|Cui, Y - TEXAS A&M UNIVERSITY|
|Orta, H - TEXAS A&M UNIVERSITY|
|Magill, C - TEXAS A&M UNIVERSITY|
Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: September 7, 1997
Publication Date: N/A
Technical Abstract: Cotton copper top disease was reported in the last two years in Texas, Louisiana, Tennessee and North Carolina. Losses in some fields were as high as 50% of the potential yield. The causal agent appears to belong to a specific group of Agrobacterium Biovar I isolates. Bacteria recovered from diseased plants were found to harbor a plasmid about 200 kb in size. PCR amplification of DNA extracts from the copper top isolates was conducted using primers designed to amplify a segment of the virC operon found on both Ri and Ti plasmids. In initial tests, 25 of the 86 isolates tested resulted in amplification of the predicted 730 bp segment. Sequence analysis of the 730 bp amplification product which was cloned from one isolate showed greater than 70% nucleotide identity to virC gene sequences from five other known Ri and Ti plasmids from A. rhizogenes and A. tumefaciens. Amplification products of 390 and/or 1600 bp were produced from 10 other isolates. Further analyses are being conducted to understand the role of the plasmid in pathogenicity and virulence.