The SLIM1 transcription factor regulates arsenic sensitivity in
Arabidopsis thaliana
Abstract
The transcriptional regulators of arsenic-induced gene expression remain
largely unknown; however, arsenic exposure rapidly depletes cellular
glutathione levels increasing demand for thiol compounds from the sulfur
assimilation pathway. Thus, sulfur assimilation is tightly linked with
arsenic detoxification. To explore the hypothesis that the key
transcriptional regulator of sulfur assimilation, SLIM1, is involved in
arsenic-induced gene expression, we evaluated the response of slim1
mutants to arsenic treatments. We found that slim1 mutants were
sensitive to arsenic in root growth assays. Furthermore, arsenic
treatment caused high levels of oxidative stress in the slim1 mutants,
and slim1 mutants were impaired in both thiol and sulfate accumulation.
We also found enhanced arsenic accumulation in the roots of slim1
mutants. Furthermore, microarray analyses identified genes from a highly
co-regulated gene cluster (the O-acetylserine gene cluster), as being
significantly upregulated in the slim1-1 mutant background in response
to arsenic exposure. The present study identified the SLIM1
transcription factor as an important component in arsenic-induced gene
expression and arsenic tolerance. Our results suggest that the severe
arsenic sensitivity of the slim1 mutants is a result of both altered
redox status as well as mis-regulation of key genes.