Xylem structure and passive bacterial spread

The bacterium Xylella fastidiosa, responsible for Pierce’s disease of grapevine, colonizes the xylem conduits of vines. Chatelet et al. examine the xylem structure of several varieties of grapevine, Vitis vinifera, and other plants to determine if anatomical differences might explain some of the differences in susceptibility to infection. They find that tolerant vines have narrower vessels and more parenchyma rays in their stems than susceptible ones, possibly restricting bacterial movement at the level of the vessels.