Use of resistance elicitors to reduce Fusarium ear rot and fumonisin accumulation in maize.

摘要

Fusarium ear rot of maize, caused by Fusarium verticillioides, reduces grain yield and quality and contaminates it with mycotoxins (fumonisin). As maize cultivars with complete resistance to Fusarium ear rot and fumonisin contamination have not been identified, and since the disease is difficult to control by conventional means, novel strategies for disease control and fumonisin reduction are required. One such strategy could involve the use of chemical elicitors that induce resistance in plants against a broad spectrum of pathogens, insects and abiotic stresses. In this study the ability of resistance elicitors to reduce infection by F. verticillioides and prevent fumonisin contamination in maize was investigated, and their impact on yield assessed. Five elicitors were selected based on their ability to activate different pathways in plant defence systems. The elicitors included beta -amino butyric acid (BABA), benzothiadiazole (BTH), harpin protein, 2,6-dichloroisonicotinic acid (INA), and methyl jasmonate (MeJA). A fungicide containing difenoconazole (triazole) and azoxystrobin (strobilurin) as active ingredients and that has known fungicidal activity in other plant-pathogen interactions, but not specifically Fusarium ear rot, was also included. The plant resistance elicitors and fungicide were evaluated in multi-site field trials. Following artificial inoculation with F. verticillioides isolate MRC 826, a high fumonisin producer, visual rating of Fusarium ear rot severity was performed and fumonisin B₁, B₂ and B₃ content of the grain quantified with high performance liquid chromatography. None of the five elicitors or the fungicide consistently reduced Fusarium ear rot and/or fumonisin contamination significantly. Treatment of maize with BTH resulted in a significant reduction in ear filling and yield in field trials. Treatment effects on fumonisin content were influenced by maize genotype and trial location, since significant interactions were observed between treatment, maize genotype and trial location. While the evaluated elicitors might be useful for prevention of maize foliar diseases, they were not effective at reducing Fusarium ear rot or fumonisin contamination. However, optimisation of elicitor application method, dose, frequency and timing could possibly yield improved results.