Microscopy Method to Compare Cyst Nematode Infection of Different Plant Species

The cyst nematode, Globodera pallida, is an obligate, biotrophic pathogen of potato, causing up to 80% yield loss. In the present study, a non-destructive imaging technique was used to compare the development and behavior of G. pallida in its host Solanum tuberosum and in the non-host S. sisymbriifolium. We used microscopy-rhizosphere chambers coupled with the fluorescent stain PKH26, and compared this with destructively sampled acid fuchsin staining. No significant difference (P ≥ 0.90) in G. pallida numbers was found whether stained with PKH26 or acid fuchsin for either plant species indicating no toxic effect from the vital stain. PKH26 labelled J2s successfully located and penetrated roots of both S. tuberosum and S. sisymbriifolium. Two days after inoculation, PKH26 stained G. pallida was clearly observed migrating intercellularly through root tissues of both S. tuberosum and the non-host S. sisymbriifolium. Overall, more nematodes were observed in S. tuberosum than in S. sisymbriifolium roots. No live J2s were observed in S. sisymbriifolium roots stained with either acid fuchsin or PKH26 after 8 days. Understanding the time line of development of G. pallida in S. sisymbriifolium is important towards comprehensive understanding of plant defense responses.