Abstract

The focus of this study revolves around Sri Lankan Cassava Mosaic Virus (SLCMV), family Geminiviridae and its vector Bemisia tabaci, commonly known as whiteflies. Geminiviruses represent a new threat to global food security and sustainability because they cause economically important plant diseases worldwide, which are spread by its vector and results in heavy losses on crops such as cassava, tomatoes, vegetables and cotton. In this study phylogenetic position of B.tabaci was identified along with the identification and localisation of its secondary endosymbionts – Arsenophonus , Rickettsia and Wolbachia followed by the mutational study of SLCMV Coat protein (CP). This involves the introduction of substitutions mutations at specific amino acid positions in SLCMV CP. Mutated agroinfectious clones of SLCMV were developed to analyse the effect of these mutations on the infectivity of the virus in the model plant Nicotiana benthamiana. Furthermore, the effect of these mutations on transmissibility of virus by its vector was also analysed by symptoms observation and estimating the viral titre levels of transmitted viral DNA in N.tabacum plant. The interaction between mutant CPs and chaperone proteins GroELs was also studied through yeast two hybrid and Bimolecular Fluorescence Complementation (BiFC) molecular techniques which showed the reduced interaction of mutant CPs with GroEL proteins, leads to the reduction in transmission of the virus. Hence targeting of the virus at specific positions may result in controlling its worldwide plant diseases.