Co‐inoculation timing affects the interspecific interactions between phoma stem canker pathogens Leptosphaeria maculans and Leptosphaeria biglobosa

• Published in: Pest management science Vol. 80; no. 5; pp. 2443 - 2452
• Main Authors: Bingol, Evren, Qi, Aiming, Karandeni‐Dewage, Chinthani, Ritchie, Faye, Fitt, Bruce D. L., Huang, Yong‐Ju
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.05.2024; Wiley Subscription Services, Inc
• Subjects: Economic importance; Host plants; Inoculation; interspecific interactions; Interspecific relationships; Leptosphaeria biglobosa; Leptosphaeria maculans; Liquid culture; Pathogens; Pest control; phoma stem canker; Phytotoxins; Rapeseed; secondary metabolites; Sirodesmin; sirodesmin PL; Stem canker; Stems; sirodesmin PL; secondary metabolites; Leptosphaeria maculans; Leptosphaeria biglobosa; phoma stem canker; interspecific interactions
• ISSN: 1526-498X; 1526-4998
• DOI: 10.1002/ps.7799

BACKGROUND Phoma stem canker is an economically important disease of oilseed rape, caused by two co‐existing fungal pathogen species, Leptosphaeria maculans (Plenodomus lingam) and Leptosphaeria biglobosa (Plenodomus biglobosus). Leptosphaeria maculans produces a phytotoxin called sirodesmin PL. Our previous work showed that L. biglobosa has an antagonistic effect on the production of sirodesmin PL if it is simultaneously co‐inoculated with L. maculans. However, the effects of sequential co‐inoculation on interspecific interactions between the two pathogens are not understood. RESULTS The interactions between L. maculans and L. biglobosa were investigated in liquid culture by inoculation with L. maculans first, followed by L. biglobosa sequentially at 1, 3, 5 or 7 days later and vice versa; the controls were inoculated with L. maculans only, L. biglobosa only, or L. maculans and L. biglobosa simultaneously. The results showed that L. biglobosa inhibited the growth of L. maculans, the production of both sirodesmin PL and its precursors if L. biglobosa was inoculated before, or simultaneously with, L. maculans. However, the antagonistic effects of L. biglobosa were lost if it was co‐inoculated 5 or 7 days after L. maculans. CONCLUSION For the first time, the results of this study provided evidence that the timing when L. maculans and L. biglobosa meet significantly influences the outcome of the interspecific competition between them. Leptosphaeria biglobosa can inhibit the production of sirodesmin PL and the growth of L. maculans if it is inoculated before L. maculans or less than 3 days after L. maculans in liquid culture. There is a need to further investigate the timing of co‐inoculation on interactions between L. maculans and L. biglobosa in their host plants for improving the control of phoma stem canker. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. For the first time, this study provides evidence that the timing of co‐inoculation influences the outcome of competition between Leptosphaeria maculans and Leptosphaeria biglobosa; L. biglobosa can inhibit sirodesmin PL production and the growth of L. maculans if it is inoculated before L. maculans or less than 3 days after L. maculans.