BACKGROUND: A key challenge for designing RNAi-based crop protection strategies is the identification of effective target
genes in the pathogenic organism. In this study, in vitro antifungal activities of a set of synthetic double-strandedRNAmolecules
on spore germination of two major pathogenic fungi of banana, Fusarium oxysporum Schlecht f. sp. cubense WC Snyder & HN
Hans (Foc) and Mycosphaerella fijiensis Morelet (Mf) were evaluated.
RESULTS: All the tested synthetic dsRNAs successfully triggered the silencing of target genes and displayed varying degrees
of potential to inhibit spore germination of both tested banana pathogens. When Foc dsRNAs were applied to Foc spores, inhibition ranged from 79.8 to 93.0%, and from 19.9 to 57.8% when Foc dsRNAs were applied to Mf spores. However, when Mf dsRNAs were applied on Mf spores, inhibition ranged from 34.4 to 72.3%, and from 89.7 to 95.9% when Mf dsRNAs were applied to Foc spores.
CONCLUSION: The dsRNAs for adenylate cyclase, DNA polymerase alpha subunit and DNA polymerase delta subunit showed high levels of spore germination inhibition during both self- and cross-species tests, making them the most promising targets for RNA-mediated resistance in banana against these fungal pathogens.