Molecular mechanism for formation of two types of flowers in Hydrangea

摘要本研究旨在阐明绣球花中两种花的形成分子机制。从大叶绣球花（H. macrophylla）中分离到3个AP1、2个A.11 1的同源物。RT-PCR分析表明，lfy9同源基因在花萼中有特异性表达。另一方面，原位杂交分析显示，两个ap3同源物之一的HmAP3在花瓣状萼片中未表达。采用抑制减法杂交（SSH）方法，分离了蕾丝花品种蓝天’和蓝天花蕾运动的黑麦品种bm - 1’花蕾上的差异表达基因。通过RT-PCR分析Blue Sky’SSH文库中16种cDNA克隆的表达情况，发现这些克隆在Blue Sky’花蕾上的表达强于在BM-1’花蕾上的表达。根据“蓝天”和“BM-1”在花蕾、叶蕾和叶片上的表达模式，将这些无性系分为4个类群。结果表明，从Blue Sky’的SSH文库中分离的cDNA克隆序列分析显示，在Blue Sky’中至少表达了1个Ty1/ copy -like和6个Ty/3/gypsy-like逆转录转座子的序列。RT-PCR分析显示，“蓝天”原品种的花蕾、叶芽、叶和根上均有反转录转座子样基因表达。在芽运动品种BM-1中，逆转录转座子样基因在花蕾上的表达受到抑制，而这些基因在叶芽、叶和根上均有表达。

The purpose of this study is the elucidation of the molecular mechanism for formation of two types of flowers in HydrangeaThree AP1, two A.11 one PIhomologues were isolated from H. macrophylla BM-1'. RT-PCR analysis for expression of several genes including these homologues showed LFYhomologue was expressed specifically in petaloid sepals of the decorative flowers. On the other hand, in situ hybridization analysis showed HmAP3, one of the two AP3homologues, was not expressed in the petaloid sepals.The suppression subtractive hybridization (SSH) method was used to isolate differentially expressed genes on the flower buds between the lacecap cultivar Blue Sky' and the hortensia cultivar BM-l' which was bud sports from Blue Sky'. As show by RT-PCR analysis for expression of sixteen kinds of cDNA clones from Blue Sky' SSH library which did not show similarity to any genes on BLAST search, these clones were expressed on flower buds of Blue Sky' more strongly than on those of 'BM-1'. These clones were classified into four groups according to the expression pattern on flower buds, leaf buds and leaves of Blue Sky' and 'BM-1'.As shown analysis for sequences of cDNA clones isolated from Blue Sky' SSH library RT sequences of at least one Ty1/copia-like and six Ty/3/gypsy-like retrotransposons were expressed in Blue Sky'. RT-PCR analysis showed retrotransposon-like genes were expressed on flower buds, leaf buds, leaves and roots in the original cultivar Blue Sky'. In the bud sport cultivar BM-1' the expression of retrotransposon-like genes were suppressed on flower buds, although these were expressed on leaf buds, leaves and roots.