Tröbner W, Ramirez L, Motte P, Hue I, Huijser P, Lönnig W E, Saedler H, Sommer H, Schwarz-Sommer Z
Max-Planck-Institut für Züchtungsforschung, Köln, Germany.
EMBO J. 1992 Dec;11(13):4693-704. doi: 10.1002/j.1460-2075.1992.tb05574.x.
GLOBOSA (GLO) is a homeotic gene whose mutants show sepaloid petals and carpelloid stamens. The similarity of Glo mutants to those of the DEFICIENS (DEFA) gene suggests that the two genes have comparable functions in floral morphogenesis. The GLO cDNA has been cloned by virtue of its homology to the MADS-box, a conserved DNA-binding domain also contained in the DEFA gene. We have determined the structure of the wild type GLO gene as well as of several glo mutant alleles which contain transposable element insertions responsible for somatic and germinal instability of Glo mutants. Analyses of the temporal and spatial expression patterns of the DEFA and GLO genes during development of wild type flowers and in flowers of various stable and unstable defA and glo alleles indicate independent induction of DEFA and GLO transcription. In contrast, organ-specific up-regulation of the two genes in petals and stamens depends on expression of both DEFA and GLO. In vitro DNA-binding studies were used to demonstrate that the DEFA and GLO proteins specifically bind, as a heterodimer, to motifs in the promoters of both genes. A model is presented which proposes both combinatorial and cross-regulatory interactions between the DEFA and GLO genes during petal and stamen organogenesis in the second and third whorls of the flower. The function of the two genes controlling determinate growth of the floral meristem is also discussed.
GLO基因是一种同源异型基因，其突变体表现出萼片状花瓣和心皮状雄蕊。GLO突变体与DEFICIENS（DEFA）基因突变体的相似性表明，这两个基因在花形态发生中具有类似的功能。通过与MADS框的同源性克隆了GLO cDNA，MADS框是DEFA基因中也包含的一个保守的DNA结合结构域。我们已经确定了野生型GLO基因以及几个glo突变等位基因的结构，这些突变等位基因包含导致GLO突变体体细胞和生殖细胞不稳定的转座元件插入。对野生型花发育过程中以及各种稳定和不稳定的defA和glo等位基因的花中DEFA和GLO基因的时空表达模式分析表明，DEFA和GLO转录是独立诱导的。相反，这两个基因在花瓣和雄蕊中的器官特异性上调取决于DEFA和GLO的表达。体外DNA结合研究表明，DEFA和GLO蛋白作为异二聚体特异性结合到两个基因启动子中的基序上。本文提出了一个模型，该模型提出了在花的第二轮和第三轮花瓣和雄蕊器官发生过程中，DEFA和GLO基因之间的组合和交叉调节相互作用。还讨论了这两个控制花分生组织确定生长的基因的功能。
