Molecular mechanism for formation of two types of flowers in Hydrangea

本研究的目的是阐明绣球花两种类型花形成的分子机制。从绣球花中分离到三个AP 1、两个A.11和一个PI同源物。macrophylla BM-1'。RT-PCR分析表明，LFY同源基因在装饰花的花瓣状萼片中特异表达。利用抑制性消减杂交（SSH）技术分离了蓝冠品种"蓝天"和"蓝天"芽变品种"BM-1"花蕾中的差异表达基因。对从蓝天SSH文库中筛选到的16个cDNA克隆进行RT-PCR分析表明，这些克隆在蓝天花蕾中的表达比在BM-1花蕾中的表达强。根据在"蓝天"和"BM-1"的花蕾、叶芽和叶片上的表达模式，这些克隆被分为四组。如对从"蓝天" SSH文库分离的cDNA克隆的序列分析所示，至少一个Ty1/copia-样和六个Ty/3/gypsy-样逆转录转座子的RT序列在"蓝天"中表达。RT-PCR分析表明，转座子样基因在原品种‘蓝天’的花芽、叶芽、叶片和根中均有表达。在芽变品种BM-1 '中，逆转录转座子样基因的表达在花芽上受到抑制，尽管这些基因在叶芽、叶和根上表达。

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.