Gravity is one of the primary environmental signals determining the orientation of root and shoot growth in many plant species. The gravitropic response involves perception of the gravity signal, transmission of the signal, and execution of a response program that re- orients growth. Thus gravitropism constitutes a plant signal transduction pathway. This pathway is known to depend on transport and reception of the plant hormone auxin. The proposed research is a continuation of our effort to identify and characterize genes involved in gravitropic signal transduction in Arabidopsis thaliana. Here we will focus on further analysis of T-DNA-tagged mutants. We will continue the physiological and molecular genetic characterization of our previously isolated mutants to establish the functional roles of the genes affected by the mutations. Molecular cloning and characterization of wild-type alleles will further define the roles of these genes. Wild-type clones will be re-introduced into Arabidopsis by Agrobacterium-mediated stable transformation to test for complementation of mutant phenotypes. Genetic and molecular approaches will be used to elucidate interactions of these genes with each other and with previously identified genes involved in gravitropism. Stable and transient transformation experiments will be used to demonstrate the biological effects of altering the normal expression patterns of these genes. This work will provide new insights into the molecular mechanisms of gravitropism and of auxin-mediated signal transduction in plants.
|Ujwal, M L; McCormac, Alex C; Goulding, Ann et al. (2002) Divergent regulation of the HEMA gene family encoding glutamyl-tRNA reductase in Arabidopsis thaliana: expression of HEMA2 is regulated by sugars, but is independent of light and plastid signalling. Plant Mol Biol 50:83-91|
|McCormac, A C; Fischer, A; Kumar, A M et al. (2001) Regulation of HEMA1 expression by phytochrome and a plastid signal during de-etiolation in Arabidopsis thaliana. Plant J 25:549-61|
|Deruere, J; Jackson, K; Garbers, C et al. (1999) The RCN1-encoded A subunit of protein phosphatase 2A increases phosphatase activity in vivo. Plant J 20:389-99|
|Kumar, M A; Chaturvedi, S; Soll, D (1999) Selective inhibition of HEMA gene expression by photooxidation in Arabidopsis thaliana. Phytochemistry 51:847-51|
|Jackson, K; Soll, D (1999) Mutations in a new Arabidopsis cyclophilin disrupt its interaction with protein phosphatase 2A. Mol Gen Genet 262:830-8|
|Garbers, C; DeLong, A; Deruere, J et al. (1996) A mutation in protein phosphatase 2A regulatory subunit A affects auxin transport in Arabidopsis. EMBO J 15:2115-24|