Regulation of flowering time in Arabidopsis



FIBR homepage


Flowering pathway

Gibberellin pathway



The Gibberellin transduction pathway


miR159 (micro-RNA 159)


Micro-RNAs are small (21-22 nucleotides long) RNA molecules that can cause complementary-dependent cleavage or translational inhibition of target messenger RNAs. Most of the predicted targets of miRNAs identified so far are transcription factors involved in differentiation or developmental patterning (Rhoades et al., 2002).

miR159 is a micro-RNA of 21 nucleotides (Reinhardt and Harberd, 2002), present as a single copy in the Arabidopsis genome. It is complementary to five other sequences in Arabidopsis: three encode GAMYB-like proteins (AtMYB33, AtMYB101 and AtMYB65), and two encode other MYB proteins (AtMYB104 and AtMYB81) (Achard et al., 2004).

In the WT, miR159 accumulates predominantly in young leaves and flowers, less in adult rosette leaves, cauline leaves and siliques. It was not detected in the roots (Achard et al., 2004).

miR159 is a negative regulator of flowering time:

Over-expression of miR159 results in delayed flowering, both in short days and in long days, but the effect is more marked in short days. miR159 over-expression in the WT background results in lower levels of LFY transcripts (Achard et al., 2004).

Interaction between miR159 and AtMYB33

Interaction between miR159, GAs and the DELLA genes