Figure 1.

BrdU Is Incorporated into Both Chromosomal and Viral DNA of Mature Leaves.

Pairs of TGMV-infected (I) and control (C) leaves were labeled with 100 μM BrdU for 24 h. Total DNA was separated on agarose, blotted, and incubated with anti-BrdU antibodies followed by chemiluminescent detection. Photon counting was used to quantify the BrdU signal (in cpm) for chromosomal DNA (bar graph). The positions of double-stranded (ds) and single-stranded (ss) TGMV and host chromosomal DNA are marked. Total viral DNA was detected with a ³²P-labeled TGMV A DNA probe. EtBr, ethidium bromide; S, DNA from healthy seedlings treated with 100 μM BrdU for 24 h; T, DNA from the leaf intercepting most of the microprojectiles (target); T−1, the leaf immediately below T; T+1, the leaf immediately above T.