Identification of regulators of heat shock-inducible gene in Arabidopsis

By using forward genetic screening, we identified an Arabidopsis mutant LL729 showing reduced expression of the luciferase reporter gene driven by the heat stress inducible promoter of AtHsp18.2 gene. Extensive phenotyping of the LL729 mutant revealed that LL729 is resistant to the toxic non-selected herbicide methyl viologen. Through positional cloning, we found that the mutation responsible for the LL729’s luciferase imaging and methyl viologen resistant phenotypes is localized in At5g05630 encoding a polyamine uptake transporter named PUT3. We deduce that the mutation resulting in a change of ser252 to asn252 in the PUT3 reduced the transport of methyl viologen as well as polyamines into Arabidopsis.