Elemental micro-PIXE mapping of hypersensitive lesions in Lagenaria sphaerica (Cucurbitaceae) resistant to Sphaerotheca fuliginea (powdery mildew)

摘要: Genotypes of the Southern African cucurbit, Lagenaria sphaerica, that are resistant to powdery-mildew (Sphaerotheca fuliginea) exhibit foliar hypersensitive (HS) lesions on inoculation with this fungal pathogen. Elemental distributions across radially symmetrical HS lesions, surrounding unlesioned leaf tissue and uninoculated tissue, were obtained using true elemental imaging system (Dynamic Analysis) NAC Van de Graaff nuclear microprobe. Raster scans 3 MeV protons complemented by simultaneous PIXE BS point analyses. The composition cellulose (C6H10O5) was used as constant matrix for scans, sample thickness found from spectra. Si elements heavier than Ca contributed within locally elevated raised limits detection some trace metals interest. In comparison inoculated characterised higher overall concentrations all measured except Cu. Fully developed, 6 day-old could be divided into five zones, centred infection site. Each zone characterized distinct local (either depletion, or accumulation potentially phytotoxic levels).