THE PLANT CELL, Vol 1, Issue 10 985-992, Copyright © 1989 by American Society of Plant Biologists
DNA Sequences Essential for Replication of the B Genome Component of Tomato Golden Mosaic Virus
G. N. Revington, G. Sunter and D. M. Bisaro
The Biotechnology Center and Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210
The genome of the geminivirus tomato golden mosaic virus (TGMV) is divided
between two DNA components, designated A and B, which differ in sequence
except for a 230-nucleotide common region. The A genome component is known
to encode viral functions necessary for viral DNA replication, while the B
genome component specifies functions necessary for spread of the virus
through the infected plant. To identify cis-acting sequences required for
viral DNA replication, several mutants were constructed by the introduction
of small insertions into TGMV B at selected sites within and just outside
the common region. Other mutants had the common region inverted or deleted.
All of the mutants were tested for their effects on infectivity and DNA
replication in whole plants and leaf discs. Our results indicate that the
common region in its correct orientation is required for infectivity and
for replication of TGMV B. Furthermore, the conserved hairpin loop sequence
located within the TGMV common region and found in all geminiviruses is
necessary for DNA replication, and may be part of the viral replication
origin.
