Genome-wide identification and expression analysis of the AhTrx family genes in peanut

Thioredoxins (Trx) are small multifunctional redox proteins that contain thioredoxin conserved domain and active site WCXXC. The Trx family has an important role in multiple processes, including electron transport, seed germination, redox regulation, biotic and abiotic stresses resistance, etc. Although Trx genes have been extensively characterized in some plants, they have not been reported in peanut until now. The identification of AhTrx genes provides potential candidate genes for studying their effects and regulatory mechanisms in peanut (Arachis hypogaea L.) growth and development, especially under aluminium (Al) stress. It is also helpful to further analyze the Al resistance pathway in plants. Seventy AhTrx genes were identified using a genome-wide search method and conservative domain analysis. Then the basic physicochemical properties, phylogenetic relationship, gene structure, chromosomal localization, and promoter prediction were studied by the bioinformatic methods. Furthermore, the expressions of AhTrx genes under different Al treatment times in two peanut cultivars were tested using a real-time quantitative polymerase chain reaction. Seventy AhTrx genes were identified and characterized. Phylogenetic tree analysis showed that all AhTrx members could be classified into 9 groups with different conserved domains. Motif 1 was found to exist in every sequence, with an active site. Furthermore, the gene structures showed that the AhTrx family was complicated and changeable during evolution. The chromosomal localization indicated that the distribution and density of the Trx family on 20 peanut chromosomes were uneven. Predictive promoter analysis indicated that AhTrx proteins might play a role in phytohormones synthesis and stress response. Finally, the expression patterns of the AhTrx genes showed that every gene was differently expressed under Al treatment in different peanut cultivars, some were obvious, others had no significant difference, some were at a high level, while others were at a low level. This study systematically identifies the Trx gene family in peanut, providing some candidates for further study on its effects and regulatory mechanism under Al stress in peanut.