Genome-Wide Identification and Expression of MAPK Gene Family in Cultivated Strawberry and Their Involvement in Fruit Developing and Ripening

Abstract

Studies on many plants have shown that mitogen-activated protein kinases (MAPKs) are key proteins involved in regulating plant responses to biotic and abiotic stresses. However, their involvement in cultivated strawberry development and ripening remains unclear. In this study, 43 FaMAPK gene family members were identified in the genome of cultivated strawberry (Fragaria × ananassa), phylogenetic analysis indicated that FaMAPKs could be classified into four groups. Systematic analysis of the conserved motif, exon–intron structure showed that there were significant varieties between different groups in structure, but in the same group they were similar. Multiple cis-regulatory elements associated with phytohormone response, and abiotic and biotic stresses were predicted in the promoter regions of FaMAPK genes. Transcriptional analysis showed that all FaMAPK genes were expressed at all developmental stages. Meanwhile, the effect of exogenous ABA and sucrose on the expression profile of FaMAPKs was investigated. Exogenous ABA, sucrose, and ABA plus sucrose treatments upregulated the expression of FaMAPK genes and increased the content of endogenous ABA, sucrose, and anthocyanin in strawberry fruits, suggesting that ABA and sucrose might be involved in the FaMAPK-mediated regulation of strawberry fruit ripening. Based on the obtained results, MAPK genes closely related to the ripening of strawberries were screened to provide a theoretical basis and support for future research on strawberries.