Advances on molecular mechanisms of plant-pathogen interactions

Plants have established a complicated immune defense system during co-evolution with pathogens. The innate immune system of plants can be generally divided into two levels. One, named PAMP-triggered immunity (PTI), is based on the recognition of pathogen-associated molecular patterns by pattern-recognition receptors, which confers resistance to most pathogenic microbes. The other begins in cytoplasm and mainly relies on recognition of microbial effectors by plant resistance proteins in direct or indirect ways, which then initiates potent defense responses. This process, termed effector-triggered immunity (ETI), is necessary for defense against pathogens that can secret effectors to suppress the first level of immunity. Activation of these two layers of immunity in plant is based on distinguishing and recognition of "self" and "non-self" signals. Recognition of "non-self" signals can activate signal cascades, such as MAPK cascades, which will then induce defense gene expression and corresponding defense responses. In this review, we focused on underlying molecular mechanisms of plant-pathogen interactions and the latest advances of the PTI and ETI signaling network.