ISHS Acta Horticulturae 273: V International Workshop on Fireblight
A CLUSTER OF PATHOGENICITY GENES FROM ERWINIA AMYLOVORA ENABLES ESCHERICHIA COLI TO ELICIT THE HYPERSENSITIVE RESPONSE |
| Authors: | Steven V. Beer, Cathy H. Zumoff, David W. Bauer, B. J. Sneath, Ron J. Laby |
| Abstract:
Hrp- mutants of E. amylovora, deficient in pathogenicity and the ability to elicit the hypersensitive reaction (HR), were created by lambda-Tn1O mutagenesis. Members of a cosmid library containing wild-type DNA of E. amylovora were mobilized into selected Hrp- mutants. Cosmids that restored pathogenicity to the mutants were self-selected on immature pear fruit and then tested for HR elicitation on tobacco. Previously identified cosmids restored pathogenicity and HR-eliciting ability to only a few mutants. In contrast, the recently identified cosmid, pCPP430, restored these properties to all 18 transposon-induced Hrp- mutants and two spontaneous Hrp- mutants. Further work showed that pCPP430 contains a cluster of hrp genes, dispersed throughout a 40 kb region of chromosomal DNA. Escherichia coli DH5(pCPP430) elicited extremely rapid and strong collapse of tobacco leaf tissue following infiltration. In addition, the cosmid conferred HR-eliciting ability (in tobacco), to several other species of Erwinia. The reaction of immature pear fruit to inoculation with several species of Erwinia was altered by the presence of pCPP430. Thus, pCPP430 contains all the genes needed for elicitation of the HR, and these genes are expressed in E. coli and in other Erwinia species. | |
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