Jiménez Víctor M., Bangerth Fritz
Institut für Obst-, Gemüse- und Weinbau (370), Universität Hohenheim, D-70593 Stuttgart, GermanyPresent address: CIGRAS, Universidad de Costa Rica, 2060 San Pedro, Costa Rica.
Physiol Plant. 2001 Mar;111(3):389-395. doi: 10.1034/j.1399-3054.2001.1110317.x.
Carrot (Daucus carota L. F1 hybrid Starca) excised hypocotyls were cultured on Murashige and Skoog medium with and without 2,4-dichlorophenoxy acetic acid (2,4-D) to determine the effect of this plant growth regulator on their further development and their endogenous hormone levels. Culture in the absence of 2,4-D stimulated root development at one end of the hypocotyl segments and increased the endogenous levels of free indole-3-acetic acid (IAA), zeatin/zeatin riboside and N6(Delta2-isopentenyl) adenine/N6(Delta2-isopentenyl) adenosine, as determined by radio-immunoassay. On the other hand, the presence of 2,4-D in the culture medium promoted callus induction and proliferation, together with abscisic acid (ABA) accumulation, in the hypocotyl segments during the first weeks of culture. When the callus segments generated in the hypocotyl sections cultured in the presence of 2,4-D were cultivated further, the development of two callus types was observed, one composed of preglobular and globular embryos and the other translucent, watery and lacking any sign of organisation. The embryos of the first type germinated when callus segments were transferred to regeneration conditions, while no change was observed when the second type was induced to regenerate. Higher levels of free IAA and ABA were obtained in the embryogenic calli when compared to the non-embryogenic, while no differences were observed among callus types in the other hormones evaluated. The possible role of the different plant hormones during induction of somatic embryogenesis is discussed.
以胡萝卜（Daucus carota L. F1杂交种Starca）的离体下胚轴为材料，在添加和不添加2,4-二氯苯氧乙酸（2,4-D）的Murashige和Skoog培养基上进行培养，以确定这种植物生长调节剂对其进一步发育及其内源激素水平的影响。在不添加2,4-D的情况下培养，可刺激下胚轴切段一端的根发育，并通过放射免疫测定法测定，使游离吲哚-3-乙酸（IAA）、玉米素/玉米素核苷以及N6（Δ2-异戊烯基）腺嘌呤/N6（Δ2-异戊烯基）腺苷的内源水平升高。另一方面，在培养基中添加2,4-D，在培养的最初几周可促进下胚轴切段的愈伤组织诱导和增殖，同时积累脱落酸（ABA）。当在添加2,4-D的培养基中培养的下胚轴切段产生的愈伤组织切段进一步培养时，观察到两种愈伤组织类型的发育，一种由前球形和球形胚组成，另一种是半透明、似水状且无任何组织迹象。当愈伤组织切段转移到再生条件下时，第一种类型的胚会萌发，而当诱导第二种类型再生时则未观察到变化。与非胚性愈伤组织相比，胚性愈伤组织中游离IAA和ABA的水平更高，而在所评估的其他激素方面，不同愈伤组织类型之间未观察到差异。本文讨论了不同植物激素在体细胞胚胎发生诱导过程中的可能作用。
