Genetic interactions among floral homeotic genes of Arabidopsis.
Genetic interactions among floral homeotic genes of Arabidopsis.
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发表时间：
1991-05
期刊：
影响因子：
4.6
通讯作者：
John L. Bowman;David R. Smyth;E. Meyerowitz
中科院分区：
文献类型：
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作者：
John L. Bowman;David R. Smyth;E. Meyerowitz
我们描述了三个位点的等位基因系列，突变导致拟南芥花中两个相邻轮的同源异型转换。用扫描电镜观察了成熟花的结构及其从原基发育的过程。APETALA 2基因座的新突变，ap 2 -2，ap 2 -8和ap 2 -9，导致外部两个轮的同源异型转换：萼片到心皮（或叶）和花瓣到雄蕊。Pistillata的两个新突变，pi-2和pi-3，导致第二和第三轮器官分化不正确。同源异型转换是花瓣到萼片和雄蕊到心皮，这一模式类似于先前描述的无花瓣3 -1突变。AGAMOUS突变，ag-2和ag-3，影响第三和第四轮，导致花瓣代替雄蕊发育，另一朵花代替雌蕊群出现。除了同源异型变化，APETALA 2、APETALA 3和PISTILLATA基因座的突变可能导致特定轮生体中器官数量减少，甚至器官缺失。还描述了用这些和先前描述的等位基因构建的双重和三重突变株的芽和花表型。基于这些结果，提出了一个模型，表明这些同源异型基因的产品是每个活跃的领域占据两个相邻的轮，AP 2在两个外轮，PI和AP 3在两个和三个轮，AG在两个内轮。因此，这三个同心重叠区域中的基因产物结合起来，指定了野生型花中的四种器官类型。此外，多个突变株系的表型表明AGAMOUS和APETALA 2基因的野生型产物拮抗性地相互作用。AP 2似乎保持AG基因在两个外轮中不活跃，而相反的情况可能在两个内轮中。该场模型成功地预测了所描述的所有单、双和三突变花的表型。
We describe allelic series for three loci, mutations in which result in homeotic conversions in two adjacent whorls in the Arabidopsis thaliana flower. Both the structure of the mature flower and its development from the initial primordium are described by scanning electron microscopy. New mutations at the APETALA2 locus, ap2-2, ap2-8 and ap2-9, cause homeotic conversions in the outer two whorls: sepals to carpels (or leaves) and petals to stamens. Two new mutations of PISTILLATA, pi-2 and pi-3, cause second and third whorl organs to differentiate incorrectly. Homeotic conversions are petals to sepals and stamens to carpels, a pattern similar to that previously described for the apetala3-1 mutation. The AGAMOUS mutations, ag-2 and ag-3, affect the third and fourth whorls and cause petals to develop instead of stamens and another flower to arise in place of the gynoecium. In addition to homeotic changes, mutations at the APETALA2, APETALA3 and PISTILLATA loci may lead to reduced numbers of organs, or even their absence, in specific whorls. The bud and flower phenotypes of doubly and triply mutant strains, constructed with these and previously described alleles, are also described. Based on these results, a model is proposed that suggests that the products of these homeotic genes are each active in fields occupying two adjacent whorls, AP2 in the two outer whorls, PI and AP3 in whorls two and three, and AG in the two inner whorls. In combination, therefore, the gene products in these three concentric, overlapping fields specify the four types of organs in the wild-type flower. Further, the phenotypes of multiple mutant lines indicate that the wild-type products of the AGAMOUS and APETALA2 genes interact antagonistically. AP2 seems to keep the AG gene inactive in the two outer whorls while the converse is likely in the two inner whorls. This field model successfully predicts the phenotypes of all the singly, doubly and triply mutant flowers described.