J. Microbiol. Biotechnol. (2009), 19(2), 000–000 doi: 10.4014/jmb.0901.0030 First published online 1 June 2009 Phoma herbarum as a New Gibberellin-Producing and Plant Growth- Promoting Fungus Hamayun, Muhammad 1 , Sumera Afzal Khan 2 , Abdul Latif Khan 1 , Gauhar Rehman 3 , Eun-Young Sohn 1 , Aamer Ali Shah 4 , Sang-Kuk Kim 5 , Gil-Jae Joo 6 , and In-Jung Lee 1 * School of Applied Biosciences, Kyungpook National University, Daegu 702-701, Korea Centre of Biotechnology and Microbiology, University of Peshawar, Peshawar Pakistan Department of Genetic Engineering, Kyungpook National University, Daegu 702-701, Korea Department of Biotechnology, Quaid-i-Azam University, Islamabad Pakistan Institute for Bioresources Research, Gyongbuk Provincial Agricultural Technology Administration, Daegu 702-708, Korea Institute of Agricultural Science and Technology, Kyungpook National University, Daegu 702-701, Korea Received: January 15, 2009 / Revised: April 13, 2009 / Accepted: April 16, 2009 Endophytic fungi are known for the production of valuable metabolites, but information on the gibberellin production capacity of this group is limited. We isolated 9 endophytic fungi from the roots of salt-stressed soybean plants and screened them on waito-c rice, in order to identify plant growth promoting fungal strains. The fungal isolate TK- 2-4 gave maximum plant length (20.35 cm) promotion in comparison with wild-type Gibberella fujikuroi (19.5 cm). In a separate experiment, bioassay of TK-2-4 promoted plant length and biomass of soybean cultivar Taegwangkong. The TK-2-4 culture filtrate was analyzed for the presence of gibberellins, and it was found that all physiologically active gibberellins, especially GA 4 and GA 7 , were present in higher amounts (GA 1 , 0.11 ng/ml; GA 3 , 2.91 ng/ml; GA 4 , 3.21 ng/ml; and GA 7 , 1.4 ng/ml) in conjunction with physiologically inactive GA 9 (0.05 ng/ml), GA 12 (0.23 ng/ ml), GA 15 (0.42 ng/ml), GA 19 (0.53 ng/ml), and GA 20 (0.06 ng/ml). The fungal isolate TK-2-4 was later identified as a new strain of Phoma herbarum, through the phylogenetic analysis of 28S rDNA sequence. Keywords: Phoma herbarum, gibberellin production, endophytic fungi, soybean, growth promotion Endophytic fungi have been shown to confer benefits to host plants, including tolerance to herbivory, heat, salt, disease, and drought, as well as an increased biomass, both above and below the ground [17, 33]. Endophytic colonization may also improve the ecological adaptability of the host by enhancing its tolerance to biotic and abiotic stresses [22]. Phoma herbarum Westend. (Fungi imperfecti) is a ubiquitous saprophyte and toxigenic pathogen to plants and animals [31], including humans under some occasions [26]. P. herbarum possesses strong adaptability to diverse environments including salty and chilly surroundings [35, 31]. P. herbarum is also a versatile producer of many natural products with potent activities [2, 5, 6, 14, 15, 23, 30, 35, 36]. Gibberellins (GAs) are diterpenoid plant hormones, first detected in the 1930s from culture filtrates of Gibberella fujikuroi, a known pathogen of rice plants [20]. GAs appear to be involved in every aspect of plant growth and development, but their most typical (and spectacular) property involves the enhancement of stem growth [19]. GAs may modify the sex expression of flowers, induce the parthenocarpic development of fruit, and delay senescence. They obviate the need for exposure to red light in the germination of seeds and spores, and the need for vernalization in the growth of bulbs and tubers. They are associated with the breaking of winter dormancy and stimulate the formation of hydrolytic enzymes in germinating cereal grain [18]. Currently, 136 GAs have been identified, and 12 fungi, pathogenic and nonpathogenic, associated with plants and/or soil have been reported as GA producers [10, 16, 28]. A new strain of Penicillium citrinum had also been reported as a GA producer [11]. However, there are no reports regarding the GA production capacity of Phoma herbarum. There is increasing concern about the excessive use of fertilizer and pesticides in agricultural fields and their subsequent negative impact on crops and the environment. The aim of the present study was to select potential fungal inoculums for plant growth promotion in order to avoid the excess use of fertilizer and pesticides in agricultural fields. *Corresponding author Phone: +82-53-950-5708; Fax: +82-53-958-6880; E-mail: ijlee@knu.ac.kr