Leptosphaeria biglobosa inhibits the production of sirodesmin PL by L. maculans

• Published in: Pest management science 2024-05, Vol.80 (5), p.2416-2425
• Main Authors: Fortune, James A., Bingol, Evren, Qi, Aiming, Baker, Daniel, Ritchie, Faye, Karandeni Dewage, Chinthani S., Fitt, Bruce D. L., Huang, Yong‐Ju
• Format: Article
• Language: English
• Subjects: ascospores; Brassica napus; Coexistence; Conidia; Cotyledons; disease progression; interspecific competition; Interspecific relationships; Lesions; liquids; Metabolites; oilseed rape; Pest control; pest management; phoma stem canker; Phoma stem canker disease; Plant extracts; Plenodomus biglobosus; Plenodomus lingam; Precursors; Rapeseed; Secondary metabolites; Sirodesmin; Stem canker
• ISSN: 1526-498X; 1526-4998
• DOI: 10.1002/ps.7275

BACKGROUND Phoma stem canker is caused by two coexisting pathogens, Leptosphaeria maculans and L. biglobosa. They coexist because of their temporal and spatial separations, which are associated with the differences in timing of their ascospore release. L. maculans produces sirodesmin PL, while L. biglobosa does not. However, their interaction/coexistence in terms of secondary metabolite production is not understood. RESULTS Secondary metabolites were extracted from liquid cultures, L. maculans only (Lm only), L. biglobosa only (Lb only), L. maculans and L. biglobosa simultaneously (Lm&Lb) or sequentially 7 days later (Lm+Lb). Sirodesmin PL or its precursors were identified in extracts from ‘Lm only’ and ‘Lm+Lb’, but not from ‘Lm&Lb’. Metabolites from ‘Lb only’, ‘Lm&Lb’ or ‘Lm+Lb’ caused significant reductions in L. maculans colony area. However, only the metabolites containing sirodesmin PL caused a significant reduction to L. biglobosa colony area. When oilseed rape cotyledons were inoculated with conidia of ‘Lm only’, ‘Lb only’ or ‘Lm&Lb’, ‘Lm only’ produced large gray lesions, while ‘Lm&Lb’ produced small dark lesions similar to lesions caused by ‘Lb only’. Sirodesmin PL was found only in the plant extracts from ‘Lm only’. These results suggest that L. biglobosa prevents the production of sirodesmin PL and its precursors by L. maculans when they grow simultaneously in vitro or in planta. CONCLUSION For the first time, L. biglobosa has been shown to inhibit the production of sirodesmin PL by L. maculans when interacting simultaneously with L. maculans either in vitro or in planta. This antagonistic effect of interspecific interaction may affect their coexistence and subsequent disease progression and management. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. For the first time, L. biglobosa has been shown to inhibit the production of sirodesmin PL by L. maculans when interacting simultaneously with L. maculans either in vitro or in planta. This antagonistic effect of interspecific interaction may affect their coexistence and subsequent disease progression and management.