Pollen mitosis and pollen tube growth inhibition by SO2 in cultured pollen tubes of Tradescantia

Mature pollen of Tradescantia paludosa Anders. Sax clone-3 was collected from greenhouse grown plants and desiccated in the dark for 4–5 hours. The pollen was sown on microslides coated with lactose agar medium (supplemented with 0.02% colchicine). Five minutes after sowing, pollen cultures were treated with various concentrations (0.075–2000 ppm) of SO₂ obtained from the chemical reaction between K₂S₂O₅ and HCl. Treatments were carried out in an airtight Plexiglas chamber throughout the full incubation period of 19 hours. Treated and control pollen cultures were fixed and stained in aceto-carmine or Feulgen reaction to determine the tube lengths and mitotic indices. Results of repeated experiments indicated that the values of mitotic indices dropped from the normal 38.7% in the control to the range of 24.3-3.8% when treated with 0.075–50.00 ppm of SO₂. Pollen tube growth was inhibited from the normal length of 1.5 mm in the control to the range of 800-100 μm when treated with 10–2000 ppm of SO₂. The inhibitory effect of SO₂ rpresumably resulted from physiological disturbance of the cell and severe damage to chromosomes of both generative and tube nuclei of the pollen tubes.