José Mogahid Fechine¹, Fabiana Aparecida Cavalcante Silva², Tereza Cristina Leal Balbino³, Tercilio Calsa Junior ¹

Throughout evolution, plants have developed strategies to protect themselves against pathogens, such as developing a cuticle, producing secondary compounds, and producing proteins that can act as antimicrobial agents. Lemnaceae (duckweed) are aquatic macrophytes known for their rapid vegetative propagation, high growth rate, and promising biotechnological characteristics. Among them, Lemna aequinoctialis stands out as an interesting model for studies of bacterial infection, including pathogenic infection. The bacterium Klebsiella pneumoniae is clinically relevant in most cases of hospital infection and has a profile of resistance to multiple drugs. In recent studies, duckweed has responded as a biological model against human pathogenic microorganisms. This study aimed to investigate whether Lemna aequinoctialis infected with Klebsiella pneumoniae can serve as a model for studies of bacterial pathogenesis. Thus, the morphophysiological and proteomic response of duckweed infected with Klebsiella pneumoniae was evaluated. Ten fronds of Lemna aequinoctialis clone M1 supplemented with different aliquots of medium containing Klebsiella pneumoniae were used. Morphophysiological parameters, such as relative growth, biomass yield, frond size, and inhibition rate, were measured. Protein extracts were separated by nano-ultra-liquid chromatography coupled with mass spectrometry (nUPLC-MS/MS) in an Orbitrap Fusion Lumos system (Thermo Scientific). Of the differentially accumulated proteins, 129 were identified as more abundant in Klebsiella pneumoniae infection and 100 proteins were more abundant in the control condition, i.e., without infection. The proteins were categorized in terms of gene ontology, and the biological processes with the greatest variation in the infected sample were associated with carbohydrate metabolism, phosphorylation, stress response, and translation. The infected plants showed a significant decrease in their phenotypic growth profile. Understanding the molecular mechanisms involved and the differential proteins identified may help elucidate functional and metabolic mechanisms in this infection of plants and/or other eukaryotes, in addition to prospecting compounds with potential antimicrobial activity, such as peptides that can be explored for future therapies.

Agradecimentos: Universidade Federal de Pernambuco UFPE; Laboratório de Genômica e Proteômica de Plantas LGPP; FIOCRU/PE e Centro de tecnologias estratégicas do nordeste CETENE.