Le Guen-Le Saos F, Hourmant A, Esnault F, Chauvin J E
Université de Bretagne Occidentale, Laboratoire de Biotechnologie et Physiologie Végétales, Brest, France.
Ann Bot. 2002 Apr;89(4):419-25. doi: 10.1093/aob/mcf063.
Bulbing was studied in shallot plants cultured in vitro. Bulbing occurred under a 16 h photoperiod with fluorescent + incandescent light and 30-50 g 1(-1) sucrose in the culture medium. Exogenous gibberellin (10 microM GA3) inhibited leaf and root growth and bulbing. When added to the medium at a concentration of 10 microM, three inhibitors of gibberellin biosynthesis (ancymidol, flurprimidol and paclobutrazol) promoted bulb formation and the percentage of bulbing. When ancymidol was used in combination with GA3, it did not reverse the effect of GA3 applied alone. Under treatments with 30-70 g l(-1) sucrose, bulbing ratios greater than those found in control plants were achieved by addition of ancymidol, and bulb fresh weight was increased in the same way. Ancymidol caused a 66% decrease in sucrose content in leaf bases but greatly increased the glucose, fructose and fructan contents. The increase in fructan content by ancymidol could result from the three-fold rise in total [14C]sucrose uptake per plant from the culture medium associated with a marked increase in leaf base labelling at the expense of root labelling. The possible role of ancymidol is discussed and evidence supports a major regulatory role for gibberellins in bulbing.
对在体外培养的葱属植物的鳞茎形成进行了研究。鳞茎形成发生在16小时光周期条件下，培养基中添加荧光灯+白炽灯照明以及30 - 50 g·L⁻¹蔗糖。外源赤霉素（10 μM GA₃）抑制叶片和根系生长以及鳞茎形成。当以10 μM的浓度添加到培养基中时，三种赤霉素生物合成抑制剂（嘧啶醇、氟节胺和多效唑）促进鳞茎形成和鳞茎形成率。当嘧啶醇与GA₃联合使用时，它并不能逆转单独施用GA₃的效果。在30 - 70 g·L⁻¹蔗糖处理下，添加嘧啶醇可使鳞茎形成率高于对照植株，鳞茎鲜重也以同样方式增加。嘧啶醇使叶基部蔗糖含量降低66%，但显著增加了葡萄糖、果糖和果聚糖含量。嘧啶醇导致果聚糖含量增加可能是由于每株植物从培养基中吸收的总[¹⁴C]蔗糖增加了三倍，同时叶基部标记显著增加，而根部标记减少。文中讨论了嘧啶醇可能的作用，有证据支持赤霉素在鳞茎形成中起主要调节作用。
