Responses of Plant Cells to Gibberellin

1. Gibberellin (GB), in the concentrations 0.01-10 mg/l, markedly accelerated the coleoptile growth of Allium fistulosum. 2. With a concentration of 100 mg/l GB, pseudochiasmata formation and induction of mitosis were noticed in the more differentiated cells of A. cepa roots. In concentrations of 10 mg/l or less, which stimulated coleoptile growth, no visible cytological effects were detected. 3. GB markedly accelerated pollen germination and pollen-tube growth of Lilium longiflorum. 4. The effects of GB upon the growth of fern protonemata and rhizoids were dependent upon the nature of the culture medium-tap water versus Knop's solution. The acceleration of spore germination and protonemal growth by GB treatment seems to be a consequence of cell elongation rather than of cell division. 5. From anatomical studies of stems of seedlings of Vigna sesquipedalis treated with lanolin containing 0.01% GB, it is concluded that growth resulting from the treatment is stimulated in the longitudinal rather than in the transverse direction and that the elongation is a consequence of accelerated cell elongation rather than of cell multiplication. 6. The physiological effects of GB are quite different from those of indole-3-acetic acid.