Abstract
Boron is an essential plant micronutrient, but excess boron is toxic. Molecular mechanisms of boron toxicity are poorly understood. We previously isolated and characterized seven Arabidopsis mutant lines sensitive to high concentrations of boric acid, and found four loci were involved in boron tolerance. Here, we present the update of the mutant analysis. Further mapping analysis revealed two novel loci. Therefore, at least six distinct genes are involved in excess boron tolerance in Arabidopsis. One of the mutants, four genes were emerged as candidates and sequenced, and then single point mutation was found. We also found that sensitivity of the mutants to salt, As and Cd stresses are similar to the wild type. Boron concentrations in shoots of the mutants are less than that in the wild type.
