J. Microbiol. Biotechnol. (2010), 20(12), 1744–1749 doi: 10.4014/jmb.1005.05018 First published online 14 September 2010 Gibberellin-Producing Endophytic Fungi Isolated from Monochoria vaginalis Ahmad, Nadeem 1 , Muhammad Hamayun 2 * , Sumera Afzal Khan 3 , Abdul Latif Khan 4 , In-Jung Lee 4 , and Dong-Hyun Shin 4 Department of Botany, Islamia College University, Peshawar, Pakistan Department of Botany, Abdul Wali Khan University, Mardan, Pakistan Center of Biotechnology and Microbiology, University of Peshawar, Pakistan School of Applied Biosciences, Kyungpook National University, Daegu 702-701, Korea Received: May 11, 2010 / Revised: August 20, 2010 / Accepted: August 21, 2010 The role of endophytic fungi in plant growth and development is well documented. However, endophytic fungi with growth promotion capacity have never been isolated from weeds previously. In the current study, we isolated 8 fungal endophytes from the roots of Monochoria vaginalis, a serious weed of rice paddy in Korea. These isolates were screened on Waito-C, in order to identify plant growth promoting metabolites. Two fungal isolates (M5.A & M1.5) significantly promoted the plant height and shoot length of Waito-C during preliminary screening experiments. The culture filtrates (CFs) of M5.A and M1.5 also promoted the shoot length of Echinocloa crusgalli. Gibberellins (GAs) analysis of the CFs of M5.A and M1.5 showed that these endophytic fungi secrete higher quantities of GAs as compared with wild-type G. fujikuroi KCCM12329. The CF of M5.A contained bioactive GAs (GA 3 , 2.8 ng/ml; GA 4 , 2.6 ng/ml, and GA 7 , 6.68 ng/ml) in conjunction with physiologically inactive GA 9 (1.61 ng/ml) and GA 24 (0.18 ng/ml). The CF of M1.5 contained physiologically active GAs (GA 3 , 1.64 ng/ml; GA 4 , 1.37 ng/ml and GA 7 , 6.29 ng/ml) in conjunction with physiologically inactive GA 9 (3.44 ng/ml), GA 12 (0.3 ng/ml), and GA 24 (0.59 ng/ml). M5.A and M1.5 were identified as new strains of Penicillium sp. and Aspergillus sp., respectively, based on their 18S rDNA sequence homology and phylogenetic analysis. Keywords: Penicillium sp., Aspergillus sp., gibberellins, endophytic fungi, Monochoria vaginalis, growth promotion The plant growth regulation potential of fungal endophytes is partly due to the endophytes’ production of phytohormones such as indole-3-acetic acid (IAA), cytokinins, and other plant growth promoting substances [30], and/or partly owing to the fact that endophytes could have enhanced the hosts’ uptake of nutritional elements such as nitrogen and phosphorus [14]. The endophytic fungi also confer benefits to host plants, including tolerance to herbivory, heat, salt, disease, and drought [15]. Penicillium citrinum and Aspergillus fumigatus have been reported as fungal endophytes that promoted plant growth by secreting gibberellins (GAs) in the rhizosphere of their hosts [11]. Penicillium sp. produce various toxins, such as penicillic acid, peptide nephrotoxin, viomellein, xanthomegin, xanthocillin X, mycophenolic acid, roquefortine C and D, citrinin, penicillin, cyclopiazonic acid, isofumigaclavine A, penitrem A, decumbin, patulin citreoviridin, griseofulvin, verruculogen, ochratoxin, chrysogine, and meleagrin. Their industrial uses include formation of Roquefort and Camembert cheeses, salami-sausages starter culture; antibacterial penicillin; and antifungal griseofulvin [1], [6]. On the other hand, Aspergillus is an opportunistic pathogen as well as a major allergen [7]. Some species can cause infection in humans and other animals. Other species are important in commercial microbial fermentations and produce natural products that can be used in the development of medications to treat human ailments. A. niger is a major source of citric acid, as it accounts for over 99% of global citric acid production. The plant growth promoting potential of Aspergillus is well known, as it produces substantial amounts of phosphatases [25]. The favorable affects of A. fumigatus on the growth and mineral nutrition of mung bean and clusterbean are also well documented [24]. GAs are diterpenoid plant hormones, first detected in the 1920s from culture filtrate (CF) of G. fujikuroi, a known pathogen of rice plants [18]. GAs appear to be involved in every aspect of plant growth and development, but their most typical property involves the enhancement of stem growth [17]. GAs may modify the sex expression of flowers, induce the parthenocarpic development of the *Corresponding author Phone: +92-937-929124; Fax: +92-937-9230619; E-mail: hamayun@awkum.edu.pk