Thiamine-induced resistance in carnation against Fusarium oxysporum f. sp dianthi and mode of action studies based on the proteomics analysis of root tissue

Abstract

Colombia is the main producer of carnations worldwide. However, its production is affected by vascular wilting caused by Fusarium oxysporum f. sp dianthi (Fod). Previous studies have proposed thiamine as a potential inducer of resistance against this pathogen, but the biochemical mechanisms involved in its action have not been elucidated. The objective of the present work was to investigate the underlying mechanism of thiamine–induced resistance by analyzing changes in the root protein profile. A greenhouse experiment was performed with two cultivars, evaluating the following treatments: control, Fod–inoculated plants, foliar application of thiamine, and application of thiamine and subsequent Fod inoculation. Incidence and severity were determined for each treatment. Applicating thiamine reduced the incidence (22%) and severity (62%) of vascular wilting in a susceptible cultivar confirming the effect as Resistance Inducer. In addition, a shotgun (nLC–MS/MS) proteomic analysis of root tissues was carried out at 96 h post–inoculation. The application of thiamine and subsequent inoculation with Fod, increased the abundance of 44 proteins in the susceptible cultivar and 70 in the resistant one. These proteins belonged to different functional groups, including protein synthesis and degradation, redox homeostasis, transport, cell organization, stress, and defense. In conclusion, the results obtained suggest that the treatment with thiamine previously to Fod inoculation allows the early activation of defense mechanisms that protect the plant against the pathogen. These results increase the knowledge of thiamine use as a biostimulant agent in plants and its protein–level mode of action against pathogens.