[Homestead] Cutting pesticides with Pectobacterium cypripedii

Tvoivozhd tvoivozd at infionline.net
Sun Sep 19 13:08:18 EDT 2004


*'Ghost bugs' could help cut pesticide use*

10:30 19 September 04
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Bacterial "ghosts" could be a new way to treat plants with pesticides. 
These empty shells of bacterial cells can be filled with chemicals and 
will stick to leaves and stems even after heavy rain.

This could eventually allow less frequent pesticide spraying, a major 
target as agriculture tries to reduce costs and pollution.

The bacterial ghosts are made from cells of /Pectobacterium cypripedii/, 
a species that has evolved to stick to plants. The cells are treated 
with a protein from a bacteriophage, a virus that infects bacteria.

The virus protein creates a tunnel between the inner and outer cell 
membranes of the bacteria, enabling the cytoplasm and genetic 
information to be removed. Since the cell can only stick to the plant if 
the outside is not damaged, the chosen protein must leave only a neat 
hole, while preserving the rest of the cell.

"It's like a bottle. You take the cork out and can remove the contents 
but the bottle itself is still intact," says Tamás Hatfaludi, the lead 
researcher from the University of Vienna, Austria.

Hatfaludi's team sprayed their bacterial ghosts onto barley, cotton, 
maize, cabbage, rice and soya plants, and doused them with simulated 
heavy rain. Between 10 and 55 per cent of the bacterial ghosts clung on, 
with rice keeping the highest proportion and soya the least (/Journal of 
Agricultural and Food Chemistry/, vol 52, p 5627).

When the researchers filled the ghosts with the widely used fungicide 
tebuconazole, and then sprayed them onto barley and wheat, pesticide 
activity was higher than with one of the commercially available 
applications of tebuconazole.


Katharine Davis


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