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Genetics Section

Hu, Jer-Ming [1], Su, Huei-Jiun [1], Wu, Cheng-Chiang [1].

Studies of floral B class gene evolution in basal core Eudicots.

Although the floral ABC model is general accepted as ubiquitous in flowering plants, variation in gene expression has been found in basal angiosperms and basal eudicots. Accordingly, the basal eudicots and basal core eudicots show highly variable floral features in terms of flower size and floral organ numbers, such as the absence of perianth in Trochodendron aralioides and size reduction in flowers of Santalales. These plants are critical to understand the evolutionary developmental program of perianth in flowering plants. Previous studies have shown that there is a major duplication event of all ABC class genes along the branch leading to core eudicot lineages. However, only one of the two B class homologues (AP3-like) is found duplicated and fixed in this major event, i.e. to euAP3 and TM6 lineages, but not PI homologue. Such duplication may be responsible for the diverse floral features among basal eudicots. Here we chose taxa from Buxaceae, Trocodendraceae, Dilleniaceae and Santalales to explore the B class gene duplication among basal core eudicots. 17 cDNAs homologous to B class gene were cloned from Buxus microphylla, T. aralioides, Thesium chinense, Loranthus kaoi, Loranthus delavayi, and Dillenia indica. All of these taxa have one to three PI homologues, and various number of AP3 homologues. Results from phylogenetic analysis suggest that the first two taxa have paleoAP3 homologues whereas the later four are most likely having either TM6 or euAP3-like homologues. Interestingly, euAP3 homolog is not found in the screening of B class genes from Santalales species, suggesting the function could be complemented by PI or TM6 homologues if they are truly absent in Santalales.

1 - National Taiwan University, Institute of Ecology and Evolutionary Biology, Rm1227, Life Science Building, 1 Roosevelt Road, Sect.4, Taipei, 106, Taiwan

ABC model
gene evolution.

Presentation Type: Poster
Session: 32-49
Location: Special Event Center (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 12:30 PM
Abstract ID:224

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