In the search for genes regulating plant signaling responses to changes in gravity, the Wyatt Lab has focused several research projects on a series of mutant Arabidopsis thaliana plants known as gps mutants. The gps mutants react to gravity differently than wild type (WT) plants. For example, when gps-2 mutants are exposed to the GPS treatment they bend the opposite way from WT plants. The predictable direction each gps mutant strain bends in response to the GPS treatment denotes a phenotype, and these physical differences are important because they are attributable to underlying genetic differences between the plants (that is, differences in genotypes).
Figure 1 – Wild type (here labeled Ws) and gps mutant phenotypes shown at room temperature “remembering” the gravity vector from an earlier GPS treatment. The wild type phenotype (panel A) demonstrates the expected gravitropic reaction; the three gps mutants show aberrant reactions to the GPS treatment characteristic of each phenotype.
One method of determining the role individual genes play in a plant genome is to randomly disrupt the WT genome and observe the effects on the plant. When the WT genome was disrupted through DNA insertion the resulting mutants reacted differently to changes in gravity (gravity persistent signaling) than WT plants. The discovery of gps mutant phenotypes allowed the Wyatt Lab to isolate early signaling events and identify genes controlling plant signal transduction by focusing on genetic differences between WT and gps mutant genotypes in response to the GPS treatment.
Figure 2 – gps2 mutant created from WT through T-DNA insertion of Feldman Tag.
Seven gps mutants have been identified to date, and three gps mutant phenotypes are currently under study at the Wyatt Lab: gps-2, gps-3, and gps-6.