Single-stranded DNA from abutilon mosaic virus is present in the plastids of infected Abutilon sellovianum

The leaf mosaic of Abutilon sellovianum is caused by abutilon mosaic virus (AbMV), a geminivirus that has a circular single-stranded DNA genome. DNA was isolated from intact plastids of AbMV-infected and noninfected plants. Plastids from infected plants were shown to contain the single-stranded AbMV DNA by Southern-blot hybridization experiments that used a probe made from highly purified AbMV DNA. The possibility of adsorption of AbMV virions or viral DNA onto the plastid envelope was ruled out by several in vitro experiments with DNase I and protease. Furthermore, the lamellar system of plastids from AbMV-infected plants was degenerated and substituted by amorphous electron-dense material. The transport of AbMV DNA across the plastid envelope has implications for the development of a chloroplast transformation vector.