Deciphering the route of Ralstonia solanacearum colonization in Arabidopsis thaliana roots during a compatible interaction: focus at the plant cell wall

Type III Secretion–Dependent and –Independent Phenotypes Caused by Ralstonia solanacearum in Arabidopsis Roots

“…The second stage of infection involves invasion of the root cortical area. In this stage, R. solanacearum quickly transverses the root cylinder centripetally via intercellular spaces, directed to the vasculature (Digonnet et al 2012;Vasse et al 1995). Massive cortical cell degeneration can be observed during this phase.…”

“…R. solanacearum in vitro inoculation assays have been successfully established for tomato (Vasse et al 1995), petunia (Zolobowska and Van Gijsegem 2006), and the model plants Medicago truncatula (Vailleau et al 2007) and Arabidopsis thaliana (Digonnet et al 2012). These studies have shed light on some common, as well as species-specific, root phenomena associated with R. solanacearum infection.…”

“…The bacterium was found to gain access into the tomato root through wound sites or natural openings such as emerging lateral roots (Saile et al 1997;Vasse et al 1995). In M. truncatula and Arabidopsis, the bacteria can also enter intact roots through the root apex (Digonnet et al 2012;Vailleau et al 2007). In petunia, it was shown that penetration occurs equally in resistant or susceptible plants (Zolobowska and Van Gijsegem 2006).…”

“…Massive cortical cell degeneration can be observed during this phase. The fact that cells not directly in contact with the bacteria also die led to a proposal that certain cell-wall fragments degraded by R. solanacearum may act as signals to induce plant programmed cell death (Digonnet et al 2012). During the third stage of infection, R. solanaceraum enters into the vascular cylinder and colonizes the xylem.…”

“…During the third stage of infection, R. solanaceraum enters into the vascular cylinder and colonizes the xylem. In Arabidopsis, it was shown that vascular invasion is promoted by collapse of two xylem pericycle cells (Digonnet et al 2012). Once inside the xylem, bacteria start proliferating and moving between adjacent vessels by degrading the cell walls but remain confined in the xylem.…”