Park W J
Institut fur Biologie III, Universitat Freiburg, Germany.
Planta. 1998 Dec;207(1):120-4. doi: 10.1007/s004250050463.
The effect of epibrassinolide (epiBR) on the growth and gravitropism of hypocotyls was investigated in diageotropica (dgt), a mutant of tomato (Lycopersicon esculentum Mill.). The elongation of (dgt) hypocotyls, which had been reported to be auxin-insensitive, was promoted by increasing concentrations of indole-3-acetic acid (IAA) in the presence of epiBR. alpha-(p-Chlorophenoxy)isobutyric acid, an inhibitor of auxin action, blocked the enhancement of growth by IAA and epiBR. Time course analysis of IAA-induced dgt hypocotyl elongation in the presence of epiBR revealed typical auxin response kinetics. These results suggest that epiBR restores the auxin responsiveness of dgt hypocotyls with respect to elongation. However, epiBR did not rescue the dgt phenotype with respect to shoot gravitropism. It was therefore concluded that brassino-steroid insensitivity or deficiency is not the primary defect of the dgt mutation.
在番茄（Lycopersicon esculentum Mill.）的一个突变体——斜生胚轴（dgt）中，研究了表油菜素内酯（epiBR）对下胚轴生长和向地性的影响。据报道，dgt下胚轴的伸长对生长素不敏感，在epiBR存在的情况下，随着吲哚-3-乙酸（IAA）浓度的增加，dgt下胚轴的伸长受到促进。生长素作用抑制剂α-（对氯苯氧基）异丁酸可阻断IAA和epiBR对生长的促进作用。对epiBR存在时IAA诱导的dgt下胚轴伸长进行的时间进程分析显示出典型的生长素反应动力学。这些结果表明，epiBR在伸长方面恢复了dgt下胚轴对生长素的反应性。然而，epiBR在茎的向地性方面并未挽救dgt表型。因此得出结论，油菜素类固醇不敏感或缺乏不是dgt突变的主要缺陷。
