UV-B-induced modulation of constitutive heterochromatin content in Arabidopsis thaliana

Sunlight regulates transcriptional programs and triggers the shaping of the genome throughout plant development. Among the different sunlight wavelengths that reach the surface of the Earth, UV-B (280-315 nm) controls the expression of hundreds of genes for the photomorphogenic responses and also induces the formation of photodamage that interfere with genome integrity and transcriptional programs. The combination of cytogenetics and deep-learning-based analyses allowed determining the location of UV-B-induced photoproducts and quantifying the effects of UV-B irradiation on constitutive heterochromatin content in different Arabidopsis natural variants acclimated to various UV-B regimes. We identified that UV- B-induced photolesions are enriched within chromocenters. Furthermore, we uncovered that UV-B irradiation promotes constitutive heterochromatin dynamics that differs among the Arabidopsis ecotypes having divergent heterochromatin contents. Finally, we identified that the proper restoration of the chromocenter shape, upon DNA repair, relies on the UV-B photoreceptor, UV RESISTANCE LOCUS 8 (UVR8). These findings shed the light on the effect of UV-B exposure and perception in the modulation of constitutive heterochromatin content in Arabidopsis thaliana.

Automated summary

Sunlight, specifically UV-B wavelength, plays a crucial role in regulating gene expression and genome integrity in plant development. Through cytogenetic and deep-learning-based analyses, researchers have identified the location of UV-B-induced photoproducts and quantified the impact of UV-B irradiation on constitutive heterochromatin content in different Arabidopsis natural variants. They also discovered that UV-B exposure promotes constitutive heterochromatin dynamics, which varies among Arabidopsis ecotypes with divergent heterochromatin contents. Additionally, the study found that the restoration of chromocenter shape relies on the UV-B photoreceptor, UVR8. These findings provide valuable insights into the modulation of constitutive heterochromatin content in Arabidopsis thaliana in response to UV-B exposure and perception.