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Studies on Antagonistic Effect Against Plant Pathogenic Fungi from Endophytic Fungi Isolated from Hottuynia cordata Thunb. and Screening for Siderophore and Indole-3-Acetic Acid Production.

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Yaovapa Aramsirirujiwet, Chenchira Gumlangmak and Vichien Kitpreechavanich

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The endophytic fungi that colonizes internal plant tissues without causing apparent

harm to their host were isolated from healthy leaf, root and stem of Hottuynia cordata

Thunb. Twelve fungal isolates found were identified by their morphological characteristic

and using molecular technique. The result showed that ten isolates belonging to

Ascomycota were presumed to be in genus Colletotrichum, Lasiodiplodia and Fusarium

in eight isolates and two isolates were identified to class Dothideomycetes and

Sordariomycetes. Two unidentified isolates (R14 and R15), confined only to root segments

were isolated, these members may be from the group of Mycelia-Sterilia. The evaluation

of antagonistic activity of twelve fungal endophytes isolated from healthy Houttuynia

cordata Thumb. against Trichoderma harzianum and five plant pathogenic fungi (Fusarium

oxysporum, Sclerotium rolfsii, Rhizoctonia sp., Alternaria brassicicola and Phytophthora

palmivora) by dual culture technique were performed. The in vitro antagonistic activities

as two types of activities in this study; mycoparasitism and competition were found.

Endophyte isolate B06, B12, B09 and R15 gave the highest percent inhibition of radial

growth against to the plant pathogenic fungi (F. oxysporum, S. rolfsii, A. brassicicola) and

T. harzianum within 24.22%, 29.07%, 13.54 and 24.15%, respectively. Endophyte isolate

R14 showed the highest antagonistic activity to Rhizoctonia sp. and P. palmivora with

39.33% and 33.34% respectively. For the siderophore production, the seven active

endophyte isolates showed orange halo formed around the colonies more than 30 mm on

CAS agar. Three endophyte isolates efficiently produced IAA more than 24 μg/ml. The

active endophyte isolates B06 identified as Lasiodiplodia pseudotheobromae showed the

highest ability to produce IAA (37.034 μg/ml) and also showed the highest orange halo

formed around the colonies which determined to siderophore production.

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Hottuynia cordata Thunb.; fungal endophytes; antagonistic activity; plant pathogenic fungi