Seen it through the grapevine
18 Mar 2010 by Evoluted New Media
Electron microscopy has enabled researchers in America to see for the first time how a bacterium that kills grape vines is able to move through the plants at the cell level.
Electron microscopy has enabled researchers in America to see for the first time how a bacterium that kills grape vines is able to move through the plants at the cell level.
Pierce’s Disease is a serious threat to wineries where the bacterium Xyella fastidiosa – injected into the vines by an insect known as the glassy-winged sharpshooter – causes the vines to weaken and die by colonising the plant. Until now, no one has been able to see how the bacteria break down cell walls.
“Basically we’ve been interested in determining how the bacteria moves,” said Dr B Greg Cobb, Texas AgriLife Research plant physiologist, “How do they go from one part of the plant to another?”
Cobb and his team concentrated on the ‘matchstick’ effect of Pierce’s Disease. When a plant suffering from the disease drop its leaves, the petiole – the stem connecting the leaf to the vine – remains and this occurs over the length of the vine.
The bacteria move through the xylem – the part of the plant which transports water. “What is happening is that the bacteria is actually able to degrade and move through these very thin parts of the cell wall between the xylem elements,” Cobb said, “You can actually see them in the pit membranes.”
The pit membrane normally blocks larger particles from passing through, but high-level photos – obtained using an electron microscope at 100,00th of a millimetre – shows the bacteria breaking down the membrane in order to get through the plant.
Cobb’s team studied syrah and cabernet sauvignon plants – both of which are known to suffer from Pierce’s Disease. They will continue to study the disease in the hopes of figuring out what can be done to help infected plants survive for longer.
