Functional genomics in the rice blast fungus to unravel the fungal pathogenicity

A rapidly growing number of successful genome sequencing projects in plant pathogenic fungi greatly increase the demands for tools and methodologies to study fungal pathogenicity at genomic scale. Magnaporthe oryzae is an economically important plant pathogenic fungus whose genome is fully sequenced. Recently we have reported the development and application of functional genomics platform technologies in M. oryzae. This model approach would have many practical ramifications in design and implementation of upcoming functional genomics studies of filamentous fungi aimed at understanding fungal pathogenicity.

Guardian of the rice:Unveiling OsSSP1 for broad-spectrum disease resistance

Plants are continuously exposed to numerous biotic stresses throughout their growth.Through arms race-driven coevolution with pathogens,plants have developed sophisticated immune systems,including pathogen-associated molecular pattern(PAMP)-triggered immunity(PTI)and effector-triggered immunity(ETI).PTI is initiated by the binding of danger signals to extracellular membrane-localized receptors calledpattern recognition receptors(PRRs).PTI triggers responses,including reactive oxygen species(ROS)bursts and the expression of defenseassociated genes.However,pathogens adapted to PTl secrete virulence proteins,effectors,to aid colonization,and ETl is then triggered by the recognition of these effectors by resistance proteins with a nucleotide-binding domain leucinerich repeat receptor(NLR).To circumvent this immune response,pathogens secrete various effectors into the host intracellular region and induce effector-triggered susceptibility(Zhou and Zhang.,2020).Currently,research on plant immunity has been primarily focused on plasma membrane and cytoplasmlocalized proteins,including oligomeric NLRs,resistosomes,and the secretion mechanisms of cytoplasmic effectors.

Ambivalent response in pathogen defense: A double-edged sword?

Plants possess effective immune systems that defend against most microbial attackers.Recent plant immunity research has focused on the classic binary defense model involving the pivotal role of small-molecule hormones in regulating the plant defense signaling network.Although most of our current understanding comes from studies that relied on information derived from a limited number of pathosystems,newer studies concerning the incredibly diverse interactions between plants and microbes are providing additional insights into other novel mechanisms.Here,we review the roles of both classical and more recently identified components of defense signaling pathways and stress hormones in regulating the ambivalence effect during responses to diverse pathogens.Because of their different lifestyles,effective defense against biotrophic pathogens normally leads to increased susceptibility to necrotrophs,and vice versa.Given these opposing forces,the plant potentially faces a trade-off when it mounts resistance to a specific pathogen,a phenomenon referred to here as the ambivalence effect.We also highlight a novel mechanism by which translational control of the proteins involved in the ambivalence effect can be used to engineer durable and broad-spectrum disease resistance,regardless of the lifestyle of the invading pathogen.