**1.5.6 Plant defensins**

Plant defensin antimicrobial peptide class present 4 disulfide bridges with a cysteine connectivity of 1-8, 2-5, 3-6, and 4-7. Their three-dimensional structures are similar to the insect defensin structure in that they have a disulfide bonds stabilized alpha-helix. Their structure also show a triple anti-parallel beta-strands. (Sagaram et al., 2011). The strong antifungal activity of the plant defensin has been associated with their alpha helix motif, in a similar fashion as for insect defensin (Lamberty et al., 2001). Conversely, heliomycin, a defensin from *Heliothis virescens*, has more structural communality with plant defensin than with insect defensin (Lamberty et al., 2001).

*P. sylvestris* defensin 1

RMCKTPSGKFKGYCVNNTNCKNVCRTEGFPTGSCDFHVAGRKCYCYKPCP
