Proteomics analysis of Medicago truncatula response to infection by the phytopathogenic bacterium Ralstonia solanacearum points to jasmonate and salicylate defence pathways

Abstract
The infection of the model legume Medicago truncatula with Ralstonia solanacearum GMI1000 gives rise to bacterial wilt disease via colonization of roots. The root and leaf responses to early infection (one and three days post infection) were characterized to investigate the molecular mechanisms of plant resistance or susceptibility. A proteomics approach based on pools of susceptible and resistant recombinant inbred lines was used to specifically target the mechanisms for tolerance. Differential abundances were evidenced for proteins involved in defense (e.g. PR5, PR10 or Kunitz protease inhibitors) and signaling pathways (such as cyclophilin). R. solanacearum inoculation modifies expression levels of those genes, either in both genotypes (AOS1, LOX4, proteinase inhibitors) or specifically in the resistant line (PR proteins). Exogenous application of salicylic acid (SA) enhanced tolerance to the bacteria while methyl jasmonate (MeJA) enhanced short‐term tolerance then promoted disease in the susceptible ecotype, suggesting that they may mediate defense responses. Conversely, proteomics‐identified genes were also shown to be SA or MeJA‐responsive. This is the first description of differential response to R. solanacearum in M. truncatula. Our results suggest that root basal defense is activated at one dpi, together with the JA pathway. Specific resistance is then evidenced at three dpi, with the up‐regulation of SA‐dependent PR proteins.

Source: Cellular Microbiology - October 31, 2017 Category: Microbiology Authors: Ahad Yamchi Tags: RESEARCH ARTICLE Source Type: research