Comparative Genomics\nScreens Identify a Novel Small\nSecretory Peptide, SlSolP12, which Activates Both Local and Systemic\nImmune Response in Tomatoes and Exhibits Broad-Spectrum Activity

Small secreted peptides (SSPs) are essential for defense\nmechanisms\nin plant–microbe interactions, acting as danger-associated\nmolecular patterns (DAMPs). Despite the first discovery of SSPs over\nthree decades ago, only a limited number of SSP families, particularly\nwithin Solanaceae plants, have been identified due to inefficient\napproaches. This study employed comparative genomics screens with\nSolanaceae proteomes (tomato, tobacco, and pepper) to discover a novel\nSSP family, SolP. Bioinformatics analysis suggests that SolP may serve\nas an endogenous signal initiating the plant PTI response. Interestingly,\nSolP family members from tomato, tobacco, and pepper share an identical\nsequence (VTSNALALVNRFAD), named SlSolP12 (also referred to as NtSolP15\nor CaSolP1). Biochemical and phenotypic analyses revealed that synthetic\nSlSolP12 peptide triggers multiple defense responses: ROS burst, MAPK\nactivation, callose deposition, stomatal closure, and expression of\nimmune defense genes. Furthermore, SlSolP12 enhances systemic resistance\nagainst Botrytis cinerea infection\nin tomato plants and interferes with classical peptides, flg22 and\nSystemin, which modulate the immune response. Remarkably, SolP12 activates\nROS in diverse plant species, such as Arabidopsis thaliana, soybean, and rice, showing a broad spectrum of biological activities.\nThis study provides valuable approaches for identifying endogenous\nSSPs and highlights SlSolP12 as a novel DAMP that could serve as a\nuseful target for crop protection.