Calcium regulation of interactions between a xylem-inhabiting pathogenic bacterium and host plants

The bacterium Xylella fastidiosa causes destructive diseases in crops such as grapes, citrus, blueberries and others. These diseases are found mainly in the Americas, but there have been recent reports of this bacterium causing problems in Asia and Europe. This bacterium, transmitted among plants by insect vectors, lives inside the xylem vessels, which are the components of the vascular system of the plant involved in transporting water and mineral nutrients from the soil to the rest of the plant. Inside the xylem the bacterium forms biofilms, or agglomerates of bacteria surrounded by a sticky matrix, that clogs the passage of nutrients in the plant and is believed to be responsible for the development of symptoms. Currently there is no cure for the diseases caused by Xylella fastidiosa, and infected plants need to be removed and discarded.

Our research has shown that one particular mineral element, calcium, has an important role during the disease development, by increasing the virulence of the bacterium, and being accumulated in infected plants. Our data indicates that the plant defense response to infection may worsen the disease, analogous to what occurs in autoimmune diseases in animals. During this project we will elucidate the key proteins in both plant and bacteria that are involved in the calcium modification occurring during disease. This information will allow us to target those proteins for specific disease control methods.

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Paul Cobine and Aaron Rashotte (Department of Biological Sciences, Auburn University)

Mickael Malnoy (Fondazione Edmund Mach)



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