Abstract: Plant defensins, a kind of cationic peptides with molecular weight ~5 kD, are the key components of plant innate immune system and play an important role in numerous plant physiological and biochemical activities. The three dimensional structure of plant defensins is so-called the Cys stabilized αβ motif(CSαβ)which three anti-parallel β-sheets and one α-helix that is stabilized by four disulfide bridges formed by eight conserved Cys residues. Plant defensins can inhibit a broad range of fungi and bacteria growth. The investigations that plant defensins were used as enzyme inhibitors, cancer cell proliferation inhibitors and ion channel blockers were done in a number of relevant literatures. The antifungal mechanism of plant defensins is more complex, but it should be first binding the complex lipids those from the outside of fungal plasma membrane, and cause a series of physiological and biochemical reaction including permeabilization of the fungal plasma membrane, increased intracellular ROS level, and fungal cell apoptosis etc. But it is not clear that plant defensin enter the fungal cell or not and its intracellular targets. The progress of the structure, function and antifungal mechanism of plant defensins in recent years were summarized.

Key words: Plant defensin,Structure and function, Antifungal mechanism