Poster: Vegetative Development
Abs #
441: bul, elaborating form in Arabidopsis
Adult morphology in animals is patterned during embryogenesis through coordinated cell division and migration. In contrast, little of an adult plant's morphology is determined during embryogenesis. Rather, only the basic stem and root polarity of the plant is determined by embryonic cell divisions, while form is elaborated post-embryonically mainly through cell expansion and localized somatic cell divisions. Because the wall of a plant cell fixes all cells in space, cell migrations do not contribute to pattern. However, the plane of cell division and expansion, as well as number of cell divisions occurring has a dramatic impact on the overall morphology. Thus, alterations in either, or both, the number or plane of cell division and expansion can have drastic influences on plant form. In a screen for mutations that would suppress the differential growth phenotypes of an nph4/arf7-null mutant of Arabidopsis, we identified a dominant gain-of-function mutant with very distinct aerial tissue phenotypes. Most notably, rosette leaves are extremely convoluted and the inflorescence stems are dramatically thickened. We have named this mutant bul since its leaves resemble those of Butterhead lettuce (Lactuca sativa). The bul phenotypes appear to be conditioned by changes in both the number and size of cells in the affected tissues. We are in the process of determining the identity of the BUL gene and its protein product. Further study of BUL and its affects on cell division and expansion is likely to contribute significantly to our understanding of how plants elaborate form.
