Biological characterization of fungal endophytes isolated from agarwood tree Aquilaria crassna Pierre ex Lecomte

Abstract

SUMMARYIn recent years, a considerable number of studies on the role of microbes in agarwood production have been carried out in plants of the species Aquilaria. Based on the fact that there is a relationship between the microorganisms residing inside the plant and the agarwood formation, we isolated and characterized endophytic fungi associated with A. crassna samples collected from Southern Vietnam. Morphological identification and DNA barcoding analysis of the fungal endophytic isolates indicated that they were classified at least into three groups of diverse genera: Geotrichum, Fusarium and Colletotrichum belonging to families Dipodascaceae, Nectriaceae and Glomerellaceae, respectively. Noteworthy, Geotrichum candium strain SHTr1 isolated from a dark colored woody sample of agarwood was able to produce a fruity odor and exhibited a slight antimicrobial activity against the test bacterium Staphylococcus aureus. Another fungal isolate, Fusarium verticillioides SHTr3's, showed a moderate antimicrobial activity against a test Gram positive bacteria Bacillus subtillis and S. aureus with MIC values at 50 µg.mL -1 . At 200 µg.mL -1 , the ethyl acetate extracts of fungal isolates F. verticillioides SHTr3 and Colletotrichum truncatum SHTrHc7 were found to have comparable scavenging abilities on DPPH-free radicals with 53.87 and 71.82%, respectively. The present results contribute to a depiction of a diverse fungal endophytic community in Vietnamese agarwood plant A. crassna and provide important information for further understanding of the role of endophytic fungi in agarwood formation and therapeutic applications of host plants in general.

Volatile Constituents of Endophytic Fungi Isolated from Aquilaria sinensis with Descriptions of Two New Species of Nemania

“…Several endophytic fungi are known as potentially bioactive metabolite producers in Aquilaria trees, and this is used in agarwood-producing trees [54][55][56]. In this study, two endophytic fungi belonging to Nemania were isolated from the dark resinous wood of Aquilaria sinensis, collected from Xishuangbanna, and this is the first report of Nemania from the host genus Aquilaria.…”

Pemberdayaan Masyarakat pada Budi Daya dan Pengembangan Produk Pohon Gaharu (Aquilaria sp.) di Kabupaten Tolitoli, Sulawesi Tengah

“…Pembentukan aroma resin gaharu dan perubahan warna kayu gaharu pada proses infeksi buatan menggunakan inokulum dipengaruhi oleh faktor biotik dan abiotik. Faktor biotik terutama cendawan sebagai agen bio-induksi yang menentukan pembentukan resin gaharu harus bersifat endofitik-patogenik-epifitik (Chi et al 2016;Chippa et al 2017).…”

Antioxidant and Antifungal Activity of Endophytic Fungi Associated with Agarwood Trees

“…Endophytic microorganisms, mostly fungi in general, are localized internally in their host plants and become an important issue in the past few decades (Faeth, 2002;Staniek et al, 2008) has been previously reports (Nimnoi et al, 2010;Shoeb et al, 2010;Chi et al, 2016).…”

“…In this study, 50 endophytic fungal isolates were evaluated for antioxidant activity. The results revealed that among 50 isolates, six had ability to reduce the absorbance of DDPH free radical with the range was 36% -82% ( (Gong and Guo, 2009;Nimnoi et al, 2010;Shoeb et al, 2010;Cui et al, 2011;Chi et al, 2016) (Tanapichatsakul et al, 2018).…”

“…Previous studies have recorded that 1) Fusarium spp. isolated from leaves, steam and root of A. sinensis showed the most potent antimicrobial activity, 2) several endophytes fungi (Gong and Guo, 2009) isolated form A. crassna showed capability to produce indole-3-acetic acid (IAA) and siderophores (Nimnoi et al, 2010), 3) F. verticillioides SHTr3 and Colletotrichum truncatum SHTrHc7 isolated from A. crassna showed comparable scavenging abilities on DPPH-free radicals (Chi et al, 2016), 4) Xylaria mali, Lasiodiplodia theobromae and Phaeoacremonium rubrigenum isolated form A. sinensis exhibited cytotoxicity against 293-T, 293-T, and SKVO3 cells lines (Cui et al, 2011), and 5) fungus AL-2 strain isolated from A. malaccensis had antibacterial activities against gram positive and negative bacteria as well as general toxicity based on brine shrimp lethality (Shoeb et al, 2010). A. sinensis have been used as traditional Chinese medicinal, a tropical evergreen tree distributed in Hainan, Guangdong, Guangxi, Yunnan and Taiwan (Chen et al, 2016); A. crassna used also as traditional medical plant and widely distributed in Indochina and Thailand (Turjaman and Hidayat, 2017); and so that for A. malaccensis which is the most popular species for its agarwood production and distributed from different countries, Bangladesh, Bhutan, Cambodia, India, Indonesia, Iran, Lao PRD, Malaysia, Myanmar, Philippines, Singapore, Thailand, Vietnam and Papua New Guinea (Oldfield et al, 1998;Premalatha and Kalra, 2013).…”