Endophytic colonisation of squash by the fungal entomopathogen Beauveria bassiana (Ascomycota: Hypocreales) for managing Zucchini yellow mosaic virus in cucurbits

Abstract

We investigated the potential of endophytic Beauveria bassiana to provide protection against Zucchini yellow mosaic virus (ZYMV), one of the most economically important viral diseases in cucurbits. Four selected B. bassiana strains were able to successfully colonise squash plants following foliar inoculation with the conidial suspension of each respective strain. However, no significant difference in percentage colonisation was observed among the tested B. bassiana strains. Disease incidence (percentage of plants showing ZYMV symptoms) and severity (rating based on a 5-point scale), sampled weekly for four weeks following the challenge inoculation of plants with ZYMV, were significantly lower in B. bassiana-inoculated plants as compared to control plants, regardless of the inoculated strain. This is, to our knowledge, the first report on the potential of endophytic B. bassiana to confer protection against plant viruses. Further studies should be conducted to determine whether such endophytic B. bassiana-mediated protection against ZYMV in squash extends to other cucurbits.

Keywords:

• Beauveria bassiana
• biocontrol
• cucurbits
• fungal endophyte
• potyviruses
• Zucchini yellow mosaic virus

Acknowledgements

The first author would like to thank E. Quesada-Moraga (University of Cordoba) for providing B. bassiana strain EABb04/01-Tip and S. Vidal (Georg-August University Goettingen) for strains ATP05 and ATP01. Both authors are grateful to S. Abu Zahra for helping them with fungal inoculation and reisolation and to D. Hattab for technical assistance with ELISA. The comments of three anonymous reviewers are appreciated.