The complex interactions between viruses and host plants, particularly in the context of vsiRNA, present a multifaceted area of study. This research explores the intricate dynamics of vsiRNA, small viral RNA molecules that are originally produced by plants for defense against viral RNA or DNA but may paradoxically turn against the host by binding to its transcripts. This investigation reveals that many target host transcripts are integral parts of essential plant functions, such as chlorophyll biosynthesis, transcription factors synthesis, immune system and various metabolic processes. Specific cases illustrate how transcripts in tobacco and wheat are targeted, resulting in symptoms reminiscent of a viral infection, along with intricate interactions in cotton that target potential MYB transcripts, and similar actions in rice that target proteins such as DCL and AGO. The research also delves into the interactions between vsiRNAs and long non-coding RNAs, where the vsiRNAs silence the expression of lncRNAs, thereby amplifying the symptoms of the viral infection, adding another layer to the intricate mechanisms by which viruses exploit host systems. The thesis leaves open the question of the underlying mechanism behind the hijacking of the RNAi system by viruses and the intricate incorporation of significant regions of the plant genome into the viral genome to facilitate virus spread.
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