Fig. 1

Schematic representation of geminivirus replication in a diseased and a CRISPR/Cas engineered resistant plant. In the plant cell of a diseased plant (left), infection geminivirus particles (virions, gray double hexagons) release the viral single-stranded DNA (ssDNA) into the plant nucleus (green dashed ellipse). Host DNA polymerase mediates the synthesis of the complementary strand, resulting in viral double-stranded DNA (dsDNA) molecules. Transcription of dsDNA leads to production of Rep protein, which initiates viral replication via rolling-circle replication (purple circle surrounded by blue open circle). Multiple cycles of viral replication (colored circles) generate new ssDNA that can re-enter replication or can be packaged into virions. In contrast, plant cells expressing a CRISPR/Cas construct that carries sgRNAs targeting sites in the viral genome (right) will become resistant to virus infection. The Cas9–sgRNA complex will target the viral dsDNA for cleavage, inhibiting viral replication. Cas CRISPR-associated, CRISPR clustered regularly interspaced short palindromic repeats, dsDNA double-stranded DNA, sgRNA single guide RNA, ssDNA single-stranded DNA