The Infection Biology of Sphaerulina musiva: Clues to Understanding a Forest Pathogen
Figure 4
Transverse sections of susceptible clone NC11505 at 3 time points (3 weeks, 5 weeks, and 7 weeks) post-inoculation (PI) depicting anatomical responses to inoculation with a conidial suspension of Sphaerulina musiva.
(A) Bright field micrograph of necrotic stem lesion 3 weeks PI. Necrotic area (Nec) bounded by layer of impervious tissue (IT indicated with arrow). (B) Fluorescent micrograph of necrotic lesion 3 weeks PI. IT layer visible as light purple fluorescence (indicated with arrows). (C) Bright field micrograph of necrotic lesion 5 weeks PI. Nec is bounded by a layer of necrophylactic periderm (NP; indicated with arrow). (D) Fluorescent micrograph of necrotic lesion 5 weeks PI. Nec is bounded by IT layer and NP layer (indicated with arrows). (E) Bright field micrograph of necrotic stem 7 weeks PI. Entire cortex (COX) is necrotic and filled with collapsed cells. (F) Fluorescent micrograph of necrotic lesion 7 weeks PI. NP and IT are absent from the Nec. Blue auto-fluorescence viewed under ultraviolet light. Filter parameters: Excitation filter G 365, Beam Splitter FT 395, Emission filter BP 445/50. Green auto-fluorescence viewed under ultraviolet light. Filter parameters: Excitation filter BP 450–490, Beam Splitter FT 510, Emission filter BP 515–565. P = periderm. Pf = primary phloem fiber. X = Xylem. VC = Vascular cambium. Scale bars = 200 µm.