Chen Ming-Kun, Lin I-Chun, Yang Chang-Hsien
Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan 40227, ROC.
Plant Cell Physiol. 2008 May;49(5):704-17. doi: 10.1093/pcp/pcn046. Epub 2008 Mar 26.
Three cDNAs showing a high degree of homology to the SQUA subfamily of MADS box genes were isolated and characterized from the lily (Lilium longiflorum). Lily MADS Box Gene 5 (LMADS5) showed high sequence identity to oil palm (Elaeis guineensis) SQUAMOSA3 (EgSQUA3). LMADS6 is closely related to LMADS5 whereas LMADS7 is more related to DOMADS2, an orchid (Dendrobium) gene in the SQUA subfamily. The expression pattern for these three genes was similar and their RNAs were detected in vegetative stem and inflorescence meristem. LMADS5 and 6 were highly expressed in vegetative leaves and carpel, whereas LMADS7 expression was absent. Ectopic expression of LMADS5, 6 or 7 in transgenic Arabidopsis plants showed novel phenotypes by flowering early and producing terminal flowers. Homeotic conversions of sepals to carpelloid structures and of petal to stamen-like structures were also observed in 35S::LMADS5, 6 or 7 flowers. Ectopic expression of LMADS6 or LMADS7 was able to complement the ap1 flower defect in transgenic Arabidopsis ap1 mutant plants. These results strongly indicated that the function of these three lily genes was involved in flower formation as well as in floral induction. Furthermore, the ability of lily LMADS6 and 7 to complement the Arabidopsis ap1 mutant provided further evidence to show that the conserved motifs (paleoAP1 or euAP1) in the C-terminus of the SQUA/AP1 subfamily of MADS box genes is not strictly necessary for their function.
从百合（Lilium longiflorum）中分离并鉴定出三个与MADS盒基因SQUA亚家族具有高度同源性的cDNA。百合MADS盒基因5（LMADS5）与油棕（Elaeis guineensis）的SQUAMOSA3（EgSQUA3）具有高度的序列同一性。LMADS6与LMADS5密切相关，而LMADS7与SQUA亚家族中的兰花（Dendrobium）基因DOMADS2关系更为密切。这三个基因的表达模式相似，在营养茎和花序分生组织中检测到它们的RNA。LMADS5和6在营养叶和心皮中高表达，而LMADS7不表达。在转基因拟南芥植株中异位表达LMADS5、6或7会表现出早花和产生顶生花的新表型。在35S::LMADS5、6或7的花中还观察到萼片向心皮状结构以及花瓣向雄蕊状结构的同源异型转变。异位表达LMADS6或LMADS7能够弥补转基因拟南芥ap1突变体植株中的ap1花缺陷。这些结果有力地表明，这三个百合基因的功能参与了花的形成以及花的诱导。此外，百合LMADS6和7弥补拟南芥ap1突变体的能力进一步证明，MADS盒基因SQUA/AP1亚家族C末端的保守基序（paleoAP1或euAP1）对其功能并非严格必需。
