In nature, plants live with a wide range of microbes that reside on the surface of or within plant tissues. Plants disregard or tolerate these nonpathogenic microbes, but mount inducible defenses when they encounter potentially infectious microbes. The danger hypothesis predicts that a plant can sense and respond to danger/damage-associated molecular patterns (DAMPs) associated with pathogen challenge in addition to the microbe-associated molecular patterns (MAMPs) that are largely shared by all microbes. Here we provide an overview of recent studies on DAMP sensing and signaling in plant immunity. We also introduce our studies pointing to the importance of layered crosstalk between MAMP and DAMP signaling pathways as a critical step in basal resistance and systemic acquired resistance.
No viruses or viroids other than Citrus vein enation virus (CVEV) were detected from Yuzu seedlings that had clear vein enation symptoms after aphid transmission. The results indicated that the vein enation symptom of Yuzu was due to a single infection of CVEV.