Induction of metabolite organic compounds by mutualistic endophytic fungi to reduce the greenhouse whitefly Trialeurodes vaporariorum (Westwood) infection on tomato
2012
Menjivar, Roy Donald | Cabrera, Jose Alfonso | Kranz, Joachim | Sikora, Richard A.
BACKGROUND AND AIMS: Six mutualistic endophytic fungi that are known to colonize the endorhiza have shown biological control properties against plant-parasitic nematodes. In this study we aim to investigate the potential of these endophytic fungi to reduce the phloem-feeding insect Trialeurodes vaporariorum (Westwood) on tomato. METHODS: To determine the host plant choice of T. vaporariorum, the total number of insects present on each plant was counted daily for 10 days, and then the second leaf below the shoot apex were examined for its chlorophyll content index (CCI).To separate and quantify the active compounds produced in the tomato leaves, a reversed phase high liquid chromatography (RP-HPLC) analysis was performed. PRINCIPLE RESULTS: A greenhouse choice test showed that Trichoderma atroviride strain MT-20, T. atroviride strain S-2 and Fusarium oxysporum strain 162 (Fo162) reduced the number of greenhouse whiteflies fifty percent when compared to the untreated control during ten days after insect release. The highest level of biocontrol activity was attained with Fo162. The strains MT20, S-2, and Fo162 all demonstrated acropedal induction of resistance to the insects. The isolate Fusarium sp. strain Bonn-7 enhanced plant growth. The negative effect on insect attraction to the leaves of the endophyte treated plants was not associated with leaf altered chlorophyll content. RP-HPLC analysis revealed that inoculation of the fungus Fo162 induced a change in the accumulation of specific organic compounds in the tomato leaves that could be the cause of insect repellence. CONCLUSIONS: This study demonstrated the high potential of mutualintic endophytic fungi, in particular of Fo162, to induce resistance in tomato against the phloemfeeding T. vaporariorum.
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