Published online: May 21, 2007
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Scientists have come up with a possible answer to the Streptomyces scabies bacteria, a pathogen that destroys potato crops. The May issue of Microbiology Today reports the researchers used DNA sequencing to make pathogen specific probes to count the deadly bacteria present in the soil and on plant surfaces and then advise growers on the best way to get rid of it.

The research was carried out by Rosemary Loria, Madhumita Joshi and Simon Mol at Cornell University's Department of Plant Pathology. "This is a large step forward in our efforts to develop practical disease control recommendations for growers," they said in their report.

There are more than a dozen different kinds of scab-producing Streptomyces that affect potato crops worldwide. The filamentous pathogens can penetrate expanding plant cells, including potato tubers, producing raised or pitted scab-like lesions.

S. scabies is pathogenic due to its ability to produce thaxtomin, a protein that breaks down the walls of growing cells, which is encoded on a short segment of DNA transferred during mating.

This gives the bacterium the ability to infect any elongating part of a plant that is underground. It is these tahxtomin biosynthetic genes that have been used to develop the pathogen-specific probes.

It is not uncommon to find more than one scab-producing species in the same place, and by using the new probes scientists can target all known variants.