Putative Arabidopsis THO/TREX mRNA export complex is involved in transgene and endogenous siRNA biosynthesis.
RNA silencing in plants and some animals has a non-cell-autonomous effect due to an RNA signal that moves between cells or organs. To identify unique factors involved in this process, we analyzed a group of Arabidopsis mutants with defective spread of RNA silencing from a transgene expressed specifically in the phloem. These mutants accumulated reduced amounts of small interfering (si)RNA from the transgene locus and from endogenous loci TAS1, TAS2, and an inverted repeat locus IR71. The defect in TAS1 and TAS2 siRNA biogenesis is in the processing of a long siRNA precursor. We mapped the mutations to a gene encoding the Arabidopsis homolog of a protein, TEX1, which is involved in intracellular transport of RNA in animals. TEX1 is a component of the THO/TREX complex, and we show that the Arabidopsis TEX1 interacts with other predicted components of a THO/TREX complex. Correspondingly, we found at least two other components of the Arabidopsis THO core complex that are involved in RNA silencing. To reconcile the effect of these mutations on transgene and endogenous gene siRNA, we propose a mechanism in which THO/TREX processes or transports a long RNA molecule so that it can be a template for secondary siRNA production.
Yelina
Nataliya E
NE
The Sainsbury Laboratory, John Innes Centre, Norwich NR4 7UH, United Kingdom.
Smith
Lisa M
LM
Jones
Alexandra M E
AM
Patel
Kanu
K
Kelly
Krystyna A
KA
Baulcombe
David C
DC
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D011485:Protein Binding; D034443:RNA Transport; D034741:RNA, Small Interfering / Q000096:biosynthesis*; D019076:Transgenes
D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; D034741:RNA, Small Interfering; C000614449:TEX1 protein, Arabidopsis