Josephine’s research combines structural and biochemical approaches to engineer novel rice immune receptors capable of conferring resistance to strains of the rice blast fungus Magnaporthe oryzae.
Magnaporthe oryzae is found in all major rice-growing regions around the world, and severe epidemics cause total crop loss. In addition to rice, strains of M. oryzae can infect and cause blast disease on other staple food crops such as wheat, barley and millet, in addition to various wild grass species.
During infection, the fungus secretes effector proteins, which manipulate the plant to promote pathogen virulence.
Some effectors are recognised by intracellular immune receptors (NLRs) to trigger plant defences. Recognition of the rice blast effector AVR-Pik is mediated by the paired rice NLRs Pik-1/Pik-2. An integrated heavy metal associated (HMA) domain was previously identified in Pik-1, to which certain alleles of AVR-Pik directly bind to trigger disease resistance. However, other stealthy AVR-Pik alleles do not interact with the HMA domain of Pik-1, evading plant defences.
Josephine’s research focuses on the biochemical and structural basis of the interaction between AVR-Pik alleles and the HMA domain of their virulence target, which resembles the integrated HMA domain of Pik-1. They aim to use this information to engineer a variant of Pik-1 which can respond to the stealthy AVR-Pik alleles.