Evolutionary Developmental Biology (Evo-Devo)
Wang, Xin .
Homology of the Carpels and Origin of the Flowers.
Angiosperms are the most diverse plant group in the global ecosystem and the most important for human well-being. Carpel is the most characteristic feature of angiosperms. Nevertheless, its nature has been misinterpreted. In the past decades much progress has been made concerning the nature of carpels independently in the fields of plant morphology, anatomy, development, genetics, and palaeobotany. It is well known that there are two growth domains in a carpel, one for placenta/ovules and the other for carpel wall. Gene expression pattern in carpels indicates that these two domains have mutually exclusively expressed genes, and ovules of angiosperms can develop without carpel wall in mutated angiosperms, just as the ovules in gymnosperms that have nothing to do with carpels. Carpel walls of plants with basal or free central placentation have little to do with placenta or ovules, except covering them. Vascular bundles of carpel wall display adnation freely either with the ovule or with the stamen in the same genus, implying independence of placenta/ovules and carpel wall. Amphicribral vascular bundles, characteristic of a stem rather than a leaf, are almost always associated with placenta/ovules. A Jurassic fossil plant from China has its ovules attached to a column within an enclosed space, just like a free central placentation. All these data from various fields of botany independently and coherently suggest that the carpel in the traditional doctrine is a composite organ of two but not one part. It is the varying combinations of these flower parts that contribute to the unprecedentedly great flower diversity in angiosperms. This conclusion lays down the foundation for future logic in interpreting the origin and history of angiosperms and their carpels, as well as the position of angiosperms among seed plants.
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Link to my monography on early angiosperms
1 - Nanjing Institute Of Geology And Palaeontology, 39 Beijing Dong Road, Nanjing, N/A, 210008, China
Presentation Type: Oral Paper:Papers for Topics
Location: Delaware C/Hyatt
Date: Tuesday, July 10th, 2012
Time: 8:30 AM