Endophytes from wheat as biocontrol agents against tan spot disease

Abstract

Endophytes from wheat cultivars isolated in Buenos Aires province, Argentina, were assessed for their potential as biocontrol agents against Pyrenophora tritici-repentis (Died.) Drechsler (anamorph Drechslera tritici-repentis) (Died.) Shoem (Dtr), the causal agent of tan spot of wheat. Endophytes were screened using dual culture techniques and examining the effect on growth, sporulation and the antifungal activity in greenhouse assays. The most of endophytes tested significantly reduced Dtr growth compared to the control except Rhodotorula rubra from 11 to 15 days post inoculation. Trichoderma hamatum, Penicillium sp., Bacillus sp. and Paecilomyces lilacinus significantly reduced the colony diameter of the pathogen. Most of the endophytes evaluated showed morphological changes in the conidia and/or the mycelia of D. tritici-repentis. In addition, two endophytes, Bacillus sp. and Fusarium sp., reduced significantly the percent spore germination of Dtr compared to the control by 82% and 52% respectively. In greenhouse experiment T. hamatum, Chaetomium globosum and Fusarium sp. significantly (P ⩽ 0.05) reduced the average disease severity on all three leaves compared to the control. However, the best antagonistic effect was shown with T. hamatum as it resulted in the greatest suppression in the greenhouse and in the dual-plate assays. Likewise, Bacillus sp. was other highlighted microorganism that antagonized the pathogen in in vitro assays. From our promising results, we conclude that endophytes have potential in the biological control of tan spot of wheat caused by D. tritici-repentis, particularly T. hamatum and Bacillus sp.