Characterization, expression, and functional analysis of polyamine oxidases for their role in selenium-induced hydrogen peroxide production in Brassica rapa.

BACKGROUND: Selenium (Se)-induced phytotoxicity has been linked to oxidative injury triggered by reactive oxygen species (ROS) accumulation due to the disturbance of anti-oxidative system. However, how Se stress induces hydrogen peroxide (H2 O2 ) production in plants is a long-standing question. Here we identified the role of polyamine oxidase (PAO) in H2 O2 production in the root of Brassica rapa upon Se stress.

RESULTS: Se induced growth inhibition, H2 O2 accumulation, and oxidative injury in root. Excessive Se exposure resulted in remarkable increase in B. rapa root PAO activity. Inhibition of PAO activity led to decreased H2 O2 content and alleviated oxidative injury in Se-treated root. These results indicated that Se stress induced PAO-dependent H2 O2 production. Next, total of six BrPAO family members were uncovered from the genome of B. rapa by in silico analysis. Se stress pronouncedly upregulated the expression of most BrPAOs that were further proved to be able to produce H2 O2 through transient expression analysis.

CONCLUSION: These results suggested that Se stress upregulated the expression of a set of BrPAOs, which further enhanced PAO activity, contributing to H2 O2 generation in roots. This article is protected by copyright. All rights reserved.