| 論文英文摘要 |
In order to explore the control mechanisms for tomato plants resistant to Fusarium wilt disease by the biocontrol agent Bacillus mycoides, a platform was set up for simultaneously culturing tomato seedlings, B. mycoides, and Fusarium oxysporum f. sp. lycopersici Fol-04 in the flask cultivation system. Biolog GP Microplate was used to analyze the utilization of carbon and nitrogen sources by F. oxysporum f. sp. lycopersici Fol-04, B. mycoides CHT2402 and NP02 isolates. The results showed that adjusting sucroseconcentration in Murashige's and Skoog's (MS) medium to 1% (w/v) was suitable for the interactions among tomato seedlings, the pathogen, and biocontrol agents. Tomato seeds were incubated in the cell suspension (108
cfu/mL) of B. mycoides CHT2402 and NP02 for 3 days, and then they were transplanted to the modified MS medium in the flask. Two weeks later, each tomato seedlings was inoculated with single spore of F. oxysporum f. sp. lycopersici Fol-04 near the root. It was found that tomato seedlings could be protected from the pathogen by B. mycoides CHT2402 and NP02 for five days in the flask cultivation system. To study the mechanisms for controlling tomato Fusarium wilt by the biocontrol agents, the root tissues of tomato plants treated respectively with B. mycoides CHT2402 and NP02 were analyzed by tissue section and real time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) techniques. The results of Spurr's resin block section indicated that the cell wall thickness of epidermis cells of the tomato plant treated with B. mycoides CHT2402 and NP02, respectively, increased 0.015-0.018 µm and 0.014-0.016 µm, whereas the cell wall thickness of cortex cells increased 0-0.008 µm and 0.014-0.03 µm. In addition, the expression of PAL (phenylalanine ammonia lyase) and LOX (lipoxygenase) genes in tomato roots was analyzed by qRT-PCR after B. mycoides CHT2402 and NP02 application in both flask cultivation and greenhouse condition. Accordingly, the results demonstrated B. mycoides CHT2402 and NP02 application induced the expression of PAL and LOX in tomato plants at different time points. Collectively, our results suggest that B. mycoides CHT2402 and NP02 are able to control tomato Fusarium wilt if they could colonize the roots and vascular tissues of tomato plants and trigger PAL and LOX expression prior to pathogen infection. |