Investigation into the molecular mechanisms underlying nematode recognition by the ma resistance protein in perennial plum roots
Plant-parasitic nematodes are major root pathogens that affect drastically plant development and growth. Predominant species, such as the root-knot nematodes (RKNs) Meloidogyne spp., represent a global threat for annual and perennial crops causing huge crop losses worldwide. In Europe, RKNs were mainly controlled by toxic pesticides that are getting banned. One of the most promising alternative to pesticides is to rely on biological control and on the plant innate immunity for disease resistance in crops. The plant immune system is a multi-layered network that enables the detection of pathogens using different classes of receptors. The presence/absence of such receptor can determine whether or not the plant will be resistant/susceptible to a particular disease. At INRA Sophia Agrobiotech Institute (ISA), an immune receptor gene Ma, from the toll/interleukin-1 receptor, nucleotide-binding and leucine-rich repeat (TIR-NB-LRR or TNL) family, has been cloned from the plum tree Prunus cerasifera where it provides a broad resistance against numerous RKN species. A unique feature of Ma resides in five repeated exons encoding a large C-terminal extention. Interestingly, each of those exons carries a recently characterized post-LRR (PL) domain which is found in a single copy in many other TNLs from different plant species. The PL domain’s function remains unknown but its conservation suggests an important role in TNLs. The peculiar architecture of Ma provides a great opportunity to decipher the involvement of the PL domain in TNL–mediated immunity. Combining complementary approaches, the proposed IMMUNE project aims to describe how Ma triggers immunity in response to RKNs in plant roots and how the PL domain participates in the recognition and signalling. This project, undertaken by Dr Simon Saucet at ISA, will provide new insights into the molecular mechanisms of plant immunity and contribute to the development of methods to control RKNs infection in crops.