Abstract

Virus Induced gene silencing (VIGS), a novel tool for functional genomics relies on environmental conditions for efficient silencing of plant genes. Therefore, standardization of different conditions such as temperatures, humidity and composition of resuspension buffer were taken into account to study the potential of pRTBV MVIGS efficiency for silencing Phytoene desaturase (pds) gene in rice. Results showed that higher percentage of plants showed pds gene silencing at high temperatures and humidity which indicates that environmental factors are also crucial for efficient gene silencing. The orientation of target gene insert in VIGS mediated silencing of endogenous gene is also expected to affect the gene silencing efficiency. Therefore, to validate target gene orientation on silencing efficiency; silencing of ChlH subunit of Magnesium chelatase gene was performed using sense, antisense and hairpin orientation of ChlH insert cloned in pRTBV MVIGS vector. The antisense orientation of ChlH insert was found to be equally efficient to hairpin orientation of ChlH insert as far as ChlH silencing was concerned. In further studies, the use of RTBV MVIGS was extended for silencing a biotic stress resistant gene Xa21 in Xanthomonas oryzae pv oryzae (Xoo) resistant rice variety PB6-Xa21 which supports the application of VIGS for functional analysis of unknown biotic resistant genes in plants.