Abstract
BackgroundSalt 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.ResultsIn this study, a novel wheat peroxidase (PRX) gene named TaPRX-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 for TaPRX-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 during TaPRX-2A evolution. Quantitative reverse transcription–polymerase chain reaction (qRT–PCR) results showed that TaPRX-2A exhibited relatively higher expression levels in root tissue than those exhibited in leaf and stem tissues. TaPRX-2A expression 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 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 cell nuclei. Survival rate, relative water content, and shoot length were higher in TaPRX-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 in TaPRX-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 that RD22, TLP4, ABAI, GST22, FeSOD, and CAT exhibited higher expressions in TaPRX-2A-overexpressing wheat than in WT under salt stress.ConclusionsThe results show that TaPRX-2A plays a positive role in the response to salt stress by scavenging ROS and regulating stress-related genes.
Highlights
Salt and drought are the main abiotic stresses that restrict the yield of crops
Our local BLAST against the identified PRXs of the 12 plants showed that the T. aestivum PRX TraesCS2A02G573900.1.cds1 from subfamily VI contained
Based on the phylogenetic and exon-intron structure analysis (Additional file 5: Figure S2), we proposed an evolutionary model to determine the origin of TaPRX2A (TraesCS2A02G573900.1.cds1), which was involved in the processes of exon fusion (Fig. 2a)
Summary
Salt and drought are the main abiotic stresses that restrict the yield of crops. Peroxidases (PRXs) are involved in various abiotic stress responses. Only few wheat PRXs have been characterized in the mechanism of the abiotic stress response Abiotic stresses such as high salinity and drought have profound negative impacts on plant development and biomass formation, resulting in significant reductions in crop yield worldwide [1]. To adapt to these abiotic stresses, plants have evolved complex mechanisms for physiological and biochemical mitigation of stress-associated damage, such as the release of reactive oxygen species (ROS) [2, 3]. PRXs have been reported to protect cells against ROS by catalyzing redox reactions [11]
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