Abstract
Superoxide dismutases (SODs) are a family of key antioxidant enzymes that play a crucial role in plant growth and development. Previously, this gene family has been investigated in Arabidopsis and rice. In the present study, a genome-wide analysis of the SOD gene family in wheat were performed. Twenty-six SOD genes were identified from the whole genome of wheat, including 17 Cu/Zn-SODs, six Fe-SODs, and three Mn-SODs. The chromosomal location mapping analysis indicated that these three types of SOD genes were only distributed on 2, 4, and 7 chromosomes, respectively. Phylogenetic analyses of wheat SODs and several other species revealed that these SOD proteins can be assigned to two major categories. SOD1 mainly comprises of Cu/Zn-SODs, and SOD2 mainly comprises of Fe-SODs and Mn-SODs. Gene structure and motif analyses indicated that most of the SOD genes showed a relatively conserved exon/intron arrangement and motif composition. Analyses of transcriptional data indicated that most of the wheat SOD genes were expressed in almost all of the examined tissues and had important functions in abiotic stress resistance. Finally, quantitative real-time polymerase chain reaction (qRT-PCR) analysis was used to reveal the regulating roles of wheat SOD gene family in response to NaCl, mannitol, and polyethylene glycol stresses. qRT-PCR showed that eight randomly selected genes with relatively high expression levels responded to all three stresses based on released transcriptome data. However, their degree of response and response patterns were different. Interestingly, among these genes, TaSOD1.7, TaSOD1.9, TaSOD2.1, and TaSOD2.3 feature research value owing to their remarkable expression-fold change in leaves or roots under different stresses. Overall, our results provide a basis of further functional research on the SOD gene family in wheat and facilitate their potential use for applications in the genetic improvement on wheat in drought and salt stress environments.
Highlights
During the growth process, plants are affected by various adverse factors
We found that the SOD1 subfamily is composed of Cu/Zn-superoxide dismutase (SOD) and the SOD2 subfamily is composed of Fe-SODs and Mn-SODs
Genome-wide analysis is an important approach for elucidating the biological roles of the SOD gene family members in given plant species
Summary
Plants are affected by various adverse factors (such as drought, water damage, heat damage, cold damage, pests and diseases, heavy metal ions, etc.). A large number of studies have shown that the expression of plant SOD gene is controlled by various environmental stresses, and different environmental conditions lead to differences in SOD gene expressions (Xia et al, 2015; Zhang et al, 2016c). Overexpression of Mn-SOD in tobacco and maize chloroplasts enhances the protective effect of transgenic tobacco and maize on the plasma membrane and tolerance to herbicide-induced oxygen stress (Bowler et al, 1991; Breusegem et al, 1999) Taken together, these results indicate that enhanced SOD activity in plants can increase plant resistance to a variety of stresses. We performed genome-wide identification of SOD gene family in wheat and comprehensively analyzed their phylogenetic relationships, genome distribution, gene structure arrangement, motifs composition, expression profiles in different tissues, and their expression patterns in response to various abiotic stresses. The identification and analysis of the wheat SOD family will lay the foundation for further research on wheat stress resistance in the future
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