An investigation of the role of stress-responsive aldo-keto reductases in Arabidopsis thaliana
Aldo-keto reductases (AKRs) are a superfamily of enzymes which participate in redox reactions involving a wide range of carbonyl-containing substrates. Due to their lack of substrate specificity, AKRs may be involved in widespread toxicant metabolism, including the reduction of toxic methylglyoxal. Overexpression of OsMYB55 conferred heat-tolerance on rice and maize while maize lines demonstrated an over-accumulation of the metabolite 1,2-propanediol and increased expression of a number of AKRs. These findings point to a biochemical mechanism, linking heat tolerance with the production of 1,2-propanediol by one or more AKRs. This study demonstrates the heat-induced expression of three Arabidopsis AKRs. T2 generation overexpression lines resisted the negative effects of paraquat toxicity, a phenotype which correlates with the affinity of recombinantly-expressed proteins for the substrate methylglyoxal in vitro. Exogenous application of 1,2-propanediol demonstrated no protective effect but recommendations are made for a robust, high-throughput method for the quantification of endogenous 1,2-propanediol using HPAEC-PAD.