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Temperature Sensitivity of the Hypersensitive Response of Bell Pepper to Xanthomonas axonopodis pv. vesicatoria

February 2002 , Volume 92 , Number  2
Pages  197 - 203

A. M. Romero , C. S. Kousik , and D. F. Ritchie

Department of Plant Pathology, North Carolina State University, Campus Box 7616, Raleigh 27695

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Accepted for publication 30 October 2001.

When bacterial spot-resistant pepper plants carrying resistance gene Bs2 and infiltrated with incompatible strains of Xanthomonas axonopodis pv. vesicatoria carrying a functional avrBs2 gene (races P1 and P3) were incubated at 32°C, they exhibited an electrolyte leakage and bacterial multiplication pattern in planta similar to that obtained with a compatible strain (race P4) carrying a nonfunctional avrBs2 gene. They also developed disease-like symptoms. Pretreatment of incompatible bacteria at 32°C before infiltration caused a delay in electrolyte leakage less pronounced than that caused by exposing plants to 32°C. Also, plants had to be exposed to 32°C for an hour prior to inoculation to increase symptom expression. These data suggest that the Bs2 gene is temperature sensitive. In other experiments, the avrBs1-Bs1 interaction appeared to be the most heat tolerant and thus the least likely to revert to compatible, whereas the avrBs3-Bs3 interaction had an intermediate sensitivity to elevated temperatures.

© 2002 The American Phytopathological Society