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. 2023 Sep-Oct;175(5):e14049.
doi: 10.1111/ppl.14049.

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

Monireh Saeid Nia  1 , Christine Desel  1 , Frauke Pescheck  1 , Karin Krupinska  1 , Wolfgang Bilger  1
Affiliations

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

Monireh Saeid Nia et al. Physiol Plant. 2023 Sep-Oct.

Abstract

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.

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References

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