Fig 3. Histological analyses of non- and nematode-infected (Litylenchus crenatae subsp. mccannii) bud scales of beech (Fagus grandifolia).

Bright-field photomicrographs of bud scale cross-sections stained with a mixture of toluidine blue and basic fuchsin. (A) Representative image of non-infected bud scale composed of four layers of cells. Spherical hyaline structures are sections through leaf hair. (B-F) Representative photomicrographs of nematode-infected bud scale cells showing different developmental stages of hypertrophy. Non-infected bud scale cells can also be seen adjacent to hypertrophied cells, as shown in figures C-F. Arrows point to nematode sections associated with hypertrophied bud scale cells. (G) Bud scale cell surface (μm²) was measured in control (n = 30 cells) and nematode-infected (n = 45 cells) whole fresh bud scales. (H) Bud scale cell surface (μm²) was measure in control (n = 115 cells) and representative nematode-infected (n = 115 cells) fixed and bud scale cross-sections. (I) Nuclear surface (μm²) of bud scale cell sections of control (n = 60 nuclei) and nematode-infected (n = 60 nuclei) buds. Thick lines in the boxplot represent medians. Different letters denote statistical differences between control and diseased bud scale cells (P < 0.05, ANOVA with Tukey-Kramer test). Scale bars: 25 μm (A-C); 50 μm (D-F).