Infectious diseases remain one of the leading causes of mortality worldwide, and antimicrobial resistance (AMR) is increasing at an alarming rate. It is estimated that drug-resistant infections cause 7.7 million deaths per year, 4.95 million of which are directly related to antibiotic-resistant bacteria [1]. AMR poses a threat to global public health, modern medical procedures, and the achievement of the sustainable development goals under the “One Health” concept [2], [3], [4]. This context has intensified the search for new therapeutic strategies beyond conventional antibiotics [5], [6], [7]. Antimicrobial peptides (AMPs) are among the emerging alternatives and are becoming increasingly recognized as promising bioactive molecules due to their broad spectrum of activity against bacteria, fungi, viruses, and parasites [1], [8], [9]. The identification of more than 3000 AMPs in microorganisms, animals, and plants highlights their ancestral evolutionary role in innate immunity [10].

Plants are a major source of bioactive compounds, and advances in omics technologies have enhanced their contribution to drug discovery [11], [12]. Because they are continuously exposed to various pathogens, plants have developed sophisticated molecular defenses, including AMPs, to provide a rapid defensive response against biotic and abiotic stresses [13], [14], [15], [16], [17]. Plant AMPs, including defensins, thionins, cyclotides, and lipid transfer proteins, constitute a diverse group of peptides with a wide range of biological activities. Their activity largely depends on physicochemical properties such as their charge, hydrophobicity, and 3-dimensional conformation [18], [19], [20], [21], [22]. Their ability to disrupt microbial membranes makes them promising candidates for the development of new antimicrobial agents.

Extremophile plants represent a promising yet underexplored source of unique AMPs and stress-related proteins. Organisms that thrive in arid, saline, and microbially competitive environments typically develop specialized molecular adaptations, including stable and highly active peptides, shaped by strong selective pressures. Recent studies have demonstrated that extremophile plant species produce distinctive metabolomic and proteomic signatures with potential antimicrobial relevance [23], [24], [25]. However, the proteomic and peptidic properties of desert flora remain poorly characterized.

We selected 4 representative endemic extremophile species from southern Tunisia that are adapted to high salinity, high humidity, intense radiation, and a rhizosphere rich in diverse microorganisms. Based on their ecology, ethnobotanical relevance, and limited molecular characterization, we focused on G.microcephala, A. armatus, R. suaveolens, and A. sericea. G. microcephala (Fabaceae) produces alkaloids, isoflavonoids, and terpenes, and its extracts exhibit antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, and Staphilococcus aureus [26]. R. suaveolens (Asteraceae), which grows in arid regions of Tunisia, produces an essential oil with broad antimicrobial properties against bacteria and fungi [27]. A. sericea and A. armatus (Fabaceae) are desert leguminous plants traditionally used to treat infections, inflammation, and envenomation [28], [29], [30], [31]. We recently reported that leaf and root extracts from both species inhibit S. aureus, S. enterica, Bacillus subtilis, and B. pumillus [32]. Despite these encouraging findings, none of these 4 species has undergone comprehensive proteomic or peptide analysis, particularly with respect to their antimicrobial potential.

To address this gap, we developed an integrated strategy combining mass-spectrometry-based molecular fingerprinting MFP, guided bioactivity assays, and proteomic characterization. This approach was designed to assess the molecular diversity in these desert plants and to identify promisingAMPs and proteins.

To our knowledge, this study presents the first comparative analysis of MALDI-MFP profiles from A. sericea, A. armatus, G. microcephala, and R. suaveolens to characterize interspecies and organ-specific molecular diversity, with particular emphasis on seed molecular richness. The antimicrobial potential of these desert extremophile plants is evaluated using selective bioactivity assays, and bioactive proteins or peptides are identified using proteomic approaches. Overall, this study aims to explore desert plants as a potential source of antimicrobial molecules.