Extracellular DNA of Fusarium oxysporum f. sp. cubense as a Priming Agent for Inducing the Resistance of Banana Plantlets

Abstract

Fusarium wilt is one of the major causes of global losses in the banana industry. The application of extracellular DNA (eDNA) is explored as a natural fungicide. eDNA is categorized on the basis of the receiving cell’s perception, namely self and non-self. The application of self-eDNA in agriculture presents the potential for limiting the growth of pathogens, while non-self-eDNA, as a vaccine for plants. This study evaluated whether the eDNA from Fusarium oxysporum f. sp. cubense (Foc) could limit the growth of Foc itself (self-inhibition test) while increasing the resistance of banana plant (priming test). A self-inhibition test showed that the administration of 400 and 800 μg mL−1 eDNA inhibited Foc TR4 spore germination. A priming test was carried out on banana plantlets in the interaction medium containing eDNA Foc TR4 suspension with final concentrations of 40, 80, and 200 μg mL−1. After 24 h, the plantlets were infected with a suspension of 106 spore mL−1. Increased resistance was observed in plantlets treated with 200 μg mL−1 of Foc TR4 eDNA, as indicated by the decrease in leaf symptoms and rhizome discoloration. The accumulation of O2- and H2O2 was observed 24 h after priming as was a significant increase in the relative expression of CAT, PR1, and chitinase 1 genes on day 9 post-infection. In conclusion, eDNA Foc TR4 as a growth inhibitor of pathogen and a priming agent to the banana plantlets could be considered as a biofungicide candidate to induce the resistance of banana plants.