Maize HC-toxin reductase-like protein in rice possesses dihydroflavonol-4-reductase (DFR) activity leading to tolerance to H₂O₂ induced cell death

Abstract

We have isolated a NADPH-dependent HC-toxin reductase-like gene in rice (YK1), which is similar to the Hm1 gene in maize. Last year, we reported that the overexpression of this gene resulted in the increase of NAD(P)(H) level and the activation of NAD synthetase and NAD kinase. Here, we noticed that YK1 is similar to the dihydroflavonol-4-reductase (DFR) and measured the DFR activity using the GST fusion protein. Capillary electrophoresis mass spectrometry (CE/MS) analysis and NADPH oxidation studies confirmed that YK1 possessed DFR activity. Furthermore, anthocyanin accumulation increased in YK1 overexpression rice cells. We found that the YK1 transgenic callus and plants possess the H₂O₂ stress tolerance by cell death assay. Based on this result, YK1 is important gene to sustain the stress tolerance in rice plant.