Mechanical stress and gibberellin: Regulation of hollowing induction in the stem of a bean plant, Phaseolus vulgaris L
Takano, M. (Tohoku Univ., Sendai (Japan). Inst. of Genetic Ecology) | Takahashi, H. | Suge, H.
In pole bean plants, mechanical stress (MS) inhibited stem elongation and induced radial thickening of the stem. Application of uniconazole, an inhibitor of gibberellin biosynthesis, also reduced stem growth but had no effect on stem diameter. Both Ms and uniconazole significantly reduced hollowing of the first internodes, but only the former increased ethylene evolution from the first internode. Application of GA3, increased the length of the first internode and decreased its diameter in bush bean plants; this was accompanied by a significant promotion of stem hollowing. Aminooxyacetic acid (AOA) decreased ethylene evolution from the GA3-treated internodes, though it did not reduce the GA3-induced hollowing of the first internodes. Application of GA3 affected neither ethylene evolution nor cellulase activity in the first internodes of bush bean plants. Application of GA3 stimulated much greater cell elongation in the center of pith tissue than in the outer surrounding tissues, suggesting a possible physical breakage of the inner cells, which leads the hollowing of bean stems. These results suggests that gibberellin is a factor responsible for stem hollowing in bean plants. Because MS is known to reduce gibberellin content in bean plants Ms may inhibit stem hollowing by reducing the amount of endogenous gibberellin
Показать больше [+] Меньше [-]