FLORAL HOMEOTIC MUTATIONS PRODUCED BY TRANSPOSON-MUTAGENESIS IN ANTIRRHINUM-MAJUS
FLORAL HOMEOTIC MUTATIONS PRODUCED BY TRANSPOSON-MUTAGENESIS IN ANTIRRHINUM-MAJUS
复制标题
DOI：
10.1101/gad.4.9.1483
复制
发表时间：
1990-09-01
影响因子：
10.5
通讯作者：
COEN, ES
中科院分区：
文献类型：
--
作者：
CARPENTER, R;COEN, ES
为了分离和研究控制花发育的基因，我们在Antirrhinum majus中进行了大规模的转座子诱变实验。获得了10个独立的花同源突变，根据它们是否影响(1)同一轮内器官的同一性，可将其分为三类；(2)螺纹的同一性，有时也包括螺纹的数量；(3)通常产生花的腋生分生组织的命运。花的表型分类提示了原基命运的遗传控制模型，其中第2类基因在相邻的轮对重叠中起作用，因此它们在花的半径上不同位置的组合可以指定轮的命运和数量。这些基因可能与1类基因相互作用，1类基因在花的垂直轴上的作用不同，从而产生两侧对称。这两个类别最终都可能由花形成所需的第3类基因调控。一些同型表型与其他物种相似，表明控制轮系身份和数量的机制在植物进化中是高度保守的。获得的许多突变显示转座子插入的体细胞和生发不稳定性特征，允许首次测试花同源基因的细胞自主性。此外，我们发现缺陷（def）基因（2类）在整个器官发育过程中起作用，但其作用在不同的发育阶段可能不同，这说明了某些缺陷等位基因赋予的中间表型。在发育早期表达def并不是其后期表达所必需的，这表明其他基因在特定器官的发育过程中起作用以维持def的表达。从叶或花色素突变体的分子分析中获得了由转座子引起突变的直接证据，这表明同源基因的分离现在应该是可能的。
To isolate and study genes controlling floral development, we have carried out a large-scale transposon-mutagenesis experiment in Antirrhinum majus. Ten independent floral homeotic mutations were obtained that could be divided into three classes, depending on whether they affect (1) the identity of organs within the same whorl; (2) the identity and sometimes also the number of whorls; and (3) the fate of the axillary meristem that normally gives rise to the flower. The classes of floral phenotypes suggest a model for genetic control of primordium fate in which class 2 genes are proposed to act in overlapping pairs of adjacent whorls so that their combinations at different positions along the radius of the flower can specify the fate and number of whorls. These could interact with class 1 genes, which vary in their action along the vertical axis of the flower to generate bilateral symmetry. Both of these classes may be ultimately regulated by class 3 genes required for flower initiation. The similarity between some of the homeotic phenotypes with those of other species suggests that the mechanisms controlling whorl identity and number have been highly conserved in plant evolution. Many of the mutations obtained show somatic and germinal instability characteristic of transposon insertions, allowing the cell-autonomy of floral homeotic genes to be tested for the first time. In addition, we show that the deficiens (def) gene (class 2) acts throughout organ development, but its action may be different at various developmental stages, accounting for the intermediate phenotypes conferred by certain def alleles. Expression of def early in development is not necessary for its later expression, indicating that other genes act throughout the development of specific organs to maintain def expression. Direct evidence that the mutations obtained were caused by transposons came from molecular analysis of leaf or flower pigmentation mutants, indicating that isolation of the homeotic genes should now be possible.