Comparative analysis of synteny and functional divergence of APX genes in Fragaria vesca and Fragaria×ananassa.

BACKGROUND

Ascorbate peroxidase (APX) is a key enzyme that removes reactive oxygen species (ROS) in the ascorbic acid-glutathione cycle. Although APX genes have been reported in many species, comparative analysis of genome-wide, promoters, and gene functions between F. vesca (Fragaria vesca L.) and F. × ananassa (Fragaria×ananassa Duch.) have not been comprehensively explored.

RESULTS

In this study, seven FvAPX and twenty FaAPX genes were divided into five subgroups. By comparative analysis of the 5 motifs between F. vesca and F. × ananassa, it was found that some fragments were gained/lost. These amino acid fragments might be closely related to the function of the APX genes. Synteny analysis of F. vesca and F. × ananassa showed that there were more collinearity genes with grapes. Compared with F. × ananassa, the FvAPX2, FvAPX3, FvAPX4, and FvAPX6 proteins were more likely to use Val and Leu in F. vesca. The RT‒qPCR results confirmed that FaAPX5 and FvAPX7 were obviously upregulated under the NaCl, PEG, and HO treatments. The GUS assay showed that FvAPX7 had stronger promoter activity than FaAPX5. Additionally, the overexpression of FvAPX7 and FaAPX5 in 'Benihoppe' leaves and Arabidopsis (Arabidopsis thaliana) improved activities of POD, SOD, CAT, and APX, and decreased the relative electrical conductivity and HO content under NaCl, HO, and drought stresses.

CONCLUSIONS

Collectively, our study provides comprehensive insight regarding the evolutionary relationship between F. vesca and F. × ananassa and offers substantial opportunities for further research on the functions of APX genes.