Root border-like cells secrete antifungal defensin peptides

The South African endemic Brassicaceae species Heliophila coronopifolia (a semi-desert flower) produces root border-like cells (BLCs), the latter originally described in Arabidopsis thaliana. Four defensin peptides (Hc-AFP1-4) have been characterised from H. coronopifolia and found to be strongly antifungal.

Characterization of root border-like cells (BLCs) of Heliophila coronopifolia using the fluorescent dye Syto-9, which binds to cellular RNA and DNA. — Characterization of root border-like cells (BLCs) of *Heliophila coronopifolia* using the fluorescent dye Syto-9, which binds to cellular RNA and DNA. (A) shows root cap and BLCs. (B) shows BLCs. Arrows indicate the root cap with the BLCs. Scale bars: 200 μm (A), 800 μm (B).

A polyclonal antibody cross-reactive with all four defensins was used in combination with fluorescence microscopy analysis by Weiller et al. to confirm the presence of the peptides at the root tip and pectin–rich mucilage BLCs. This study provides a link between defensin peptides (as pre-formed defence) and root BLCs, embedded in pectin mucilage, during plant growth and development.