608 / 2019-04-23 03:57:41

ECHIDNA, a key regulator of defensive secretion and salicylic acid-dependent immunity in Arabidopsis

secretion pathway,plant immunity,salicylic acid

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ECHIDNA (ECH) protein plays a key role in trans-Golgi-network trafficking and is required for trafficking the AUX1 to the plasma membrane, and secreting cell wall polysaccharides and surface wax. Here, we found that Arabidopsis ech mutant conferred strong resistance to powdery mildew (Erysiphe cichoracearum). ECH mutation disturbed the sortation and secretion of plant defense-responsive proteins PEN1, PEN3, PR1, and PDF1 and cell wall components callose and lignin. Furthermore, we showed the enhanced immunity in ech mutant was salicylic acid (SA)-dependent and abolished in NahG and sid2-1 background. Moreover, ech constitutively accumulated an extremely high level of endogenous SA, indicating ECH protein was necessary to modulate cellular SA homeostasis. Notably, constitutive cell death was observed on leaf tissues of ech mutant and SA-independent. Together, our results identify the ECH as a key regulator of plant immunity and provide new insights into understanding the links between the secretion pathway and plant immunity.