Effectors are key organism-associated molecules that aid in the establishment of interactions with other organisms. Effectoromics has become an important area of research in phytopathology. The lack of sequence conservation among effectors, even in closely related organisms, has led us to believe that effectors from organisms of different kingdoms are completely unrelated, which has fostered the independent development of effector identification strategies in bacteria, fungi, phytoplasmas, etc. This review focuses on the different algorithms available for effector identification in different plant pathogens and pests, using the following classification: (1) translocated effectors (bacteria, oomycete) and (2) secreted effectors (phytoplasmas, fungi, insects, nematodes). The objective of this type of classification is to identify, for the first time, the common features that exist among these organisms to streamline future effectoromics identification strategies. Among the organisms’ commonalities, certain bacteria, fungi, phytoplasmas, and nematodes may cause similar symptoms, and some of their effectors may target the same proteins or biological processes in the plant hosts. The integration of effector analyses of organisms of different living kingdoms, through the identification of common short linear motifs, domains, and three-dimensional structures, may aid in the development of novel algorithms for effectoromics. Future algorithms may contemplate these highlighted features and will be better equipped to identify not only canonical effectors but highly elusive non-canonical effectors as well.

Both plants and animals have developed a sophisticated two-tiered innate immune system. This involves an initial recognition of microbial patterns conserved on the cell surface (PAMP-triggered immunity) and a subsequent more specific intracellular recognition of pathogenic effectors or their activities (effector-triggered immunity). A common fundamental feature is the use of NLR-like intracellular receptors to detect insider threats. Both plant NLRs (receptors containing nucleotide-binding domains and leucine-rich repeats) and animal NLRs (NOD-like receptors) share a modular tripartite architecture, typically featuring a central nucleotide-binding domain (NBD/NOD) and C-terminal leucine-rich repeats (LRRs). The NBD/NOD is crucial for facilitating the exchange of ADP/ATP, acting as a molecular switch to promote oligomerization and activation of NLRs in both kingdoms. In this review, we summarize the similarities and differences between plant and animal molecular perception and immunity mechanisms. Additionally, we highlight the fact that some human pathogens can infect plants, and crucially, some plant pathogens are capable of causing disease in humans. This suggests conserved molecular strategies to invade and manipulate host cells belonging to different biological kingdoms, uncovering that plant and human pathology may benefit from future investigations in their respective fields.