Abstract
To elucidate the molecular mechanism of hydrotropism in roots of Arabidopsis thaliana, we have isolated 7 hydrotropic mutants from 4860 T-DNA tagged lines. All of these mutants showed a normal response to gravity. In this study, we report on phenotypic and molecular analysis of a hydrotropic mutant, cs2448.
The roots of cs2448 grow faster than those of wild-type and coiled clockwise on inclined agar plate. However, microscopy showed that there is no obvious morphological difference between cs2448 and its wild-type.
TAIL-PCR showed that the T-DNA was inserted in AKT2 gene. Three T-DNA insertion lines whose T-DNAs were inserted in 3 different sites of AKT2 gene were found to produce an altered hydrotropic response. These results suggested that the partial response of cs2448 to water stimulus was due to the disruption of AKT2 gene, which encodes a potassium channel. Expression of pAKT2::GUS was detected in the stele, primarily in the phloem.
