UV-B regulation of plant growth by E2F transcription factors in Arabidopsis thaliana

SHERIDAN, MARÍA L.; FALCONE FERREYRA, MARÍA L.; GÓMEZ, MARÍA S.; CASATI P

Congreso; Plant Biology 2019; 2019

Plant growth is regulated by environmental conditions, including UV-B radiation. UV-B inhibits leaf and root growth, and inhibition of plant growth is, in part, regulated by the E2Fe transcription factor. E2Fe is a target of regulation by two transcription factors from the same family, E2Fb and E2Fc. While E2Fc acts as a repressor, E2Fb is a transcriptional activator of E2Fe. Therefore, we investigated if the modulation of UV-B responses by E2Fe is through its regulation by E2Fb and/or E2Fc. At UV-B intensities that produce DNA damage, inhibition of cell proliferation is regulated by both E2Fc and E2Fb. E2Fc controls plant growth under UV-B conditions regulating DNA damage responses, as E2Fc deficient plants show decreased programmed cell death in the roots after exposure and altered SOG1 and ATR expression. In addition, E2Fc has an epistatic role over the miR396 pathway under UVB, which also regulates leaf growth under these conditions. In contrast, while E2Fb also controls cell proliferation under UV-B conditions; it does not regulate programmed cell death in the roots after exposure. Interestingly, E2Fb deficient leaf cells have increased DNA ploidy levels after UV-B exposure, similarly as E2Fe deficient cells. Together, our results demonstrate that E2Fc is required for miR396 activity on cell proliferation under UV-B, and that its role is independent of E2Fe, probably modulating DNA damage responses through the regulation of SOG1 and ATR levels. On the contrary, the regulation of DNA ploidy in leaf cells under UV-B previously described in E2Fe deficient plants could be regulated by E2Fb activity.