A member of wheat class III peroxidase gene family,TaPRX-2A,enhanced the tolerance of salt stress

Background Salt and drought are the main abiotic stresses that restrict the yield of crops. Peroxidases (PRXs) are involved in various abiotic stress responses. Furthermore, only few wheat PRXs have been characterized in the mechanism of the abiotic stress response. Results In this study, a novel wheat peroxidase (PRX) gene namedTaPRX-2A,a member of wheat class III PRX gene family, was cloned and its response to salt stress was characterized. Based on the identification and evolutionary analysis of class III PRXs in 12 plants, we proposed an evolutionary model forTaPRX-2A, suggesting that occurrence of some exon fusion events during evolution. We also detected the positive selection of PRX domain in 13 PRXs involving our evolutionary model, and found 2 or 6 positively selected sites duringTaPRX-2Aevolution. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) results showed thatTaPRX-2Aexhibited relatively higher expression levels in root tissue than those exhibited in leaf and stem tissues.TaPRX-2Aexpression was also induced by abiotic stresses and hormone treatments such as polyethylene glycol 6000, NaCl, hydrogen peroxide (H2O2), salicylic acid (SA), methyljasmonic acid (MeJA) and abscisic acid (ABA). Transgenic wheat plants with overexpression ofTaPRX-2Ashowed higher tolerance to salt stress than wild-type (WT) plants. Confocal microscopy revealed thatTaPRX-2A-eGFP was mainly localized in cell nuclei. Survival rate, relative water content, and shoot length were higher inTaPRX-2A-overexpressing wheat than in the WT wheat, whereas root length was not significantly different. The activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were enhanced inTaPRX-2A-overexpressing wheat compared with those in the WT wheat, resulting in the reduction of reactive oxygen species (ROS) accumulation and malondialdehyde (MDA) content. The expression levels of downstream stress-related genes showed thatRD22,TLP4,ABAI,GST22,FeSOD, andCATexhibited higher expressions inTaPRX-2A-overexpressing wheat than in WT under salt stress. Conclusions The results show thatTaPRX-2Aplays a positive role in the response to salt stress by scavenging ROS and regulating stress-related genes.