AtDRTS2 and AtDRTS3 are downregulated by E2F transcription factors.
(A) AtDRTS2 and AtDRTS3 are downregulated in transgenic lines overexpressing the AtE2Fa factor whereas AtDRTS1 expression increases. The qRT-PCR analyses were repeated three times using independent biological replicates and quantification was normalized to 18S RNA levels. The level of expression of the AtDRTSs in two E2FaOE lines compared to untransformed control is reported. The bars show standard errors. ** p<0.01, ***p<0.001. (B) to (G) The E2F-like sites in the AtDRTS2 and AtDRTS3 promoters exert repressive roles. Mutation of the E2F sites located upstream of AtDRTS2 (A) and AtDRTS3 (D) increases the strength of both promoters (B and E) without altering their spatial pattern of activity (C and F). Fluorimetric analysis of GUS activity in Arabidopsis plants harbouring the DRTS2 and DRTS2ΔE2F promoter constructs (B) or the DRTS3 and DRTS3ΔE2F promoter constructs (E) was carried out in triplicate on extracts from pooled two-week-old seedlings of all the single insertion transgenic lines. The bars show standard errors. ***p<0.001.