van der Krol A R, Brunelle A, Tsuchimoto S, Chua N H
Laboratory of Plant Molecular Biology, Rockefeller University, New York, New York 10021.
Genes Dev. 1993 Jul;7(7A):1214-28. doi: 10.1101/gad.7.7a.1214.
The petunia mutant green petal (gp, line PLV) shows a homeotic effect in one floral whorl, that is, the conversion of petal to sepal. We demonstrate that this mutant contains a chromosomal deletion, including the petunia MADS box gene pMADS1. Second whorl petal development in this null mutant can be restored with a CaMV 35S-pMADS1 transgene, demonstrating the essential role of pMADS1 in this process. Because gp (PLV) shows only a minor effect on stamen development, the homeotic effects of pMADS1 are different from those of B-type genes in Antirrhinum and Arabidopsis. Two other MADS box genes, pMADS2 and fbp1 (Angenent et al. 1992), require pMADS1 to maintain expression in the second whorl. However, in the absence of pMADS1 these two genes continue to be expressed in the third whorl. The functions assigned to pMADS1 are further supported by experiments in which we phenocopy gp by cosuppression of pMADS1 gene expression. The flowers, obtained through cosuppression and phenotype restoration, display different degrees of sepal to petal conversion. Analysis of these flowers indicate that pMADS1 controls growth under the zone of petal and stamen initiation, which causes the corolla tube and stamen filaments to emerge as a congenitally fused structure.
矮牵牛突变体绿色花瓣（gp，品系PLV）在一个花轮中表现出同源异型效应，即花瓣向萼片的转变。我们证明该突变体包含一个染色体缺失，包括矮牵牛MADS盒基因pMADS1。用CaMV 35S - pMADS1转基因可以恢复该无效突变体第二轮花瓣的发育，这表明pMADS1在此过程中起关键作用。由于gp（PLV）对雄蕊发育仅产生轻微影响，pMADS1的同源异型效应与金鱼草和拟南芥中B类基因的不同。另外两个MADS盒基因pMADS2和fbp1（安根内特等人，1992年）需要pMADS1来维持在第二轮中的表达。然而，在没有pMADS1的情况下，这两个基因在第三轮中继续表达。通过共抑制pMADS1基因表达模拟gp的实验进一步支持了赋予pMADS1的功能。通过共抑制和表型恢复获得的花朵表现出不同程度的萼片向花瓣的转变。对这些花朵的分析表明，pMADS1控制花瓣和雄蕊起始区域下方的生长，这导致花冠管和雄蕊花丝以先天性融合结构出现。
