Fig. 3
From: Macro- and microscopic leaf injury triggered by ozone stress in beech foliage (Fagus sylvatica L.)
Tissue- and cell-level changes caused by oxidative stress within foliage of beech trees. Changes in segments of leaf blades underlying bronzing (c, d, l), stippling (e, f, i, j, m, o) and yellowish dots (g, h, n) versus asymptomatic material (a, b, k). Bronzing symptoms (c, d): condensed tannins inside vacuoles of upper epidermis (UE, blue) and palisade parenchyma (PP), sometimes in the form of plugs (*), condensation of cytoplasm (c) and nucleus (n), decrease in chloroplast (ch) size and increase in plastoglobule (pg) size and frequency. Stippling symptoms (e, f, i, j, m, o): changes observed in the case of bronzing interspersed with dead, disrupted and partly cytorrhyzed cells in upper palisade parenchyma (e, f); groups of cytorrhyzed, disrupted and condensed (#) cells extending into lower palisade, in the case of stronger reactions (2003; i, j). Less injury in spongy parenchyma (SP) and lower epidermis (LE; l, m, o). Yellowish dots (g, h, n): injury by oxidative stress more severe in abaxial than adaxial tissues, with parts of lower mesophyll disrupted and the cells cytorrhyzed (&; g). Lesions consisting of cell strands either collapsed and condensed (#) or deformed and degenerated (§; h) and containing oxidized condensed tannins (oct; g, h). Leakage of cell debris in the intercellular space (is) of lower leaf blade (n). Other structures: st: starch, oct: oxidized condensed tannins. Technical specifications: staining with Toluidine blue and p-phenylenediamine, observation in bright field microscopy (a, c, e, g, i), using phase contrast (b, d, f, h, j–o)