Identification and expression analysis of MAPK cascade gene family in foxtail millet ().

The mitogen-activated protein kinase (MAPK) cascade pathway is a highly conserved plant cell signaling pathway that plays an important role in plant growth and development and stress response. Currently, MAPK cascade genes have been identified and reported in a variety of plants including , , and , but have not been identified in foxtail millet (). In this study, a total of 93 MAPK cascade genes, including 15 , 10 and 68 genes, were identified by genome-wide analysis of foxtail millet, and these genes were distributed on nine chromosomes of foxtail millet. Using phylogenetic analysis, we divided the and into four subgroups, respectively, and the into three subgroups (Raf, ZIK, and MEKK). Whole-genome duplication analysis revealed that there are 14 duplication pairs in the MAPK cascade family in foxtail millet, and they are expanded by segmental replication events. Results from quantitative real-time PCR (qRT-PCR) revealed that the expression levels of most and were changed under both exogenous hormone and abiotic stress treatments, with and being induced under almost all treatments, while the expression of was repressed. In a nutshell, this study will shed some light on the evolution of MAPK cascade genes and the functional mechanisms underlying MAPK cascade genes in response to hormonal and abiotic stress signaling pathways in foxtail millet ().