The influence of the detergent Triton X-100 on the growth and ultrastructure of tobacco pollen tubes

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Abstract
The influence of the detergent Triton X-100 on the growth and ultrastructure of tobacco pollen tubes was studied using a culture technique. Tube growth inhibition increased with increasing concentration of the detergent in the culture medium. At a concentration of 7.5 mg∙l−1 (effective dose) the detergent induced a 50% reduction of pollen tube growth. The effective dose is defined as the concentration of a toxic substance that causes a decrease of a metabolic process to 50% of the control. Growth inhibition was reflected by changes of tube ultrastructure and shape at the tip region. The ultrastructural alterations in the pollen tube following the cytotoxic effect of the detergent included (i) disturbance of the cytoplasmic zonation in the tip region of the tube, (ii) numerical decrease of stacked dictyosomes (reduction of Golgi activity), (iii) damage of the plasma membrane and deposition of vesicular structures in the periplasmic space, (iv) formation of concentric arrangements of rough ER, (v) damage of the mitochondrial matrix and cristae and (vi) tube wall thickening-and loosening. The Thiéry reaction revealed the polysaccharide nature of the vesicle contents and the glycolipid nature of the lipid bodies. Scanning electron microscopy demonstrated curvature and tip swelling of the detergent-treated pollen tubes. Most of these changes were likely due to the action of the detergent on membranes. Key words: Nicotiana sylvestris, pollen tubes, detergent, growth inhibition, ultrastructure, biomembranes.