UV-B-induced dynamics of constitutive heterochromatin 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 heterochromatin dynamics and structure in Arabidopsis thaliana. Statements and DeclarationsAll authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript.