UV-B radiation effect on the primary roots of Arabidopsis thaliana

MARIA LUJAN SHERIDAN; PAULA CASATI

Congreso; THE 31st INTERNATIONAL CONFERENCE ON ARABIDOPSIS RESEARCH; 2021

Because of their sessile lifestyle, plants are continuously exposed to solar UV-B radiation. Inhibition of leaf growth is one of the most consistent responses of plants upon exposure to UV-B radiation. In this work, we investigated responses of primary roots upon exposure to UV-B radiation. Primary root elongation is inhibited when seedlings are exposed to UV-B radiation. We have demonstrated that this is reflected in a decrease in the length and in the number of cells of the meristematic zone of the primary roots. On the other hand, there are at least 3 different response pathways that are activated by UV-B radiation in Arabidopsis, one is dependent on the UVR8 photoreceptor, and the other pathways are mostly activated after DNA damage occurs. One of these pathways require the activation of the MAP kinases 3 and 6 (MPK3 and MPK6), while a different pathway is dependent on different kinases, ATM and ATR. We have analyzed the effect of UV-B radiation on primary roots of mpk3 and uvr8 mutant lines and we found that none of these proteins regulates the UV-B responses in roots. On the contrary, we analyzed root responses to UV-B using mutant lines in ATR and ATM. Our results provide evidence that the inhibition of primary root elongation after UV-B exposure mostly requires ATR but not ATM. Together, our data demonstrate that the inhibition of primary root elongation in Arabidopsis plants exposed to UV-B is mostly activated after DNA damage occur through the ATR pathway..