中藥之水萃取液對Alternaria
brassicicola
孢子發芽的影響



及五倍子抑菌物質的特性



 Effect of Chinese medicines on spore
germination of Alternaria



brassicicola and nature of
inhibitory substances from Galla rhois

















 






  研究生:李智緯  Jhih-Wei Li



 



指導教授:何婉清  Wang-Ching Ho



摘要



    農藥雖有防治病、蟲、草害的效果,但其長期使用的結果會導致病原菌及害蟲抗藥性的產生,並引起環境的污染、土壤結構的劣化及微生物生態平衡的破壞等問題;非農藥的防治策略已成為未來病、蟲、草害管理的趨勢,抑菌中藥的開發是其中的一個重要方向。本實驗以植物病原孢子的發芽率來測定中藥水萃取液對植物病原真菌的抑菌作用。選用發芽率高且對植物中抑菌活性成份敏感的十字花科黑斑病菌(Alternaria
brassicicola
(Schw) Wiltshire)
作為供試真菌來進行抑菌中藥抑菌能力的評估。結果顯示在供試的70種中藥中,以虎杖、黃芩、黃柏、黃連及五倍子等5種中藥具有最明顯的抑菌效果,其高溫高壓(12115 lb/in220min)水萃取液的400倍稀釋液能完全抑制A.
brassicicola
孢子的發芽。進一步的研究更發現,上述五種中藥中又以五倍子的抑菌效果最佳,抑菌範圍也最廣,其1000倍稀釋水萃取液除了可以完全抑制A. brassicicola孢子的發芽外,也對火鶴花花腐病菌(Corynespora cassicola)、蓮霧炭疽病菌(Colletotrichum
gloesporioides
)
、甜椒疫病菌(Phytophthora
capsici
)
、蕃茄晚疫病菌(Phytophthora infestans)及長豇豆萎凋病菌(Fusarium
oxysporum
f. sp. tracheiphilum)
等孢子的發芽,具有完全的抑制效果。以離花接種法測試五倍子水萃取液對火鶴花花腐病的防治效果時發現,五倍子400倍稀釋液可預防火鶴花花腐病的發生;但在已有花腐病病徵的火鶴花苞片上,則無法抑制其病勢的進展。結果顯示,五倍子水萃取液或其抑菌活性成份,有潛力發展成為預防多種植物病害的植物源保護劑。在探討五倍子抑菌物質的特性時發現,其抑菌活性物質對強酸有耐受性,但卻亦受強鹼影響,其抑菌活性物質在pH12的強鹼條件下24小時就會喪失其活性;酸鹼值會影響五倍子水萃取液的抑菌效果,將五倍子水萃取液的pH值由3.3調整到7以上時,就會喪失其抑菌作用;其抑菌活性成份可溶於極性溶劑,但卻不可溶於非極性溶劑中,可被分子量為1000孔徑的透析膜透析,並可經陽離子交換樹脂交換而失去其抑菌活性,顯示五倍子水萃取液中的抑菌物質為分子量500-100之間的帶正電荷分子。



關鍵字:非農藥防治、中藥五倍子、十字花科黑斑病菌(Alternaria brassicicola (Schw) Wiltshire)、發芽率火鶴花花腐病菌(Corynespora cassicola



Abstract



    Widespread usage of pesticides for
control of diseases, insects pests and weed of agricultural crops has become a
global problem due to the adverse effects of pesticides on human health and the
environment. Development of alternative method for
disease control is, therefore, needed. A total of 70
Chinese medicines
was screened for ability to control fungal plant pathogens using conidial germination of Alternaria brassicicola as a bioassay. Aqueous extract of Galla
rhois was found be most effective in suppressing germination of A.
brassicicola
conidia. The extract was also strongly
inhibitory to spore germination of Corynespora cassicola, Colletotrichum
gloesporioides
, Phytophthora capsici,
P. infestans, and Fusarium oxysporum f. sp. tracheiphilum, but not Pestalotiopsis euginae. The
aqueous extract at 400 fold dilution was able to protect the detached
anthurium spathes from infection by C. cassicola. The inhibitory substance in Galla rhois was sobuble in polar
solvents but not non-polar solvents. The extract became lees inhibitory when
the pH was adjusted from the original 3.3 to 7, and non-inhibitory at pH values
of 8 to 10. The inhibitor in the aqueous extract was dialyzable in the membrane
tubing with molecular weight cut-off
of 1000, but not in that with
molecular weight cut-off of 500. It was exchangeabe by cation but not anion
exchange resins. Results suggest that the in
inhibitor has a molecular weight between 500 and 1000, and positive
charge on its molecule.



KeywordsAlternative method for disease control, Chinese medicines, Galla rhois, Alternaria brassicicola, spore germination, Corynespora cassiicola



 



 

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