Genome-wide identification and transcriptomic analysis of the MAPK family provides insights into the molecular basis of disease resistance of postharvest eggplant in response to Botrytis cinerea

Eggplant (<i>Solanum melongena</i>), an important crop for food supply, can suffer from severe gray mold rot caused by <i>Botrytis cinerea</i>, resulting in huge postharvest damage every year. Mitogen-activated protein kinase (MAPK) cascades, important to the signal transduction pathway, were identified in many species and proved to be involved in plant growth, development, and immune response, although our knowledge of this cascade in eggplant is scarce. In this work, based on the state-of-art genome sequencing data, the MAPK cascades of eggplant were identified. The result showed that there were 117 <i>MAP3Ks</i>, 5 <i>MAP2Ks</i>, and 16 <i>MAPKs</i> in the eggplant genome. All the proteins possessed traditional MAPK domains. Phylogenetic and collinear analysis showed that eggplant MAPKs was homologous with <i>Arabidopsis</i> and tomato. <i>Cis</i>-acting element analysis indicated that eggplant MAPKs may participate in defense and stress responsiveness. Meanwhile, transcriptomic analysis of postharvest eggplant after <i>Botrytis cinerea</i> infection showed that most of the <i>MAPK</i> genes had altered expression; further functional assays indicate that SmMAP3K38 likely operates as a negative regulator of eggplant immunity against <i>Botrytis cinerea</i> infection, which provides us new insights into the molecular basis of this important crop in disease resistance to <i>Botrytis cinerea</i> and gives us new potential targets for the prevention and control of gray mold.