Developmental and Structural Section
Wu, Chi-Chih , Diggle, Pamela K. , Friedman, William E. .
Development of the female gametophyte and young fruit of Balsas teosinte, Zea mays subsp. parviglumis.
Balsas teosinte, Zea mays subsp. parviglumis, is the closest wild relative of cultivated maize (corn), Zea mays subsp. mays. Maize and teosinte differ in many morphological characters, including those of the fruit or kernels. Maize has large, starchy, soft kernels, whereas the kernel of teosinte is far smaller and surrounded by a hard cupulate fruitcase. The development of the kernel, especially in the female gametophyte, embryo and endosperm, has been studied for cultivated maize; however, little is known about these components of sexual reproduction in teosinte. In order to understand the evolutionary transition of these traits during the domestication of maize from teosinte, we used a comparative developmental and morphological approach to study megasporogenesis, megagametogenesis, embryogenesis and the formation of young fruit of teosinte. In addition, we investigated the timing of key features of sexual reproduction, including double fertilization, the first mitotic division of the zygote and the primary endosperm nucleus, and the cellularization of endosperm. Our results show that, in general, the developmental pattern of the female gametophyte of teosinte is similar to that of cultivated maize. Both are varieties of the Polygonum type with proliferative antipodal cells at maturity. In addition, our analysis of the growth rate of pollen tube in teosinte suggests that as the length of the silk (stigma) increased during the maize domestication, there was a coordinated increase in pollen tube growth rates. Finally, although similar in pattern, many features of endosperm development appear to be initiated precociously in teosinte compared with cultivated maize. The relatively short period of free-nuclear endosperm development and early onset of cellularization of endosperm in teosinte may be critical features that result in a smaller seed/fruit compared to maize.
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1 - University of Colorado Boulder, Department of Ecology and Evolutionary Biology, Ramaley N122, Campus Box 334, Boulder, CO, 80309, USA
2 - University of Colorado, Department of Ecology and Evolutionary Biology, UCB 334, Boulder, Colorado, 80309, USA
3 - University of Colorado, Department of Ecology and Evolutionary Biology, Campus Box 334, Boulder, CO, 80309, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 551A/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 2:00 PM