Process Biochemistry 46 (2011) 440–447 Contents lists available at ScienceDirect Process Biochemistry journal homepage: www.elsevier.com/locate/procbio Gibberellins producing endophytic Aspergillus fumigatus sp. LH02 influenced endogenous phytohormonal levels, isoflavonoids production and plant growth in salinity stress Abdul Latif Khan a,b , Muhammad Hamayun c , Yoon-Ha Kim a , Sang-Mo Kang a , Joon-Hee Lee a , In-Jung Lee a,∗ a School of Applied Biosciences, Kyungpook National University, Daegu 702-701, Republic of Korea b Kohat University of Science & Technology, Kohat, Pakistan c Department of Botany, Abdul Wali Khan University Mardan, Khyber Pukhtoonkhwa, Pakistan article info Article history: Received 26 May 2010 Received in revised form 21 September 2010 Accepted 21 September 2010 Keywords: Aspergillus fumigatus Endophyticism Plant growth Salinity alleviation Isoflavones Phytohormones abstract Endophytic fungi are little known for exogenous gibberellins (GAs) production and plant growth pro- motion under salt stress conditions. We isolated 13 endophytic fungi from soybean roots, which were screened on Waito-C rice for plant growth promoting capacity. Endophytic strain, GMH-1a exhibited maximum growth during screening and thus was investigated for GAs production and host plant inter- action. GMH-1a was identified as a new strain of Aspergillus fumigatus sp. LH02 through phylogenetic analysis of 18S rDNA sequence. Analysis of GMH-1a culture filtrate showed presence of GA 4 (24.8 ng/ml), GA 9 (1.2 ng/ml) and GA 12 (9.8 ng/ml). Soybean plants inoculated with GMH-1a significantly increased shoot length, shoot fresh and dry biomass, leaf area, chlorophyll contents and photosynthetic rate under salt stress (70 and 140 mM) as compared to non-inoculated plants. GMH-1a inoculated plants had con- tained significantly lower endogenous abscisic acid (ABA) and elevated free proline, salicylic acid (SA) and jasmonic acid (JA) contents in comparison to their respective control treatments. Isoflavones, quan- tified through excessive HPLC analysis, showed that GMH-1a inoculated plants with/without salt stress contained higher isoflavones than non-inoculated plants and with/without NaCl stress. This novel endo- phytic fungus has reprogrammed soybean metabolism to improve plant growth and increase isoflavone contents under salt stress. © 2010 Elsevier Ltd. All rights reserved. 1. Introduction Interactions between plants and microorganisms are pervasive and they play an essential role in functioning of agricultural sys- tem [1,2]. Endophytism has gained tremendous applause due to its mutualistic interactions between host crops and non-pathogenic fungi. Endophytic fungi have mostly been reported for their behav- ior to enhance plant growth and condone environmental stresses [3,4]. Development of endophytic association in roots changes key aspects of plant physiology, including mineral nutrient composi- tion in tissues, plant hormonal balance, chemical composition of rhizosphere and physical modification in soil [2,5–7]. Plant growth promoting fungi (PGPF) are beneficial to plant growth and develop- ment, as they cope with a large number of biotic and abiotic stresses in crops [4,8]. ∗ Corresponding author. Tel.: +82 53 950 5708; fax: +82 53 958 6880. E-mail address: ijlee@knu.ac.kr (I.-J. Lee). Salinity is a major problem that restricts yield on almost 40 million hectares of irrigated land, which is approximately one- third of the irrigated land on earth [9]. It was estimated that about 50% of the arable land will be affected by salt stress by the year 2050 [10]. Saline soils possess high levels of sodium and chloride contents and thus exert adverse abiotic stress on plants. Salin- ity induce osmotic and ionic imbalance inside plant’s cell, thus affecting plant growth and metabolism. Accumulation of attuned osmolytes, such as proline, ABA are thought to function as osmo- protectants [9,10]. In case of salt stress, aggregation of compatible osmolytes, involved in osmoregulation allows uptake of additional water from environment, thus buffering immediate effect within plant cell [11–13]. Salinity has been reported a strong limiting factor for the growth of leguminous plants especially soybean [14]. Moreover, salt stress affects symbiotic processes established between rhizobia and legumes [15,16]. Soybean is an important source of food nutrition in the world and is popularly known as a healthy food in many Asian coun- tries. In China, Japan, and Korea, soybean and products made from the bean (tofu, doenjang, douchi, miso, natto, chungkookjang, gan- 1359-5113/$ – see front matter © 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.procbio.2010.09.013