Antagonistic activity of fungal root endophytes from solanaceous plants against potato late blight (Phytophthora infestans)

Publikations-Art

Kongressbeitrag

Autoren

G. Ngatia, A. El-Hasan, R. Vögele

Erscheinungsjahr

2015

Tagungsname

XVIII. International Plant Protection Congress (IPPC)

Tagungsort

Berlin

Tagungsdatum

24–27 August 2015

Fungal endophytes have been shown to produce secondary metabolites that can protect plants from pathogens. The antifungal activity of 354 root-endophytic fungi isolated from four solanaceous species obtained from Kenya against Phytophthora infestans was screened in vitro. Accordingly, 60 isolates were selected and further evaluated in dual culture tests. The results revealed that mycelial growth of P. infestans was differentially effected by the tested endophytes. Trichoderma harzianum along with two endophytes (KB1S2-4 and KA1S1-1) suppressed mycelial growth of the pathogen by 84.5%, 78.2% and 76.5%, respectively. Other endophytes however, were either only moderate (KB1S4-7, NA1S2-10, KT1S1-6) or slight (KT2S2-5, KB2S2-5) inhibitors. The potential of bioactive crude extracts of culture filtrates obtained from 10 endophytes was evaluated against sporangia germination of P. infestans. The results revealed that, sporangia germination was repressed by more than 88% in the presence of extracts from isolates KT1S1-2, KB1S1-10 and KB1S1-8 compared to the control. The activity of crude extracts was further assessed using thin layer chromatography and bioautography techniques. Out of 10 crude extracts tested, two showed inhibition zones corresponding to the Rf values of 0.23, 0.43 for isolate KB1S1-8 and 0.40 for the isolate KT1S1-2. Both isolates were identified as Aspergillus aureofulgens and Aspergillus flavipes using ribosomal gene sequence analysis of the ITS region.