No abstract

Plants respond to invading pathogens by exploiting their innate immune system. Microbe-associated molecular pattern (MAMP)triggered immunity (MTI) and effector-triggered immunity (ETI) have been described as the two main layers of defence during the

No abstract

Ralstonia solanacearum depends on numerous virulence factors, also known as effectors, to promote disease in a wide range of economically important host-plants. Although some of these effectors have been characterized, none has been shown to target the host secretion machinery so far. Here, a screening was performed, using an extended library of NLR plant immune receptors integrated domains (IDs), to identify new effector targets. The results uncovered that the core effector RipE1, of the R. solanacearum species complex, among other targets, associates with Arabidopsis exocyst component Exo70B1. RipE1, in accordance with its predicted cysteine protease activity, cleaves Exo70B1 in vitro between its sequence and is able to promote Exo70B1 degradation in planta. RipE1 enzymatic activity additionally results in the activation of TN2-dependent cell death. TN2 is an atypical NLR that has been proposed to guard Exo70B1. Despite the fact that RipE1 has been previously reported to activate defense responses in model plant species, we present here a Nicotiana species, in which RipE1 expression does not activate cell death. Overall, this study uncovers a new RipE1 host target, while providing evidence and novel tools to advance in-depth studies of RipE1 and homologues effectors.