In most ecosystems, plants establish complex symbiotic relationships with organisms, such as bacteria and fungi, which significantly influence their health by promoting or inhibiting growth. These relationships involve biochemical exchanges at the cellular level that affect plant physiology and have evolutionary implications, such as species diversification, horizontal gene transfer, symbiosis and mutualism, environmental adaptation, and positive impacts on community structure and biodiversity. For these reasons, contemporary research, moving beyond observational studies, seeks to elucidate the molecular basis of these interactions; however, gaps in knowledge remain. This is particularly noticeable in understanding how plants distinguish between beneficial and antagonistic microorganisms. In light of the above, this literature review aims to address some of these gaps by exploring the key mechanisms in common interspecies relationships. Thus, our study presents novel insights into these evolutionary archetypes, focusing on the antibiosis process and microbial signaling, including chemotaxis and quorum sensing. Additionally, it examined the biochemical basis of endophytism, pre-mRNA splicing, and transcriptional plasticity, highlighting the roles of transcription factors and epigenetic regulation in the functions of the interacting organisms. These findings emphasize the importance of understanding these confluences in natural environments, which are crucial for future theoretical and practical applications, such as improving plant nutrition, protecting against pathogens, developing transgenic crops, sustainable agriculture, and researching disease mechanisms. It was concluded that because of the characteristics of the various biomolecules involved in these biological interactions, there are interconnected molecular networks in nature that give rise to different ecological scaffolds. These networks integrate a myriad of functionally organic units that belong to various kingdoms. This interweaving underscores the complexity and multidisciplinary integration required to understand plant–microbe interactions at the molecular level. Regarding the limitations inherent in this study, it is recognized that researchers face significant obstacles. These include technical difficulties in experimentation and fieldwork, as well as the arduous task of consolidating and summarizing findings for academic articles. Challenges range from understanding complex ecological and molecular dynamics to unbiased and objective interpretation of diverse and ever-changing literature.