J. Microbiol. Biotechnol. (2011), 21(9), 893–902 doi: 10.4014/jmb.1103.03012 First published online 28 July 2011 Salinity Stress Resistance Offered by Endophytic Fungal Interaction Between Penicillium minioluteum LHL09 and Glycine max. L Khan, Abdul Latif 1,2 , Muhammad Hamayun 3 , Nadeem Ahmad 4 , Javid Hussain 2,5 , Sang-Mo Kang 1 , Yoon-Ha Kim 1 , Muhammad Adnan 2 , Dong-Sheng Tang 6 , Muhammad Waqas 1 , Ramalingam Radhakrishnan 1 , Young-Hyun Hwang 1 , and In-Jung Lee 1 * School of Applied Biosciences, College of Agriculture and Life Sciences, Kyungpook National University, Daegu 701-702, Korea Kohat University of Science and Technology, Kohat, Pakistan Department of Botany, Abdul Wali Khan University, Mardan, Pakistan Department of Botany, Islamia College University, Peshawar, Pakistan Department of Biological Sciences and Chemistry, College of Arts and Sciences, University of Nizwa, Nizwa, Oman Key Laboratory of Agri-biodiversity and Pest Management, Yunnan Agricultural University, Kunming 650201, Yunnan, China Received: March 7, 2011 / Revised: May 25, 2011 / Accepted: June 2, 2011 Endophytic fungi are little known for their role in gibberellins (GAs) synthesis and abiotic stress resistance in crop plants. We isolated 10 endophytes from the roots of field-grown soybean and screened their culture filtrates (CF) on the GAs biosynthesis mutant rice line - Waito-C. CF bioassay showed that endophyte GMH-1B significantly promoted the growth of Waito-C compared with controls. GMH-1B was identified as Penicillium minioluteum LHL09 on the basis of ITS regions rDNA sequence homology and phylogenetic analyses. GC/MS-SIM analysis of CF of P. minioluteum revealed the presence of bioactive GA 4 and GA 7. In endophyte- soybean plant interaction, P. minioluteum association significantly promoted growth characteristics (shoot length, shoot fresh and dry biomasses, chlorophyll content, and leaf area) and nitrogen assimilation, with and without sodium chloride (NaCl)-induced salinity (70 and 140 mM) stress, as compared with control. Field-emission scanning electron microcopy showed active colonization of endophyte with host plants before and after stress treatments. In response to salinity stress, low endogenous abscisic acid and high salicylic acid accumulation in endophyte-associated plants elucidated the stress mitigation by P. minioluteum. The endophytic fungal symbiosis of P. minioluteum also increased the daidzein and genistein contents in the soybean as compared with control plants, under salt stress. Thus, P. minioluteum ameliorated the adverse effects of abiotic salinity stress and rescued soybean plant growth by influencing biosynthesis of the plant’s hormones and flavonoids. Keywords: Penicillium minioluteum, soybean plant growth, phytohormones, salt stress, daidzein, genistein Endophytic fungi, either ascomycetes or basidiomycetes, live inside roots or tissues of the host plants without causing any disease symptoms or injury [4, 16, 33, 42]. These poorly known fungi represent a trove of unexplored biodiversity and are a frequently overlooked component of forest [5] and crop ecologies. In mutualistic mode, endophytic fungi increase plant fitness by dissuading herbivory and pathogenic attacks while also facilitating plant growth through nutrients uptake, water use efficiency, and curtailing of environmental stresses [6, 9, 38, 42, 52]. The endophytic fungi, in return, obtain access to the host plant’s nutrients and dissemination to the next generation (e.g., members of Clavicipitaceous and Dikarya) [4, 24]. Endophytic fungi produce a wide array of biochemically important metabolites. Among these, endophytic fungi have been reported for synthesis of various plant hormones such as gibberellins (GAs) reported by Khan et al. [26, 27], Khan et al. [28], and Hamayun et al. [18, 19]. Currently, 136 GAs have been identified, and more than two dozen fungi, pathogenic and nonpathogenic, associated with plants and/or soil, have been reported as GAs producers [1, 7]. Salinity stress prevails throughout our agriculture lands affecting crops and their productivity. With the human population expanding, food demands have been at a sturdy rate and therefore, minimizing such stresses would be an urgent issue to resolve. Salt stress induces ionic and osmotic imbalance inside plant cells. Accumulation of attuned osmolytes transduces signals to aggregate phytohormones *Corresponding author Phone: +82-53-950-5708; Fax: +82-53-958-6880; E-mail: ijlee@knu.ac.kr