Remember meForgot password?
    Log in with Twitter

article imageHelping California's grape and wine industries with vine disease

By Tim Sandle     Jan 14, 2016 in Science
San Fransisco - Researchers have pinpointed how Pierce's disease is transmitted from insects to grapevines. The disease costs California's grape and wine industries in excess of $100 million each year.
Pierce's disease is a longstanding disease of grapevines. It is bacterial in origin, caused by the species Xylella fastidiosa. Infection leads to yellowing and browning of grapevine leaves. After a period of time the leaves fall from the vine and, at the wrong time, the vine looks unseasonably bare. The vine is therefore unable to produce grapes. Grape varieties Chardonnay and Pinot noir are especially sensitive.
The bacterial disease reaches grapevines via insects. The carrier, a tiny flying insect called a blue-green sharpshooter, is associated with rivers and streams. The most devastating loss of vines occurred in 1996; although each year several hundred vines are affected, and this carries significant economic implications.
Once inside the stem of the plant, the invasive bacteria form a biofilm and coat the water-transmitting xylem, within the plant, with a sticky substance. It has long been thought that the sticky substance blocks the flow of water and this prevents water reaching the leaves, causing them to wither and die. However, more in-depth analysis has shown some plants to be heavily blocked, yet have leaves that remain green; whereas other plants show little evidence of the sticky substance yet the leaves are affected. This led a research group took look for something else at play, and for this they have gone down to the biochemical level.
It has been shown that the key to transmission is an enzyme, which allows the bacterial disease to act upon grapevines. Here proteins secreted by the bacteria appear to trigger the disease. At the base of this is an enzyme, coded LesA. The enzyme is capable of breaking down plant walls. This finding was confirmed by genetic engineering strains of the bacterium without the enzyme, which showed it could no longer infect grapevines.
Researchers hope the information will provide insights into how the disease spreads, how it is transferred from vine-to-vine, how it might be controlled.
The research was conducted by scientists at UC Davis and the findings are published in the journal Scientific Reports. The research is titled “The Type II Secreted Lipase/Esterase LesA is a Key Virulence Factor Required for Xylella fastidiosa Pathogenesis in Grapevines.”
More about grapevines, Wine, Leaves, Bacteria, Infection
More news from