1. Trans-acting siRNA
Brett Johnson
BMS265

2. Trans-acting siRNA is just like “normal” siRNA

3. Trans-acting siRNA is just like “normal” siRNA
…except for when its not.

4. Discovery

5. ta-siRNAs come from TAS genes
Biogenesis
ta-siRNAs come from TAS genes

7. Trans-acting siRNAs act in trans!
Mechanism of Action
Trans-acting siRNAs act in trans!

8. 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)

9. 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)

10. Potential as a Tool
Replaced the ta-siRNAs in TAS1c and silenced FAD2 activity to levels comparable to a null mutant

11. There’s More!

12. There’s More!
Read the wiki.