評估以幾丁質分解細菌防治土壤傳播性植物病害之潛力

Abstract

本研究以幾丁質分解能力作為篩選標的，成功分離到能夠有效降低土壤傳播性病害之南方根瘤線蟲感染的菌株 Lysobacter sp. HSL。根據研究結果顯示，當 Lysobacter sp. HSL 在 KBM 培養基上與 DC 和 XS 兩族群根瘤線蟲卵共培養時，分別能使 DC 和 XS 之卵產生異常達 98.60 ± 1.13% 和 100%；後續於紅豆的第一次植株試驗中發現，在 Lysobacter sp. HSL 細菌懸浮液中額外添加 2 mL 之液態 KBM 澆灌植株後，DC 感染紅豆並產生卵塊之數量為 197.33 ± 44.19 顆，顯著低於只接種線蟲的正對照 CK (+) 之 350.33 ± 14.17 顆，顯示在有外加的營養源時能夠顯著降低南方根瘤線蟲卵孵化並感染寄主之能力。而在與真菌的對峙培養試驗中，Lysobacter sp. HSL 對 LP 和 TS 兩株白絹病菌 Sclerotium rolfsii 菌株分別造成 16.16 ± 1.10% 與 18.83 ± 3.84% 的抑制效果，然而在植株試驗中即使有外加 KBM 的情形下，所有處理組仍與對照組無顯著差異。綜合以上結果，本研究所分離之 Lysobacter sp. HSL 雖對白絹病這個土壤傳播性真菌病害無顯著之防治效果，但是在提供 KBM 的情形下能顯著影響南方根瘤線蟲的卵與其對紅豆植株的感染。總結而言，本研究除驗證有益菌之篩選及建立評估其防治能力的方法外，亦發現使用有益微生物時若搭配額外營養源，或許是一種能簡單而有效提升其對害物防治效果的策略，該發現對未來以活體有益微生物進行使用之研究或農業實務上或許能夠提供一發想之方向。

This study aimed to isolate beneficial strains capable of reducing a soilborne disease caused by Meloidogyne incognita, using chitinolytic activity as a selection criterion, and successfully identified Lysobacter sp. HSL. The results showed that when Lysobacter sp. HSL was co-cultured with nematode eggs on KBM media, the percentage of abnormal eggs for Meloidogyne incognita strains DC and XS reached 98.60 ± 1.13% and 100%, respectively. In subsequent initial pot experiments with Vigna angularis, drenching plants with a bacterial suspension of Lysobacter sp. HSL supplemented with 2 mL of liquid KBM resulted in 197.33 ± 44.19 egg masses of M. incognita DC, which was significantly lower than that of the nematode-only control group CK (+) (350.33 ± 14.17 egg masses), indicating that the supplementation of external nutrient sources can significantly reduce the ability of root-knot nematode eggs to hatch and infect hosts. In antagonistic tests against fungi, Lysobacter sp. HSL achieved 16.16 ± 1.10% and 18.83 ± 3.84% inhibition against Sclerotium rolfsii strains LP and TS, respectively. However, in pot experiments, no significant difference was observed between the treatments and the control, regardless of KBM supplementation. In conclusion, although the Lysobacter sp. HSL strain isolated in this study showed no significant control effect against the soilborne fungal pathogen Sclerotium rolfsii, it significantly affected root-knot nematode eggs and their infection on Vigna angularis under KBM supplementation. Ultimately, in addition to validating the screening of beneficial bacteria and establishing evaluation methods for their biocontrol efficacy, this study reveals that pairing beneficial microorganisms with additional nutrient sources may serve as a simple and effective approach to enhance pest control efficacy, potentially providing a valuable perspective for future research and agricultural practices utilizing live beneficial microorganisms.