Phytotoxicity and Iron Homeostasis Disturbance of Bismuth on <I>IRT1</I> Promoter Knockout<i> Arabidopsis thaliana</i>

Bismuth (Bi) is used in semiconductors and water pipes as a substitute for lead. The Bi concentration the soil has not been investigated, there no environmental quality standard Japan. We previously reported accumulation phytotoxicity Arabidopsis thaliana (A. thaliana) Solanum lycopersicum, which were presented that disturb iron (Fe) homeostasis both plants. However, mechanism of remains unclear. examined toxic effect expression Fe-related genes A. thaliana. microarray analysis revealed an increase Fe regulation cascade including subgroup Ib transcription factor. tried to clear using Iron-Regulated Transporter 1 (IRT1) promoter knockout line. inhibits root growth lateral development, while induces contents. In wild type, was located stem cell niche (SCN) without condition. location IRT1 line disturbed by 2 µM treatment. Moreover, death found treated-roots. These results suggest homeostasis, overaccumulation enhanced thaliana, damaged SCN tip.