Functional varieties of floral homeotic genes caused by gene duplications

A类基因的功能我们发现矮牵牛卷叶同源基因PhCLF1和PhCLF2在盲突变体的所有花器官和叶片中都有表达，并且通过对它们的cDNA序列分析和杂交，发现PhCLF1和PhCLF2都不是BL基因。基因组序列分析表明，在PhCLF1的一个内含子中插入转座元件导致了其mRNA的选择性剪接。过量表达PhCLF1基因的转基因烟草植株表现为野生型。B类基因的功能过表达PIiTM6或pMADS2基因的转基因矮牵牛表现出从花冠到花瓣的同源异型变化，以及子房的形态异常。这些结果表明这些基因具有B类同源异型基因的功能。利用酵母三杂交系统，我们还发现pMADS2基因产物与C类和F类基因产物形成了异源三聚体。FBP2基因在花瓣中表现出形态异常。当这些植物与pMADS3过表达基因杂交时，pMADS3过表达基因的表型得到了增强，例如从花瓣到雄蕊的同源异型变化。

Function of class A-type genesWe found that petunia CURLY LEAF homologs, PhCLF1 and PhCLF2, were expressed in all the floral organs and leaves of the blind (bl) mutant, and that either PhCLF1 or PhCLF2 were not the BL gene, by analysis of their cDNA sequences, as well as by crossing. Genomic sequence analysis suggested that the insertion of transposable elements in an intron of PhCLF1 caused alternative splicing of its mRNA. Transgenic tobacco plants which overexpressed PhCLF1 cDNA showed wild-type phenotypes. We are going to produce transgenic petunia plants which repress expression of PbCLF genes by RNAi.Function of class B-type genesTransgenic petunia plants which overexpress cDNA of PIiTM6 or pMADS2 showed homeotic changes from sepals to petals, as well as morphological abnormalities in the ovary. These show that these genes have function of the class B homeotic gene. We also found that the pMADS2 gene product forms a heterotrimer with products of class C and class F genes, by using the yeast three-hybrid system.Function of the class E-type geneTransgenic petunia plants which overexpress. FBP2 cDNA showed morphological abnormalities in petals. When these plants were crossed with the pMADS3 overexpresser, phenotypes of the pMADS3 overexpresser, such as a homeotic change from petals to stamens, were enhanced.