Effects of endophytes Trichoderma amazonicum and Acremonium strictum on fungal pathogens of Paspalum

Abstract

In natural ecosystems, many plants engage in symbiotic interactions with fungal endophytes which can have impacts on host plant communities. In South American grasslands, several endophytes have been isolated from different Paspalum species. The aim of this work was to evaluate the antagonistic effect of endophytes Trichoderma amazonicum and Acremonium strictum against Claviceps paspali through in vitro and in vivo assays. In addition, they were evaluated as biocontrol agents against fungal pathogens which produce leaf spots such as Alternaria alternata and ipolaris sp. through in vitro experiments. The in vitro assessment was conducted by dual culture between the antagonists and the three pathogens. For the in vivo assay, plants of Paspalum notatum and Paspalum dilatatum were planted in the field in a completely randomized block design with six replications. Three treatments were applied: T1 = endophyte inoculum, T2 = fungicide, and T3 = control. Seed yield, seed set, healthy seed set, and weight of healthy seed set per kilogram of seeds were evaluated for three timepoints. Trichoderma amazonicum exhibited a high growthinhibition, while A. strictum a moderate to low effect in vitro. In the in vivo assay, significant differences were observed among treatments in both species. T1 increased the kilogram of healthy seed set per 100 kg of seed by increasing the seed set and weight of healthy seed set in at least one of the evaluated dates in P. notatum and P. dilatatum. Based on these results, T. amazonicum and A. strictum have antagonistic effects on the pathogens assessed.