Oral Presentation Australian Society for Microbiology Annual Scientific Meeting 2019

Bacterial consortia reduce severity of Fusarium wilt in cotton (#157)

Zhiguang Qiu 1 , Jay Prakash Verma 1 2 , Jenendra Wadduwage 1 , Pankaj Trivedi 1 3 , David Tissue 1 , Brajesh Singh 1 4
  1. Western Sydney University, Richmond, NSW, Australia
  2. Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, Uttar Pradesh, India
  3. Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, CO, USA
  4. Global Centre for Land-based Innovation, Western Sydney University, Penrith, NSW, Australia

Soil bacteria colonise plant roots and interact intimately with their plant host. Some colonisers promote plant growth and may also exhibit antagonistic activities against pathogenic microorganisms. There have been a number of studies using biocontrol agents to control crop pathogens with mixed results. It has been proposed that inconsistent outcomes of biological approach are linked to use of single species biocontrol products. Only few studies have attempted to use a consortium which can arguably have better ability to survive in new environment and hence improved efficacy.

Our aim was to isolate multiple bacterial species and to develop a bacterial consortium which demonstrated antagonistic activities against Cotton Fusarium Wilt disease caused by Fusarium oxysporum f.sp. vasinfectum (Fov). The cotton wilt is a major constraint of cotton farm productivity in Australia. We tested if applying the bacterial consortium improve control of Fusarium wilt compared to single isolates and no treatment.

In this study, two glasshouse experiments were conducted to (1) test the efficacy of three single isolates in reducing impact of Fusarium wilt on germination and disease severity at early stage of plant development, and (2) test whether a consortium could provide a better control of pathogen and if the efficacy of biocontrol agents is modified by cotton cultivars. A number of antagonistic bacteria was isolated from the roots of healthy cotton plants and a bacterial consortium was developed based on their ability to grow together with synergistic relation. Our results showed that single isolate reduces disease incidence by up to 97%. Bacterial consortia also improved seed germination by 50% but impact of disease incidence was modified by crop cultivars.

Overall, our results demonstrated that biocontrol agents are effective in reducing disease incidence under glasshouse conditions with two different soils. Currently we are investigating whether soil and plant microbiomes have responded either to disease incidence or to use of biocontrol agents and this result will also be presented.