescheck, Karin Krupinska, Wolfgang Bilger. WHIRLY1-deficient chloroplasts display enhanced formation of cyclobutane pyrimidine dimers during exposure to UV-B radiation. Physiologia plantarum. 2023 Sep-Oct;175(5):e14049

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PMID: 37882276

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