Development of microbial tools to control Rhizoctonia bare patch disease of wheat

Abstract

Wheat is one of the major staple foods in the world and global demand is growing. However, global wheat production is constrained by many abiotic and biotic factors. Rhizoctonia bare patch disease of wheat limits wheat production in Australia and other areas of the world. The disease is caused by the soil borne necrotrophic fungus Rhizoctonia solani AG8. Current control strategies such as crop rotation, use of registered fungicides and tillage practices provide only a partial protection. Further, extensive usage of chemical fungicides can adversely affect crop, soil, and human health. Therefore, it is crucial to identify disease management strategies that reduce chemical inputs while improving plant and soil health.

In this thesis, I isolated bacteria and fungi from the wheat root endosphere, screened them for potential biocontrol activity against R. solani AG8 and for plant growth promotion under in vitro conditions. Best candidates were then tested in a short-term glasshouse assay for their efficacy of biocontrol in wheat. The findings of this chapter showed that two BCAs; Diaporthe sp. (an endophytic fungus) and Pseudomonas TK32 (and endophytic bacterium) significantly reduced disease incidence and improved plant dry weight under pathogen challenged condition.

Overall, this study provides important new insights into biological control approaches of Rhizoctonia bare patch disease of wheat. It demonstrated that wheat rhizosphere and root endosphere samples of different plant fitness levels could serve as good sources for potential biocontrol agents against R. solani AG8 (chapter 2 and chapter 3). Compatibility of BCAs with chemical fungicides and the fact that BCAs can successfully be combined with chemical fungicides for improved disease control (chapter 4) is significant for expanding management approaches to successfully control Rhizoctonia bare patch disease of wheat in future.

Date of Thesis submission	2022
Original language	English
Awarding Institution	Western Sydney University
Supervisor	Catriona Macdonald (Supervisor), Brajesh Singh (Supervisor), Juntao Wang (Supervisor) & Bruna Batista (Supervisor)