Patil, Basavaprabhu , Bagewadi, Basavaraj , Yadav, Jitender , Taylor, Nigel , Fauquet, Claude .
Optimization of Gene Silencing Constructs to control Cassava Mosaic Disease.
Cassava mosaic disease is one of the major diseases of cassava (Manihot esculenta) caused by cassava mosaic geminiviruses (Geminiviridae). Cassava mosaic virus has two small (DNA-A & DNA-B), circular and ssDNA genomes. DNA-A encodes 6 genes (AC1 to 4 & AV1 to 2) required for replication & encapsidation, whereas DNA-B encodes 2 genes (BC1 & BV1) for inter- and intracellular movement. AC1 is the main protein required for virus replication and the genes AC2/AC4 is known to play a role in suppression of gene silencing. RNA interference is a powerful tool to render plant resistant against viruses via post-transcriptional gene silencing (PTGS) through expression of hairpin dsRNA, homologous to virus sequences.
To identify the best region/s of viral genome for dsRNA trigger, the entire genome of ACMV-[CM] -A & B was scanned, by making 12 dsRNA constructs (with size 343-781nt) for each ORF. A modified binary vector with GFP-dsRNA as an internal control was developed for transient studies in GFP-N. benthamiana (C16). Transient virus protection assay by agroinfiltration was used to identify the best constructs for stable transformation in cassava. The dsRNA constructs were agro-infiltrated 2 to 9 days before virus inoculation, and the maximum protection was obtained for 3 days. Of these the full length AC1 & its central region gave highest resistance, followed by AC4 & AC2 and N-terminal of BC1. These have been transformed into cassava & N. benthamiana, for resistance in stable transformations. The profiling of siRNA & dsRNA levels is being done to find a correlation between the resistance and type/amount of siRNA/dsRNA. Similar investigation is being done in EACMV.
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ILTAB, Donald Danforth Plant Science Center, St. Louis, MO 63132 USA
1 - Donald Danforth Plant Science Center, International Laboratory for Tropical Agricultural Biotechnology (ILTAB), 975 N. Warson Rd., St. Louis, MO, 63132, USA
2 - Danforth Plant Science Center, International Laboratory for Tropical Agricultural Biotechnology (ILTAB)
3 - Donald Danforth Plant Science Center, 975 N. Warson Rd., St. Louis, MO, 63132, USA
4 - Donald Danforth Plant Science Center, International Laboratory for Tropical Agricultural Biotechnology (ILTAB)
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM