Identification and Characterization of the MAPK Genes in Sorghum and Their Expression in Response to Aphid Infestation

Abstract Mitogen-activated protein kinase (MAPK) cascades are key signaling molecules involved in plant growth, development, and defense. This study presents a genome-wide analysis of MAPK genes in sorghum, focusing on their role in plant defense against insects and pathogens. We identified 19 distinct MAPKs in the sorghum genome through comprehensive bioinformatic analysis, examining sequence alignment, gene structures, conserved motifs, and phylogenetic relationships. Phylogenetic analysis classified SbMAPK family members into four subfamilies (A, B, C, and D), with subfamilies A containing TEY motifs, B featuring both TEY and MEY motifs, C comprising both TEY and TDY motifs and D possessing TDY motifs. Evolutionary analysis suggested that tandem duplication and strong purifying selection played a crucial role in the expansion of the MAPK family in sorghum. Promoter analysis revealed that most SbMAPK s contain cis-regulatory elements associated with plant hormones and responses to biotic and abiotic stress. Furthermore, quantitative real-time PCR (qRT-PCR) analysis demonstrated that nine SbMAPK genes responded to aphid infestation, highlighting their potential involvement in sorghum defense mechanisms. Overall, these findings enhance our understanding of MAPK gene evolution in sorghum and their functional roles in host defense against aphids.