Proteomic Analysis Reveals
an Aflatoxin-Triggered
Immune Response in Cotyledons of <i>Arachis hypogaea</i> Infected with <i>Aspergillus flavus</i>
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Abstract
An immune response is triggered in host cells when host
receptors
recognize conserved molecular motifs, pathogen-associated molecular
patterns (PAMPs), such as β-glucans, and chitin at the cell
surface of a pathogen. Effector-triggered immunity occurs when pathogens
deliver effectors into the host cell to suppress the first immune
signaling. Using a differential proteomic approach, we identified
an array of proteins responding to aflatoxins in cotyledons of peanut
(<i>Arachis hypogaea</i>) infected with aflatoxin-producing
(toxigenic) but not nonaflatoxin-producing (atoxigenic) strains of <i>Aspergillus flavus</i>. These proteins are involved in immune
signaling and PAMP perception, DNA and RNA stabilization, induction
of defense, innate immunity, hypersensitive response, biosynthesis
of phytoalexins, cell wall responses, peptidoglycan assembly, penetration
resistance, condensed tannin synthesis, detoxification, and metabolic
regulation. Gene expression analysis confirmed the differential abundance
of proteins in peanut cotyledons supplemented with aflatoxins, with
or without infection with the atoxigenic strain. Similarly, peanut
germination and <i>A. flavus</i> growth were altered in
response to aflatoxin B1. These findings show an additional immunity
initiated by aflatoxins. With the PAMP- and effector-triggered immune
responses, this immunity constitutes the third immune response of
the immune system in peanut cotyledon cells. The system is also a
three-grade coevolution of plant–pathogen interaction