Use of the cotton leaf curl Multan alphasatellite as a silencing or expression vector.

Alphasatellites, formerly known as DNA 1, are a satellite-like components associated with begomoviruses (the family Geminiviridae) that require betasatellite for symptom induction but depend on DNA-A for systemic movement. We have converted alphasatellite into gene-silencing vector (modified alphasatellite (∆DNA 1)) by deleting its A-rich region that does not affect the replication nor the movement of the helper virus. Insertion of a transgene green florescence protein (GFP) into ∆DNA 1 resulted in the silencing g of the cognate gene in Nicotiana benthamiana. The silencing persisted for more than one and half month and was associated with the decreased level of mRNA of the target gene. This satellite-like DNA vector induced gene silencing (VIGS) promises to be applicable to other begomovirus/alphasatellite systems, thereby providing the powerful approach to gene discovery and the analysis of gene functions in malvaceous crops. Keywords: cotton; begomovirus; alphasatellite; RNAi.