Abstract
Background: Salt and drought are the main abiotic stresses that restrict yield of crops. It is reported that peroxidases (PRXs) are involved in various abiotic stress responses. However, few wheat PRXs are characterized in the mechanism of abiotic stresses. Results: In this study, a novel wheat peroxidase (PRX) gene named TaPRX-2A, a member of wheat class III peroxidase gene family, was cloned and characterized in salt stress response. Based on the identification and evolutionary analysis of class III PRXs in 12 plants, we proposed an evolutionary model that TaPRX-2A might have experienced 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 during TaPRX-2A evolution. The results of expression pattern showed that TaPRX-2A exhibited relatively higher expression levels in root tissue compared with that of leaf and stem tissues by using qRT-PCR. This TaPRX-2A was also induced by some stresses and hormone treatments including PEG6000, NaCl, hydrogen peroxide (H 2 O 2 ), salicylic acid (SA), methyljasmonic acid (MeJA) and abscisic acid (ABA). Transgenic wheat plants with overexpression of TaPRX-2A showed higher tolerance to salt stress than wild type (WT) plants. Confocal microscopy revealed that TaPRX-2A :eGFP was mainly localized in nuclei. The survival rate, relative water content and shoot length were higher in TaPRX-2A -overexpressing wheat than WT. However, root lengths were no significant difference between transgenic wheat and WT. The activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were enhanced in TaPRX-2A -overexpressing wheat than WT, resulting in the reduction of reactive oxygen species (ROS) accumulation and malondialdehyde (MDA) content. We also measured the expression levels of downstream stress-related genes ( RD22 , TLP4 , ABAI , GLP4 , GST22 , FeSOD, CuSOD, and CAT ). The results showed that RD22 , TLP4 , ABAI , GST22 , FeSOD, and CAT exhibited higher expression in TaPRX-2A -overexpressing lines than in WT under salt stress. Conclusions: The results show that TaPRX-2A plays a positive factor in response to salt stress by scavenging ROS and regulating stress-related genes.
Characterisation of the class III peroxidase gene family in carrot taproots and its role in anthocyanin and lignin accumulation
