Molecular Traits of Rapid Alkalinization Factor Family and Functional Analysis of SlRALF2 in Tomato Resistance to Phytophthora infestans

Late blight, caused by Phytophthora infestans (P. infestans), poses a significant threat to tomato yield and quality. Traditional disease control strategies rely heavily on frequent applications of chemical pesticides, leading to environmental pollution and the emergence of pesticide-resistant pathogens. This highlights the urgent need for environmentally friendly plant disease control technologies. Rapid alkalinization factors (RALFs) are secreted peptides that play crucial roles in plant defense. Here, 11 SlRALF genes were identified in tomato. Bioinformatics analyses were conducted to characterize them. SlRALF2, which responded significantly to P. infestans infection, was chosen for investigation. Functional analyses demonstrated that SlRALF2 enhances tomato resistance by promoting the expression level of SlPRs and modulating key enzyme activities. GO and KEGG analyses of key genes influenced by SlRALF2 revealed its involvement in several critical pathways. Altogether, our findings establish SlRALF2 as a pivotal component of tomato defense signaling, offering valuable insights for crop breeding.