Fischer C., Speth V., Fleig-Eberenz S., Neuhaus G.
University of Freiburg, Institute of Biology II, Cell Biology, Schanzlestrasse 1, D-79104 Freiburg, Germany.
Plant Cell. 1997 Oct;9(10):1767-1780. doi: 10.1105/tpc.9.10.1767.
The effects of two auxin polar transport inhibitors, N-1-naphthylphthalamic acid (NPA) and 3,3[prime],4[prime],5,7-pentahydroxyflavone (quercetin), on attaining bilateral symmetry from radial symmetry during early wheat embryogenesis were investigated by using an in vitro culture system. Although NPA and quercetin belong to two different classes of auxin transport inhibitors, the phytotropins and the flavonoids, respectively, they induced the same specific abnormal phenotypes during embryo development. These abnormal embryos differentiated multiple meristems (i.e., multiple shoot and root meristems) and multiple organs (i.e., multiple coleoptiles and scutella). Multiple shoot apical meristem phenotypes were characterized by partly multiplied embryonic axes and supernumerary scutella. The differentiation of multiple primary roots in addition to multiple shoot meristems and multiple scutella led to the formation of polyembryos. The occurrence of multiple shoot meristem phenotypes depended on the concentration of the inhibitor and the developmental stage of the isolated embryo. Embryos treated with NPA or quercetin developed multiple radicle phenotypes less frequently than they developed multiple shoot meristem phenotypes. Our observations suggest that the root meristem differentiates later than the shoot meristem. Our data support the hypothesis that polar transport of auxin has a determining influence on the differentiation of the embryonic axis and the scutellum.
利用体外培养系统，研究了两种生长素极性运输抑制剂——N-1-萘基邻苯二甲酸（NPA）和3,3′,4′,5,7-五羟基黄酮（槲皮素）对小麦早期胚胎发育过程中从辐射对称向两侧对称转变的影响。尽管NPA和槲皮素分别属于两类不同的生长素运输抑制剂，即植物生长素运输抑制剂和黄酮类化合物，但它们在胚胎发育过程中诱导了相同的特定异常表型。这些异常胚胎分化出多个分生组织（即多个茎尖和根尖分生组织）和多个器官（即多个胚芽鞘和盾片）。多个茎尖分生组织表型的特征是部分胚胎轴倍增和盾片多余。除了多个茎尖分生组织和多个盾片外，多个初生根的分化导致了多胚的形成。多个茎尖分生组织表型的出现取决于抑制剂的浓度和分离胚胎的发育阶段。用NPA或槲皮素处理的胚胎形成多个胚根表型的频率低于形成多个茎尖分生组织表型的频率。我们的观察结果表明，根分生组织的分化晚于茎尖分生组织。我们的数据支持这样的假说，即生长素的极性运输对胚胎轴和盾片的分化具有决定性影响。
