SlLTPg1, a tomato lipid transfer protein, positively regulates in response to biotic stresses

Late blight, caused by Phytophthora infestans (P. infestans), is among the most devastating diseases affecting tomato and other Solanaceae species. Lipid transfer proteins (LTPs) represent a class of small, basic proteins that play a crucial role in combating biotic stresses. Previous studies have shown that SlLTPg1 most strongly responds after P. infestans infestation among the LTPs family in tomato. However, the function of SlLTPg1 in disease resistance remains unclear. Here, we constructed transient overexpression and VIGS-silenced plants of SlLTPg1. Our results revealed that SlLTPg1 plays a regulatory role in enhancing tomato resistance against P. infestans. This enhancement was attributed to the upregulation of defense-related genes and reactive oxygen species (ROS) scavenging genes, as well as increased enzymatic antioxidant activities. Importantly, we found that the SlLTPg1 protein significantly inhibited the growth of Fusarium oxysporum (F. oxysporum) by observing the zone of inhibition. Interestingly, we found smaller lesion diameters and upregulated expression levels of PR genes in transient overexpression SlLTPg1 of tobacco. Therefore, we further constructed transgenic tobacco lines of SlLTPg1, presenting evidence that overexpression of SlLTPg1 could positively regulate the resistance of tobacco to F. oxysporum. These findings revealed the role of SlLTPg1 in tomato resistance to P. infestans and tobacco resistance to F. oxysporum. Moreover, we propose SlLTPg1 as a potential candidate gene for augmenting broad-spectrum plant resistance against pathogens.