Analysis of Floral Organ Identity in Arabidopsis

植物发育与动物发育在许多基本方面不同。十字花科植物拟南芥的花被用作模型，试图了解控制植物发育的基本分子机制。特别是，拟议的实验集中在花中器官身份的指定上。近年来在许多植物物种中进行的实验表明，控制花器官特性的基因在不同的植物物种中高度保守。因此，收集到的有关拟南芥花发育的信息可能适用于其他植物物种。这里提出的实验涉及APETALA3(AP3)的特征，AP3是一个同源异型基因，与花瓣和雄蕊的发育有关。AP3已被克隆，并对其RNA和蛋白质的表达模式进行了研究。AP3蛋白有一个保守的57个氨基酸结构域，称为MADS结构域。MADS结构域被认为编码DNA结合功能，有证据表明AP3与DNA结合。然而，由于缺乏与生物相关的靶(DNA结合)序列，植物MADS结构域蛋白的生物学功能的阐明一直受到阻碍。第一组拟议的实验旨在确定AP3启动子中涉及AP3的建立、维持(自动调节)和胚珠特异性表达的序列。第二组拟议的实验旨在识别相互作用、调节或受AP3调节的基因。抑制子和增强子突变与AP3和其他花同源异型突变体的遗传相互作用将被描述。

Plant development differs from animal development in a variety of fundamental ways. The flower of the cruciferous plant Arabidopsis thaliana is being used as a model to attempt to understand the basic molecular mechanisms that control plant development. In particular, the proposed experiments focus on the specification of organ identity in the flower. Experiments performed in recent years in a number of plant species, in particular in Arabidopsis and snapdragon, have revealed that the genes that control the specification of organ identity in the flower are highly conserved in different plant species. Thus, information gathered about flower development in Arabidopsis is likely to be applicable to other plant species. The experiments proposed here deal with the characterization of APETALA3 (AP3), a homeotic gene involved in specifying the development of petals and stamens in the flower. AP3 has been cloned and its RNA and protein expression patterns characterized. The AP3 protein has a conserved 57 amino acid domain called the MADS domain. The MADS domain is postulated to encode a DNA binding function, and there is evidence that AP3 binds DNA. Elucidation of the biological function o the plant MADS domain proteins, however, has been hindered by the lack of a biologically relevant target (DNA binding) sequence. The first set of proposed experiments is aimed at defining the sequences in the AP3 promoter involved in establishment, maintenance (autoregulation), and ovule- specific expression of AP3. The second set of proposed experiments is designed to identify genes that interact, regulate, or are regulated by AP3. The genetic interactions of the suppressor and enhancer mutations with both ap3 and the other floral homeotic mutants will be characterized.