Image-Based Lignin Detection in Nematode-Induced Feeding Sites in Arabidopsis Roots

Cyst and root-knot nematodes are sedentary biotrophic parasites that infect a wide range of plant species, causing significant annual yield and economic losses. Cyst nematodes (genera Heterodera and Globodera) induce specialized feeding structures called syncytia in host plant roots, while root-knot nematodes (Meloidogyne spp.) form galls containing feeding cells known as giant cells. This protocol describes the visualization of lignin in Arabidopsis roots infected by beet cyst nematode H. schachtii and root-knot nematode M. incognita using histochemical staining. We present two distinct approaches for lignin detection: direct staining of root segments containing syncytia and galls and histopathological detection in thin longitudinal sections of the feeding sites. Key features • First approach: Staining of intact roots visualizes lignin in nematode feeding sites and requires only simple specimen preparation and staining solution, with no sectioning needed. • Second approach: Staining of longitudinal sections of feeding sites visualizes cell-specific lignin localization and requires moderate tissue preparation and sectioning. • Both approaches enable specific detection and visualization of lignin in nematode-infected Arabidopsis tissues. Graphical overview.