ABSTRACT
This chapter considers mechanisms by which the 35 S RNA, which is used as an intermediate of replication, may also serve as a messenger RNA for the expression of Cauliflower mosaic virus (CaMV) genes. The CaMV circular DNA molecule found in mature virions orignates from reverse transcription of a long RNA transcript that represents the entire viral genome and features a direct terminal repeat. Two major capped and polyadenylated transcripts can be detected in CaMV-infected plants: the 19 S RNA, which is the messenger for gene VI, 17,18,45 and a 35 S RNA that covers the whole viral genome plus a terminal direct repeat of 180 nucleotides. The structural organization of CaMV open reading frame IV and V also follows the gag-pol scheme and may correspond to a similar strategy of gene expression. Several groups have studied in vitro the synthesis of CaMV DNA directed by viral replication complexes preinitiated in vivo.
