Discovery of genes controlling solute accumulation by either known or random gene activation In the epidermal and cortical root cells of Arabidopsis

摘要

Control of shoot nutrieat content is determined by cell-specific processes in the root, including control of the initial entry of nutrients into epidermal and cortical cells. Opposite processes at the cellular level in the inner and outer halves of the root are likely to have the same net effect on shoot nutrient accumulation, so genetic manipulation of nutrient transport processes in specific cell types is likely to be more efficient than constitutive manipulations. To do this, four enhancer trap lines of Arabidopsis were selected for specific and stable expression of GAL4-GFP in mature epidermal and cortical root cells. Two of the lines were found to have one copy of the T-DNA and were selfed to ensure homozygosity. The epidermal and cortical expressing enhancer trap lines were then transformed with either genes of known function behind the UAS_(GAL4) or the gain-of-function plasmid (pGof1), which contains only the UAS_(GAL4) adjacent to the right border, thus randomly activating genes. In both cases, this gene expression will occur only in the outer root cells. A total of 1,125 independently transformed plants have been generated. Plant were screened for 23 elements using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) resulting in the identification of 153 putative mutants with altered accumulation of Na~+ and other inorganic solutes in the shoot. Each mutant may have one or a small number of genes activated or inhibited specifically in the epidermis and cortex, to control delivery to the shoot of solutes. We are currently confirming the putative mutants, and characterising activated genes in these lines.