Kapoor Meenu, Tsuda Shinzo, Tanaka Yoshikazu, Mayama Tomoko, Okuyama Yohei, Tsuchimoto Suguru, Takatsuji Hiroshi
Developmental Biology Laboratory, Plant Physiology Department, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan.
Plant J. 2002 Oct;32(1):115-27. doi: 10.1046/j.1365-313x.2002.01402.x.
pMADS3, a petunia class C gene, is the candidate homologue of Arabidopsis AGAMOUS (AG), which is involved in the specification of stamens and carpels. We report the characterization of loss-of-function phenotype of pMADS3 that resulted from silencing of this gene. Silencing of pMADS3 resulted in homeotic conversion of stamens into petaloid structures, whereas the carpels were only weakly affected. Ectopic secondary inflorescences emerged from the interstamenal region in the third whorl, which is unique and has not been reported for any class C gene of other plant species. Third-order inflorescences emerged at corresponding positions in the third whorl of inner flowers of secondary inflorescences, indicating reiterative conversion of parts of the floral meristem into inflorescence meristem. On the basis of phenotypic analysis of the pMADS3-silenced plants, we propose that pMADS3 is involved in determination of floral organ and floral meristem identity in petunia. Two hybrid studies in yeast showed that PMADS3 protein interacted specifically with FBP2, a candidate homologue of Arabidopsis SEPALLATA3 (SEP3). The evidence presented here suggest that a complex involving PMADS3 and FBP2 is responsible for specification of organ identity in the third whorl.
pMADS3是矮牵牛C类基因，是拟南芥AGAMOUS（AG）的候选同源基因，参与雄蕊和心皮的特化。我们报道了该基因沉默导致的pMADS3功能缺失表型的特征。pMADS3的沉默导致雄蕊同源异型转变为花瓣状结构，而心皮仅受到轻微影响。异位二级花序从第三轮雄蕊间区域长出，这一现象十分独特，在其他植物物种的任何C类基因中均未报道过。三级花序在二级花序内花的第三轮相应位置出现，表明花分生组织的部分区域反复转变为花序分生组织。基于对pMADS3沉默植株的表型分析，我们认为pMADS3参与矮牵牛花器官和花分生组织特征的决定。两项酵母杂交研究表明，PMADS3蛋白与FBP2特异性相互作用，FBP2是拟南芥SEPALLATA3（SEP3）的候选同源基因。此处提供的证据表明，一个涉及PMADS3和FBP2的复合体负责第三轮器官特征的特化。
