Microbe-induced gene silencing of fungal gene confers efficient resistance against Fusarium graminearum in maize

Abstract

Small RNAs (sRNAs), the main effectors of RNA interference (or RNA silencing, RNAi), mediate cell-autonomous and non-cell-autonomous gene silencing. The discoveries of trans-kingdom RNAi and interspecies RNAi have accelerated the development of RNAi-based crop protection technologies. Recently, based on interspecies RNAi, a practical technology termed microbe-induced gene silencing (MIGS) without the need of host genetic modification is developed for crop protection against Verticillium dahliae and Fusarium oxysporum in cotton and rice plants. In this study, we utilized MIGS technology to protect maize against Fusarium graminearum, which is responsible for maize stalk rot. An RNAi-engineered Trichoderma harzianum strain, Th-FgPmt2i, was exploited to generate double-stranded RNAs (dsRNAs) to trigger the silencing of the FgPTM2 gene. Our data verify that sRNAs generated from Th-FgPmt2i can silence the FgPMT2 gene via translational inhibition in F. graminearum. We further demonstrated that Th-FgPmt2i has a stronger capacity than does the T. harzianum chassis for protection of maize against F. graminearum. Coupled with our studies on crop protection against V. dahliae and F. oxysporum, our findings reveal that MIGS can be exploited to protect various crops against distinct fungal pathogens and has extensive applicability.