Evolutionary Developmental Biology (Evo-Devo)
Chang, Tien-Hao , Hu, Jer-Ming .
Petaloidy and floral organ identity genes in Hydrangea chinensis (Hydrangeaceae).
Pseudanthia are quite common in the family Hydrangeaceae, which is formed by enlarged sepals on peripheral flowers of the inflorescence. The flowers with these petaloid sepals are generally sterile and served as attractants to the pollinators. In order to examine the underlying mechanism of the petaloidy formation, we have identified homologues to the A, B, and E classes floral homeotic genes from Hydrangea chinensis. One A-class (HycFL), three B-class (HycPI, HycAP3, HycTM6), one C-class (HycAG) and one E-class (HycMADS1) floral homeotic genes were identified. RT-PCR results show that HycFL, HycTM6, and HycMADS1 have ubiquitous expression in all floral parts. In contrast, HycAP3, HycPI, and HycAG do not show expression on the sepals. Under SEM examination, the epidermal surfaces of cells on examined floral parts all have cuticular striation, while only adaxial epidermal cells of enlarged sepals show conical shape. We have also successfully cloned HycMYB1, a homolog of MIXTA that were shown to be responsible for conical cell formation in Antirrhinum majus. The RT-PCR result shows that HycMYB1 is highly expressed in enlarged sepals and much less in normal sepals and petals. Since HycFL, HycTM6, HycMADS1 and HycMYB1 are all expressed in enlarged sepals, they are the candidate genes involved in the formation of petaloid sepals of H. chinensis.
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1 - National Taiwan University, Institute of Ecology and Evolutionary Biology, Rm1227, Life Science Building, 1 Sec.4 Roosevelt Road, Taipei, 10617, Taiwan
Presentation Type: Oral Paper:Papers for Topics
Location: Cottonwood A/Snowbird Center
Date: Wednesday, July 29th, 2009
Time: 11:15 AM