E2Fb and E2Fa transcription factors independently regulate UV-B
responses in Arabidopsis
AbstractUV-B radiation affects plant growth inhibiting cell proliferation. This
inhibition is in part controlled by the activity of transcription
factors of the E2F family. In particular, the participation of E2Fc and
E2Fe in responses to UV-B in Arabidopsis plants was previously reported.
However, the contribution of E2Fa and E2Fb in these processes has not
been yet investigated. Thus, in this work, we provide evidence that, in
Arabidopsis, both E2Fa and E2Fb control leaf size under UV-B conditions
without participating in DNA damage repair. On the contrary, in
seedlings exposed to UV-B, E2Fa but not E2Fb regulates primary root
elongation, cell proliferation and programmed cell death in the
meristematic zone. Using e2fa mutants that overexpress E2Fb, we here
demonstrate that the role of E2Fa in the roots cannot be replaced by
E2Fb. Finally, the results presented show that E2Fa and E2Fb
differentially regulate the expression of genes that activate the DNA
damage response, both under conditions without UV-B and after exposure.
Together, we here show that both E2Fa and E2Fb have different and
non-redundant roles in developmental and DNA damage responses in
Arabidopsis plants exposed to UV-B radiation.