蘭花的花器構造由外而內為：花萼、花瓣、唇瓣、合蕊柱及子房。唇瓣為高度特化的花瓣，吸引授粉者前來為其授粉。本篇研究旨在探討屬於MADS-box 轉錄因子的AGL6基因如何參與蘭花發育。
本研究發現姬蝴蝶蘭保存有三個AGL6-like 基因，分別為PeAGL6a，PeAGL6b及PeAGL6c。依據序列比對及演化樹分析的結果，推測姬蝴蝶蘭的AGL6-like 基因經過ㄧ次複製產生兩條同物種同源基因，其中PeAGL6c在序列上與單子葉植物的同源基因相似而較為保留; 另外一條AGL6-like 基因經過突變而改變了部份的胺基酸，並且再次複製而產生PeAGL6a及PeAGL6b，這兩個基因在親緣上獨立於被子植物及裸子植物之間，同時我們發現文心蘭的AGL6-like 基因 (OMADS1)也歸屬此外群，究竟此獨特的AGL6-like外群基因在蘭花花部發育上扮演什麼樣的角色。由RT-PCR及in situ localization的結果得知PeAGL6c在各個花器皆微量表現，但主要表現於花梗，花梗未來會發育成子房的構造，因而保留有大部份植物AGL6基因表現子房的特性。此外PeAGL6c也表現於花發育始原細胞，可能調控始原細胞走向分化。PeAGL6b於花器分化早期表現於各花器，分化晚期於花萼及花瓣內的表現下降，集中表現於唇瓣與合蕊柱，在成熟花苞中則可以看到PeAGL6b在各花器內些微表現。PeAGL6a表現於花發育初期及花苞的唇瓣、花萼與合蕊柱中。由yeast two-hybrid的結果可知PeAGL6a、PeAGL6b、PeAGL6c蛋白皆可與B群PeMADS2~6以及E群的PeMADS8蛋白結合，並與AGL6蛋白相互結合形成異質二元體 (heterodimer)，唯一不同的是PeAGL6a與PeAGL6b皆可形成同質二元體 (homodimer) ，但PeAGL6c則否，推測是因為胺基酸的改變造成結合能力差異。由結果推測，表現於花器分化早期的PeAGL6b與 PeAGL6a可能B群及C群MADS-box蛋白形成聚合體，形成調控花部發育的MADS-box轉錄因子複合體。

Phalaenopsis is a member of the Orchidaceae, its flowers contain three sepals, two petals and a highly modified petal, the labellum or lip. Because of lip faces to column (a fusion of the male and female reproductive organs, with stamen on the column top), it is considered to be important for both pollination and evolution of orchids. Previously, we have identified an AGL6-like gene, PeAGL6a, will highly expressed in lip and ectopic expressed in lip-like petal of peloric mutant. In this study we further investigation of whether AGL6-likge genes involved in flower development of Phalaenopsis orchid.
In this study, three AGL6-like genes of P. equestris were found. According to the results of sequence and phylogenetic analyses, suggesting that the ancient AGL6-like gene of P. equestris was duplicated into two paralogous genes. One of them is PeAGL6c which is most similar to AGL6-like gene of monocots in amino acid sequence. The other paralogous gene was duplicated again to produce PeAGL6a and PeAGL6b. PeAGL6a and PeAGL6b were classified with OMADS1 of Oncidium into the branch-group of angiosperm. The role of unique branch-group of AGL6-like genes for orchid floral morphogenesis is interesting. Results of RT-PCR and in situ hybridization revealed that PeAGL6c expressed in all floral organs but higher expressed in pedicle which contains immature ovary. These expression profiles were similar to that of most AGL6-like genes. In addition, PeAGL6c also highly expressed in floral meristem and primodium, and may be related to floral transition identity. PeAGL6b were expressed in all floral organs in early floral differentiation stage, and it continued to highly express in lip and column and slightly express in sepal and petal until floral development complete. In mature flower buds, PeAGL6b was slightly expressed in all floral organs. PeAGL6a was specific expressed in sepal, lip and column in both of early floral development stage and floral bud. In yeast two-hybrid analysis, PeAGL6a、PeAGL6b and PeAGL6c all could interact with B-class MADS proteins and E-class MADS protein (PeMADS8). Moreover, they could interact with each other to form heterodimers. However, PeAGL6a and PeAGL6b could form homodimer, but PeAGL6c could not. It suggested that the capacity of forming homodimer of PeAGL6a and PeAGL6b result from some amino acids were changed. Furthermore, I presumed PeAGL6b and PeAGL6a which expressed in early flower development stage will combine with B-class proteins and E-class MADS proteins to form MADS-box transcription factor complex to regulate floral organ identity.

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