Poster: Tropisms

Abs # 410: Molecular Mapping of the Gravity Persistent Signal Loci of Arabidopsis thaliana

Presenter:	Withers, John C., johnw21@frognet.net
Authors	Withers, John C. (A)   McCallister, Jennifer E. (A)   King, Ryan C. (A)   Wyatt, Sarah E. (A)
Affiliations:	(A): Ohio University

Gravity is an important factor influencing plant growth. When shoots are gravistimulated at room temperature, they respond by bending away from the gravity vector. When gravistimulated at 4°C, the inflorescence stems do not respond until they are returned to room temperature. The gravity persistent signal (gps) mutants of Arabidopsis respond abnormally after cold gravistimulation. Three phenotypes have been identified: no response, wrong way response, and the over-achiever. Molecular mapping is a technique that is useful for determining the position of the gene of interest, in relation to loci that have been defined as positional markers of the genome. To generate a mapping population, the gps mutants (ecotype WS) were crossed with wildtype Columbia plants. Progeny of the F1 generation were allowed to self-pollinate, and seeds from the F2 population were germinated, grown to maturity, and screened for a gps response. Forty six plants, from approximately 200, were selected that showed the no response phenotype. Several markers were then selected on the basis of sequence polymorphisms between the WS and Columbia ecotypes. The genotype for each marker was determined for the 46 individuals by a standard PCR amplification, using primers that were specifically designed to amplify the regions of the selected markers. Linkage was determined by comparing the genotype segregation ratios in the selected plants. Of all of the markers analyzed, only T16K5-TGF, a marker on the short arm of chromosome 3, was found to be linked with the no response phenotype. (Supported by NASA: NAG2-1608; US Department of Agriculture: 2002-35304-12333; and the Ohio University Provost’s Undergraduate Research Fund.)