ISHS Acta Horticulturae 513: XXV International Horticultural Congress, Part 3: Culture Techniques with Special Emphasis on Environmental Implications, Disease, Pest Control and Integrated Pest Strategies
A MICROCIN PRODUCED BY A STRAIN OF ERWINIA HERBICOLA IS INVOLVED IN BIOLOGICAL CONTROL OF FIRE BLIGHT AND SOFT ROT CAUSED BY ERWINIA SP |
| Authors: | J.L. Vanneste, D.A. Cornish, J. Yu, M.D. Voyle |
| Keywords: | Erwinia herbicola, bacterial diseases, biological control, fire blight, microcin, soft rot |
| Abstract:
Strain Eh252 of Erwinia herbicola produces a compound which inhibits on plate the fire blight pathogen (Erwinia amylovora) and strains of Erwinia species responsible for soft rot on vegetables and ornamentals in the field and during storage (Erwinia carotovora pv carotovora, Erwinia carotovora pv atroseptica, and Erwinia chrysanthemi). Determination of the biochemical characteristics of this compound as well as DNA sequence analysis of the genes necessary for its production indicate that this compound is a small peptide with modifications such as adenylation. Its production is not regulated by the SOS system and it retains activity after exposure to extreme pH and extreme temperature. All these characteristics indicate that this compound belongs to a family of antibiotic called microcin. Transposon induced mutants of Eh252 which do not produce this microcin are not able to protect immature pear fruits against fire blight as well as the wild type strain. Similarly, these mutants do not protect carrot or potato slices as well as Eh252 against soft rot. Ability to control soft rot and fire blight is restored when the mutants are complemented for microcin production. This is the first microcin produced by a strain of E. herbicola and the first time a microcin has been involved in control of plant pathogenic bacteria. The genes for production of this microcin have been cloned, and can be expressed in other bacteria than E. herbicola. This allows us to develop a strategy of biological control for fire blight and bacterial soft rot based on superior biocontrol agents to which we would confer ability to produce this microcin. | |
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