Phytophthora infestans, the causative agent of late blight in potatoes and tomatoes, remains a major threat to global food security. As part of their defense, potato plants accumulate steroidal glycoalkaloids (SGA), primarily α-solanine and α-chaconine which exhibit antifungal toxicity. However, P. infestans secretes effector proteins, including glycoside hydrolases (GHs) such as rhamnosidases, which are hypothesized to detoxify SGA by cleaving their sugar moieties, an essential determinant of glycoalkaloid toxicity. In this study we investigate the potential molecular interactions between P. infestans rhamnosidases and potato SGAs using an integrated computational framework to evaluate their potential role in SGA detoxification. Five rhamnosidase proteins (PITG₁9230, PITG₁9561, PITG₂2085, PITG₀5097, and PITG₀1760) were analyzed through sequence and structural characterization, confirming their classification as α-L-rhamnosidases with conserved catalytic domains. Molecular docking and 50 ns molecular dynamic simulations revealed stable binding of both α-solanine and α-chaconine within the catalytic regions of all five enzymes. Notably α-chaconine consistently exhibited stronger binding affinity, enhanced conformational stability and more favorable binding free energies than α-solanine. Among the evaluated proteins, PITG₁9230 and PITG₀1760 demonstrated the lowest RMSD values, reduced residue-level fluctuations, and favorable MM-GBSA energies, indicating their potential role in glycoalkaloid interaction and detoxification processes. Protein-ligand complexes were stabilized through a combination of hydrogen bonding and hydrophobic interactions, with α-chaconine complexes displaying superior dynamic stability throughout the simulations. MMGBSA results supported these findings by quantifying robust binding free energies, reinforcing α-chaconine’s stronger affinity. Collectively, these findings provide computational evidence supporting a preferential interaction between P. infestans rhamnosidases and α-chaconine, offering mechanistic insights into glycoalkaloid detoxification and pathogen virulence. While these results are derived from silico analyses and require experimental validation, they identify promising molecular targets for functional disruption. The integration of genome editing approaches, such as RNA interference and CRISPR/Cas9-mediated gene editing, may facilitate the development of potato cultivars with enhanced resistance to late blight and contribute to sustainable disease management strategies.
Abbasi et al. (Sun,) studied this question.