Dr. Ariyawansa's research team has made significant progress in the control of Welsh onion leaf diseases. Leaf diseases caused by Stemphylium and Colletotrichum species are major biotic limiting factors for the Welsh onion industry in Taiwan. Considering pathogen resistance to existing fungicides and potential environmental pollution, Dr. Ariyawansa aims to use endophytes from Welsh onions as a biological control method to replace chemical control.
The research team isolated several bacterial and fungal strains from healthy Welsh onion leaves. These strains were classified into 16 bacterial and 9 fungal genera through morphological and DNA sequence-based molecular identification techniques. Subsequent evaluation through dual culture assays and greenhouse experiments assessed the biocontrol mechanisms of these endophytic strains against the major leaf pathogens Colletotrichum spaethianum and Stemphylium vesicarium.
The results indicated that Bacillus velezensis GFB08 possesses multiple antimicrobial peptide genes and the ability to secrete cell wall-degrading enzymes. It demonstrated significant preventive and curative effects against diseases caused by C. spaethianum and S. vesicarium. This strain can serve as a biocontrol agent to reduce leaf diseases in Welsh onions in Taiwan, thereby decreasing the use of fungicides.
- Paper link:
Wang, J.-Y., Jayasinghe, H., Cho, Y.-T., Tsai, Y.-C., Chen, C.-Y., Doan, H. K., Ariyawansa, H. A. (2023). Diversity and biocontrol potential of endophytic fungi and bacteria associated with healthy welsh onion leaves in Taiwan. Microorganisms. 11(7):1801. Doi:10.3390/microorganisms11071801