Trans-acting siRNA

Brett JohnsonBMS265

Trans-acting siRNA is just like “normal” siRNA

Trans-acting siRNA is just like “normal” siRNA

…except for when its not.

Discovery

Biogenesis

ta-siRNAs come from TAS genes

Mechanism of Action

Trans-acting siRNAs act in trans!

Cellular Functions

• All ta-siRNAs from a TAS gene tend to have similar targets.

• Four TAS families in Arabidopsis:– TAS1 regulates at least 5 different targets of

unknown function– TAS2 targets 2 Pentatricopeptide Repeat (PPR)

proteins of disputed function– TAS3 targets three Auxin Response Factor (ARF)

genes (tasiR-ARF)– TAS4 targets MYB transcripts (cell cycle,

metabolism)

Evolution and Conservation

• TAS1 and TAS2 ta-siRNAs are unique to Arabidopsis

• TAS3 is conserved in rice, Arabidopsis and maize (monocot vs. dicot lineages)

• miR390 directed biogenesis of ta-siRNAs is conserved in moss (400 million years)

Potential as a Tool

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Replaced the ta-siRNAs in TAS1c and silenced FAD2 activity to levels comparable to a null mutant

There’s More!

There’s More!

Read the wiki.